Csr Bc Corr February 2009

Bulk Carrier CSR – Revision History (Click Corrigenda # or Rule Changes you wish to see)

Feb 2009

Amendment Type /

No.

Approval Date

Effective Date *

Remark Reference

Rule Edition

1 Corrigenda 1 15 May 2006

1 Apr. 2006 1 Jan 2006

edition

2 Corrigenda 2 29 Jan 2007 1 Apr. 2006

1 Jan 2006 edition

3 Corrigenda 3 19 July 2007 1 Apr. 2006

1 Jan 2006 edition

4 Corrigenda 4 3 Sept 2007 1 Apr. 2006 1 Jan 2006

edition

5 Rule Change Notice 1 30 Nov 2007 1 Apr. 2008

TB 1 Jan 2006 edition

6 Rule Change Notice 2 25 Feb 2008 1 July 2008

TB 1 Jan 2006

edition

7 Corrigenda 5 15 May 2008

1 April 2006

1 Jan 2006 edition

8 Rule Change Notice 3

(Urgent) 12 Sept 2008

12 Sept 2008

TB 1 Jan 2006

edition

9 Rule Change Notice 1 (1 July 2008 consolidated

edition) 27 Jan 2009 1 July 2009

TB

1 July 2008 consolidated edition

* For effective date, refer to the implementation statements of relevant Corrigenda / Rule Changes.

19 May 2006 Bulk Carrier CSR Corrigenda 1

Page 1/19

IACS Common Structural Rules for Bulk Carriers, January 2006

Corrigenda 1

May 2006

Before amendment After amendment Reference

Contents Contents Explanation

Ch 3, Sec 2, [2.1.3]

The ship is to be built at least with the gross scantlings obtained by

adding the corrosion additions, specified in Ch 3, Sec 3, to the net

scantlings. The thickness for voluntary additions to be added as an

extra.

The ship is to be built at least with the gross scantlings obtained by

adding the corrosion additions, specified in Ch 3, Sec 3, to the net

scantlings. The thickness for voluntary addition is to be added as an

extra.

Editorial correction

Ch 3, Sec 2, [3.2]

Add the following requirement after [3.2.6]:

3.2.7 Check of primary supporting members for ships

less than 150 m in length L

The net thickness of plating which constitutes primary supporting

members for ships less than 150 m in length L, to be checked

according to Ch 6, Sec 4, [2], is to be obtained by deducting tC from

the gross thickness.

Addition of a missing information

Ch 3, Sec 3, Tab 1

Corrosion additions for “Dry bulk, cargo hold”

Upper part (4) Lower stool sloping and top plate Transverse

bulkhead Other parts

Corrosion additions for “Dry bulk, cargo hold”

Upper part (4) Lower stool: sloping plate, vertical plate and top plate Transverse

bulkhead Other parts

Editorial correction in the third column of Tab 1


Page 2/19



Ch 3, Sec 6, [6.5.2]

Bilge keels are not be welded directly to the shell plating. An

intermediate flat whose thickness is equal to that of the bilge strake is

required on the shell plating. The ends of the bilge keel are to be sniped

as shown in Fig.18 or rounded with large radius. The ends are to be

located in way of transverse bilge stiffeners inside the shell plating and

the ends of intermediate flat are not to be located at the block joints.

The bilge keel and the intermediate flat are to be made of steel with the

same yield stress as the one of the bilge strake. The bilge keel with a

length greater than 0.15L is to be made with the same grade of steel as

the one of bilge strake.

The net thickness of the intermediate flat is to be equal to that of the

bilge strake. However, this thickness may generally not be greater than

15 mm.

Scallops in the bilge keels are to be avoided.

Bilge keels are not be welded directly to the shell plating. An

intermediate flat is required on the shell plating. The ends of the

bilge keel are to be sniped as shown in Fig.18 or rounded with large

radius. The ends are to be located in way of transverse bilge

stiffeners inside the shell plating and the ends of intermediate flat are

not to be located at the block joints.

The bilge keel and the intermediate flat are to be made of steel with

the same yield stress as the one of the bilge strake. The bilge keel

with a length greater than 0.15L is to be made with the same grade

of steel as the one of bilge strake.

The net thickness of the intermediate flat is to be equal to that of the

bilge strake. However, this thickness may generally not be greater

than 15 mm.

Scallops in the bilge keels are to be avoided.

Sentence stated twice in the requirement.

Ch 4, Sec 3, Figure 1

Figure 1: Sign conventions for shear forces Q and bending moments MSW, MWV, M H

Figure 1: Sign conventions for shear forces Q and bending moments MSW, MWV, M WH


Ch4, Sec5, [1.6.1]

For the positive hydrodynamic pressure at the waterline (in load cases

H1, H2, F1, R1, R2 and P1), the hydrodynamic pressure PW,C at the side

above waterline is given (see Fig 5), in kN/m2, by:

………………….

For the positive hydrodynamic pressure at the waterline (in load

cases H1, H2, F2, R1, R2 and P1), the hydrodynamic pressure PW,C

at the side above waterline is given (see Fig 5), in kN/m2, by:

………………….


Ch4, Sec5, [1.6.2]

For the negative hydrodynamic pressure at the waterline (in load

cases H1, H2, F2, R1, R2, and P2), the hydrodynamic pressure PW,C,

under the waterline is given (see Fig 5), in kN/m2, by:

………………….

For the negative hydrodynamic pressure at the waterline (in load

cases H1, H2, F1, R1, R2 and P2), the hydrodynamic pressure

PW,C, under the waterline is given (see Fig 5), in kN/m2, by:

………………….



Page 3/19



Ch 4, Sec 6, Symbols

ρC : Density of the dry bulk cargo, in t/m3, taken equal to:

• the value given in Tab 1 for ships having a length of

150 m and above

• the maximum density from the loading manual for

ships having a length less than 150 m

ρC : Density of the dry bulk cargo, in t/m3, taken equal to:

• the value given in Tab 1 for ships having a length L

of 150 m and above

• the maximum density from the loading manual for

ships having a length L less than 150 m


Ch 4, Sec 6, [1.1.2]

where:

h1 : Vertical distance obtained from the following formula, see Fig

2.

…………..

VTS : Total volume of transverse stools at bottom of transverse

bulkheads within the concerned cargo hold length �H. This

volume excludes the part of hopper tank passing through the

transverse bulkhead.

h2 : Bulk cargo upper surface, depending on y, given by:

............................

where:

h1 : Vertical distance, in m, obtained from the following formula,

see Fig 2.

…………..

VTS : Total volume, in m3, of transverse stools at bottom of

transverse bulkheads within the concerned cargo hold length

�H. This volume excludes the part of hopper tank passing

through the transverse bulkhead.

h2 : Bulk cargo upper surface, in m, depending on y, given by:

............................

Editorial correction (Units for h1, VTS and h2)

Ch 4, Sec 7, [1.1]

1.1 Ships having a length less than 150 m 1.1 Ships having a length L less than 150 m Editorial correction

Ch 4, Sec 7, [1.2]

1.2 Ships having a length of 150 m and above 1.2 Ships having a length L of 150 m and above Editorial correction

Ch 4, Sec 7, [1.2.1]

The requirements in [2] to [4] are applicable to ships having a length of

150 m and above.

The requirements in [2] to [4] are applicable to ships having a

length L of 150 m and above.


Ch 4, Sec 8, [1.2]

1.2 Ships equal to or greater than 150 m in length 1.2 Ships equal to or greater than 150 m in length L Editorial correction

Ch 4, Sec 8, [2.1.2]

2.1.2 Ships equal to or greater than 150 m in length

In addition to [2.1.1], for BC-A, BC-B, and BC-C ships, the loading

manual is also to describe:

2.1.2 Ships equal to or greater than 150 m in length L

In addition to [2.1.1], for BC-A, BC-B and BC-C ships, the loading

manual is also to describe:

Editorial corrections


Page 4/19



Ch 4, Sec 8, [2.2.2]


In addition to [2.2.1], for BC-A, BC-B, and BC-C ships, the following

loading conditions, ...............


In addition to [2.2.1], for BC-A, BC-B and BC-C ships, the

following loading conditions, ................


Ch 4, Sec 8, [3.1.2]


For BC-A, BC-B, and BC-C ships, the loading instrument is .......


For BC-A, BC-B and BC-C ships, the loading instrument is .......


Ch 4, Sec 8, [3.2.2]


In addition, for BC-A, BC-B, and BC-C ships, the approval .......


In addition, for BC-A, BC-B and BC-C ships, the approval .......


Ch 4, App 1, [1.1.1]

The requirements of this Appendix apply to ships of 150 m in length

and above.

The requirements of this Appendix apply to ships of 150 m in length

L and above.


Ch 4, App 1, [2.2.2]

The maximum permissible cargo mass and the minimum required cargo

mass corresponding to draught for loading/unloading conditions in

harbour may be increased or decreased by 15% of the maximum

permissible mass for the cargo hold in seagoing condition. However,

maximum permissible mass is in no case to be greater than the

maximum permissible cargo mass at designed maximum load draught

for each cargo hold.

The maximum permissible cargo mass and the minimum required

cargo mass corresponding to draught for loading/unloading

conditions in harbour may be increased or decreased by 15% of the

maximum permissible mass at the maximum draught for the cargo

hold in seagoing condition. However, maximum permissible mass is

in no case to be greater than the maximum permissible cargo mass at

designed maximum load draught for each cargo hold.


Ch 4, App 1, [3.2.2]

The maximum permissible cargo mass and minimum required cargo



permissible mass for the cargo hold. However, maximum permissible

mass is in no case to be greater than the maximum permissible cargo

mass at designed maximum load draught for each cargo hold.

The maximum permissible cargo mass and minimum required cargo



permissible mass at the maximum draught for the cargo hold in

seagoing condition. However, maximum permissible mass is in no

case to be greater than the maximum permissible cargo mass at

designed maximum load draught for each cargo hold.



Page 5/19



Ch 5, Sec 1, [1.4.2]

..................

• if continuous trunks or hatch coamings are taken into

account in the calculation of IY , as specified in [1.2.2]:

( ) NzB

YNzV D

TTD −≥��

�

��

� +−= 2.09.0

..................

..................

• if continuous trunks or hatch coamings are taken

into account in the calculation of IY , as specified in [1.2.2]:

( ) NzBy

NzV DT

TD −≥��

��

� +−= 2.09.0

..................

Editorial correction (change “Y” in the formula into small letter)

Ch 5, Sec 1, Fig 2

��

��

� � � � ��

∆

� �

∆ �� α

��

� � � � ��

� � � � � � � �� !

Correction of cross-reference

Ch 5, Sec 1, [5.1.3]

................

WVCY

P QQS

tk

Q −��

��

� ∆+Ι

=δ

ε 120

................

................

WVCY

P QQS

tk

Q −��

��

� += ∆Ιδ

ε 120

................

Editorial correction (change “I” in the formula into Italic)

Ch 5, Sec 1, [5.3.3]

................

FWVCY

FP QQS

tk

Q ,,120 −�

�

��

� ∆+Ι

=δ

ε

................

................

FWVCY

FP QQS

tk

Q ,,120 −�

�

��

� += ∆Ιδ

ε

................

Editorial correction (change “I” in the formula into Italic)

Ch 5, Sec 2, [1.1.1]

The requirements of this Section apply to ships equal to or greater than

150 m in length.

The requirements of this Section apply to ships equal to or greater

than 150 m in length L.



Page 6/19



Ch5, App1, Symbols

IY : Moment of inertia, in m4, of the hull transverse section

around its horizontal neutral axis, to be calculated according

to Ch 5, Sec 1, [1.4]

IY : Moment of inertia, in m4, of the hull transverse section

around its horizontal neutral axis, to be calculated

according to Ch 5, Sec 1, [1.5.1]

Correction of cross-reference

Ch5, App1, [2.2.3]

Φ : Edge function, equal to:

� = -1 for � < -1

� = � for -1 < � < 1

� = 1 for � > 1


� = -1 for � < -1

� = � for 11 ≤≤− ε

� = 1 for � > 1



ca : Aspect ratio of the plate panel, equal to:

……………

ca : Coefficient of aspect ratio of the plate panel, equal to:

……………


Ch 6, Sec 1, [2.5.3]

......................

This increase in net thickness is to be equal to 40%, but need not

exceed 4.5 mm.

......................

......................

This increase in net thickness is not to be less than 40% of the net

thickness of sheerstrake, but need not exceed 4.5 mm.

......................


Ch 6, Sec 1, [2.6.2]

......................

This increase in net thickness is to be equal to 40%, but need not

exceed 4.5 mm.

......................

......................

This increase in net thickness is not to be less than 40% of the net

thickness of stringer plate, but need not exceed 4.5 mm.

......................


Ch 6, Sec 1, [2.7.2]

.....................

F : Force, in kg, taken equal to:

3

21

nnWn

KF S= ,

......................

.....................


3

21

nnWn

KF S=

......................

Editorial correction (comma deleted)


Page 7/19




Inn. BTM Floor

BTM

Steel coil Dunnage

n 2 and l' are given by Table 1 and 2

Steel coil

FloorInner bottom

Bottomn2 and are given byTables 3 and 4

�′

DunnageEditorial and cross-reference correction


Inn. BTMFloorl'

BTM

Steel coilDunnage

FloorInner bottom

Bottom

Steel coilDunnage

�′


Ch 6, Sec 1, [3.1.5]

……………:

310)()( −

��

�

�−−+−= y

IM

CNzI

MCNz

IM

CCZ

WHWH

Y

WVWV

Y

SWSWX �

σ

where:

C�� : Coefficient taken equal to:

Lx

C3.0

=� for 3.00 <≤Lx

……………:

310)()( −

��

�

�−−+−= y

IM

CNzI

MCNz

IM

CZ

WHWH

Y

WVWV

Y

SWSWXσ

.……..



Page 8/19



0.1=�

C for 7.03.0 ≤≤Lx

��

��

� −=Lx

C 13.0

1�

for 0.17.0 ≤<Lx

………..

Ch 6, Sec 2, [2.5.3]

……………

φϕτ sinsin'5

a

Ysh

FaA =

where:

……………

ϕ : Angle, in deg, between inner bottom plating and hopper

sloping plate or inner hull plating.

……………

310sinsin'5 −=

φϕτ a

Ysh

FaA

where:

……………

ϕ : Angle, in deg, between inner bottom plating and hopper

sloping plate or inner hull plating

�’ : Distance, in m, between load points per elementary plate

panel of inner bottom plate in ship length, sloping plate or

inner hull plating, as defined in Ch 6, Sec 1, [2.7.2].

Editorial correction in formula and addition of a missing information

Ch 6, Sec 2, [3.1.5]

……………:

310)()( −

��

�

�−−+−= y

IM

CNzI

MCNz

IM

CCZ

WHWH

Y

WVWV

Y

SWSWX �

σ

where:


Lx

C3.0

=� for 3.00 <≤Lx

……………:

310)()( −

��

�

�−−+−= y

IM

CNzI

MCNz

IM

CZ

WHWH

Y

WVWV

Y

SWSWXσ

.……..



Page 9/19



0.1=�

C for 7.03.0 ≤≤Lx

��

��

� −=Lx

C 13.0

1�

for 0.17.0 ≤<Lx

………..

Ch 6, Sec 2, [3.2.4]

3.2.4 Net section modulus of corrugated bulkhead of

ballast hold for ships having a length less than 150m

The net section modulus w, in cm3, of corrugated bulkhead of ballast

hold for ships having a length less than 150m subjected to lateral

pressure are to be not less than the values obtained from the following

formula:

........................

3.2.4 Net section modulus of corrugated bulkhead of

ballast hold for ships having a length L less than 150m

The net section modulus w, in cm3, of corrugated bulkhead of ballast

hold for ships having a length L less than 150m subjected to lateral

pressure are to be not less than the values obtained from the

following formula:

........................


Ch 6, Sec 2, [3.3.3]

……………..

31

2'

��

�

�

��

�

�=

w

LBLB t

tt

……………..

( ) 31

2'WLBLB ttt =


Ch 6, Sec 2, Tab 6, Note 1

α : Coefficient defined in [3.2.4] α : Coefficient defined in [3.2.5] Correction of cross-reference


……………….

eσ : Reference stress, taken equal to:

2

9.0 ��

��

�=bt

Eeσ

……………….

……………….


2

'9,0 �

�

��

�⋅=bt

Eeσ

b’ : shorter side of elementary plate panel

……………….

Correction of one parameter


Page 10/19



Ch 6, Sec 3, Tab 2

Row of buckling load case 8:

97.6=K 8

a · b

t

sx sx

b

=== 32≥α

32<α

22 55.2

1 αα

++=K

Row of buckling load case 8:

32≥α 97.6=K

8

a · b

t

sx sx

b

===

32<α

22 55.2

1 αα

++=K

Add line in third column

Ch 6, Sec 3, [3.1.2]

………………

Each term of the above conditions must be less than 1.0.

The reduction factors κx and κy are given in Tab 2 and/or Tab 3.

The coefficients e1, e2 and e3 are defined in Tab 4.

………………

Each term of the above conditions must be less than 1.0.

The reduction factors κx and κy are given in Tab 2 and/or Tab 3

The coefficients e1, e2 and e3 are defined in Tab 4. For the

determination of e3, κy is to be taken equal to 1 in case of

longitudinally framed plating and κx is to be taken equal to 1 in case

of transversely framed plating.

Information missing

Ch 6, Sec 3, [4.2.2]

ta : Gross offered thickness of attached plate, in mm ta : Net thickness offered of attached plate, in mm Editorial correction

Ch 6, Sec 3, [4.2.2]

yx AA , : Net sectional area, in mm2, of the longitudinal or transverse

stiffener respectively without attached plating

022

21

1 ≥��

�

�

��

��

� +−=b

m

a

mERt eHττ

yx AA , : Net sectional area, in mm2, of the longitudinal or

transverse stiffener respectively without attached plating

022

21

1 ≥��

�

�

��

��

� +−=b

m

a

mERt eHττ

Editorial correction (line under formula deleted)

Ch 6, Sec 3, [4.2.3]

Longitudinal and transverse ordinary stiffeners not subjected to lateral

pressure are considered as complying with the requirement of [4.2.1] if

their gross moments of inertia Ix and Iy , in cm4, are not less than the

value obtained by the following formula:

………………….

Longitudinal and transverse ordinary stiffeners not subjected to

lateral pressure are considered as complying with the requirement of

[4.2.1] if their net moments of inertia Ix and Iy , in cm4, are not less

than the value obtained by the following formula:

…………………….



Page 11/19



Ch 6, Sec 3, [6.1.1]

32for

341

3

32for E

eH

E

eHeHc

eHEc

RRR

R

>��

�

�

��

�

�−=

≤=

ττ

τ

τττ

Ec ττ = for 32

eHE

R≤τ

��

�

�

��

�

�−=

E

eHeHc

RR

ττ

341

3 for

32eH

E

R>τ

Editorial corrections (1st line subscript “E” into Italic, and 2nd line: add subscript “E”)

Ch 6, Sec 4, [1.2]

1.2 Primary supporting members for ships less than

150 m in length

1.2 Primary supporting members for ships less than

150 m in length L


Ch 6, Sec 4, [1.2.1]

For primary supporting members for ships having a length less than 150

m, the strength check of such members is to be carried out according to

the provisions specified in [2] and [4].

For primary supporting members for ships having a length L less

than 150 m, the strength check of such members is to be carried out

according to the provisions specified in [2] and [4].


Ch 6, Sec 4, [1.3]

1.3 Primary supporting members for ships of 150 m or

more in length

1.3 Primary supporting members for ships of 150 m

or more in length L


Ch 6, Sec 4, [1.3.1]

For primary supporting members for ships having a length of 150 m or

more, the direct strength analysis is to be carried out according to the

provisions specified in Ch 7. In addition, ............

For primary supporting members for ships having a length L of 150

m or more, the direct strength analysis is to be carried out according

to the provisions specified in Ch 7. In addition, ............


Ch 6, Sec 4, [2]

2. Scantling of primary supporting members for ships

of less than 150 m in length

2. Scantling of primary supporting members for

ships of less than 150 m in length L


Ch 6, Sec 4, [2.1.5]

……………:

310)()( −

��

�

�−−+−= y

IM

CNzI

MCNz

IM

CCZ

WHWH

Y

WVWV

Y

SWSWX �

σ

where:


Lx

C3.0

=� for 3.00 <≤Lx

……………:

310)()( −

��

�

�−−+−= y

IM

CNzI

MCNz

IM

CZ

WHWH

Y

WVWV

Y

SWSWXσ

.……..



Page 12/19



0.1=�

C for 7.03.0 ≤≤Lx

��

��

� −=Lx

C 13.0

1�

for 0.17.0 ≤<Lx

………..

Ch 6, Sec 4, [2.6.3]

………………..

3

51075.1 sh

aww A

Ch

tτ

⋅=

where:

…………

………………..

3

5410

75.1 shaw

w AC

ht

τ⋅=

where:

…………


Ch 6, Sec 4, [3.1.3]

Ag : Sectional area, in mm2, of the girder panel adjacent to the

stool (or transverse bulkhead, if no stool is fitted)

Ag : Net sectional area, in mm2, of the girder panel adjacent to

the stool (or transverse bulkhead, if no stool is fitted)


Ch 6, Sec 4, [3.1.4]

X : Pressure, in kN/m2 , to be obtained from the following

formulae:

• for dry bulk cargoes, the lesser of:

( )( )11

1.0 1

−+

−−+=

perm

hDzgZX

C

FF

ρρ

ρ

( )permhDzgZX FF −−+= 11,0ρ

• for steel mill products:

( )

C

FF hDzgZX

ρρ

ρ

−

−−+=

1

1.0 1

………..

X : Pressure, in kN/m2 , to be obtained from the following

formulae:

• for dry bulk cargoes, the lesser of:

( )( )11

1.0 1

−+

−−+=

perm

hDzgZX

C

FF

ρρ

ρ

( )permhDzgZX FF −−+= 11.0ρ

• for steel mill products:

( )

C

FF hDzgZX

ρρ

ρ

−

−−+=

1

1.0 1

………..

Editorial correction (Correction of comma and small letter)


Page 13/19



hf : Inner bottom flooding head is the distance, in m, measured

vertically with the ship in the upright position, from the inner

bottom to a level located at a distance zF, in m, from the

baseline.

hF : Inner bottom flooding head is the distance, in m,

measured vertically with the ship in the upright position,

from the inner bottom to a level located at a distance zF, in

m, from the baseline.

Ch 7, Sec 1, Fig 1

..........................

..........................

Editorial and cross-reference corrections

Ch 7, Sec 2, [2.5.4]

2.5.4 Influence of local loads. 2.5.4 Influence of local loads Editorial correction (comma deleted)

Ch7, App 2, Symbols

C : Coefficient taken equal to:

)1(2 2ν−= E

C

C : Coefficient taken equal to:

for 4-node buckling panel:)1(2 2ν−

= EC

for 8-node buckling panel:)1(4 2ν−

= EC


Ch 7, App 2 [2.2.2]

LC 3: shear

=

=4

1

25.0i

iττ

LC 5: shear:

4

4321 τττττ +++=


Fatigue Assessment

(Sec 3 & Ch 8)

Bulk Carrier > 150 m

Fatigue Assessment

(Sec 4 & Ch 8)

Bulk Carrier ≥ 150 m


Page 14/19



Ch7, App 2, [2.2.3] 2.2.3 8-node buckling panel

(Figure)

Stress displacement relationship for a 8-node buckling panel

(compressive stresses are positive)

Figure 2: 8-node buckling panel

2.2.3 8-node buckling panel Stress displacement relationship for a 8-node buckling panel (compressive stresses are positive)

(Figure)

Figure 2: 8-node buckling panel

Text was not in the right place

Ch7, App 2, [2.2.3], Fig 2

1 to 4: Displ. & Stress Nodes

5 & 6: Stress Nodes

5 to 8: Displacement Nodes


Ch7, App 2, [2.2.3]

The term in line 15 / column 12 of the matrix is 6m/b.

The term in line 5 / right end column is u2

The term in line 15 / column 12 of the matrix is to be replaced by

6m/a.

The term in line 5 / right end column is to be replaced by u3


Ch 7, App 2 [2.2.3]

LC 1: longitudinal compression LC 1: longitudinal compression Editorial correction


Page 15/19



( )

xlx

llx

xxxxxxl

xxxxxxl Max

σσψσσσ

σσσσσσσ

σσσσσσσ

/1

5.031

2,

2,

2

236514

325641

∆−=

∆+=

−+−+−=∆

��

��

� +++=

( )

xlx

llx

xxxxxxl

xxxxxxl Max

σσψ

σσσ

σσσσσσσ

σσσσσσσ

/1

5.031

2,

2,

2

236514

325641

∆−=

∆+=

−++−−=∆

��

��

� +++=

Ch 7, App 2 [2.2.3]

LC 5: shear

=

=6

161

iiττ

LC 5: shear

��

�� ++++++=

4,

465326541 τττττττττ Max


Ch 8, Sec 2, [2.3.2]

σm , j : Local hot spot mean stress, in N/mm2, in the condition “j”,

obtained from the following formulae:

��

��

�

≥∆∆−≤∆+++>∆++∆−

=

eHWW

eHWmeanresresmean

eHWmeanresWeH

m

R

R

RR

1,1,

1,1,1,

1,1,1,

1,

6.0for18.06.0for6.0for6.0

σσσσσσσσσσσ

σ

��

��

�

≥∆∆−−≤∆−+−∆+−−>∆−+−+−

=≠

eHjWjW

eHjWjmeanmeanmjWeH

eHjWjmeanmeanmjmeanmeanm

jjm

R

RR

R

,,

,,1,1,,

,,1,1,,1,1,

)1(,

6.0for18.024.0for24.024.0for

σσσσσσσσσσσσσσ

σ

σm ,1 : Local hot spot mean stress, in N/mm2, in the condition

“1”, obtained from the following formulae:

• if eHW R5.26.0 1, ≥∆σ :

1,1, 18.0 Wm σσ ∆−=

• if eHW R5.26.0 1, <∆σ :

1,1, 6.0 WeHm R σσ ∆−= for

1,1,6.0 meanreseHW R σσσ −−>∆

resmeanm σσσ += 1,1, for

1,1,6.0 meanreseHW R σσσ −−≤∆

σm , j : Local hot spot mean stress, in N/mm2, in the condition “j”,

obtained from the following formulae:

• if eHjW R≥∆ ,24.0 σ :

Coefficient in the third condition corrected from 0.6 to 0.24 and rearrangement of the conditional statements


Page 16/19



jWjjm ,)1(, 18.0 σσ ∆−=≠

• if eHjW R<∆ ,24.0 σ :

jWeHjjm R ,)1(, 24.0 σσ ∆+−=≠ for

jmeanmeanmeHjW R ,1,1,,24.0 σσσσ +−+>∆

jmeanmeanmjjm ,1,1,)1(, σσσσ +−=≠ for

jmeanmeanmeHjW R ,1,1,,24.0 σσσσ +−+≤∆

Ch 8, Sec 3, [3.2.1]

………….

)(1, kiLWσ , )(2, kiLWσ : As defined in 2.2.1

………….

)(1, kiLWσ , )(2, kiLWσ : As defined in 2.2.1

Line under formula deleted.

Ch 9, Sec 1, Tab 2

Net thickness, in mm Intact conditions

Y

WSra R

ppscct

7.08.15

+=

Bow flare area

Y

FBra R

pscct

7.08.15=

Testing conditions

Y

Tra R

pscct

05.18.15=


Y

WSra R

ppscct

9.08.15

+=

Bow flare area

Y

FBra R

pscct

9.08.15=

Testing conditions

Y

Tra R

pscct

05.18.15=

Editorial correction in the formulae for intact conditions and bow flare area

Ch 9, Sec 1, Tab 3

Formula for net section modulus of stiffeners in bow flare area:

32

109,0 Y

FB

mRsp

w�=

Formula for net section modulus of stiffeners in bow flare area:

32

109.0 Y

FB

mRsp

w�=

Editorial correction (comma)

Ch 9, Sec 1, [5.2.1]

eH

SLsra R

PCsCCt 8.15=

eH

SLsra R

pCsCCt 8.15=

Editorial correction (small letter)


Page 17/19



Ch 9, Sec 1, [5.3.1]

32

1016 eH

SLs

RsPC

w�= 3

2

1016 eH

SLs

RspC

w�

= Editorial correction (small letter)

Ch 9, Sec 1, [5.3.2] φsin

)5.0(35

eH

SL

RssP

A−= �

φsin)5.0(35

eH

SL

Rssp

A−

=�

Editorial correction (small letter)

Ch 9, Sec 1, [7.1.1]

An enclosed forecastle is to be fitted on the freeboard deck.

The aft bulkhead of the enclosed forecastle is to be fitted in way or aft

of the forward bulkhead of the foremost hold, as shown in Fig 3.

An enclosed forecastle is to be fitted on the freeboard deck.

The aft bulkhead of the enclosed forecastle is to be fitted in way or

aft of the forward bulkhead of the foremost hold, as shown in Fig 2.

However, if this requirement hinders hatch cover operation, the aft

bulkhead of forecastle may be fitted forward of the forward bulkhead

of the foremost cargo hold provided the forecastle length is not less

than 7% of ship length for freeboard as specified in Ch 1, Sec 4,

[3.2] abaft the fore side of stem.

Correction of cross-reference and correction in order to comply with IACS UR S28 Rev.2 Sept. 2005

Ch 9, Sec 2, Tab 2


Y

WSra R

ppscct

7.08.15

+=

Testing conditions

Y

Tra R

pscct

05.18.15=


Y

WSra R

ppscct

9.08.15

+=

Testing conditions

Y

Tra R

pscct

05.18.15=

Editorial correction in the formula for intact conditions

Ch 9, Sec 5, [2.4.3]

Hold accesses located on the weather deck are to be provided with

watertight metallic hatch covers, unless they are protected by a closed

superstructure. The same applies to accesses located on the forecastle

deck and leading directly to a dry cargo hold through a trunk.

Hold accesses located on the weather deck are to be provided with

weathertight metallic hatch covers, unless they are protected by a

closed superstructure. The same applies to accesses located on the

forecastle deck and leading directly to a dry cargo hold through a

trunk.


Ch 9, Sec 5, [4.1.3]

If applicable, the still water and wave lateral pressures are ......... If applicable, the static and dynamic lateral pressures are ......... Editorial correction

Ch 9, Sec 5, [4.2.1]

The wave lateral pressure to be considered as acting on each hatch

cover is to be calculated at a point located:

The wave lateral pressure to be considered as acting on each hatch




Page 18/19




• longitudinally, at the hatch cover mid-length

• transversely, on the longitudinal plane of symmetry of the ship

• vertically, at the top of the hatch coaming.


• longitudinally, at the hatch cover mid-length

• transversely, on the longitudinal plane of symmetry of the

ship

vertically, at the top of the hatch cover.

Ch 9, Sec 5, [6.3.2]

eHp

C

Rmcslp

w3210

21.1= eHp

C

Rmcsp

w3210

21.1�=

Editorial correction (l to �)

Ch 9, Sec 6, [5.4.2]

cSH : Coefficient which accounts for the absence of sheer, if

applicable, to be taken equal to:

cSH = 1.0 in the case of standard sheer or sheer greater than standard

sheer

cSH = 1.5 in the case of no sheer

CSH : Coefficient which accounts for the absence of sheer, if

applicable, to be taken equal to:

CSH = 1.0 in the case of standard sheer or sheer greater than standard

sheer

CSH = 1.5 in the case of no sheer


Ch 10, Sec 1, Fig20

t = plate thickness in accordance with Section 14, E.3.1 [mm] t = thickness of rudder plating, in mm Editorial correction

Ch 10, Sec 2, [2.1.1]

................

Bulwarks are to be aligned with the beams located below or are to be

connected to them by means of local transverse stiffeners.

As an alternative, the lower end of the stay may be supported by a

longitudinal stiffener.

................

Stay and brackets of bulwarks are to be aligned with the beams

located below or are to be connected to them by means of local

transverse stiffeners.

As an alternative, the lower end of the stay and bracket may be

supported by a longitudinal stiffener.


Ch 10, Sec 3, [3.7.6]

A windlass brake is to be provided having sufficient capacity to stop the

anchor and chain cable when paying out the latter with safety, in the

A windlass brake is to be provided having sufficient capacity to stop

the anchor and chain cable when paying out the latter with safety, in



Page 19/19



event of failure of the power supply

to the prime mover. Windlasses not actuated by steam are also to be

provided with a non-return device.

the event of failure of the power supply to the prime mover.

Windlasses not actuated by steam are also to be provided with a

non-return device.

Ch 10, Sec 3, [3.7.8]

For ships of length 80 m or more, where the height of the exposed deck

in way of the item .....................

Where the height of the exposed deck in way of the

item .....................


Ch 11, Sec 2, Table 1

(2) Leg length of fillet welds is made fine adjustments corresponding

to the corrosion addition tC specified in Ch 3, Sec 3, Tab 1 as

follows:

(2) Leg length of fillet welds is made fine adjustments

corresponding to the corrosion addition tC specified in Ch 3, Sec

3, Tab 1 as follows:


Ch 13, Sec 2, Symbol

tc : Corrosion addition, in mm, defined in Ch 3, Sec3

……………….

tvoluntary_addition : Voluntary thickness addition; Thickness, in mm,

voluntarily added as the Owner’s extra margin for

corrosion wastage in addition to tc

tC : Corrosion addition, in mm, defined in Ch 3, Sec3

……………….

tvoluntary_addition : Voluntary thickness addition; Thickness, in mm,

voluntarily added as the Owner’s extra margin for

corrosion wastage in addition to tC

Editorial correction (capital letter in tC)

CORRIGENDA 2 COMMON STRUCTURAL RULES FOR BULK CARRIERS

PAGE 1 OF 32

Common Structural Rules for Bulk Carriers, January 2006

Corrigenda 2 Rule Editorials

Notes: (1) These Rule Corrigenda enter into force on 1 April 2006.

(2) This document contains a copy of the affected rule along with the editorial change or clarification noted as applicable.

Copyright in these Common Structural Rules for Bulk Carriers is owned by:

American Bureau of Shipping Bureau Veritas China Classification Society Det Norske Veritas Germanischer Lloyd Korean Register of Shipping Lloyd's Register Nippon Kaiji Kyokai Registro Italiano Navale Russian Maritime Register of Shipping

Copyright © 2006 The IACS members, their affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as the ‘IACS Members’. The IACS Members, individually and collectively, assume no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant IACS Member entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.

COMMON STRUCTURAL RULES FOR BULK CARRIERS CORRIGENDA 2

PAGE 2 OF 32

CHAPTER 3 – STRUCTURAL DESIGN PRINCIPLES SECTION 6 STRUCTURAL ARRANGEMENT PRINCIPLES

7. Double side structure

7.1 Application

7.1.1

The requirement of this article applies to longitudinally or transversely framed side structure.

The transversely framed side structures are built with transverse frames possibly supported by horizontal side girders.

The longitudinally framed side structures are built with longitudinal ordinary stiffeners supported by vertical primary supporting members.

The side within the hopper and topside tanks is, in general, to be longitudinally framed. It may be transversely framed when this accepted for the double bottom and the deck according to 6.1.1 6.1.2 and 9.1.1 respectively.

Reason for the Rule Clarification:

Editorial correction – incorrect reference.

10. Bulkhead structure

10.4 Corrugated bulkheads

10.4.1 General

For ships of 190m of length L and above, the transverse vertically corrugated watertight bulkheads are to be fitted with a lower stool, and generally with an upper stool below the deck. For ships less than 190m in length L, In ships less than 150 m in length, corrugations may extend from the inner bottom to the deck provided the global strength of hull structures are satisfactorily proved for ships having ship length L of 150m and above by DSA as required by Ch 7 of the Rules.


The correction is made to be in line with IACS UR S18.


PAGE 3 OF 32

10.4.8 Upper stool

The upper stool, when fitted, is to have a height in general between two and three times the depth of corrugations. Rectangular stools are to have a height in general equal to twice the depth of corrugations, measured from the deck level and at the hatch side girder.

The upper stool of transverse bulkhead is to be properly supported by deck girders or deep brackets between the adjacent hatch end beams.

The width of the upper stool bottom plate is generally to be the same as that of the lower stool top plate. The stool bottom top of non-rectangular stools is to have a width not less than twice the depth of corrugations.

The thickness and material of the stool bottom plate are to be the same as those of the bulkhead plating below. The thickness of the lower portion of stool side plating is to be not less than 80% of that required for the upper part of the bulkhead plating where the same material is used.

The ends of stool side ordinary stiffeners when fitted in a vertical plane, are to be attached to brackets at the upper and lower end of the stool.

The stool is to be fitted with diaphragms in line with and effectively attached to longitudinal deck girders extending to the hatch end coaming girders or transverse deck primary supporting members as the case may be, for effective support of the corrugated bulkhead.

Scallops in the brackets and diaphragms in way of the connection to the stool bottom plate are to be avoided.




PAGE 4 OF 32

CHAPTER 4 – DESIGN LOADS SECTION 3 HULL GIRDER LOADS

1. General

1.1 Sign conversions of bending moments and shear forces

1.1.1

Absolute values are to be taken for bending moments and shear forces introduced in this Section. The sign of bending moments and shear forces is to be considered according to Sec 4, Tab 3. The sign conventions of vertical bending moments, horizontal bending moments and shear forces at any ship transverse section are as shown in Fig 1, namely:

• the vertical bending moments MSW and MWV are positive when they induce tensile stresses in the strength deck (hogging bending moment) and are negative in the opposite case (sagging bending moment)

• the horizontal bending moment MWH is positive when it induces tensile stresses in the starboard and is negative in the opposite case.

• the vertical shear forces Q QSW, QWV is are positive in the case of downward resulting forces preceding and upward resulting forces following the ship transverse section under consideration, and is negative in the opposite case.

(+) Q

MSW, MWV (+)

Fore

Fore

Aft

Aft

MWH (+)

(+) Q

MSW, MWV (+)

Fore

Fore

Aft

Aft

MWH (+)

QSW, QWV

(+) Q

MSW, MWV (+)

Fore

Fore

Aft

Aft

MWH (+)

QSW, QWV

Figure 1: Sign conventions for shear forces Q QSW, QWV and bending moments MSW, MWV and MWH




PAGE 5 OF 32

CHAPTER 5 – HULL GIRDER STRENGTH SECTION 1 YIELDING CHECK

2. Hull girder stresses

2.2 Shear stresses

2.2.2 Simplified calculation of shear stresses induced by vertical shear force

The shear stresses induced by the vertical shear forces in the calculation point are obtained, in N/mm2, from the following formula:

…………….

∆Q

C

Full hold Empty hold

Correctedshear force

Shear force obtained asspecified in Ch 4, Sec 3

∆QC = pαT1

∆Q

C


Correctedshear force

Shear force obtained asspecified in Ch 4, Sec 3

∆QC = ραTLC

Figure 2 : Shear force correction ∆QC


Editorial correction – correction of equation in Figure 2


PAGE 6 OF 32

4. Section modulus and moment of inertia

4.4 Midship section moment of inertia

4.4.1

The net midship section moment of inertia about its horizontal neutral axis is to be not less than the value obtained, in m4, from the following formula:

2103 −⋅= LZI MINRYR'

,

where Z’R,MIN is the required net midship section modulus ZR,MIN, in m3, calculated as specified in [4.2.1] or [4.2.2], but assuming k = 1.


The correction is made to be in line with IACS UR.


PAGE 7 OF 32

CHAPTER 5 – HULL GIRDER STRENGTH APPENDIX 1 HULL GIRDER ULTIMATE STRENGTH

2. Criteria for the calculation of the curve M-χ

2.2 Load-end shortening curves σ-ε

2.2.4 Beam column buckling

The equation describing the load-end shortening curve σCR1-ε for the beam column buckling of ordinary stiffeners composing the hull girder transverse section is to be obtained from the following formula (see Fig 3):

pStif

pEStifCCR stA

tbAΦ

1010

11 +

+= σσ

where:

Φ : Edge function defined in [2.2.3]

AStif : Net sectional area of the stiffener, in cm2, without attached plating

σC1 : Critical stress, in N/mm2, equal to:

εσ

σ 11

EC = for εσ

21eH

ER

≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

11 4

1E

eHeHC

RΦR

σε

σ for εσ21eH

ER

>

ε : Relative strain defined in [2.2.3]

σE1 : Euler column buckling stress, in N/mm2, equal to:

42

21 10−=

lAIEE

EE πσ

IE : Net moment of inertia of ordinary stiffeners, in cm4, with attached shell plating of width bE1

bE1 : Effective width, in m, of the attached shell plating, equal to:

EE

sbβ

=1 for 01.>Eβ

sbE =1 for 01.≤Eβ

ER

ts eH

pE

εβ 310=

AE : Net sectional area, in cm2, of ordinary stiffeners with attached shell plating of width bE

bE : Effective width, in m, of the attached shell plating, equal to:

sbEE

E ⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

251252ββ.. for 251.>Eβ


PAGE 8 OF 32

sbE = for 251.≤Eβ

Figure 3 Load-end shortening curve σCR1-ε for beam column buckling


Editorial correction of formula.

2.2.5 Torsional Buckling

The equation describing the load-end shortening curve σCR2-ε for the flexural-torsional buckling of ordinary stiffeners composing the hull girder transverse section is to be obtained according to the following formula (see Fig 4).

pStif

CPpCStifCR stA

stAΦ

10102

2 +

+=

σσσ

where:




εσ

σ 22

EC = for εσ

22eH

ER

≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

22 4

1E

eHeHC

RΦR

σε

σ for εσ22eH

ER

>

σE2 : Euler torsional buckling stress, in N/mm2, defined in Ch 6, Sec 3, [4.3]


σCP : Buckling stress of the attached plating, in N/mm2, equal to:

eHEE

CP R⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

251252ββ

σ .. for 251.>Eβ

eHCP R=σ for 251.≤Eβ

βE : Coefficient defined in [2.2.4]


PAGE 9 OF 32

Figure 4 Load-end shortening curve σCR2-ε for flexural-torsional buckling



2.2.7 Web local buckling of ordinary stiffeners made of flat bars

The equation describing the load-end shortening curve σCR4-ε for the web local buckling of flat bar ordinary stiffeners composing the hull girder transverse section is to be obtained from the following formula (see Fig 5):

PStif

CStifCPPCR stA

AstΦ

1010 4

4 +

+=

σσσ

where:



σCP : Buckling stress of the attached plating, in N/mm2, defined in [2.2.5]


εσ

σ 44

EC = for εσ

24eH

ER

≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

44 4

1E

eHeHC

RΦR

σε

σ for εσ24eH

ER

>

σE4 : Local Euler buckling stress, in N/mm2, equal to: 2

4 160000 ⎟⎟⎠

⎞⎜⎜⎝

⎛=

w

wE h

tσ

ε : Relative strain defined in [2.2.3].


PAGE 10 OF 32

Figure 5 Load-end shortening curve σCR4-ε for web local buckling




PAGE 11 OF 32

CHAPTER 6 – HULL SCANTLINGS SECTION 1 PLATING

2. General requirements

2.5 Sheerstrake

2.5.1 Welded sheerstrake

The net thickness of a welded sheerstrake is to be not less than the actual net thicknesses of the adjacent 2 m width side plating, taking into account higher strength steel corrections if needed.



SECTION 2 ORDINARY STIFFENERS

3. Yielding check

3.3 Strength criteria for single span ordinary stiffeners other than side frames of single side bulk carriers

3.3.2 Supplementary strength requirements

In addition to [3.3.1], the net moment of inertia, in cm4, of the 3 side frames located immediately abaft the collision bulkhead is to be not less than the value obtained from the following formula:

( )npp

.Ι WS4

180l+

=

where:

ℓ : Side frame span, in m

n : Number of frames from the bulkhead to the frame in question, taken equal to 1, 2 or 3

s : Frame spacing, in m

As an alternative, supporting structures, such as horizontal stringers, are to be fitted between the collision bulkhead and a side frame which is in line with transverse webs fitted in both the topside tank and hopper tank, maintaining the continuity of forepeak stringers within the foremost hold.


Editorial correction – definition of frame spacing is deleted.


PAGE 12 OF 32

3.4 Upper and lower connections of side frames of single side bulk carriers

3.4.2

The net connection area, Ai, in cm2, of the bracket to the i-th longitudinal stiffener supporting the bracket is to be obtained from the following formula:

ilg

bktii k

kswA

,. 2

1

40l

=

where:

wi : Net section modulus, in cm3, of the i-th longitudinal stiffener of the side or sloped bulkheads that support the lower or the upper end connecting bracket of the side frame, as applicable

ℓ1 : As defined in [3.4.1]

kbkt : Material factor for the bracket

klg,i : Material factor for the i-th longitudinal stiffener

s : Frame spacing, in m




PAGE 13 OF 32

4. Web stiffeners of primary supporting members

4.1 Net scantlings

4.1.3 Connection ends of web stiffeners

The stress at ends of web stiffeners of primary supporting members in water ballast tanks, in N/mm2, is to comply with the following formula when no bracket is fitted:

…………….

b'

b s

b'

b s

Standard shapes of the end ofthe stiffener

b'

b s

Shape of the end of thestiffener considering fatiguestrength in comparison withthe standard shape

b'

b s

b'

b s

Standard shapes of the end ofthe stiffener

b'

b s

Shape of the end of thestiffener considering fatiguestrength in comparison withthe standard shape

Figure 9 : Shape of the end of the web stiffener


Editorial correction – correction of the indication of the smallest breadth (b') shown in the left-hand figure


PAGE 14 OF 32

SECTION 3 BUCKLING & ULTIMATE STRENGTH OF ORDINARY STIFFENERS AND STIFFENED PANELS

1. General

1.1

1.1.2

The buckling checks have to be performed for the following elements:

a) according to requirements of [2], [3] and [4] and for all load cases as defined in Ch 4, Sec 4 in intact condition:

• Elementary plate panels and ordinary stiffeners in a hull transverse section analysis,

• Elementary plate panels modeled in FEM as requested in Ch 7.

b) according to requirements of [6] and only in flooded condition:

• transverse vertically corrugated watertight bulkheads for BC-A and BC-B ships.



4. Buckling criteria of partial and total panels

4.2 Ultimate strength in lateral buckling mode

4.2.2 Evaluation of the bending stress bσ

The bending stress bσ , in N/mm2, in the stiffeners is equal to:

310

10stb W

MM +=σ

with:

M0 : Bending moment, in N.mm, due to the deformation w of stiffener, taken equal to:

zf

zKi pc

wpFM−

=0

with ( ) 0>− zf pc

M1 : Bending moment, in N.mm, due to the lateral load p, taken equal to:

3

2

1 1024 ⋅=

pbaM for longitudinal stiffeners


PAGE 15 OF 32

( )3

2

1 108 ScbnpaM ⋅

= for transverse stiffeners, with n equal to 1 for ordinary

transverse stiffeners.

Wst : Net section modulus of stiffener (longitudinal or transverse), in cm3, including effective width of plating according to 5, taken equal to:

• if a lateral pressure is applied on the stiffener:

Wst is the net section modulus calculated at flange if the lateral pressure is applied on the same side as the stiffener.

Wst is the net section modulus calculated at attached plate if the lateral pressure is applied on the side opposite to the stiffener.

• if no lateral pressure is applied on the stiffener:

Wst is the minimum net section modulus among those calculated at flange and attached plate

cS : Factor accounting for the boundary conditions of the transverse stiffener

cS = 1.0 for simply supported stiffeners

cS = 2.0 for partially constraint stiffeners

p : Lateral load in kN/m2 , as defined in Ch 4, Sec5 and Ch 4, Sec 6 calculated at the load point as defined in Ch 6, Sec 2, [1.4.21.4]

KiF : Ideal buckling force, in N, of the stiffener, taken equal to:

42

2

10xKix EIa

F π= for longitudinal stiffeners

( )

42

2

10yKiy EInb

F π= for transverse stiffeners

yx II , : Net moments of inertia, in cm4, of the longitudinal or transverse stiffener including effective width of attached plating according to 5. Ix and Iy are to comply with the following criteria:

4

3

1012 ⋅≥

btIx

4

3

1012 ⋅≥

atIy

pz : Nominal lateral load, in N/mm2, of the stiffener due to xσ , yσ and τ

⎟⎟⎠

⎞⎜⎜⎝

⎛++⎟

⎠⎞

⎜⎝⎛= 22 1

2

τσπ

σ yyxla

zx cab

btp for longitudinal stiffeners

⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛+= 212 1

2

τπ

σσa

yyxlx

azy at

Anb

ac

atp for transverse stiffeners

⎟⎟⎠

⎞⎜⎜⎝

⎛+=

a

xxxl bt

A1σσ

ta : Net thickness offered of attached plate, in mm


PAGE 16 OF 32

yx cc , : Factor taking into account the stresses vertical to the stiffener's axis and distributed variable along the stiffener's length taken equal to:

)(. ψ+150 for 10 ≤≤ψ

ψ−150. for 0<ψ

yx AA , : Net sectional area, in mm2, of the longitudinal or transverse stiffener respectively without attached plating

022

21

1 ≥⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎠⎞

⎜⎝⎛ +−=

bm

amERt eHττ

m1, m2 : Coefficients taken equal to:

for longitudinal stiffeners: 37096102

49047102

21

21

..:.

..:.

==<

==≥

mmba

mmba

for transverse stiffeners:

221

221

47149050

96137050

nmm

bna

nmm

bna

..:.

..:.

==<⋅

==≥⋅

10 www +=

0w : Assumed imperfection, in mm, taken equal to:

),,min( 102502500

baw = for longitudinal stiffeners

),,min( 102502500

bnaw ⋅= for transverse stiffeners

For stiffeners sniped at both ends w0 must not be taken less than the distance from the midpoint of attached plating to the neutral axis of the stiffener calculated with the effective width of its attached plating.

1w : Deformation of stiffener, in mm, at midpoint of stiffener span due to lateral load p. In case of uniformly distributed load the following values for w1 may be used:

xEI

pbaw 7

4

1 10384 ⋅= for longitudinal stiffeners

27

4

1 103845

SycEInbapw

⋅=

)( for transverse stiffeners

fc : Elastic support provided by the stiffener, in N/mm2, taken equal to:

• for longitudinal stiffeners

)( pxKixf ca

Fc += 12

2π


PAGE 17 OF 32

xa

xpx

cbt

Ic

⎟⎟⎠

⎞⎜⎜⎝

⎛−

⋅

+

=

110129101

1

3

4

.

xac : Coefficient taken equal to :

22

2 ⎥⎦⎤

⎢⎣⎡ +=

ab

bacxa for ba 2≥

22

21

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎠⎞

⎜⎝⎛+=

bacxa for ba 2<

• for transverse. stiffeners :

( )

( )pyKiySf cbn

Fcc +⋅

= 12

2π

ya

ypy

c

atI

c

⎟⎟⎠

⎞⎜⎜⎝

⎛−

⋅

+

=

11012

910

1

1

3

4

.

yac : Coefficient taken equal to :

22

2 ⎥⎦⎤

⎢⎣⎡ +=

nba

anbcya for anb 2≥

22

21

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎠⎞

⎜⎝⎛+=

anbcya for anb 2<


Editorial correction – error in reference

4.2.3 Equivalent criteria for longitudinal and transverse ordinary stiffeners not subjected to lateral pressure

Longitudinal and transverse ordinary stiffeners not subjected to lateral pressure are considered as complying with the requirement of [4.2.1] if their net moments of inertia Ix and Iy , in cm4, are not less than the value obtained by the following formula:

• For longitudinal stiffener :

⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜

⎝

⎛

+−

=E

a

SR

hwapIx

eH

wxzxx 2

20

42

2

10 πσπ

⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜

⎝

⎛

+−

=E

a

SR

hwapIx

eH

wzxx 2

20

42

2

10 πσπ


PAGE 18 OF 32

• For transverse stiffener :

⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜

⎝

⎛

+−

=E

nb

SR

hwnbpI

yeH

wyzyy 2

20

42

2

10 πσπ)()(

⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜

⎝

⎛

+−

=E

nb

SR

hwnbpI

yeH

wzyy 2

20

42

2

10 πσπ)()(


Editorial correction of symbols in formulae. w0y and w0z corrected to w0.

4.3 Torsional buckling

4.3.1 Longitudinal stiffeners

The longitudinal ordinary stiffeners are to comply with the following criteria:

01.≤eHT

x

RS

κσ

Tκ : Coefficient taken equal to:

01.=Tκ for 20.≤Tλ

22

1

TT

ΦΦ λκ

−+= for 2.0>Tλ

( )( )220210150 TTΦ λλ +−+= ...

Tλ : Reference degree of slenderness taken equal to:

KiT

eHT

Rσ

λ =

⎟⎟⎠

⎞⎜⎜⎝

⎛+= T

PKiT I

aI

IE 385010

2

22

.επ

σ ω , in N/mm2

PI : Net polar moment of inertia of the stiffener, in cm4, defined in Tab 5, and related to the point C as shown in Fig 2

TI : Net St. Venant's moment of inertia of the stiffener, in cm4, defined in Tab 5,

ωI : Net sectorial moment of inertia of the stiffener, in cm6, defined in Tab 5, related to the point C as shown in Fig 2

ε : Degree of fixation taken equal to:

⎟⎠

⎞⎜⎝

⎛ ++= −

334

43

34

43

101

w

ww t

ht

bI

a

πε

wA : Net web area equal to: www thA =

fA : Net flange area equal to: fff tbA =


PAGE 19 OF 32

2f

wft

he += , in mm

� ��

��

��

� ��

��

��

� � � �

� ��

Figure 2: Dimensions of stiffeners

Table 5: Moments of inertia Profile IP IT Iw

Flat bar 4

3

103 ⋅wwth

⎟⎟⎠

⎞⎜⎜⎝

⎛−

⋅ w

www

htth

6301103 4

3

. 6

33

1036 ⋅wwth

Sections with bulb or flange

422

103

−⎟⎟⎠

⎞⎜⎜⎝

⎛+ ff

ww eAhA

⎟⎟⎠

⎞⎜⎜⎝

⎛−

⋅ w

www

htth

6301103 4

3

.

+

⎟⎟⎠

⎞⎜⎜⎝

⎛−

⋅ f

fff

bttb

6301103 4

3

.

for bulb and angle sections:

⎟⎟⎠

⎞⎜⎜⎝

⎛

+

+

⋅ wf

wffff

AAAAbeA 62

1012 6

22 .

for tee-sections

6

23

1012 ⋅fff etb


Editorial correction – delete the definition in the figure.

6. Transverse vertical corrugated watertight bulkhead in flooded conditions for BC-A and BC-B ships




PAGE 20 OF 32

SECTION 4 PRIMARY SUPPORTING MEMBERS

3. Additional requirements for primary supporting members of BC-A and BC-B ships

3.1 Evaluation of double bottom capacity and allowable hold loading in flooded conditions

3.1.4 Allowable hold loading

The allowable hold loading is to be obtained, in t, from the following formula:

FVW C

1ρ=

where:

F : Coefficient to be taken equal to: F = 1.1 in general F = 1.05 for steel mill products

V : Volume, in m3, occupied by cargo at a level hB

hB : Level of cargo, in m2, to be obtained from the following formula:

gXhC

B ρ=

X : Pressure, in kN/m2, to be obtained from the following formulae:

• for dry bulk cargoes, the lesser of: ( )

( )11

10 1

−+

−−+=

perm

hDzgZX

C

FF

ρρ

ρ .

( )permhDzgZX FF −−+= 110.ρ

• for steel mill products: ( )

C

FF hDzgZX

ρρ

ρ

−

−−+=

1

10 1.

D1 : Distance, in m, from the base line to the freeboard deck at side amidships

hf : Inner bottom flooding head is the distance, in m, measured vertically with the ship in the upright position, from the inner bottom to a level located at a distance zF, in m, from the baseline.

zF : Flooding level, in m, defined in Ch 4, Sec 6, [3.3.3 3.4.3]

perm : Permeability of cargo, which need not be taken greater than 0.3

Z : Pressure, in kN/m2, to be taken as the lesser of:

HDB

H

ACZ

,=

EDB

E

ACZ

,=


PAGE 21 OF 32

CH : Shear capacity of the double bottom, in kN, to be calculated according to [3.1.1], considering, for each floor, the lesser of the shear strengths Sf1 and Sf2 (see [3.1.2]) and, for each girder, the lesser of the shear strengths Sg1 and Sg2 (see [3.1.3])

CE : Shear capacity of the double bottom, in kN, to be calculated according to [3.1.1], considering, for each floor, the shear strength Sf1 (see [3.1.2]) and, for each girder, the lesser of the shear strengths Sg1 and Sg2 (see [3.1.3])

• ∑=

=n

iiDBiHDB BSA

1,,

• ( )∑=

−=n

iDBiEDB sBSA

1,

n : Number of floors between stools (or transverse bulkheads, if no stool is fitted)

Si : Space of i-th floor, in m

BDB,i : Length, in m, to be taken equal to : BDB,i = BDB - s for floors for which Sf1 < Sf2 (see [3.1.2]) BDB,i = BDB,h for floors for which 21 ff SS ≥ (see [3.1.2])

BDB : Breadth, in m, of double bottom between the hopper tanks (see Fig 3)

BDB,h : Distance, in m, between the two openings considered (see Fig 3)

s : Spacing, in m, of inner bottom longitudinal ordinary stiffeners adjacent to the hopper tanks.




PAGE 22 OF 32

CHAPTER 7 – DIRECT STRENGTH ANALYSIS SECTION 2 GLOBAL STRENGTH EF ANALYSIS OF CARGO HOLE

STRUCTURES

2. Analysis model

2.5 Consideration of hull girder loads

2.5.4 Influence of local loads The distribution of hull girder shear force and bending moment induced by local loads applied on the model are calculated using a simple beam theory for the hull girder.

Reaction forces at both ends of the model and distributions of shearing forces and bending moments induced by local loads can be determined by following formulae:

aftfore

iiafti

foreV xx

zfxxR

−

⋅−−=∑ rr

)(

_ foreVi

iaftV RzfR __ +⋅= ∑ rr

aftfore

iiafti

foreH xx

yfxxR

−

⋅−=

∑ rr)(

_ foreHi

iaftH RyfR __ +⋅−= ∑ rr

zfRxQi

iaftVFEMVrr

⋅−= ∑__ )( when xxi <

yfRxQi

iaftHFEMHrr

⋅+= ∑__ )( when xxi <

zfxxRxxxMi

iiaftVaftFEMVrr

⋅−−−= ∑ )()()( __ when xxi <

yfxxRxxxMi

iiaftHaftFEMHrr

⋅−+−= ∑ )()()( __ when xxi <

where:

aftx : Location of the aft end support

forex : Location of the fore end support

x : Considered location

aftVR _ , foreVR _ , aftHR _ and foreHR _ : Vertical and horizontal reaction forces at the fore and aft ends

FEMVQ _ , FEMHQ _ , FEMVM _ and FEMHM _ : Vertical and horizontal shear forces and bending moments created by the local loads applied on the FE model. Sign of QV_FEM, MV_FEM and MH_FEM is in accordance with the sign convention defined in Ch 4, Sec 3. The sign convention for reaction forces is that a positive creates a positive shear force.

ifr

: Applied force on node i due to all local loads


PAGE 23 OF 32

ix : Longitudinal coordinate of node i


Clarification of sign convention

2.5.6 Direct method In direct method the effect of hull girder loads are directly considered in 3D FE model. The equilibrium loads are to be applied at both model ends in order to consider the hull girder loads as specified in [2.5.2] and [2.5.3] and influence of local loads as specified in [2.5.4].

In order to control the shear force at the target locations, two sets of enforced moments are applied at both ends of the model. These moments are calculated by following formulae:

[ ])()()(

______ eqFEMVeqTVaftfore

SFforeYSFaftY xQxQxx

MM −−

==2

[ ])()()(

______ eqFEMHeqTHaftfore

SFforeZSFaftZ xQxQxx

MM −−

==2

In order to control the bending moments at the target locations, another two sets of enforced moments are applied at both ends of the model. These moments are calculated by following formulae:

⎥⎥⎦

⎤

⎢⎢⎣

⎡

⎟⎟⎠

⎞⎜⎜⎝

⎛−

−

−−−−=−= 12

aftfore

afteqSFaftYeqFEMVeqTVBMforeYBMaftY xx

xxMxMxMMM ________ )()(

⎥⎥⎦

⎤

⎢⎢⎣

⎡

⎟⎟⎠

⎞⎜⎜⎝

⎛−

−

−−−−=−= 12

aftfore

afteqSFaftZeqFEMHeqTHBMforeZBMaftZ xx

xxMxMxMMM ________ )()(

where:

eqx : Considered location for the hull girder loads evaluation,

FEMVQ _ , FEMHQ _ , FEMVM _ , FEMHM _ : As defined in [2.5.4]

TVQ _ , THQ _ , TVM _ , THM _ : Target vertical and horizontal shear forces and bending moments, defined in Tab 3 or Tab 4, at the location eqx . Sign of QV_T, MV_T and MH_T is in accordance with sign convention defined in Ch 4, Sec 3.

SFaftYM __ , SFforeYM __ , BMaftYM __ , BMforeYM __ : Enforced moments to apply at the aft and fore ends for vertical shear force and bending moment control, positive for clockwise around y-axis. The sign convention for MY_aft_SF, MY_fore_SF, MY_aft_BM and MY_fore_BM is that of the FE model axis. The sign convention for other bending moment, shear forces and reaction forces is in accordance with the sign convention defined in Ch 4, Sec 3.

SFaftZM __ , SFforeZM __ , BMaftZM __ , BMforeZM __ : Enforced moments to apply at the aft and fore ends for horizontal shear force and bending moment control, positive for clockwise around z-axis. The sign convention for MZ_aft_SF,


PAGE 24 OF 32

MZ_fore_SF, MZ_aft_BM and MZ_fore_BM is that of the FE model axis. The sign convention for other bending moment, shear forces and reaction forces is in accordance with the sign convention defined in Ch 4, Sec 3.

The enforced moments at the model ends can be generated by one of the following methods:

• to apply distributed forces at the end section of the model, with a resulting force equal to zero and a resulting moment equal to the enforced moment. The distributed forces are applied to the nodes on the longitudinal members where boundary conditions are given according to Tab 1. The distributed forces are to be determined by using the thin wall beam theory

• to apply concentrated moments at the independent points defined in [2.3.1].


Clarification of sign conventions


PAGE 25 OF 32

CHAPTER 8 – FATIGUE CHECK OF STRUCTURAL DETAILS

SECTION 2 FATIGUE STRENGTH ASSESSMENT

3. Calculation of fatigue damage

3.2 Long-term distribution of stress range 3.2.1

The cumulative probability density function of the long-term distribution of combined notch stress ranges is to be taken as a two-parameter Weibull distribution:

( )⎥⎥

⎦

⎤

⎢⎢

⎣

⎡

⎟⎟⎠

⎞⎜⎜⎝

⎛

∆−−= ξ

ξ

σ11 R

jWNxxF lnexp)(

,

( )⎥⎥

⎦

⎤

⎢⎢

⎣

⎡

⎟⎟⎠

⎞⎜⎜⎝

⎛

∆−−= R

jENxxF lnexp)(

,

ξ

σ1

where:

ξ : Weibull shape parameter, taken equal to 1.0

NR : Number of cycles, taken equal to 104.


Editorial correction - correction of error in formula


PAGE 26 OF 32

SECTION 4 STRESS ASSESSMENT OF STIFFENERS

3. Hot spot mean stress

3.3 Mean stress according to the superimposition method 3.3.2

The hot spot stress due to still water bending moment, in N/mm2, in loading condition “(k)” is to be obtained with the following formula:

( ) 310−−

=Y

kSghkGS I

NzMK )(,

)(,σ

where:

MS , (k) : Still water vertical bending moment, in kN.m, defined in Sec 3, [3.2.13.2.2].


Editorial correction – error in reference.


PAGE 27 OF 32

APPENDIX1 CROSS SECTIONAL PROPERTIES FOR TORSION

1. Calculation formulae

1.4 Computation of cross sectional properties for the entire cross section

Asymmetric cross section: Symmetric cross section (only half of the section is modeled)

A = ∑ A A = ∑ A2

sy = ∑∑

A

Sz

sz = ∑∑

A

Sy sz =

∑∑

A

Sy

yI = 2sy zAI ∑∑ − yI = ( )22 sy zAI ∑∑ −

zI = 2sz yAI ∑∑ −

zI = ( )22

sz yAI ∑∑ −

( )22 sz yAI ∑∑ −

yzI = ssyz zyAI ∑∑ −

TI = ∑ 3

3ts

TI = ( )⎥⎥⎦

⎤

⎢⎢⎣

⎡Φ+∑ ∑

iCelliyiA

ts2

32

3

0ω = ∑∑

A

Sω

yIω = 0ωω ∑∑ − sy yAI yIω = ∑ yIω2

zIω = 0ωω ∑∑ − sz zAI

My = 2yzzy

yzyzz

IIIIIII

−

− ωω

Mz = 2yzzy

yyyzz

IIIIIII

−

− ωω Mz =

z

y

IIω

−

ωI = zMym IyIzAI ωωω ω −+− ∑∑ 20 ωI = ym IzI ωω +∑2


Editorial correction – correction of error in formula


PAGE 28 OF 32

CHAPTER 9 – OTHER STRUCTURES SECTION 1 FORE PART

3. Load model

3.2 Pressure in bow area

3.2.2 Lateral pressure in testing conditions

The lateral pressure pT in testing conditions is defined in Ch 4, Sec 6, [4] taken equal to:

• pT = pST – pS for bottom shell plating and side shell plating

• pT = pST otherwise

where:

pST : Testing pressure defined in Ch 4, Sec 6, [4]

pS : Pressure taken equal to:

• if the testing is carried out afloat: hydrostatic pressure defined in Ch 4, Sec 5, [1] for the draught T1, defined by the Designer, at which the testing is carried out. If T1 is not defined, the testing is considered as being not carried out afloat.

• if the testing is not carried out afloat: pS = 0


Editorial correction – this correction is made to be consistent with Ch 6, Sec 1, [3.1.4] and Ch 6, Sec 2, [3.1.4]


PAGE 29 OF 32

SECTION 2 AFT PART

2. Load model

2.2 Lateral pressures

2.2.2 Lateral pressure in testing conditions

The lateral pressure pT in testing conditions is defined in Ch 4, Sec 6, [4] taken equal to:

• pT = pST – pS for bottom shell plating and side shell plating

• pT = pST otherwise

where:

pST : Testing pressure defined in Ch 4, Sec 6, [4]

pS : Pressure taken equal to:

• if the testing is carried out afloat: hydrostatic pressure defined in Ch 4, Sec 5, [1] for the draught T1, defined by the Designer, at which the testing is carried out. If T1 is not defined, the testing is considered as being not carried out afloat.

• if the testing is not carried out afloat: pS = 0


Editorial correction – this correction is made to be consistent with Ch 6, Sec 1, [3.1.4] and Ch 6, Sec 2, [3.1.4]


PAGE 30 OF 32

SECTION 3 MACHINERY SPACE

7. Main machinery seating

7.2 Minimum scantlings

7.2.1

The net scantlings of the structural elements in way of the internal combustion engine seatings are to be obtained from the formulae in Tab 2.

Table 1: Minimum scantlings of the structural elements in way of machinery seatings

Scantling minimum value Scantling minimum value Net cross-sectional area, in cm2, of each bedplate of the seatings

Er LnP7040 +

Bedplate net thickness, in m mm Bedplates supported by two or more girders:

Er LnP175240 +

Bedplates supported by one girder:

Er LnP1752405 ++

Total web net thickness, in mm, of girders fitted in way of machinery seatings

Bedplates supported by two or more girders:

Er LnP215320 +


Er LnP6595 +

Web net thickness, in mm, of floors fitted in way of machinery seatings

Er LnP4055 +


Editorial correction – correction of unit


PAGE 31 OF 32

SECTION 5 HATCH COVERS

4. Load model

4.1 Lateral pressures and forces

4.1.2 Sea pressure

The still water and wave lateral pressures are to be considered and are to be taken equal to:

• still water pressure: 0=Sp

• wave pressure pW , as defined in Ch 4, Sec 5 [2.25.2].



5. Strength check

5.2 Plating

5.2.2 Minimum net thickness

Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 16 (5, c))

In addition to [5.2.1], the net thickness, in mm, of the plating forming the top of the hatch cover is to be not less than the greater of the following values:

st 010.=

st 10=

6=t




PAGE 32 OF 32

CHAPTER 10 – HULL OUTFITTING SECTION 1 RUDDER AND MANOEUVRING ARRANGEMENT

4. Rudder couplings

4.5 Cone couplings with special arrangements for mounting and dismounting the couplings

4.5.1

Where the stock diameter exceeds 200 mm, the press fit is recommended to be effected by a hydraulic pressure connection. In such cases the cone is to be more slender, 2:1≈c 12:1≈c to 20:1≈ .




PAGE 1 OF 2



Notes: (1) These Rule Corrigenda enter into force on 1 April 2006






PAGE 2 OF 2

CHAPTER 6 SECTION 3 BUCKLING & ULTIMATE STRENGTH OF ORDINARY

STIFFENERS AND STIFFENED PANELS

Symbols


2

9.0 ⎟⎠⎞

⎜⎝⎛=

btEeσ

The reference stress, eσ , is to be corrected as follows:

Reference stress, to be the following for LC 1 and 2:

b' : shorter side of elementary plate panel Reference stress, to be the following for LC 3 through 10:

Reason for the Rule Clarification: Editorial correction – correction of error in the definition.

* * *


PAGE 1 OF 35









PAGE 2 OF 35

CHAPTER 2 – GENERAL ARRANGEMENT DESIGN

SECTION 1 SUBDIVISION ARRANGEMENT

2. Collision bulkhead

2.1 Arrangement of collision bulkhead

2.1.2 Ref. SOLAS Ch. II-1, Part B, Reg. 11

Where any part of the ship below the waterline extends forward of the forward perpendicular, e.g. a bulbous

bow, the distances, in metres, stipulated in [2.1.1] are to be measured from a point either:

• at the mid-length of such extension, or

• at a distance 1.5 per cent of the length LLL of the ship forward of the forward perpendicular, or

• at a distance 3 metres forward of the forward perpendicular,

, whichever gives the smallest measurement.

Reason for the Rule Clarification: This editorial correction is made to be in accordance with SOLAS Ch II-1, Regulation 11.


PAGE 3 OF 35

CHAPTER 3 – STRUCTURAL DESIGN PRINCIPLES

SECTION 1 MATERIAL

2. Hull structural steel

2.3 Grades of steel

Table 3 Material grade requirements for classes I, II and III

Class I II III As-built Tthickness (mm) NSS HSS NSS HSS NSS HSS

t ≤ 15 A AH A AH A AH 15 < t ≤ 20 A AH A AH B AH 20 < t ≤ 25 A AH B AH D DH 25 < t ≤ 30 A AH D DH D DH 30 < t ≤ 35 B AH D DH E EH 35 < t ≤ 40 B AH D DH E EH 40 < t ≤ 50 D DH E EH E EH

Notes : NSS : Normal strength steel HSS : Higher strength steel


PAGE 4 OF 35

Table 4 Application of material classes and grades

Material class Structural member category Within 0.4L

amidship Outside 0.4L

amidship SECONDARY Longitudinal bulkhead strakes, other than that belonging to the Primary category Deck Plating exposed to weather, other than that belonging to the Primary or Special category Side plating (7)

I A/AH

PRIMARY Bottom plating, including keel plate Strength deck plating, excluding that belonging to the Special category Continuous longitudinal members above strength deck, excluding hatch coamings Uppermost strake in longitudinal bulkhead Vertical strake (hatch side girder) and uppermost sloped strake in top wing tank

II A/AH

SPECIAL Sheer strake at strength deck (1), (6) Stringer plate in strength deck (1), (6) Deck strake at longitudinal bulkhead (6) Strength deck plating at corners of cargo hatch openings in bulk carriers, ore carriers, combination carriers and other ships with similar hatch openings configuration (2) Bilge strake (3), (4), (6) Longitudinal hatch coamings of length greater than 0.15L (5) Lower bracket of side frame of single side bulk carriers having additional service feature BC-A or BC-B (5) End brackets and deck house transition of longitudinal cargo hatch coamings (5)

III II

(I outside 0.6L amidships)

Notes: (1) Not to be less than grade E/EH within 0.4L amidships in ships with length exceeding 250 m.

(2) Not to be less than class III within 0.6L amidships and class II within the remaining length of the

cargo region.

(3) May be of class II in ships with a double bottom over the full breadth and with length less than

150 m.

(4) Not to be less than grade D/DH within 0.4L amidships in ships with length exceeding 250 m.

(5) Not to be less than grade D/DH.

(6) Single strakes required to be of class III or of grade E/EH and within 0.4L amidships are to have

breadths, in m, not less than 0.8 + 0.05L 0.8 + 0.005L, need not be greater than 1.8 m, unless

limited by the geometry of the ship's design.

(7) For BC-A and BC-B ships with single side skin structures, side shell strakes included totally or

partially between the two points located to 0.125l above and below the intersection of side shell

and bilge hopper sloping plate are not to be less than grade D/DH, l being the frame span.

2.3.5


PAGE 5 OF 35

The steel grade is to correspond to the as-built gross thickness when this is greater than the gross thickness

obtained from the net thickness required by the Rules.

2.3.6 Steel grades of plates or sections of as-builtgross thickness greater than the limiting thicknesses in Tab 3 are

considered by the Society on a case by case basis.

2.3.11 In highly stresses area, the Society may require that plates of gross thickness greater than 20mm are of grade

D/DH or E/EH.

Table 6 Material grade requirements for class I at low temperature

-20 / -25 °C -26 / -35 °C -36 / -45 °C -45 / -55 °C As-built Tthickness

(mm) NSS HSS NSS HSS NSS HSS NSS HSS

t ≤ 10 A AH B AH D DH D DH 10 < t ≤ 15 B AH D DH D DH D DH 15 < t ≤ 20 B AH D DH D DH E EH 20 < t ≤ 25 D DH D DH D DH E EH 25 < t ≤ 30 D DH D DH E EH E EH 30 < t ≤ 35 D DH D DH E EH E EH 35 < t ≤ 45 D DH E EH E EH - FH 45 < t ≤ 50 E EH E EH - FH - FH

Note: ”NSS” and “HSS” mean, respectively “Normal Strength Steel” and “Higher Strength Steel”

Table 7 Material grade requirements for class II at low temperature

-20 / -25 °C -26 / -35 °C -36 / -45 °C -45 / -55 °C As-built Thickness


t ≤ 10 B AH D DH D DH E EH 10 < t ≤ 20 D DH D DH E EH E EH 20 < t ≤ 30 D DH E EH E EH - FH 30 < t ≤ 40 E EH E EH - FH - FH 40 < t ≤ 45 E EH - FH - FH - - 45 < t ≤ 50 E EH - FH - FH - -


Table 8 Material grade requirements for class III at low temperature

-20 / -25 °C -26 / -35 °C -36 / -45 °C -45 / -55 °C As-built Tthickness


t ≤ 10 D DH D DH E EH E EH 10 < t ≤ 20 D DH E EH E EH - FH 20 < t ≤ 25 E EH E EH - FH - FH 25 < t ≤ 30 E EH E EH - FH - FH 30 < t ≤ 40 E EH - FH - FH - - 40 < t ≤ 45 E EH - FH - FH - - 45 < t ≤ 50 - FH - FH - - - -



PAGE 6 OF 35

2.4 Structures exposed to low air temperature 2.4.6 Single strakes required to be of class III or of grade E /EH and FH are to have breadths not less than the values,

in m, given by the following formula, but need not to be greater than 1.8 m:

b = 0.05L + 0.8 b = 0.005L + 0.8

Reason for the Rule Clarification: The editorial correction is made to clarify the plate thickness for the application of steel grade, i.e., thickness is replaced by “as-built thickness”. As the grades of steel in highly stressed area specified in requirement of 2.3.11 are covered by Table 4 and the requirement of 2.3.2, the requirement of 2.3.11 is not necessary. Note (6) of Table 4 and the formula in 2.4.6 are typo.


PAGE 7 OF 35

SECTION 2 NET SCANTLING APPROACH

3. Net scantling approach

3.1 Net scantling definition

3.1.4 Net section modulus for stiffener The net transverse section scantling is to be obtained by deducting tC from the gross thickness offered of the

elements which constitute the stiffener profile as shown in Fig.1.

For bulb profiles, an equivalent angle profile, as specified in Ch 3, Sec 6 [4.1.1], may be considered.

The net strength characteristics are to be calculated for the net transverse section.

In assessing the net strength characteristics of stiffeners reflecting the hull girder stress and stress due to local

bending of the local structure such as double bottom structure, the section modulus of hull girder or rigidity of

structure is obtained by deducting 0.5tC from the gross thickness offered of the related elements.

Shadow area is corrosion addition.

For attached plate, the half of the considered corrosion addition specified in 3.2 is deducted from both sides of

the attached plate.

Fig. 1 Net scantling of stiffener

Reason for the Rule Clarification: To clarify the requirement that the net transverse section scantling is to be obtained by deducting tC from the gross thickness offered of the elements which constitute the stiffener profile, the figure indicating how to deduct the corrosion additions from the gross thickness is added.

tf

hw tw

bp

tp

bf


PAGE 8 OF 35

SECTION 4 LIMIT STATES

2. Strength criteria

2.4 Accidental limit state

2.4.3 Bulkhead structure Bulkhead structure in cargo hold flooded condition is to be assessed in accordance with Ch. 6 Sec4 Sec 1, Sec 2

and Sec 3.

Reason for the Rule Clarification: Reference number is corrected


PAGE 9 OF 35

SECTION 5 CORROSION PROTECTION

1. General

1.1 Structures to be protected 1.1.2 Void double side skin spaces in cargo length area for vessels having a length (LLL) of not less than 150 m are to

be coated in accordance with [1.2].

1.2 Protection of seawater ballast tanks and void double skin spaces

1.2.1 All dedicated seawater ballast tanks anywhere on the ship ( excluding ballast hold) for vessels having a length

(L) of not less than 90m and void double side skin spaces in the cargo length area for vessels having a length

(LLL) of not less than 150m are to have an efficient corrosion prevention system, such as hard protective coatings

or equivalent, applied in accordance with the manufacturer’s recommendation.

The coatings are to be of a light colour, i.e. a colour easily distinguishable from rust which facilitates inspection.

Where appropriate, sacrificial anodes, fitted in accordance with [2], may also be used.

Reason for the Rule Clarification: This editorial correction is made to clarify the extent of void double skin spaces.


PAGE 10 OF 35

SECTION 6 STRUCTURAL ARRANGEMENT PRINCIPLES

2. General principles

2.2 Structural continuity

2.2.5 Platings A change in plating thickness in as-built is not to exceed 50% of thicker plate thickness for load carrying

direction. The butt weld preparation is to be in accordance with the requirements of Ch 11, Sec 2, [2.2].

Reason for the Rule Clarification: Clarification of the plate thickness


10.4 Corrugated bulkhead

10.4.2 Construction The main dimensions a, R, c, d, t, ϕ and sC of corrugated bulkheads are defined in Fig 28.

The bending radius is not to be less than the following values, in mm:

tR 0.3=

where :

t : As-built Net thickness, in mm, of the corrugated plate.

The corrugation angle ϕ shown in Fig 28 is to be not less than 55°.

The thickness of the lower part of corrugations is to be maintained for a distance from the inner bottom (if no

lower stool is fitted) or the top of the lower stool not less than 0.15lC.

The thickness of the middle part of corrugations is to be maintained for a distance from the deck (if no upper

stool is fitted) or the bottom of the upper stool not greater than 0.3lC.

The section modulus of the corrugations in the remaining upper part of the bulkhead is to be not less than 75% of

that required for the middle part, corrected for different minimum yield stresses.

When welds in a direction parallel to the bend axis are provided in the zone of the bend, the welding procedures

are to be submitted to the Society for approval.

Fig.28 Dimensions of a corrugated bulkhead

a

c

sC

tw

d

tf

o55≥ϕR


PAGE 11 OF 35

Reason for the Rule Clarification: This correction is made to be in line with IACS UR S18.


PAGE 12 OF 35

CHAPTER 4 – DESIGN LOADS

SECTION 5 EXTERNAL PRESSURES

3. External pressures on superstructures and deckhouses

3.4 Superstructure end bulkheads and deckhouse walls 3.4.1

Table 9: Minimum lateral pressure pAmin pAmin, in kN/m2

L Lowest tier of unprotected fronts Elsewhere (1)

25090 ≤< L 10

25 L+

105.12 L

+

205.12 L

+

250>L 50 25 (1) For the 4th tier and above, minAp is to be taken equal to

2.5 kN/m2.

Reason for the Rule Clarification: This correction is made to be in line with IACS UR S3 Table 1.


PAGE 13 OF 35

SECTION 6 INTERNAL PRESSURES AND FORCES

1. Lateral pressure due to dry bulk cargo

1.3 Inertial pressure due to dry bulk cargo 1.3.1 The inertial pressure induced by dry bulk cargo pCW, in kN/m2, for each load case is given by the following

formulae.

• for load case H: ( ) ( )[ ]zhhaKxxap DBCZCGXCCW −++−= 25.0ρ

• for load case F: 0=CWp

• for load cases R and P: ( ) ( )[ ]zhhaKyyap DBCZCGYCCW −++−= 25.0ρ

(x-xG) is to be taken as 0.25lH in the load case H1 or -0.25lH in the load case H2 for local strength by Ch 6 and

fatigue check for longitudinal stiffeners by Ch 8.

The total pressure (pCS + pCW ) is not to be negative.

2. Lateral pressure due to liquid

2.2 Inertial pressure due to liquid 2.2.1 The inertial pressure due to liquid pBW, in kN/m2, for each load case is given as follows. When checking ballast

water exchange operations by means of the flow through method, the inertial pressure due to ballast water is not

to be considered for local strength assessments and direct strength analysis.

• for load case H: pBW = ρL [aZ (zTOP – z) + aX (x – xB)]

(x-xB) is to be taken as 0.75lH in the load case H1 or -0.75lH in the load case H2 for local strength by

Ch 6 and fatigue check for longitudinal stiffeners by Ch 8

• for load case F: pBW = 0

• for load cases R and P: pBW = ρL [aZ (zB –z)+ aY (y–yB)]

where:

xB : X co-ordinate, in m, of the aft end of the tank when the bow side is downward, or of the fore end of

the tank when the bow side is upward, as defined in Fig 3

yB : Y co-ordinate, in m, of the tank top located at the most lee side when the weather side is downward, or

of the most weather side when the weather side is upward, as defined in Fig 3

zB : Z co-ordinate of the following point:

• for completely filled spaces: the tank top

• for ballast hold: the top of the hatch coaming

The reference point B is defined as the upper most point after rotation by the angle ϕ between the vertical axis

and the global acceleration vector GAr

shown in Fig 3. ϕ is obtained from the following formulae:

• load cases H1 and H2:


PAGE 14 OF 35

)cos

||(tan 1

Z

X

aga

+= −

Φϕ

• load cases R1(P1) and R2(P2):

)cos

||(tan 1

Z

Y

aga

+= −

θϕ

where:

θ : Single roll amplitude, in deg, defined in Ch4, Sec 2, 2.1.1.

Φ : Single pitch amplitude, in deg, defined in Ch4, Sec 2, 2.2.1

The total pressure (pBS + pBW) is not to be negative.

Reason for the Rule Clarification: The total internal pressure obtained by adding the static internal pressure to inertial internal pressure is not to be negative that is the same manner for the external pressure specified in Ch 4 Sec 5 1.1.1. The editorial correction is made to reflect the original intention on the treatment of the total internal pressure.


PAGE 15 OF 35

CHAPTER 6 – HULL SCANTLINGS

SECTION 1 PLATING


2.2 Minimum net thickness 2.2.1

The net thickness of plating is to be not less than the values given in Table 2. In addition, in the cargo area, the net thickness of side shell plating, from the normal ballast draught to 0.25 Ts (minimum 2.2 m) above Ts, is to be not less than the value obtained, in mm, from the following formula:

eHRBTst

25.0)()7.0(28 += eH

S

RBT

st25.0)(

)7.0(28 +=

Reason for the Rule Clarification: This editorial correction is made to clarify the definition of draft as scantling basis.


PAGE 16 OF 35

SECTION 2 ORDINARY STIFFENERS

4. Web stiffeners of primary supporting members

4.1 Net scantlings 4.1.3 Connection ends of web stiffeners Where the web stiffeners of primary supporting members are welded to ordinary stiffener face plates, Tthe stress

at ends of web stiffeners of primary supporting members in water ballast tanks, in N/mm2, is to comply with the

following formula when no bracket is fitted:

175≤σ

where:

θσσ

cos1.1 Δ

= stifflongicon KKK

conK : Coefficient considering stress concentration, taken equal to:

5.3=conK for stiffeners in the double bottom or double side space (see Fig 8)

0.4=conK for other cases (e.g. hopper tank, top side tank, etc.) (see Fig 8)

longiK : Coefficient considering shape of cross section of the longitudinal, taken equal to:

0.1=longiK for symmetrical profile of stiffener (e.g. T-section, flat bar)

3.1=longiK for asymmetrical profile of stiffener (e.g. angle section, bulb profile)

stiffK : Coefficient considering the shape of the end of the stiffener, taken equal to:

stiffK = 1.0 for standard shape of the end of the stiffener (see Fig 9)

stiffK = 0.8 for the improved shape of the end of the stiffener (see Fig 9)

θ : As given in Fig 10

σΔ : Stress range, in N/mm2, transferred from longitudinals into the end of web stiffener, as obtained from

the following formula:

( ) ( )[ ] 02211'322.02

sww AAAhW

++=Δ

llσ

W : Dynamic load, in N, as obtained from the following formula:

( )spsW 5.01000 −= l

p : Maximum inertial pressure due to liquid according to Ch 4 Sec 6 [2.2.1], in kN/m2, of the probability

level of 10-4.,calculated at mid-span of the ordinary stiffener

l : Span of the longitudinal, in m

s : Spacing of the longitudinal, in m

0sA , 1wA , 2wA : Geometric parameters as given in Fig 10, in mm2

1l , 2l : Geometric parameters as given in Fig 10, in mm

'h : As obtained from following formula, in mm:

'' 0hhh s +=


PAGE 17 OF 35

sh : As given in Fig 10, in mm

'0h : As obtained from the following formula, in mm

'636.0'0 bh = for 150'≤b

63'216.0'0 += bh for '150 b<

'b : Smallest breadth at the end of the web stiffener, in mm, as shown in Fig 910

Fig. 10 Definition of geometric parameters

Note:

ts: net thickness of the web stiffener, in mm.

tw: net thickness of the collar plate, in mm.

Reason for the Rule Clarification: This requirement is also based on the net scantling approach. In addition, the application of this requirement and the pressure to be considered is clarified in order to respond to the industry comment.


PAGE 18 OF 35


3. Buckling criteria of elementary plate panel

3.1 Plates

3.1.2 Verification of elementary plate panel in a transverse section analysis Each elementary plate panel is to comply with the following criteria, taking into account the loads defined in

[2.1]:

• longitudinally framed plating

0,13

31

≤⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⋅

⋅⋅+⎟

⎟⎠

⎞⎜⎜⎝

⎛

⋅

⋅e

eH

e

eHx

x

RS

RS

τκτ

κσ for stress combination 1 with σ x = σ n and τ = 0,7τSF

0,13

31

≤⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⋅

⋅⋅+⎟

⎟⎠

⎞⎜⎜⎝

⎛

⋅

⋅e

eH

e

eHx

x

RS

RS

τκτ

κσ for stress combination 2 with σ x = 0,7σ n and τ = τSF

• transversely framed plating

0,13

32

≤⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⋅

⋅⋅+

⎟⎟⎟

⎠

⎞

⎜⎜⎜

⎝

⎛

⋅

⋅e

eH

e

eHy

y

RS

R

S

τκτ

κ

σ for stress combination 1 with σ y = σ n and τ = 0,7τSF

0,13

32

≤⎟⎟⎠

⎞⎜⎜⎝

⎛

⋅⋅⋅

+⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⋅

⋅e

eH

e

eHy

x

RS

R

S

τκτ

κ

σ 0,1

33

2

≤⎟⎟⎠

⎞⎜⎜⎝

⎛

⋅⋅⋅

+⎟⎟⎟

⎠

⎞

⎜⎜⎜

⎝

⎛

⋅

⋅ e

eH

e

eHy

y

RS

R

S

τκτ

κ

σfor stress combination 2

with σ y = 0,7σ n and τ = τSF

Reason for the Rule Clarification: Editorial correction. The index of the compression stress in the fourth formula has to be “y”.


PAGE 19 OF 35

APPENDIX 1 BUCKLING & ULTIMATE STRENGTH

1. Application of Ch 6, Sec 3

1.3 Additional application to FEM analysis 1.3.4 Buckling assessment of corrugated bulkhead The transverse elementary plate panel (face plate) is to be assessed using the normal stress parallel to the

corrugation. The slanted elementary plate panel (web plate) is to be assessed using the combination of normal

and shear stresses. The plate panel breadth b is to be measured according to Fig 8.

Fig. 8 Measuring b of corrugated bulkheads ��

�

a) Face plate assessment

• F1 = 1.1 is to be used

• The buckling load case 1, according to Ch 6, Sec 3, Tab 2, is to be used

• The size of the buckling field to be considered is b times b ( 1=α )

• 0.1=ψ

• The maximum vertical stress in the elementary plate panel is to be considered in applying the criteria

• The plate thickness t to be considered is the one at the location where the maximum vertical stress

occurs

b) Web plate assessment

• F1 = 1.1 is to be used

• The buckling load cases 1 and 5, according to Ch 6, Sec 3, Tab 2, are to be used.

• The size of the buckling field to be considered is 2b times b ( 2=α )

• 0.1=ψ

• The following two stress combinations are to be considered:

• The maximum vertical stress in the elementary plate panel plus the shear stress and longitudinal

stress at the location where maximum vertical stress occurs

• The maximum shear stress in the elementary plate panel plus the vertical stress and longitudinal

stress at the location where maximum shear stress occurs

• The plate thickness t to be considered is the one at the location where the maximum vertical/shear stress

occurs.

Reason for the Rule Clarification: Correction factor F1 is not used for the buckling load cases 1 and 5 specified in Ch 6 Sec 3 Table 2 as mentioned in the second sentences.


PAGE 20 OF 35

CHAPTER 7 – DIRECT STRENGTH ANALYSIS

SECTION 4 HOT SPOT STRESS ANALYSIS FOR FATIGUE STRENGTH ASSESSMENT

3. Hot Spot Stress

3.2 Evaluation of hot spot stress 3.2.1 The hot spot stress in a very fine mesh is to be obtained using a linear extrapolation. The surface stresses located

at 0.5 times and 1.5 times the net plate thickness are to be linearly extrapolated at the hot spot location, as

described in Fig 3 and Fig.4.

The principal stress at the hot spot location having an angle with the assumed fatigue crack greater than 45° is to

be considered as the hot spot stress.

Reason for the Rule Clarification: Editorial correction is made for the clarification of the stress obtained by FEA.


PAGE 21 OF 35

σix

σiy

a

1

3

2

4 b

5

6

uj

vj

a

3

2

b

5

7 8

1

4

6

uj σix

vj σiy

a

1

3

2

4

b

5 6 5

6 7 8

APPENDIX 2 DISPLACEMENT BASED BUCKLING ASSESSMENT IN FINITE ELEMENT ANALYSIS

2. Displacement method

2.2 Calculation of buckling stresses and edge stress ratios 2.2.3 8-node buckling panel Stress displacement relationship for a 8-node buckling panel (compressive stresses are positive)

Fig.2 8-node buckling panel

(a) Displacement Nodes

(b) Stress Nodes

Reason for the Rule Clarification: This correction is to clarify the figure.

1 to 4: Displ. & Stress Nodes 5 & 6: Stress Nodes 5 to 8: Displacement Nodes


PAGE 22 OF 35


SECTION 5 STRESS ASSESSMENT OF HATCH CORNERS

2. Nominal stress range

2.1 Nominal stress range due to wave torsional moment 2.1.1 The nominal stress range, in N/mm2, due to cross deck bending induced by wave torsion moments is to be

obtained from the following formula:

Q

HLSWT W

BQFF

⋅=Δ

10002σ

where:

Q

H

Q

sH

EAB

EIbB

uQ 6.212

)³(1000

++=

u : Displacement of hatch corner in longitudinal direction, in m, taken equal to:

DOCEI

MuT

WT ω1000

2.31=

DOC : Deck opening coefficient, taken equal to:

∑=

= n

iiHiH

C

BL

BLDOC

1,,

MWT : Maximum wave torsional moment, in kN.m, defined in Ch 4, Sec 3, [3.4.1], with fp = 0.5

FS : Stress correction factor, taken equal to:

5=SF

FL : Correction factor for longitudinal position of hatch corner, taken equal to:

LxFL 75.1= for 85.0/57.0 ≤≤ Lx

0.1=LF for x/L < 0.57 and x/L > 0.85

BH : Breadth of hatch opening, in m

WQ : Section modulus of the cross deck about z-axis, in m3, including upper stool, near hatch corner (see

Fig 2)

IQ : Moment of inertia of the cross deck about z-axis, in m4, including upper stool, near the hatch corner

(see Fig 2)

AQ : Shear area of the cross deck, in m2, including upper stool, near the hatch corner (see Fig 2)

bS : Breadth of remaining deck strip on one side, in m, beside the hatch opening


PAGE 23 OF 35

IT : Torsion moment of inertia of ships cross section, in m4, calculated within cross deck area by

neglecting upper and lower stool of the bulkhead (see Fig 1). It may be calculated according to App 1

ω : Sector coordinate, in m2, calculated at the same cross section as IT and at the Y and Z location of the

hatch corner (see Fig 1) It may be calculated according to App 1

LCC : Length of cargo area, in m, being the distance between engine room bulkhead and collision bulkhead

BH,i : Breadth of hatch opening of hatch i, in m

LH,i : Length of hatch opening of hatch i, in m

n : Number of hatches.

Elements to be considered for the determination of AQ, WQ and IQ

Reason for the Rule Clarification: Editorial correction for typo

Editorial corrections of the definition of symbols are made for clarification


PAGE 24 OF 35

APPENDIX 1 CROSS SECTIONAL PROPERTIES FOR TORSION

1. Calculation formulae

1.4 Computation of cross sectional properties for the entire cross section

Asymmetric cross section: Symmetric cross section (only half of the section is modeled)

A = ∑ A A = ∑ A2

sy = ∑∑

A

Sz sy = ∑∑

A

Sz

sz = ∑∑

A

Sy sz =

∑∑

A

Sy

yI = 2sy zAI ∑∑ − yI = ( )22 sy zAI ∑∑ −

zI = 2sz yAI ∑∑ − zI = ( )22 sz yAI ∑∑ −

yzI = ssyz zyAI ∑∑ −

TI = ∑ 3

3ts ( )∑∑ Φ+

iCelliyiAts 2

3

3

TI = ( )

⎥⎥⎦

⎤

⎢⎢⎣

⎡Φ+∑ ∑

iCelliyiA

ts2

32

3

0ω = ∑∑

A

Sω

yIω = 0ωω ∑∑ − sy yAI yIω = ∑ yIω2

zIω = 0ωω ∑∑ − sz zAI

My = 2yzzy

yzyzz

IIIIIII

−

− ωω

Mz = 2yzzy

yyyzz

IIIIIII

−

− ωω Mz = z

y

IIω

−

ωI = zMym IyIzAI ωωω ω −+− ∑∑ 20

ωI = zMyM IyIzAI ωωω ω −+− ∑∑ 20

ωI = ym IzI ωω +∑2

ωI = yM IzI ωω +∑2

yzzy III ,, are to be computed with relation to the centre of gravity.

S zyyx IandIISSS ωωωω ,,,, , ωI are to be computed with relation to shear centre M

The sector-coordinate ω has to be transformed with respect to the location of the shear centre M. For cross

sections of type A, 0ω is to be added to each iω and kω as defined in [1.3]

For cross sections of type B and C, ωΔ can be calculated as follows:

iωΔ = ( ) ( )iMiMO zyyz −=−ωω iMi yz=Δω


PAGE 25 OF 35

where:

Oω : Calculated sector co-ordinate with respect to the centre of the coordinate system (O) selected for the

calculation according to the formulae for kω given in [1.3]

ω : Transformed sector co-ordinate with respect to shear centre M

MM zy , : Distance between shear centre M and centre of the coordinate system B.

The transformed values of ω can be obtained by adding ωΔ to the values of Oω obtained according to the

formulae in [1.3].

The transformed value for ω is to be equal to zero at intersections of the cross section with the line of symmetry

(centreline for ship-sections).

Reason for the Rule Clarification: Editorial correction and clarification


PAGE 26 OF 35

CHAPTER 9 – OTHER STRUCTURES


2. Double bottom

2.1 Arrangement 2.1.8 Floors stiffeners In addition to the requirements in Ch 3, Sec 6, floors are to have web stiffeners sniped at the ends and spaced not

more than approximately 1 m apart.

The section modulus of web stiffeners is to be not less than 1.2 times that required in Ch 6, Sec 2, [4] 4.1.2

Reason for the Rule Clarification: Editorial correction of the reference number


PAGE 27 OF 35

CHAPTER 10 – HULL OUTFITTING

SECTION 3 EQUIPMENT

2. Equipment number

2.1 Equipment number

Table 1: Equipment

Stockless anchors Stud link chain cables for anchors Equipment number EN

A < EN ≤ B Diameter, in mm

A B

N (1) Mass per anchor,

in kg

Total length, in m

Grade 1 Grade 2 Grade 3 50 70 2 180 220.0 14.0 12.5 70 90 2 240 220.0 16.0 14.0 90 110 2 300 247.5 17.5 16.0 110 130 2 360 247.5 19.0 17.5 130 150 2 420 275.0 20.5 17.5 150 175 2 480 275.0 22.0 19.0 175 205 2 570 302.5 24.0 20.5 205 240 3 660 302.5 26.0 22.0 20.5 240 280 3 780 330.0 28.0 24.0 22.0 280 320 3 900 357.5 30.0 26.0 24.0 320 360 3 1020 357.5 32.0 28.0 24.0 360 400 3 1140 385.0 34.0 30.0 26.0 400 450 3 1290 385.0 36.0 32.0 28.0 450 500 3 1440 412.5 38.0 34.0 30.0 500 550 3 1590 412.5 40.0 34.0 30.0 550 600 3 1740 440.0 42.0 36.0 32.0 600 660 3 1920 440.0 44.0 38.0 34.0 660 720 3 2100 440.0 46.0 40.0 36.0 720 780 3 2280 467.5 48.0 42.0 36.0 780 840 3 2460 467.5 50.0 44.0 38.0 840 910 3 2640 467.5 52.0 46.0 40.0 910 980 3 2850 495.0 54.0 48.0 42.0 980 1060 3 3060 495.0 56.0 50.0 44.0

1060 1140 3 3300 495.0 58.0 50.0 46.0 1140 1220 3 3540 522.5 60.0 52.0 46.0 1220 1300 3 3780 522.5 62.0 54.0 48.0 1300 1390 3 4050 522.5 64.0 56.0 50.0 1390 1480 3 4320 550.0 66.0 58.0 50.0 1480 1570 3 4590 550.0 68.0 60.0 52.0 1570 1670 3 4890 550.0 70.0 62.0 54.0 1670 1790 3 5250 577.5 73.0 64.0 56.0 1790 1930 3 5610 577.5 76.0 66.0 58.0


PAGE 28 OF 35

Stockless anchors Stud link chain cables for anchors Equipment number EN

A < EN ≤ B Diameter, in mm

A B

N (1) Mass per anchor,

in kg

Total length, in m

Grade 1 Grade 2 Grade 3 1930 2080 3 6000 577.5 78.0 68.0 60.0 2080 2230 3 6450 605.0 81.0 70.0 62.0 2230 2380 3 6900 605.0 84.0 73.0 64.0 2380 2530 3 7350 605.0 87.0 76.0 66.0 2530 2700 3 7800 632.5 90.0 78.0 68.0 2700 2870 3 8300 632.5 92.0 81.0 70.0 2870 3040 3 8700 632.5 95.0 84.0 73.0 3040 3210 3 9300 660.0 97.0 84.0 76.0 3210 3400 3 9900 660.0 100.0 87.0 78.0 3400 3600 3 10500 660.0 102.0 90.0 78.0 3600 3800 3 11100 687.5 105.0 92.0 81.0 3800 4000 3 11700 687.5 107.0 95.0 84.0 4000 4200 3 12300 687.5 111.0 97.0 87.0 4200 4400 3 12900 715.0 114.0 100.0 87.0 4400 4600 3 13500 715.0 117.0 102.0 90.0 4600 4800 3 14100 715.0 120.0 105.0 92.0 4800 5000 3 14700 742.5 122.0 107.0 95.0 5000 5200 3 15400 742.5 124.0 111.0 97.0 5200 5500 3 16100 742.5 127.0 111.0 97.0 5500 5800 3 16900 742.5 130.0 114.0 100.0 5800 6100 3 17800 742.5 132.0 117.0 102.0 6100 6500 3 18800 742.5 120.0 107.0 6500 6900 3 20000 770.0 124.0 111.0 6900 7400 3 21500 770.0 127.0 114.0 7400 7900 3 23000 770.0 132.0 117.0 7900 8400 3 24500 770.0 137.0 122.0 8400 8900 3 26000 770.0 142.0 127.0 8900 9400 3 27500 770.0 147.0 132.0 9400 10000 3 29000 770.0 152.0 132.0

10000 10700 3 31000 770.0 137.0 10700 11500 3 33000 770.0 142.0 11500 12400 3 35500 770.0 147.0 12400 13400 3 38500 770.0 152.0 13400 14600 3 42000 770.0 157.0 14600 16000 3 46000 770.0 162.0

(1) See [3.2.4].

2.1.2 The equipment number EN is to be obtained from the following formula:

EN = Δ 2/3 2/3+ 2 h B + 0.1 A

where:.

Δ : Moulded displacement of the ship, in t, to the summer load waterline

h : Effective height, in m, from the summer load waterline to the top of the uppermost house, to be

obtained in accordance with the following formula:

h = a + Σ hn

When calculating h, sheer and trim are to be disregarded

a : Freeboard amidships from the summer load waterline to the upper deck, in m


PAGE 29 OF 35

hn : Height, in m, at the centreline of tier “n” of superstructures or deckhouses having a breadth greater

than B/4. Where a house having a breadth greater than B/4 is above a house with a breadth of B/4 or

less, the upper house is to be included and the lower ignored

A : Area, in m2, in profile view, of the parts of the hull, superstructures and houses above the summer load

waterline which are within the length L and also have a breadth greater than B/4

Fixed screens or bulwarks 1.5 m or more in height are to be regarded as parts of houses when determining h and

A. In particular, the hatched area shown in Fig 1 is to be included.

The height of hatch coamings and that of any deck cargo, such as containers, may be disregarded when

determining h and A.

3.7 Windlass 3.7.9 Forces in the securing devices of windlasses due to green sea loads Forces in the bolts, chocks and stoppers securing the windlass to the deck are to be calculated by considering the

green sea loads specified in [3.7.8].

The windlass is supported by N bolt groups, each containing one or more bolts (see also Fig 3).

The axial force Ri in bolt group (or bolt) i, positive in tension, is to be obtained, in kN, from the following

formulae:

• Rxi = Px hxi Ai / Ix Rxi = Px hxi Ai / Ix

• Ryi = Py hyi Ai / Iy Ryi = Py hyi Ai / Iy

• Ri = Rxi + Ryi – Rsi

where:

Px : Force, in kN, acting normal to the shaft axis

Py : Force, in kN, acting parallel to the shaft axis, either inboard or outboard, whichever gives the greater

force in bolt group i

H h : Shaft height, in cm, above the windlass mounting

xi, yi : X and Y co-ordinates, in cm, of bolt group i from the centroid of all N bolt groups, positive in the

direction opposite to that of the applied force

Ai : Cross-sectional area, in cm2, of all bolts in group I

Ix, Iy : Inertias, for N bolt groups, equal to:

Ix = ΣAi xi2

Iy = ΣAi yi2

Ri Rsi : Static reaction force, in kN, at bolt group i, due to weight of windlass.

Shear forces Fxi , Fyi applied to the bolt group i, and the resultant combined force Fi are to be obtained, in kN,

from the following formulae:

• Fxi = (Pi - α g M) / N Fxi = (Px - α g M) / N

• Fyi = (Py - α g M) / N

• Fi = (Fxi2 + Fyi

2 )0,5

where:

α : Coefficient of friction, to be taken equal to 0.5

M : Mass, in t, of windlass

N : Number of bolt groups.


PAGE 30 OF 35

Axial tensile and compressive forces and lateral forces calculated according to these requirements are also to be considered in the design of the supporting structure.

Reason for the Rule Clarification: Editorial correction – correction of error in formula


PAGE 31 OF 35

CHAPTER 11 – CONSTRUCTION AND TESTING

SECTION 1 CONSTRUCTION

1. Structural details

1.2 Cold forming 1.2.1 For cold forming (bending, flanging, beading) of plates the minimum average bending radius is to be not less

than 3t (t = gross plate thickness as-built thickness).

In order to prevent cracking, flame cutting flash or sheering burrs are to be removed before cold forming. After

cold forming all structural components and, in particular, the ends of bends (plate edges) are to be examined for

cracks. Except in cases where edge cracks are negligible, all cracked components are to be rejected. Repair

welding is not permissible.

Table 1 Alignment (t, t1, and t2: as-built thickness)

Detail Standard Limit Remarks Alignment of butt welds

a ≤ 0.15t strength a ≤ 0.2t other

a ≤ 3.0 mm

Alignment of fillet welds

a) Strength and higher tensile steel

a ≤ t1 / 4 measured on the median

a ≤ (5t1 – 3t2) / 6 measured on the

heel line

b) Other


a ≤ (2 t1 – t2) / 2 measured on the

heel line

Where t2 is less than t1, then t2 should be substituted for t1.

Alignment of fillet welds

a) Strength and higher tensile steel



PAGE 32 OF 35

Detail Standard Limit Remarks

b) Other

a ≤ t1 / 2 measured on the heel line

Note: “strength” means the following elements: strength deck, inner bottom, bottom, lower stool, lower part of transverse bulkhead, bilge hopper and side frames of single side bulk carriers. Alignment of face plates of T longitudinal

a ≤ 0.04b strength a = 8.0 mm

Alignment of height of T-bar, L-angle bar or bulb

a ≤ 0.15 t for primary supporting members

a ≤ 0.2 t for ordinary stiffeners 3.0 mm

Alignment of panel stiffener

d ≤ L / 50

Note: “strength” means the following elements: strength deck, inner bottom, bottom, lower stool, lower part of transverse bulkhead, bilge hopper and side frames of single side bulk carriers.

Reason for the Rule Clarification: Editorial correction for clarification of the thickness


PAGE 33 OF 35

SECTION 2 WELDING

2. Types of welded connection

2.2 Butt welding 2.2.2 Welding of plates with difference thicknesses In the case of welding of plates with a difference in gross thickness as-built thickness equal to or greater than 4

mm, the thicker plate is normally to be tapered. The taper has to have a length of not less than 3 times the

difference in gross thickness as-built thickness.

Reason for the Rule Clarification: Editorial correction for clarification of the thickness

2.6 Fillet welds 2.6.1 Kinds and size of fillet welds and their applications Kinds and size of fillet welds for as-built thickness of abutting plating up to 50 mm are classed into 5 categories

as given in Tab 1 and their application to hull construction is to be as required by Tab 2.

In addition, for zones “a” and “b” of side frames as shown in Ch 3, Sec 6, Fig 19, the weld throats are to be

respectively 0.44t and 0.4t, where t is as-built thickness of the thinner of two connected members.

Table 1 Categories of fillet welds

Category Kinds of fillet welds

As-built gross thickness of abutting

plate, t, in mm (1)

Leg length of fillet weld, in mm (2)

Length of fillet welds, in

mm

Pitch, in mm

F0 Double continuous weld t 0.7t - -

t ≤ 10 0.5t + 1.0 - - 10 ≤ t < 20 0.4t + 2.0 - - F1 Double

continuous weld 20 ≤ t 0.3t + 4.0 - - t ≤ 10 0.4t + 1.0 - -

10 ≤ t < 20 0.3t + 2.0 - - F2 Double continuous weld

20 ≤ t 0.2t + 4.0 - - t ≤ 10 0.3t + 1.0

10 ≤ t < 20 0.2t + 2.0 F3 Double continuous weld

20 ≤ t 0.1t + 4.0 - -

t ≤ 10 0.5t + 1.0 10 ≤ t < 20 0.4t + 2.0 F4 Intermittent weld

20 ≤ t 0.3t + 4.0 75 300

(1) t is as-built thickness of the thinner of two connected members (2) Leg length of fillet welds is made fine adjustments corresponding to the corrosion addition tC specified

in Ch 3, Sec 3, Tab 1 as follows: + 1.0 mm for 5>Ct

+ 0.5 mm for 45 ≥≥ Ct 45 >≥ Ct

- 0.5 mm for 4<Ct 3≤Ct


PAGE 34 OF 35

Table 2 Application of fillet welds

Connection Category Hull area Of To

Watertight plate Boundary plating F1 Brackets at ends of members F1

Deep tank bulkheads F3 Ordinary stiffener and collar plates

Cut-out in way of primary supporting members Web of primary supporting members and collar plates

F2

Plating (Except deep tank bulkhead) F4 At ends (15% of span) F2 Web of ordinary

stiffener Face plates of built-up stiffeners Elsewhere F4

General, unless otherwise specified in the table

End of primary supporting members and ordinary stiffeners

Deck plate, shell plate, inner bottom plate, bulkhead plate F0

Ordinary stiffener Bottom and inner bottom plating F3 Shell plates in strengthened bottom forward F1

Center girder Inner bottom plate and shell plate except the above F2

Side girder including intercostal plate

Bottom and inner bottom plating F3

Shell plates and inner bottom plates

At ends, on a length equal to two frame spaces F2

Center girder and side girders in way of hopper tanks F2 Floor

Elsewhere F3 Bracket on center girder Center girder, inner bottom and shell plates F2

Bottom and double bottom

Web stiffener Floor and girder F3 Side and inner side in double side structure

Web of primary supporting members

Side plating, inner side plating and web of primary supporting members F2

Side frame and end bracket Side shell plate

F1 See Ch 3 Sec 6 Fig.

19

Side frame of single side structure

Tripping bracket Side shell plate and side frame F1

Side shell plating within 0.6L midship Deep penetration t ≥ 13

Elsewhere F1 Strength deck

t < 13 Side shell plating F1 Side shell plating F2

Other deck Ordinary stiffeners F4

Ordinary stiffener and intercostal girder

Deck plating F3

At corners of hatchways for 15% of the hatch length F1

Hatch coamings Deck plating Elsewhere F2

Deck

Web stiffeners Coaming webs F4


PAGE 35 OF 35

Connection Category Hull area Of To

Non-watertight bulkhead structure Boundaries Swash bulkheads F3

Bulkheads Ordinary stiffener Bulkhead plating At ends (25% of span), where

no end brackets are fitted F1

At end (15% of span) F1 Shell plating, deck plating, inner bottom plating, bulkhead

Elsewhere F2

In tanks, and located within 0.125L from fore peak F2

Face area exceeds 65 cm2 F2

Primary supporting members

Web plate and girder plate

Face plate

Elsewhere F3 After peak Internal members Boundaries and each other F2

Bed plate In way of main engine, thrust bearing, boiler bearers and main generator engines

F1

Girder plate In way of main engine and thrust bearing F1 Seating Girder and bracket

Inner bottom plate and shell

In way of main engine and thrust bearing F2

Super-structure External bulkhead Deck F1

Pillar Pillar Heel and head F1 Ventilator Coaming Deck F1

Vertical frames forming main piece F1 Rudder plate F3 Rudder Rudder frame Rudder frames except above F2

Reason for the Rule Clarification: (1) Editorial correction for clarification of the thickness (2) Editorial error for the threshold of corrosion addition. This correction is made to be in line with the technical background. (3) The requirement for weld of side frame is in accordance with IACS UR S12.

RULE CHANGE NOTICE NO. 1 (NOV 2007) COMMON STRUCTURAL RULES FOR BULK CARRIERS

PAGE 1 OF 4


Rule Change Notice No. 1 November 2007

Notes: This rule change is to be implemented by IACS Members on ships contracted for construction from a date not later than 1 April 2008.





PAGE 2 OF 4

For technical background for Rule Changes in this present document, reference is made to separate document Technical Background for Rule Change Notice No.1.

CHAPTER 5 – HULL GIRDER STRENGTH

APPENDIX 1 HULL GIRDER ULTIMATE STRENGTH


2.2 Load-end shortening curve σ-ε

2.2.4 Beam column buckling The equation describing the load-end shortening curve σCR1-ε for the beam column buckling of ordinary

stiffeners composing the hull girder transverse section is to be obtained from the following formula (see Fig 3):

pStif

pEStifCCR stA

tbAΦ

1010

11 +

+= σσ

where:




εσ

σ 11

EC = for εσ

21eH

ER

≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

11 4

1E

eHeHC

RΦR

σε

σ ⎟⎟⎠

⎞⎜⎜⎝

⎛−=

11 4

1E

eHeHC

RR

σε

σ for εσ21eH

ER

>



42

21 10−=

lAI

EE

EE πσ



EE

sbβ

=1 for 0.1>Eβ

sbE =1 for 0.1≤Eβ

ER

ts eH

pE

εβ 310=

AE : Net sectional area, in cm2, of ordinary stiffeners with attached shell plating of width bE


PAGE 3 OF 4


sbEE

E ⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

25.125.2ββ

for 25.1>Eβ

sbE = for 25.1≤Eβ

2.2.5 Torsional buckling The equation describing the load-end shortening curve σCR2-ε for the flexural-torsional buckling of ordinary

stiffeners composing the hull girder transverse section is to be obtained according to the following formula (see

Fig 4).

pStif

CPpCStifCR stA

stAΦ

10102

2 +

+=

σσσ

where:




εσ

σ 22

EC = for εσ

22eH

ER

≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

22 4

1E

eHeHC

RΦR

σε

σ ⎟⎟⎠

⎞⎜⎜⎝

⎛−=

22 4

1E

eHeHC

RR

σε

σ for εσ22eH

ER

>




eHEE

CP R⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

25.125.2ββ

σ for 25.1>Eβ

eHCP R=σ for 25.1≤Eβ


2.2.7 Web local buckling of ordinary stiffeners made of flat bars The equation describing the load-end shortening curve σCR4-ε for the web local buckling of flat bar ordinary


PStif

CStifCPPCR stA

AstΦ

1010 4

4 +

+=

σσσ

where:





PAGE 4 OF 4


εσ

σ 44

EC = for εσ

24eH

ER

≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

44 4

1E

eHeHC

RΦR

σε

σ ⎟⎟⎠

⎞⎜⎜⎝

⎛−=

44 4

1E

eHeHC

RR

σε

σ for εσ24eH

ER

>


4 160000 ⎟⎟⎠

⎞⎜⎜⎝

⎛=

w

wE h

tσ


2.2.8 Plate buckling The equation describing the load-end shortening curve σCR5-ε for the buckling of transversely stiffened panels

composing the hull girder transverse section is to be obtained from the following formula:

⎪⎪⎩

⎪⎪⎨

⎧

⎥⎥

⎦

⎤

⎢⎢

⎣

⎡

⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟

⎟⎠

⎞⎜⎜⎝

⎛−

=2

225 1111.025.125.2min

EEEeH

eH

CR ssR

ΦR

βββσ

ll

⎪⎪⎩

⎪⎪⎨

⎧

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟⎟

⎠

⎞⎜⎜⎝

⎛−

=2

225 1111.025.125.2min

EEEeH

eH

CR ssΦR

ΦR

βββσ

ll

where:

Φ : Edge function defined in [2.2.3].

βE : Coefficient defined in [2.2.4].

TECHNICAL BACKGROUND FOR RCN NO. 1 (NOV 2007) COMMON STRUCTURAL RULES FOR BULK CARRIERS

PAGE 1 OF 8


Technical Background for Rule Change Notice No. 1,

November 2007

Copyright in these Common Structural Rules for Bulk Carriers is owned by: American Bureau of Shipping Bureau Veritas China Classification Society Det Norske Veritas Germanischer Lloyd Korean Register of Shipping Lloyd's Register Nippon Kaiji Kyokai Registro Italiano Navale Russian Maritime Register of Shipping



PAGE 2 OF 8

Technical Background for the Changes in: Chapter 5/Appendix 1 1. Reason for the Rule Change:

The original formulae in Appendix 1 of Chapter 5 which are the determination of the load-end shortening curve are some class Rules, however, some formulae is not consistent with the assumption of the method adopted in CSR. This rule change proposal is made to fix the inconsistency. 2. Explanation of the modified formula 2.1 Main assumptions of the method

The hull girder is treated as a beam subjected exclusively to bending, excluding shear. It corresponds to the assumption of the cross section remaining plane during loading. The method adopted uses the so-called "component approach" and is based on the following simplifying assumptions:

• each cross section is made of an assembly of independent elements or components (plates and stiffened plates),

• transverse cross-sections of the ship hull remain plane after deformation and perpendicular, to the neutral surface, which enables to calculate for any curvature Ф the strain ε according to the following formula : Ф = zε (z distance from the element under consideration to the neutral axis), • collapse occurs for panels located between two adjacent transverse primary members, • elasto-plastic behaviour of each panel is determined under tension and compression; • influence of shear stresses is neglected.

The method takes also advantage of the possibility to determine for each panel its load-end

shortening curve σCR1-ε, as indicated hereafter. 2.2 Determination of the load-end shortening curve σCR1-ε – beam column buckling The Euler column buckling stress is taken as:

42

'2 10−=

le

eE A

IEπσ

where 'eI : moment of inertia, in cm4, of the stiffener with attached plating of width be’ taken

as: bbbe

e ≤=β

125.1'

Ae : cross sectional area, in cm², of the stiffener with an attached plating of width be taken as:

⎪⎪⎩

⎪⎪⎨

⎧

<=

≥⎟⎟⎠

⎞⎜⎜⎝

⎛−=

25.1

25.125.125.22

ee

eee

e

forbb

forbb

β

βββ

Et

b c

pe

1σβ =

tp : thickness of attached plating l: span of stiffeners

Since the effective width be of attached plating may be calculated for any strain level by considering the generalized slenderness of plating )(εβe :


PAGE 3 OF 8

⎪⎪⎩

⎪⎪⎨

⎧

<=

≥⎟⎟⎠

⎞⎜⎜⎝

⎛−=

25.1)()(

25.1)()(

25.1)(

25.2)( 2

εβε

εβεβεβ

ε

ee

eee

e

forbb

forbb

the Euler column buckling stress can be expressed as:

2

'2

)(

)()(

lε

επεσ

e

eE

A

IE=

where 'eI = moment of inertia of the stiffener with attached plating of width )(' εeb taken

as

bb

be

e ≤=)(

125.1)('

εβε

If we assume that the Johnson-Ostenfeld correction is applicable to any edge stress the maximum stress that the stiffener with attached plate of width )(εeb can sustain is:

Y

E

Yeee

E

e σεσ

σεεσ

εσ

σεσ

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛Φ−Φ=

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛−=

)(4)(1)(

)(41)(max for 5.0

)(>

e

E

σ

εσ

)()(max εσεσ E= for 5.0)(

≤e

E

σ

εσ

where Y

ee σ

σε =Φ )( .

The )(εφe is defined as e

Ee σ

εσεφ

)()( = , then the above formulae can be expressed as follows.

Y

e

e σεφ

εεσ⎟⎟

⎠

⎞

⎜⎜

⎝

⎛−Φ=

)(4

11)()(max for 5.0)( >εφe

Yee σεεφεσ )()()(max Φ= for 5.0)( ≤εφe

where e

Ee σ

εσεφ

)()( =

For any relative strain ε , the average stress avσ in the stiffener with attached plate of width

)(εeb is given by

( ) ( ) )()( max εσεσ peStifavpStif tbAtbA +=+

YepStif

pwStifeav tbA

tbAσ

εφε

εσ ⎟⎟⎠

⎞⎜⎜⎝

⎛−

+Φ+

Φ=)(4

11)(

)( for 5.0)( >εφe

YpStif

pwStifeeav tbA

tbAσ

εεεφσ

+Φ+

Φ=)(

)()( for 5.0)( ≤εφe

CSR for Bulk Carriers, σav = σCR1 and σy = ReH, so the formulae are as follows:

eHepStif

pwStifeCR R

tbAtbA

⎟⎟⎠

⎞⎜⎜⎝

⎛−

+Φ+

Φ=)(4

11)(

)(1 εφε

εσ for 5.0)( >εφe


PAGE 4 OF 8

eHE

e

pStif

peStifeCR R

tbAtbA

⎟⎟⎠

⎞⎜⎜⎝

⎛−

++

Φ=)(4

1)(

)(1 εσσε

εσ for 5.0)(>

e

E

σεσ

pStif

peStifCeCR tbA

tbA+

+Φ=

)()( 11

εσεσ for 5.0)(

>e

E

σεσ

where ⎟⎟⎠

⎞⎜⎜⎝

⎛−=

)(411 εσ

σσE

eeHC R and εσ eHe R=

pStif

peStifCeCR tbA

tbA+

+Φ=

)()( 11

εσεσ for

2)( εεσ eH

ER

>

where ⎟⎟⎠

⎞⎜⎜⎝

⎛−=

)(411 εσ

εσE

eHeHC

RR for 2

)( εεσ eHE

R>

Therefore, the formula for 1Cσ for εσ21eH

ER

> is modified to

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

)(411 εσ

εσE

eHeHC

RR from ⎟⎟⎠

⎞⎜⎜⎝

⎛ Φ−=

)(411 εσ

εσE

eHeHC

RR

The formula for 1Cσ for εσ21eH

ER

≤ is obtained as follows in the same manner.

YpS

pwSeeCR tbA

tbAσ

εεεφσ

+

Φ+Φ=

)()()(1 for 5.0)( ≤εφe

eHpS

peSe

e

ECR R

tbAtbA

++

Φ=)(

)()(1

εε

σεσσ for 5.0)(

≤e

E

σεσ

eHpS

peSe

eH

ECR R

tbAtbA

R +

+Φ=

)()()(

1

εε

εεσσ for

2)( εεσ eH

ER

≤

pS

peSe

ECR tbA

tbA+

+Φ=

)()()(

1

εε

εεσσ for

2)( εεσ eH

ER

≤

pS

peSCeCR tbA

tbA+

+Φ=

)()( 11

εσεσ for

2)( εεσ eH

ER

≤

where ε

εσσ )(1

EC = for

2)( εεσ eH

ER

≤

Therefore, the modification of formula for 1Cσ for εσ21eH

ER

≤ is not necessary.

The proposed modification of the formula for the load-end shortening curve of torsional buckling and web local buckling of ordinary stiffeners made of flat bars can be obtained by the same manner mentioned above. 2.3 Determination of the load-end shortening curve σCR1-ε – plate buckling The ultimate strength for plate panel element is approximated by the following formula.


PAGE 5 OF 8

Ycr ab

ab σ

βββσ

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟⎟

⎠

⎞⎜⎜⎝

⎛−=

2

20

200

1111.025.125.2

where Et

b Yσβ =0

As for transversely stiffened panels, the above equation can be generalised to any edge stress

eσ according to:

Yweew σεεσεεσ )()()()(max ΦΦ=Φ=

where 2

22 )(1111.0

)(25.1

)(25.2)( ⎟⎟

⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟⎟

⎠

⎞⎜⎜⎝

⎛−=Φ

εβεβεβε

eeew a

bab

( )εβ e = εβ0 yee σεσ )(Φ= In CSR for Bulk Carriers, σmax = σCR5 and σy = ReH,, a = l and b = s, so the formula is as follows:

eHeee

eCR Rss⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟⎟

⎠

⎞⎜⎜⎝

⎛−Φ=

2

225 )(1111.0

)(25.1

)(25.2)()(

εβεβεβεεσ

ll

In addition, ultimate strength of transversely stiffened panels is controlled by the yielding stress of the material.

Therefore, 5CRσ is modified to

{

{⎪⎪⎩

⎪⎪⎨

⎧

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟⎟

⎠

⎞⎜⎜⎝

⎛−Φ

Φ

=2

225 1111.025.125.2min

EEEeH

eH

CR

ls

lsR

R

βββσ

from

{

{⎪⎪⎩

⎪⎪⎨

⎧

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟⎟

⎠

⎞⎜⎜⎝

⎛−

Φ

=2

225 1111.025.125.2min

EEEeH

eH

CR

ls

lsR

R

βββσ

3. Impact on Scantling 3.1 The effect due to the modification of formula At first, the investigation was carried out how this modification of the formula affects the load-end shortening curve. The load-shortening curve was calculated for the following stiffened panel and plate. The material of all plates and stiffeners is HT32. Type of stiffener or plate

Angle T-Bar Flat Bar Plate

Size of stiffener 250x90x10.0/15.0 350x11.0/100x17.0 300x17.0 - Size of plate 2400x800x15.0 2400x800x15.0 2400x800x25.0 800x8000x15.0


PAGE 6 OF 8

The Fig.1 shows the results of load-shortening curve. In Fig.1, the solid line is the modified one and the broken line is the current one, and vertical line means the relative stress and horizontal line means the relative strain.

(a) Angle (b) T-Bar (c) Flat Bar (d) Plate

Fig.1 The results of load-shortening curve As shown in Fig. 1 (a), (b) and (c), the load-shortening curve for the longitudinal stiffened panel is not affected by this modification. However, as shown in Fig. 1 (d), the load-shortening curve for the buckling of plate (transversely stiffened panel) is affected by this modification, especially critical stress is decreased. In order to investigate a large decrease in critical stress for the plate due to the modification of the formulae, additional calculation of the load-shortening curve of the plate with different aspect ratio and thickness as given in the table below is carried out.

Aspect ratio = 3 Aspect ratio = 5 Aspect ratio = 10 2400 * 800*15.0, HT32 4000 * 800*15.0, HT32 8000 * 800*15.0, HT32 2400 * 800*20.0, HT32 4000 * 800*20.0, HT32 8000 * 800*20.0, HT32

The comparisons on load-shortening curves of plates with 3 different aspect ratio subjected to transverse thrust are shown in Fig.2.


PAGE 7 OF 8

(a) Aspect ratio = 10 (8000*800)

(b) Aspect ratio = 5 (4000*800)

(c) Aspect ratio = 3 (2400*800)

Fig.2 The comparison results on load-shortening curves of plates with 3 different aspect ratio


PAGE 8 OF 8

From Fig. 2, it is found that the load-shortening curve for buckling of plate decrease due to the modification of the formulae. From these results, it is obvious that this modification does not give the impact for Double side skin BC with longitudinal framing system. 3.2 Scantling impact due to this modification According to the results specified in 3.1, it was found that this modification affects the scantling of ships with transversely framing system. Then the scantling impact calculation was carried out for the following three kinds of single side skin BCs, i.e., Handy Max, Panamax and Cape size. In addition, the scantling impact calculation was carried out for one double side skin BC for reference. The ultimate bending moment capacities obtained by the modified formula were compared with those of the current one as given in the table below. The scantling impact due to this modification was calculated based on the following assumption. (1) The ultimate bending moment capacity of each ship calculated according to the current

formula is equal to the required value. (2) In order to satisfy with the required ultimate bending moment capacity, only the

thickness of upper deck plating is increased. Because as the deck plating is located apart from the neutral axis of transverse section, increasing the thickness of deck plating is very effective to improve the ultimate hull girder bending capacity.

(3) The scantling calculation is calculated based on the increase of the transverse section area within 0.4 L amidships.

The scantling increase due to this modification was also given in the table. Ratio

(=Modification/ current) Difference of ultimate bending moment capacities

Scantling increase

SSS Handy max 96.1 % -3.9% 0.82 % SSS Panamax 97.6% -2.4% 0.68% SSS Cape size 98.4% -1.6% 0.58% DSS Cape size 100.0% 0.0% 0.0%

***** End *****

RULE CHANGE NOTICE 2 COMMON STRUCTURAL RULES FOR BULK CARRIERS

PAGE 1 OF 7


Rule Change Notice 2 February 2008

Notes: (1) This Rule change shall apply to ships contracted for construction on or after 1 July 2008. The Rule change may be adopted before 1 July 2008 at the discretion of the Society.





PAGE 2 OF 7

For technical background for Rule Changes in this present document, reference is made to separate document Technical Background for Rule Change Notice 2.

CHAPTER 3 – STRUCTURAL DESIGN PRINCIPLES SECTION 6 STRUCTURAL ARRANGEMENT PRINCIPLES

9. Deck structure

9.5 Hatch supporting structure 9.5.2

Clear of openings, adequate continuity of strength of longitudinal hatch coamings is to be ensured by under deck girders.

The connection of hatch end beams to longitudinal girders and web frames is to be ensured. Hatch end beams are to be aligned with transverse web frames in top side tanks.

9.5.3

Clear of openings, adequate continuity of strength of longitudinal hatch coamings is to be ensured by under deck girders.

At hatchway corners, the face plate of hatch coamings and longitudinal deck girders or their extension parts provided under deck in line with hatch coamings and the face plates of hatch end beams girders on both sides are to be effectively connected so as to maintain the continuity in strength.

9.6 Openings in the strength deck 9.6.3 Corner of hatchways

For hatchways located within the cargo area, insert plates, whose thickness is to be determined according to the formula given after, are generally to be fitted in way of corners where the plating cut-out has a circular profile.

The radius of circular corners is to be not less than 5% of the hatch width, where a continuous longitudinal deck girder is fitted below the hatch coaming.

Corner radius, in the case of the arrangement of two or more hatchways athwartship, is considered by the Society on a case by case basis.

For hatchways located within the cargo area, insert plates are, in general, not required in way of corners where the plating cut-out has an elliptical or parabolic profile and the half axes of elliptical openings, or the half lengths of the parabolic arch, are not less than:

• 1/20 of the hatchway width or 600 mm, whichever is the lesser, in the transverse direction


PAGE 3 OF 7

• twice the transverse dimension, in the fore and aft direction.

Where insert plates are required, their net thickness is to be obtained, in mm, from the following formula:

tbt INS )/..( l4080 +=

without being taken less than t or greater than 1.6t

where:

l : Width, in m, in way of the corner considered, of the cross deck strip between two consecutive hatchways, measured in the longitudinal direction (see Fig 23)

b : Width, in m, of the hatchway considered, measured in the transverse direction (see Fig 23)

t : Actual net thickness, in mm, of the deck at the side of the hatchways.

For the extreme corners of end hatchways, the thickness of insert plates is to be 60% greater than the actual thickness of the adjacent deck plating. A lower thickness may be accepted by the Society on the basis of calculations showing that stresses at hatch corners are lower than permissible values.

Where insert plates are required, the arrangement is shown in Fig 25, in which d1, d2, d3 and d4 are to be greater than the ordinary stiffener spacing.

For hatchways located outside the cargo area, a reduction in the thickness of the insert plates in way of corners may be considered by the Society on a case by case basis.

For ships having length L of 150 m or above, the corner radius, the thickness and the extent of insert plate may be determined by the results of a direct strength assessment according to Ch 7, Sec 2 and Sec 3, including buckling check and fatigue strength assessment of hatch corners according to Ch 8, Sec 5.

Figure 25: Hatch corner insert plate


PAGE 4 OF 7

CHAPTER 4 – DESIGN LOADS SECTION 3 HULL GIRDER LOADS

2. Still water loads

2.1 General 2.1.2 Partially filled ballast tanks in ballast loading conditions

Ballast loading conditions involving partially filled peak and/or other ballast tanks at departure, arrival or during intermediate conditions are not permitted to be used as design conditions unless:

• design stress limits are satisfied for all filling levels between empty and full, and

• for BC-A and BC-B ships, longitudinal strength of hull girder in flooded condition according to Ch 5, Sec 1, [2.1.3] is complied with for all filling levels between empty and full.

However, for the purpose of design, it is acceptable if, in each condition at departure, arrival and, where required by [2.1.1], any intermediate condition, the tanks intended to be partially filled are assumed to be empty and full.

In addition, the specified partly filled level in the intended condition is to be considered.

To demonstrate compliance with all filling levels between empty and full, it will be acceptable if, in each condition at departure, arrival, and where required by [2.1.1], any intermediate condition, the tanks intended to be partially filled are assumed to be:

• empty

• full

• partially filled at intended level

Where multiple tanks are intended to be partially filled, all combinations of empty, full or partially filled at intended level for those tanks are to be investigated.

2.1.4 Sequential ballast water exchange

Requirements of [2.1.2] and [2.1.3] are not applicable to ballast water exchange using the sequential method.


PAGE 5 OF 7

CHAPTER 9 – OTHER STRUCTURES SECTION 2 AFT PART

5. Connection of hull structures with the rudder horn

5.1 Connection of aft peak structures with the rudder horn

5.1.3 Hull structures

Between the horn intersection with the shell and the peak tank top, the vertical extension of the hull structures is to be not less than the horn height, defined as the distance from the horn intersection with the shell to the mid-point of the lower horn gudgeon.

The vertical extension of hull structure to support the rudder horn between the horn intersection with the shell and the peak tank top is in accordance with the requirements of Ch 10, Sec 1, [9.2.6] and [9.2.7].

The thickness of the structures adjacent to the rudder horn, such as shell plating, floors, platforms and side girders, the centreline bulkhead and any other structures, is to be adequately increased in relation to the horn scantlings.

SECTION 4 SUPERSTRUCTURES AND DECKHOUSES

5. Superstructure end bulkheads and deckhouse walls End bulkheads of superstructure and deckhouse

5.1 Application

5.1.1

The requirements in 5.2 and 5.3 apply to end bulkhead of superstructure and deckhouse superstructure end bulkheads and deckhouse walls forming the only protection for openings, are required by ILLC as amended, and for accommodation.

5.3 Scantling

5.3.1 Stiffeners

The section modulus w, in cm3, and the shear area Ash, in cm2, of the stiffeners is not to be less than the value obtained from the following formula:

2350 lskpw A.=

This requirement assume the webs of lowest tier stiffeners to be efficiently welded to the decks. Scantlings for other types of end connections may be specially considered.


PAGE 6 OF 7

The section modulus of deckhouse side stiffeners needs not to be greater than that of side frames on the deck situated directly below; taking account of spacing s and span l .


PAGE 7 OF 7

CHAPTER 13 – SHIPS IN OPERATION, RENEWAL CRITERIA

SECTION 1 MAINTENANCE OF CLASS

1. General

1.2 Definitions

1.2.2 Substantial corrosion

Substantial corrosion is an extent of corrosion such that assessment of the corrosion pattern indicates a wastage in excess of 75% of allowable margins but within acceptable limits gauged (or measured) thickness between trenewal and trenewal + treserve.

The allowable margin is the total corrosion addition tC, as defined in Ch 3, Sec 3.

TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE 2 COMMON STRUCTURAL RULES FOR BULK CARRIERS

PAGE 1 OF 7


Technical Background for Rule Change Notice 2

February 2008




PAGE 2 OF 7

Technical Background for the Changes in: Chapter 3/Section 6/9.5.2 1. Reason for the Rule Change: Chapter 3/Section 6/9.5.2 This change is made to clarify the requirement. In order to clarify the requirement, the first sentence is moved to 9.5.3. 2. Impact on Scantling There is no change in terms of the steel weight by comparing that before and after the proposed Rule change. Chapter 3/Section 6/9.5.3 1. Reason for the Rule Change: Chapter 3/Section 6/9.5.3 The change is made to clarify the requirement. The word “the face plate of” was deleted, taking into account the current design of BC. 2. Impact on Scantling There is no change in terms of the steel weight by comparing that before and after the proposed Rule change.


PAGE 3 OF 7

Chapter 3/Section 6/9.6.3 Corner of hatchways 1. Reason for the Rule Change: Chapter 3/Section 6/9.6.3 For ships having length L of 150 m and above, FEA including buckling check, hull girder ultimate strength check and fatigue check of hatch corners are required by the CSR for bulk carriers. Therefore, it is considered that the extent of insert plate can be determined based on such evaluation result in lieu of the requirement of this sub-section. 2. Impact on Scantling There may be slight change in terms of the steel weight by comparing that before and after the proposed Rule change. In any case, however, there is no influence for on the structural integrity of the ship.


PAGE 4 OF 7

Chapter 4/Section 3/2.1.2 and 2.1.4 1. Reason for the Rule Change: Chapter 4/Section 3/2.1.2 and 2.1.4 This rule change is made to be in line with the revision 5 (Jan 2005) of IACS UR S11. The last 2 sentences of [2.1.2] and new paragraph [2.1.4] correspond to the applicable parts of IACS UR S11.2.1.3 and S11.2.1.5 respectively. 2. Impact on Scantling The rule change proposal has no impact on scantling as the IACS UR S11 should have been applied by designer. No consequence assessment is considered necessary.


PAGE 5 OF 7

Chapter 9/Section 2/5.1.3 Hull structures 1. Reason for the Rule Change: Chapter 9/Section 2/5.1.3 A significant number of questions and comments have been raised with respect to the vertical extension of the internals in way of the rudder horn (e.g., aft peak floors). When the vertical extension is required not to be less than the horn height, defined as the distance from the horn intersection with the shell to the mid-point of the lower horn gudgeon, it is quite different from the current designs and designers have indicated that this is excessive. The change is made so that the required vertical extension becomes practical and a cross reference to the floor and girder requirements of Ch.10, Sec.1 [9.2.6] and 9.2.7] is provided. The requirements of Ch.10, Sec.1 [9.2.6] through [9.2.10] include general prescriptive requirements for the strengthening and alignment of floors and girders in way of the rudder horn. These prescriptive requirements have been shown to provide adequate stiffness in the stern construction area in order to support the rudder forces and to prevent unfavourable hull vibration due to the propeller wake, as they are similar to the existing rules which have resulted in sufficient structure. The aft peak structure in the vicinity of the attachment of horn, peak tank plate and closely spaced floors, can fairly distribute rudder force into hull structures. As is the case with any other part of the structure, unless there is some unusual or novel arrangement, further detailed analytical checks are not considered necessary. The connection of the rudder horn is handled in CSR for Double Hull Oil Tankers 8/5.2.2.3 and are fairly similar to the above mentioned Ch.10 Sec. 1 [9.2.6] through [9.2.10]. 2. Impact on Scantling There may be slight change in terms of the steel weight by comparing that before and after the proposed Rule change. In any case, however, there is no influence on the structural integrity of the ship. Chapter 9/Section 4/5 & 5.1.1 Application Considering the comments from Technical Committee, the editorial correction of the title of Ch 9 Sec 4 [5] and the text of Ch 9 Sec 4 [5.1.1] is made to be in line with IACS UR S 3. Chapter 9/Section 4/5.3.1 Stiffeners There is no formula for required shear area for stiffeners of end bulkheads of superstructure and deckhouses. Therefore, the corresponding words are deleted.


PAGE 6 OF 7

There is no formula for required shear area for stiffeners of superstructure end bulkheads and deckhouses wall. Therefore, the corresponding words are deleted. 2. Impact on Scantling There is no change in terms of the steel weight by comparing that before and after the proposed Rule change.


PAGE 7 OF 7

Chapter 13/Section 1/1.2.2 Substantial corrosion 1. Reason for the Rule Change: Chapter 13/Section 1/1.2.2 This change is made to be consistent with Chapter 13/Section 2/3.2.2 and IACS UR Z10.2.1.2.11 (Rev. 22 June 2006). 2. Impact on Scantling There is no change in terms of the steel weight by comparing that before and after the proposed Rule change.

***** End *****


PAGE 1 OF 40





(3) Users are reminded that the formula in Chapter 5, Appendix 1, 2.2.8, was corrected by Rule Change Notice No.1, November 2007.

• Details about the IACS CSR Knowledge Centre (KC) ID Numbers can be found on

the IACS CSR web site (www.iacs.org.uk) under the headings of ‘Questions and Answers and Common Interpretations‘.




PAGE 2 OF 40

CHAPTER 1 – GENERAL PRINCIPLES

SECTION 4 SYMBOLS AND DEFINITIONS

2. Symbols

2.1 Ship’s main data

2.1.1

V : Maximum ahead service speed, in knots, means the greatest speed which the ship is designed to maintain in

service at her deepest seagoing draught at the maximum propeller RPM and corresponding engine MCR

(Maximum Continuous Rating).

Reason for the Rule Clarification: This editorial correction is made to be in line with the definition in the IACS Common Structural Rules for Double Hull Oil Tankers. (Refer to KC ID 514)


PAGE 3 OF 40

CHAPTER 2 – GENERAL ARRANGEMENT DESIGN

SECTION 3 ACCESS ARRANGEMENT

2. Technical provisions for means of access

2.3 Construction of ladders

2.3.2 Inclined ladders Ref. IMO Technical Provisions, 3.6 (Resolution MSC.158(78))

The width of inclined ladders between stringers is to be not less than 400 mm. The treads are to be equally

spaced at a distance apart, measured vertically, of between 200 mm and 300 mm. When steel is used, the treads

are to be formed of two square bars of not less that than 22 mm by 22 mm in section, fitted to form a horizontal

step with the edges pointing upward. The treads are to be carried through the side stringers and attached thereto

by double continuous welding. All inclined ladders are to be provided with handrails of substantial construction

on both sides, fitted at a convenient distance above the treads.

Reason for the Rule Clarification: Editorial correction.


PAGE 4 OF 40

CHAPTER 3 – STRUCTURAL DESIGN PRINCIPLES

SECTION 1 MATERIAL

2. Hull structural steel

2.3 Grades of steel

2.3.7 In specific cases, such as [2.3.6] [2.3.8], with regard to stress distribution along the hull girder, the classes

required within 0.4L amidships may be extended beyond that zone, on a case by case basis.



PAGE 5 OF 40

Table 4 Application of material classes and grades

Material class Structural member category Within 0.4L

amidship Outside 0.4L

amidship SECONDARY Longitudinal bulkhead strakes, other than that belonging to the Primary category Deck Plating exposed to weather, other than that belonging to the Primary or Special category Side plating (7)

I A/AH

PRIMARY Bottom plating, including keel plate Strength deck plating, excluding that belonging to the Special category Continuous longitudinal members above strength deck, excluding hatch coamings Uppermost strake in longitudinal bulkhead Vertical strake (hatch side girder) and uppermost sloped strake in top wing tank

II A/AH

SPECIAL Sheer strake at strength deck (1), (6) Stringer plate in strength deck (1), (6) Deck strake at longitudinal bulkhead (6) Strength deck plating at corners of cargo hatch openings in bulk carriers, ore carriers, combination carriers and other ships with similar hatch openings configuration (2) Bilge strake (3), (4), (6) Longitudinal hatch coamings of length greater than 0.15L (5) Web of lower bracket of side frame of single side bulk carriers having additional service feature BC-A or BC-B (5) End brackets and deck house transition of longitudinal cargo hatch coamings (5)

III II

(I outside 0.6L amidships)

Notes: (1) Not to be less than grade E/EH within 0.4L amidships in ships with length exceeding 250 m.

(2) Not to be less than class III within 0.6L amidships and class II within the remaining length of the

cargo region.

(3) May be of class II in ships with a double bottom over the full breadth and with length less than

150 m.

(4) Not to be less than grade D/DH within 0.4L amidships in ships with length exceeding 250 m.

(5) Not to be less than grade D/DH.

(6) Single strakes required to be of class III or of grade E/EH and within 0.4L amidships are to have

breadths, in m, not less than 0.8 + 0.005L, need not be greater than 1.8 m, unless limited by the

geometry of the ship's design.

(7) For BC-A and BC-B ships with single side skin structures, side shell strakes included totally or

partially between the two points located to 0.125l above and below the intersection of side shell

and bilge hopper sloping plate are not to be less than grade D/DH, l being the frame span.

Reason for the Rule Clarification: The editorial correction is made to clarify the application of structural members. (Refer to KC ID 502)


PAGE 6 OF 40

SECTION 6 STRUCTURAL ARRANGEMENT PRINCIPLES

8. Single side structure

8.3 Side frames

8.3.1 General Frames are to be built-up symmetrical sections with integral upper and lower brackets and are to be arranged

with soft toes.

The side frame flange is to be curved (not knuckled) at the connection with the end brackets. The radius of

curvature is not to be less than r, in mm, given by:

Cf

f

ttb

r+

=23.0

Cf

f

ttb

r+

=24.0

where:

tC : Corrosion addition, in mm, specified in Ch 3, Sec 3

bf and tf : Flange width and net thickness of the curved flange, in mm. The end of the flange is to be sniped.

In ships less than 190 m in length, mild steel frames may be asymmetric and fitted with separate brackets. The

face plate or flange of the bracket is to be sniped at both ends. Brackets are to be arranged with soft toes.

The dimensions of side frames are defined in Fig 19.

Reason for the Rule Clarification: This correction is made to be in line with IACS UR S12. (Refer to KC ID 564)


10.4 Corrugated bulkhead

10.4.4 Span of corrugations The span lC of the corrugations is to be taken as the distance shown in Fig 29.

For the definition of lC, the height of the upper and lower stools may not be taken smaller than the values

specified in [10.4.7] and [10.4.8] the internal end of the upper stool is not to be taken more than a distance from

the deck at the centre line equal to:

- 3 times the depth of corrugation, in general

- 2 times the depth of corrugation, for rectangular stool

Reason for the Rule Clarification: This correction is made to be in line with IACS UR S18. (Refer to KC ID 424 & 445)

10.4.7 Lower stool The lower stool, when fitted, is to have a height in general not less than 3 times the depth of the corrugations.


PAGE 7 OF 40

The net thickness and material of the stool top plate are to be not less than those required for the bulkhead

plating above. The thickness and material properties of the upper portion of vertical or sloping stool side plating

within the depth equal to the corrugation flange width from the stool top are to be not less than the required

flange plate thickness and material to meet the bulkhead stiffness requirement at the lower end of the

corrugation.

The ends of stool side ordinary stiffeners, when fitted in a vertical plane, are to be attached to brackets at the

upper and lower ends of the stool.

The distance d from the edge of the stool top plate to the surface of the corrugation flange is to be in accordance

with Fig 30.

The stool bottom is to be installed in line with double bottom floors or girders as the case may be, and is to have

a width not less than 2.5 times the mean depth of the corrugation.

The stool is to be fitted with diaphragms in line with the longitudinal double bottom girders or floors as the case

may be, for effective support of the corrugated bulkhead. Scallops in the brackets and diaphragms in way of the

connections to the stool top plate are to be avoided.

Where corrugations are cut at the lower stool, corrugated bulkhead plating is to be connected to the stool top

plate by full penetration welds. The stool side plating is to be connected to the stool top plate and the inner

bottom plating by either full penetration or deep penetration welds. The supporting floors are to be connected to

the inner bottom by either full penetration or deep penetration weld. The weld of corrugations and stool side

plating to the stool top plate are to be full penetration one. The weld of stool side plating and supporting floors to

the inner bottom plating are to be full penetration or deep penetration welds.

Reason for the Rule Clarification: This correction is made to be in line with IACS UR S18. (Refer to KC ID 337)


PAGE 8 OF 40

CHAPTER 4 – DESIGN LOADS

SECTION 5 EXTERNAL PRESSURES AND FORCES

3. External pressures on superstructures and deckhouses

3.2 Exposed wheel house tops 3.2.1 The lateral pressure for exposed wheel house tops, in kN/m2, is not to be taken less than:

5.2=p 5.12=p

Reason for the Rule Clarification: Editorial correction regarding the minimum pressure for superstructures, etc. is made because it is a typo (Refer to KC ID 478).

3.4 End Superstructure end bulkheads of superstructure and deckhouse 3.4.1 The lateral pressure, in kN/m2, for determining the scantlings is to be obtained from the greater of the following

formulae:

[ ])( TzbCncpA −−=

minAA pp =

where:

n : Coefficient defined in Tab 7, depending on the tier level.

The lowest tier is normally that tier which is directly situated above the uppermost continuous deck to

which the depth D is to be measured. However, where the actual distance (D-T) exceeds the minimum

non-corrected tabular freeboard according to ILLC as amended by at least one standard superstructure

height as defined in Ch 1, Sec 4, [3.18.1], this tier may be defined as the 2nd tier and the tier above as

the 3rd tier

c : Coefficient taken equal to:

1

17.03.0Bbc +=

For exposed parts of machinery casings, c is not to be taken less than 1.0

1b : Breadth of deckhouse at the position considered

1B : Actual maximum breadth of ship on the exposed weather deck at the position considered.

11 Bb is not to be taken less than 0.25

b : Coefficient defined in Tab 8

x : X co-ordinate, in m, of the calculation point for the bulkhead considered. When determining sides of a

deckhouse, the deckhouse is to be subdivided into parts of approximately equal length, not exceeding

L15.0 each, and x is to be taken as the X co-ordinate of the centre of each part considered.

z : Z co-ordinate, in m, of the midpoint of stiffener span, or to the middle of the plate field


PAGE 9 OF 40

l : Span, in m, to be taken as the superstructure height or deckhouse height respectively, and not less than

2.0 m

pAmin : Minimum lateral pressure, in kN/m2, defined in Tab 9.

Table 7 : Coefficient n

(Note: Change in title only, no change in Tab 7)

Table 8 : Coefficient b

(Note: Change in title only, no change in Tab 8)

Table 9 : Minimum lateral pressure pAmin

pAmin, in kN/m2

L Lowest tier of unprotected fronts Elsewhere (1)

25090 ≤< L 10

25 L+

205.12 L

+

250>L 50 25 (1) For the 4th tier and above, minAp is to be taken equal to 2.5 12.5kN/m2.

Reason for the Rule Clarification: Editorial correction (Refer to KC ID 478 and 479)

4. PRESSURE IN BOW AREA

4.1Bow flare area pressure

4.1.1 The bow pressure, in kN/m2, to be considered for the reinforcement of the bow flare area is to be obtained from


( )WSFB ppKp +=

where:

pS, pW : Hydrostatic pressure and maximum hydrodynamic pressures among load cases H, F, R and P,

calculated in normal ballast condition at TB

K : Coefficient taken equal to:

( )( )

( )B

BB

FL Tz

Lx

CCC

LVcK −+

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛⎟⎠⎞

⎜⎝⎛ −++

+= 10

7.02017.042

6.02.02

2

to be taken not less than 1.0

cFL : Coefficient taken equal to:

cFL = 0.8 in general

αsin09.12.14.0

−=FLc where the flare angle α is greater than 40°


PAGE 10 OF 40

Where, the flare angle α at the load calculation point is to be measured in plane of the frame between a vertical line and the tangent to the side shell plating. (see Fig 7)

Figure 7: The definition of the flare angle Reason for the Rule Clarification: Clarification of the definition of flare angle (Refer to KC ID 533)

z

Flare angle

tangent to the side shell

α

C L TB

load calculation point

Plane of the frame x


PAGE 11 OF 40

CHAPTER 5 – HULL GIRDER STRENGTH

SECTION 1 YIELDING CHECK

3. Checking criteria

3.1 Normal stresses 3.1.1 It is to be checked that the normal stresses σ1 calculated according to [2.1.2] and, when applicable, [2.1.3] are in

compliance with the following formula:

σ1 ≤ σ1,ALL

where:

σ1,ALL : Allowable normal stress, in N/mm2, obtained from the following formulae:

9.0for130

9.07.0for7.01500190

7.03.0for190

3.01.0for3.01500190

1.0for130

,1

2

,1

,1

2

,1

,1

≥=

<<⎟⎠⎞

⎜⎝⎛ −−=

≤≤=

<<⎟⎠⎞

⎜⎝⎛ −−=

≤=

Lx

k

Lx

Lx

kk

Lx

k

Lx

Lx

kk

Lx

k

ALL

ALL

ALL

ALL

ALL

σ

σ

σ

σ

σ

Reason for the Rule Clarification: Editorial correction

4. Section modulus and moment of inertia

4.5 Extent of higher strength steel 4.5.1 When a material factor for higher strength steel is used in calculating the required section modulus at bottom or

deck according to [4.2] or [4.3], the relevant higher strength steel is to be adopted for all members contributing to

the longitudinal strength (see [1]), at least up to a vertical distance, in m, obtained from the following formulae:

• above the baseline (for section modulus at bottom):

DDB

ALLBHB z

kV

11

,11

σσσσ

+

−=

9.0for130

9.07.0for7.01500190

7.03.0for190

3.01.0for3.01500190

1.0for130

,1

2

,1

,1

2

,1

,1

≥=

<<⎟⎠⎞

⎜⎝⎛ −−

≤≤=

<<⎟⎠⎞

⎜⎝⎛ −−=

≤=

Lx

k

Lx

Lx

kk

Lx

k

Lx

Lx

kk

Lx

k

ALL

ALL

ALL

ALL

ALL

σ

σ

σ

σ

σ


PAGE 12 OF 40

• below a horizontal line located at a distance VD (see [1.4.2]) above the neutral axis of the hull

transverse section (for section modulus at deck):

( )DDB

ALLDHD VN

kV +

+

−=

11

,11

σσσσ

where:

σ1B, σ1D : Normal stresses, in N/mm2, at bottom and deck, respectively, calculated according to [2.1.2]

zD : Z co-ordinate, in m, of the strength deck defined in [1.3], with respect to the reference co-ordinate

system defined in Ch 1, Sec 4, [4]



PAGE 13 OF 40

APPENDIX 1 - HULL GIRDER ULTIMATE STRENGTH

Symbols For symbols not defined in this Appendix, refer to Ch 1, Sec 4.

IY : Moment of inertia, in m4, of the hull transverse section around its horizontal neutral axis, to be

calculated according to Ch 5, Sec 1, [1.5.1]

ZAB, ZAD : Section moduli, in cm3 m3 at bottom and deck, respectively, defined in Ch 5, Sec 1, [1.4.2].


2. CRITERIA FOR THE CALCULATION OF THE CURVE M-Χ

2.1 Simplified method based on incremental-iterative approach

2.1.2 Assumption In applying the procedure described in [2.1.1], the following assumptions are generally to be made:

• the ultimate strength is calculated at hull transverse sections between two adjacent transverse webs.

• the hull girder transverse section remains plane during each curvature increment.

• the hull material has an elasto-plastic behaviour.

• the hull girder transverse section is divided into a set of elements, which are considered to act

independently.

These elements are: – transversely framed plating panels and/or ordinary stiffeners with attached plating, whose structural

behaviour is described in [2.2.1]

– hard corners, constituted by plating crossing, whose structural behaviour is described in [2.2.2].

• according to the iterative procedure, the bending moment Mi acting on the transverse section at each

curvature value χi is obtained by summing the contribution given by the stress σ acting on each element. The

stress σ, corresponding to the element strain ε, is to be obtained for each curvature increment from the non-

linear load-end shortening curves σ- ε - of the element.

These curves are to be calculated, for the failure mechanisms of the element, from the formulae specified in

[2.2]. The stress σ is selected as the lowest among the values obtained from each of the considered load-end

shortening curves σ- ε.

• The procedure is to be repeated until the value of the imposed curvature reaches the value χF, in m-1, in

hogging and sagging condition, obtained from the following formula:

Y

YF EI

M003.0±=χ

where:

MY : the lesser of the values MY1 and MY2, in kN.m:

MY1 = 10-3 ReH ZAB MY1 = 103 ReH ZAB


PAGE 14 OF 40

MY2 =10-3 ReH ZAD MY2 =103 ReH ZAD

If the value χF is not sufficient to evaluate the peaks of the curve M-χ, the procedure is to be repeated until the

value of the imposed curvature permits the calculation of the maximum bending moments of the curve.



2.2.6 Web local buckling of ordinary stiffeners made of flanged profiles The equation describing the load-end shortening curve σCR1-ε σCR3-ε for the web local buckling of flanged

ordinary stiffeners composing the hull girder transverse section is to be obtained from the following formula:

ffwwp

ffwwepEeHCR tbthst

tbthtbΦR

++

++= 3

3

3 10

10σ

where


bE : Effective width, in m, of the attached shell plating, defined in [2.2.4]

hwe : Effective height, in mm, of the web, equal to:

www

we hh ⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

25.125.2ββ

for 25.1>wβ

wwe hh = for 25.1≤wβ

ER

th eH

w

ww

εβ =





⎪⎪⎩

⎪⎪⎨

⎧

⎥⎥

⎦

⎤

⎢⎢

⎣

⎡

⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟

⎟⎠

⎞⎜⎜⎝

⎛−

=2

225 1111.025.125.2min

EEEeH

eH

CR ssR

ΦR

βββσ

ll

where:


βE : Coefficient defined in [2.2.4]. ER

ts eH

pE

εβ 310=

s: plate breadth, in m, taken as the spacing between the ordinary stiffeners


PAGE 15 OF 40

l: longer side of the plate, in m.

Reason for the Rule Clarification: Clarification of the formula (Refer to KC ID 428) Note: Users are reminded that the formula in Chapter 5, Appendix 1, 2.2.8, was corrected by Rule Change

Notice No.1, November 2007.


PAGE 16 OF 40

CHAPTER 6 – HULL SCANTLINGS

SECTION 1 PLATING

2. Sheer strake

2.5 Welded sheer strake

2.5.3 Net thickness of the sheer strake in way of breaks of long effective superstructures The net thickness of the sheer strake is to be increased in way of breaks of long effective superstructures

occurring within 0.5L amidships, over a length of about one sixth of the ship’s breadth on each side of the

superstructure end.

This increase in net thickness is to be equal to 40% of the net thickness of sheer strake, but need not exceed

4.5 mm.

Where the breaks of superstructures occur outside 0.5L amidships, the increase in net thickness may be reduced

to 30%, but need not exceed 2.5 mm.

2.5.4 Net thickness of the sheer strake in way of breaks of short non-effective superstructures The net thickness of the sheer strake is to be increased in way of breaks of short non-effective superstructures

occurring within 0.6L amidships, over a length of about one sixth of the ship’s breadth on each side of the

superstructure end.

This increase in net thickness is to be equal to 15% of the net thickness of sheer strake, but need not exceed

4.5 mm.

Reason for the Rule Clarification: This correction is made to be in line with the definition specified in Ch 9 Sec 4 [1.1.5] (Refer to KC ID 518).

Similar correction is made for “short superstructure”.

3. STRENGTH CHECK OF PLATING SUBJECTED TO LATERAL PRESSURE

3.1 Load model

3.1.3 Lateral pressure in flooded conditions The lateral pressure in flooded conditions pF is defined in Ch 4, Sec 6, [3.2.1].

Reason for the Rule Clarification: This correction is made for the clarification of the lateral pressure in flooding condition to be considered. (Refer to KC ID 402)


PAGE 17 OF 40

SECTION 2 - ORDINARY STIFFENERS

3. YIELDING CHECK

3.1 Load model

3.1.3 Lateral pressure in flooded conditions The lateral pressure in flooded conditions pF is defined in Ch 4, Sec 6, [3.2.1].

Reason for the Rule Clarification: This correction is made for the clarification of the lateral pressure in flooding condition to be considered. (Refer to KC ID 402)

3.4 Upper and lower connections of side frames of single side bulk carriers

3.4.1 The section moduli of the:

• side shell and hopper tank longitudinals that support the lower connecting brackets,

• side shell and topside tank longitudinals that support the upper connecting brackets

are to be such that the following relationship is separately satisfied for each lower and upper connecting bracket

(see also Ch 3, Sec 6, Fig 22):

( )∑ +≥

n Y

WSTii R

ppdw

16

21

2llα

where:

n : Number of the longitudinal stiffeners of side shell and hopper / topside tank that support the lower /

upper end connecting bracket of the side frame, as applicable

wi : Net section modulus, in cm3, of the i-th longitudinal stiffener of the side shell or hopper / topside tank

that support the lower / upper end connecting bracket of the side frame, as applicable

di : Distance, in m, of the above i-th longitudinal stiffener from the intersection point of the side shell and

hopper /topside tank

l1 : Spacing, in m, of transverse supporting webs in hopper / topside tank, as applicable

Ry : Lowest value of equivalent yield stress, in N/mm2, among the materials of the longitudinal stiffeners

of side shell and hopper / topside tanks that support the lower / upper end connecting bracket of the

side frame

αT : Coefficient taken equal to:

αT = 150 for the longitudinal stiffeners supporting the lower connecting brackets

αT = 75 for the longitudinal stiffeners supporting the upper connecting brackets

l : Side frame span, in m, as defined in [3.3.1].

pS , pW : Still water and wave pressures as those for the side frame.


PAGE 18 OF 40

Reason for the Rule Clarification: This correction is made for the clarification of the pressures for upper and lower connections if side frames. (Refer to KC ID 216)

4. WEB STIFFENERS OF PRIMARY SUPPORTING MEMBERS

4.1 Net scantlings

4.1.3 Connection ends of web stiffeners Where the web stiffeners of primary supporting members are welded to ordinary stiffener face plates, the stress

at ends of web stiffeners of primary supporting members in water ballast tanks, in N/mm2, is to comply with the

following formula when no bracket is fitted :

175≤σ

where:

θσσ

cos1.1 Δ

= stifflongicon KKK

conK : Coefficient considering stress concentration, taken equal to:

5.3=conK for stiffeners in the double bottom or double side space (see Fig 8)

0.4=conK for other cases (e.g. hopper tank, top side tank, etc.) (see Fig 8)

longiK : Coefficient considering shape of cross section of the longitudinal, taken equal to:

0.1=longiK for symmetrical profile of stiffener (e.g. T-section, flat bar)

3.1=longiK for asymmetrical profile of stiffener (e.g. angle section, bulb profile)

stiffK : Coefficient considering the shape of the end of the stiffener, taken equal to:

stiffK = 1.0 for standard shape of the end of the stiffener (see Fig 9)

stiffK = 0.8 for the improved shape of the end of the stiffener (see Fig 9)

θ : As given in Fig 10

σΔ : Stress range, in N/mm2, transferred from longitudinals into the end of web stiffener, as obtained from


( ) ( )[ ] 02211'322.02

sww AAAhW

++=Δ

llσ

W : Dynamic load, in N, as obtained from the following formula:

( )spsW 5.01000 −= l

p : Maximum inertial pressure due to liquid in the considered compartment where the web stiffener

is located according to Ch 4 Sec 6 [2.2.1], in kN/m2, of the probability level of 10-4, calculated at

mid-span of the ordinary stiffener

l : Span of the longitudinal, in m

s : Spacing of the longitudinal, in m

0sA , 1wA , 2wA : Geometric parameters as given in Fig 10, in mm2

1l , 2l : Geometric parameters as given in Fig 10, in mm


PAGE 19 OF 40

'h : As obtained from following formula, in mm:

'' 0hhh s +=

sh : As given in Fig 10, in mm

'0h : As obtained from the following formula, in mm

'636.0'0 bh = for 150'≤b

63'216.0'0 += bh for '150 b<

'b : Smallest breadth at the end of the web stiffener, in mm, as shown in Fig 10

Reason for the Rule Clarification: This correction is made for the clarification of the pressure to be applied in the calculation of dynamic load transferred from the ordinary stiffeners to the ends of web stiffeners of the primary supporting members in water ballast tanks. (Refer to KC ID 327)


PAGE 20 OF 40


Symbols For symbols not defined in this Section, refer to Ch 1, Sec 4.

In this section, compressive and shear stresses are to be taken positive, tension stresses are to be taken negative.

a : Length in mm of the longer side of the partial plate field in general or length in mm of the side of the

partial plate field according Table 2, BLC 3 - 10

b : Length in mm of the shorter side of the partial plate field in general or length in mm of the side of the

partial plate field according Table 2, BLC 3 - 10

α : Aspect ratio of elementary plate panel, taken equal to:

ba

=α

n : Number of elementary plate panel breadths within the partial or total plate panel

�

�

��

��

��

��

��

��

��

Figure 1: General arrangement of panel


This correction is made for the clarification of the definition of the dimensions a and b.（Refer to KC ID 360）


PAGE 21 OF 40

Table 3: Buckling and reduction factor for curved plate panel with R/t ≤ 2500 1

Buckling-

Load Case

Aspect ratio

Rb

Buckling factor K Reduction factor κ

1a

��

��

��

tR

Rb 63.1≤

( )35.0

175.03

btR

tRbK +=

1b

��

�

��

��

�

��

��

�� !

tR

Rb 63.1>

22

2

225.23.0 ⎟⎟

⎠

⎞⎜⎜⎝

⎛+=

tbR

RbK

1=xκ for 4.0≤λ 2 λκ ⋅−= 686.0274.1x for 2.14.0 ≤< λ

265.0

λκ =x for 2.1>λ

tR

Rb 63.1≤

( )35.0

175.03

btR

tRbK +=

1a

��

��

��

1b

��

�

��

��

�

��

��

�� !

tR

Rb 63.1>

22

2

225.23.0 ⎟⎟

⎠

⎞⎜⎜⎝

⎛+=

tbR

RbK

1=xκ for 4.0≤λ 2 λκ ⋅−= 686.0274.1x for 2.14.0 ≤< λ

265.0

λκ =x for 2.1>λ

tR

Rb 5.0≤

tRbK

2

321+=

2

��

��

�

�� tR

Rb 5.0>

⎥⎥⎦

⎤

⎢⎢⎣

⎡−=

Rt

Rb

tRbK 3267.0

2

tR

b24.0≥

1=yκ for 25.0≤λ 2

λκ ⋅−= 933.0233.1y for 125.0 ≤< λ 3/3.0 λκ =y for 5.11 ≤< λ 2/2.0 λκ =y for 5.1>λ

tR

Rb

≤ 23.06.0b

tRb

tR

tRbK −+

⋅=

3

��

��

�

��

tR

Rb

> 22

2

2291.03.0 ⎟⎟

⎠

⎞⎜⎜⎝

⎛+=

tbR

RbK

as in load case 1a

tR

Rb 7.8≤

3τKK = 5.0

5.15.1

367.03.28⎥⎥⎦

⎤

⎢⎢⎣

⎡+=

tRbKτ

4

��

�

�

tR

Rb 7.8>

tRRbK

228.0=τ

1=τκ for 4.0≤λ λκτ ⋅−= 686.0274.1 for 2.14.0 ≤< λ

265.0

λκτ = for 2.1>λ


PAGE 22 OF 40

Explanations for boundary conditions - - - - - plate edge free ──── plate edge simply supported ▬▬▬ plate edge clamped 1 For curved plate fields with a very large radius the κ-value need not to be taken less than for the expanded plane field 2 For curved single fields, e.g. bilge strake, which are located within plane partial or total fields, the reduction factor κ may taken as follow:

Load case 1b: 0,18.02 ≤=

λκ x Load case 2: 0.165.0

2 ≤=λ

κ y

Reason for the Rule Clarification: This correction is made for the clarification of the buckling check for the curved plate. (Refer to KC ID 483)


PAGE 23 OF 40

SECTION 4 - PRIMARY SUPPORTING MEMBERS

1. GENERAL

1.1 Application

1.1.1 The requirements of this Section apply to the strength check of pillars and primary supporting members,

subjected to lateral pressure and/or hull girder normal stresses for such members contributing to the hull girder

longitudinal strength.

The yielding check is also to be carried out for such members subjected to specific loads.

Reason for the Rule Clarification: Editorial correction is made for the clarification of application of the primary supporting members. (Refer to KC ID 525)

1.3 Primary supporting members for ships of 150 m or more in length L

1.3.1 For primary supporting members for ships having a length L of 150 m or more, the direct strength analysis is to

be carried out according to the provisions specified in Ch 7, and the requirements in [4] are also to be complied

with. In addition, the primary supporting members for BC-A and BC-B ships are to comply with the

requirements in [3] and [4].

Reason for the Rule Clarification: Editorial correction is made for the clarification of application of the primary supporting members. (Refer to KC ID 373)

2. Scantling of primary supporting members for ships of less than 150m in length (L)

2.3 Floors

2.3.1 Net web thickness The net thickness of floors in the double bottom structure, in mm, is not to be less than the greatest of either of

the values t1 to t3 specified in the followings according to each location:

( ) ⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎟⎟⎠

⎞⎜⎜⎝

⎛ −−⎟

⎟⎠

⎞⎜⎜⎝

⎛

−=

2

'10

21 212

DB

c

DBa

DB

lxx

B

ydd

pSBCt

τ, where cxx − is less than DBl25.0 , cxx − is to be taken as

DBl25.0 , and where y is less than 4/'DBB , y is to be taken as 4/b′ 4/DBB′ ,

3 12

22

2 75.1 tCaH

t a′

⋅=τ

kS

t 23

5.8=

where :


PAGE 24 OF 40

S : Spacing of solid floors, in m

0d : Depth of the solid floor at the point under consideration in m

1d : Depth of the opening, if any, at the point under consideration in m

'DBB : Distance between toes of hopper tanks at the position of the solid floor under consideration, in m

2C : Coefficient obtained from Tab 5 depending on DBDBB l/ . For intermediate values of DBDBB l/ , 2C

is to be obtained by linear interpolation

p , BDB , cx , DBl : As defined in [2.2.1]

a : Depth of the solid floor at the point under consideration, in m. However, where horizontal stiffeners

are fitted on the floor, a is the distance from the horizontal stiffener under consideration to the bottom

shell plating or the inner bottom plating or the distance between the horizontal stiffeners under

consideration

1S : Spacing, in m, of vertical ordinary stiffeners or girders

2C ′ : Coefficient given in Tab 6 depending on 01 / dS . For intermediate values of 01 / dS , 2C ′ is to be

determined by linear interpolation.

H : Value obtained from the following formulae:

a) where openings with reinforcement or no opening are provided on solid floors:

1) where slots without reinforcement are provided:

0.10.41

2 −=Sd

H , without being taken less than 1.0

2) where slots with reinforcement are provided: 0.1=H

b) where openings without reinforcement are provided on solid floors:

1) where slots without reinforcement are provided:

0.10.45.011

2

0−⎟⎟

⎠

⎞⎜⎜⎝

⎛+=

Sd

dH φ , without being taken less than

05.01

dφ

+

2) where slots with reinforcement are provided:

05.01

dH φ

+=

2d : Depth of slots without reinforcement provided at the upper and lower parts of solid floors, in m,

whichever is greater

φ : Major diameter of the openings, in m

2S : The smaller of 1S or a , in m.



PAGE 25 OF 40

CHAPTER 7 – DIRECT STRENGTH ANALYSIS

SECTION 4 HOT SPOT STRESS ANALYSIS FOR FATIGUE STRENGTH ASSESSMENT

3. Hot Spot Stress

3.3 Simplified method for the bilge hopper knuckle part 3.3.1

Table 1: Stress concentration factor K0

Angle of hopper slope plate to the horizontal θ(deg.) Plate net thickness in FE model

t (mm) 40 45 50 90

16 3.0 3.2 3.4 4.2 18 2.9 3.1 3.3 4.0 20 2.8 3.0 3.2 3.8 22 2.7 2.9 3.1 3.6 24 2.6 2.8 3.0 3.5 26 2.6 2.7 2.9 3.4 28 2.5 2.7 2.8 3.3 30 2.4 2.6 2.7 3.2

Note: Alternatively, K0 can be determined by the following formula.

)0028.02.0(0 )5.0()0033.015.1(14.0

θθθ

+−⋅

=t

K

Reason for the Rule Clarification: Editorial correction is made for the clarification of the plate thickness. (Refer to KC ID 287)


PAGE 26 OF 40


SECTION 5 STRESS ASSESSMENT OF HATCH CORNERS

2. Nominal stress range

2.1 Nominal stress range due to wave torsional moment 2.1.1 The nominal stress range, in N/mm2, due to cross deck bending induced by wave torsion moments is to be


Q

HLSWT W

BQFF

⋅=Δ

10002σ

where:

Q

H

Q

sH

EAB

EIbB

uQ 6.212

)³(1000

++=

u : Displacement of hatch corner in longitudinal direction, in m, taken equal to:

DOCEI

MuT

WT ω1000

2.31=

DOC : Deck opening coefficient, taken equal to:

∑=

= n

iiHiH

C

BL

BLDOC

1,,

MWT : Maximum wave torsional moment, in kN.m, defined in Ch 4, Sec 3, [3.4.1], with fp = 0.5

FS : Stress correction factor, taken equal to:

5=SF

FL : Correction factor for longitudinal position of hatch corner, taken equal to:

LxFL 75.1= for 85.0/57.0 ≤≤ Lx

0.1=LF for x/L < 0.57 and x/L > 0.85

BH : Breadth of hatch opening, in m

WQ : Section modulus of the cross deck about z-axis, in m3, including upper stool, near hatch corner (see

Fig 2)

IQ : Moment of inertia of the cross deck about z-axis, in m4, including upper stool, near the hatch corner

(see Fig 2)

AQ : Effective shear area of the whole section of the cross deck, in m2, including upper stool, near the hatch

corner (see Fig 2). For the determination of the effective shear area the consideration of only the plate

elements is sufficient, and the stiffeners can be neglected.

bS : Breadth of remaining deck strip, in m, beside the hatch opening


PAGE 27 OF 40

IT : Torsion moment of inertia of ships cross section, in m4, calculated within cross deck area by

neglecting upper and lower stool of the bulkhead (see Fig 1). It may be calculated according to App 1

ω : Sector coordinate, in m2, calculated at the same cross section as IT and at the Y and Z location of the

hatch corner (see Fig 1) It may be calculated according to App 1

LC : Length of cargo area, in m , being the distance between engine room bulkhead and collision bulkhead

BH,i : Breadth of hatch opening of hatch i, in m

LH,i : Length of hatch opening of hatch i, in m

n : Number of hatches.

Reason for the Rule Clarification: Editorial correction is made for the clarification of the shear area of the cross-deck. (Refer to KC ID 355)

3. Hot spot stress

3.1 Hot spot stress range 3.1.1 The hot spot stress range, in N/mm², is to be obtained from the following formula:

WTghW K σσ Δ⋅=Δ where, Kgh : Stress concentration factor for the hatch corner, taken equal to:

⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎟⎟⎠

⎞⎜⎜⎝

⎛+

+⋅+

=65.0

22.08.023.1

13

2

a

CD

CDa

bagh r

lbl

br

rrK , to be taken not less than 1.0

⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎟⎟⎠

⎞⎜⎜⎝

⎛+

+⋅+

=65.0

22.06.123.1

213

2

a

CD

CDa

bagh r

lbl

br

rrK , to be taken not less than 1.0

where: ar : Radius, in m, in major axis

br : Radius, in m, in minor axis (if the shape of corner is a circular arc, rb is to be equal to ra)

CDl : Length of cross deck, in m, in longitudinal direction

b : Distance, in m, from the edge of hatch opening to the ship’s side

Reason for the Rule Clarification: Editorial Correction of a typo in the formula of Kgh. (Refer to KC ID 386.)


PAGE 28 OF 40

CHAPTER 9 – OTHER STRUCTURES

SECTION 1 FORE PART

3. Load model

3.2 Pressure in bow area 3.2.1 Lateral pressure in intact condition The pressure in bow area, in kN/m2, is to be taken equal to (pS+ pW).

where:


according to Ch 4, Sec 5, or internal still water and inertial pressures according to Ch 4, Sec 6, [2], to be

considered among load cases H, F, R and P.

Reason for the Rule Clarification: Editorial correction is made for the clarification of the lateral pressure in bow area. (Refer to KC ID 495)

5. Strengthening of flat bottom forward area

5.4 Primary supporting members 5.4.1 Girders The net thickness of girders in double bottom forward area, in mm, is not to be less than the greatest of either of

the value t1 to t3 specified in the followings according to each location:

( ) a

SLA

ddSpc

tτ10

1 2 −=

l

3 11

22

2 75.1 tC

aHt a

′=τ

kaC

t 13

′′=

where:

cA : Coefficient taken equal to:

cA = 3/A, with 0.13.0 ≤≤ Ac

A : Loaded area, in m2, between the supports of the structure considered, obtained from the following

formula:

A=Sl

pSL : As defined in [3.4]

S : Spacing of centre or side girders under consideration, in m

l : Spacing Span of floors centre or side girders between floors under consideration, in m

d0 : Depth of the centre or side girder under consideration, in m

d1 : Depth of the opening, if any, at the point under consideration, in m



PAGE 29 OF 40

(a) Where the girder is provided with an unreinforced opening:αφ5.01+=H

(b) In other cases: 0.1=H

φ : Major diameter of the openings, in m

α : The greater of a or 1S , in m.

a : Depth of girders at the point under consideration, in m, Where, however, if horizontal stiffeners are

fitted on the girder, “a” is the distance from the horizontal stiffener under consideration to the bottom

shell plating or inner bottom plating, or the distance between the horizontal stiffeners under

consideration

1S : Spacing, in m, of vertical ordinary stiffeners or floors

1C ′ : Coefficient obtained from Tab 5 depending on aS /1 . For intermediate values of aS /1 , 1C ′ is to be


1C ′′ : Coefficient obtained from Tab 6 depending on aS /1 . For intermediate values of aS /1 , 1C ′′ is to be

obtained by linear interpolation.

5.4.2 Floors The net thickness of floors in double bottom forward area, in mm, is not to be less than the greatest of either of

the value t1 to t3 specified in the followings according to each location:

( ) a

SLA

ddSpct

τ101 2 −

=l

3 12

22

2 75.1 tCaH

t a

′⋅=

τ

kS

t 23

5.8=

where :

cA : As defined in [5.4.1]

cA : Coefficient taken equal to:

cA = 3/A, with 0.13.0 ≤≤ Ac

A : Loaded area, in m2, between the supports of the structure considered, obtained from the following

formula:

A=Sl

pSL : As defined in [3.4]

S : Spacing of solid floors under consideration, in m

l : Spacing of girders Span of floors between centre girder and side girder or side girders under

consideration, in m

0d : Depth of the solid floor at the point under consideration in m

1d : Depth of the opening, if any, at the point under consideration in m


c) Where openings with reinforcement or no opening are provided on solid floors:


PAGE 30 OF 40

3) Where slots without reinforcement are provided:

0.10.41

2 −=Sd

H , without being taken less than 1.0

4) Where slots with reinforcement are provided: 0.1=H

d) Where openings without reinforcement are provided on solid floors:

3) Where slots without reinforcement are provided:

0.10.45.011

2

0−⎟⎟

⎠

⎞⎜⎜⎝

⎛+=

Sd

dH φ , without being taken less than

05.01

dφ

+

4) Where slots with reinforcement are provided:

05.01

dH φ

+=

2d : Depth of slots without reinforcement provided at the upper and lower parts of solid floors, in m,

whichever is greater

1S : Spacing, in m, of vertical ordinary stiffeners or girders

φ : Major diameter of the openings, in m.

a : Depth of the solid floor at the point under consideration, in m, Where, however, if horizontal

stiffeners are fitted on the floor, “a” is the distance from the horizontal stiffener under consideration

to the bottom shell plating or the inner bottom plating or the distance between the horizontal stiffeners

under consideration

2S : The smaller of 1S or a , in m

2C′ : Coefficient given in Tab 7 depending on 01 / dS . For intermediate values of 01 / dS , 2C ′ is to be


Reason for the Rule Clarification: Editorial correction is made for the clarification of spacing and span of primary supporting members. (Refer to KC ID 500)


PAGE 31 OF 40

SECTION 2 AFT PART

2. Load model

2.2 Lateral pressures 2.2.1 Lateral pressure in intact condition The aft part lateral pressure in intact conditions, in kN/m2, is to be taken equal to (pS + pW).

where:


according to Ch 4, Sec 5, or internal still water and inertial pressures according to Ch 4, Sec 6, [2], to be

considered among load cases H, F, R and P.

Reason for the Rule Clarification: Editorial correction is made for the clarification of the lateral pressure in the aft part, similar to the same clarification made in the bow area in Ch. 9, Sec.1 [3.2.1]. (Refer to KC ID 495)

4. SCANTLINGS

4.1 Side plating Plating



PAGE 32 OF 40


1. GENERAL

1. GENERAL

1.2 Scantlings 1.2.1 Net scantlings As specified in Ch 3, Sec 2 all scantlings referred to in this Section are net, i.e. they do not include any margin

for corrosion.

The gross scantlings are obtained as specified in Ch 3, Sec 3 Sec 2, 3.1[3.1].



PAGE 33 OF 40

SECTION 4 SUPERSTRUCTURES AND DECKHOUSES

1. GENERAL

1.1 Definitions

1.1.3 Long deckhouse A long deckhouse is a deckhouse the length of which within 0.4L amidships exceeds 0.2L or 12 m, whichever is

the greater. The strength of a long deckhouse is to be specially considered.

1.1.5 Non-effective superstructure For the purpose of this section, all superstructures being located beyond 0.4L amidships or having a length of

less than 0.15L or less than 12 m are considered as non-effective superstructures.

1.1.7 Effective superstructure Effective superstructure is a superstructure not covered by the definition given in [1.1.5].

Reason for the Rule Clarification: The definition for “Effective superstructure” is added for clarification.

In addition, considering the ship’s length of CSR application, unnecessary wording “12m” which is always less

than 0.15L or 0.2L is deleted.


PAGE 34 OF 40

CHAPTER 10 – HULL OUTFITTING

SECTION 1 – RUDDER AND MANOEUVRING ARRANGEMENT

3. Scantlings of the rudder stock

3.1 Rudder stock diameter

3.1.1 The diameter of the rudder stock, in m mm, for transmitting the rudder torque is not to be less than:

32.4 rRt kQD =

where:

QR : As defined in [2.1.2], [2.2.2] and [2.2.3]

The related torsional stress, in N/mm2, is:

rt k

68=τ

where:

kr : As defined in [1.4.2] and[1.4.3].


3.3 Analysis

3.3.2 Data for the analysis 10l ,.., 50l : Lengths, in m, of the individual girders of the system

10I ,.., 50I : Moments of inertia of these girders, in cm4

For rudders supported by a sole piece the length 20l is the distance between lower edge of rudder body and

centre of sole piece, and 20I is the moment of inertia of the pintle in the sole piece.

Load on rudder body, in kN/m, (general):

310 10⋅

=l

RR

Cp

Load on semi-spade rudders, in kN/m:

320

120

310

210

10

10

⋅=

⋅=

l

l

RR

RR

Cp

Cp

CR, CR1, CR2 : As defined in [2.1] and [2.2]


PAGE 35 OF 40

Z : Spring constant, in kN/m, of support in the sole piece or rudder horn respectively:

for the support in the sole piece (see Fig 3):

350

5018.6l

IZ =

for the support in the rudder horn (see Fig 4):

tb ffZ

+=

1

fb : Unit displacement of rudder horn, in m/kN, due to a unit force of 1 kN acting in the centre of support

nb IE

df3

103.1 83=

nb I

df3

21.0= (guidance value for steel)

In : Moment of inertia of rudder horn, in cm4, around the x-axis at d/2 (see Fig 4)

ft : Unit displacement due to a torsional moment of the amount 1, in m/kN

tt JG

edf2

=

28

2

1017.3

/

T

iit F

tuedf

⋅= ∑ 28

2

1014.3/

T

iit F

tuedf

⋅= ∑

for steel

G : Modulus of rigity, kN/m2: 71092.7 ⋅=G for steel

Jt : Torsional moment of inertia, in m4

FT : Mean sectional area of rudder horn, in m2

ui : Breadth, in mm, of the individual plates forming the mean horn sectional area

ti : Plate thickness of individual plate having breadth ui, in mm

e, d : Distances, in m, according to Fig 4

K11, K22, K12 : Rudder horn compliance constants calculated for rudder horn with 2-conjugate elastic supports

(Fig 5).The 2-conjugate elastic supports are defined in terms of horizontal displacements, yi, by the

following equations:

at the lower rudder horn bearing:

y1 = − K12 FA2 − K22 FA1 y1 = − K12 B2 − K22 B1

at the upper rudder horn bearing:

y2 = − K11 FA2 − K12 FA1 y2 = − K11 B2 − K12 B1

where

y1, y2 : Horizontal displacements, in m, at the lower and upper rudder horn bearings, respectively

FA1, FA2 B1,B2 :Horizontal support forces, in kN, at the lower and upper rudder horn bearings, respectively

K11, K22, K12 : Obtained, in m/kN, from the following formulae:

thh GJe

EJK λλ 2

1

3

11 33.1 +=


PAGE 36 OF 40

( )thhh GJ

eEJd

EJK λλλλ 2

1

2

1

3

12 233.1 +

⎥⎥⎦

⎤

⎢⎢⎣

⎡ −+=

( ) ( ) ( )thhhhh GJde

EJd

EJd

EJd

EJK

2

2

3

1

2

1

2

1

3

22 333.1 +

⎥⎥⎦

⎤

⎢⎢⎣

⎡ −+

−+

−+=

λλλλλλ

d : Height of the rudder horn, in m, defined in Fig 5. This value is measured downwards from the upper

rudder horn end, at the point of curvature transition, till the mid-line of the lower rudder horn pintle

λ : Length, in m, as defined in Fig 5. This length is measured downwards from the upper rudder horn end,

at the point of curvature transition, till the mid-line of the upper rudder horn bearing. For λ = 0, the

above formulae converge to those of spring constant Z for a rudder horn with 1-elastic support, and

assuming a hollow cross section for this part

e : Rudder-horn torsion lever, in m, as defined in Fig 5 (value taken at z = d/2)

J1h : Moment of inertia of rudder horn about the x axis, in m4, for the region above the upper rudder horn

bearing. Note that J1h is an average value over the length λ (see Fig 5)

J2h : Moment of inertia of rudder horn about the x axis, in m4, for the region between the upper and lower

rudder horn bearings. Note that J2h is an average value over the length d − λ (see Fig 5)

Jth : Torsional stiffness factor of the rudder horn, in m4

For any thin wall closed section

∑=

i i

i

Tth

tu

FJ24

FT : Mean of areas enclosed by outer and inner boundaries of the thin walled section of rudder horn, in m2

ui : Length, in mm, of the individual plates forming the mean horn sectional area

ti : Thickness, in mm, of the individual plates mentioned above.

Note that the Jth value is taken as an average value, valid over the rudder horn height.

Figure 5 Semi-spade rudder (with 2-conjugate elastic supports)

B3

B1

B2


PAGE 37 OF 40

Reason for the Rule Clarification: Editorial correction is made to be in line with IACS UR S10. (Refer to KC ID 558)

3.4 Rudder trunk

3.4.4 The weld at the connection between the rudder trunk and the shell or the bottom of the skeg is to be full

penetration.

The fillet shoulder radius r, in mm, is to be as large as practicable and to comply with the following formulae:

r = 60 when σ ≥ 40 / k N/mm2

r = 0.1D1 , without being less than 30, when σ < 40 / k N/mm2

without being less than 30,

where D1 is defined in [3.2.1].

The radius may be obtained by grinding. If disk grinding is carried out, score marks are to be avoided in the

direction of the weld.

The radius is to be checked with a template for accuracy. Four profiles at least are to be checked. A report is to

be submitted to the Surveyor.


5. Rudder body, rudder bearings

5.1 Strength of rudder body

5.1.3 For rudder bodies without cut-outs the permissible stress are limited to:

• bending stress, in N/mm2, due to MR defined in [3.3.3]:

110=bσ

• shear stress, in N/mm2, due to Q1 defined in [3.3.3]:

50=tτ

• equivalent stress, in N/mm2, due to bending and shear:

12032 2 =+= τσσbv 1203 22 =+= τσσ bv

In case of openings in the rudder plating for access to cone coupling or pintle nut the permissible stresses

according to [5.1.4] apply. Smaller permissible stress values may be required if the corner radii are less than

oh15.0 , where oh is the height of opening.



PAGE 38 OF 40

5.2 Rudder plating

5.2.1 The thickness of the rudder plating, in mm, is to be determined according to the following formula:

5.274.1 += kpat RP 5.274.1 += kpat RP β

where:

AC

Tp RR 310

10 += , in kN/m2

a : Smaller unsupported width of a plate panel, in m.

The influence of the aspect ratio of the plate panels may be taken into account according to Ch 3.

2

5.01.1 ⎟⎠⎞

⎜⎝⎛−=

baβ max, 1.00, if 5.2≥

ab

b greatest unsupported width of a plate panel, in m.

However, the thickness is to be not less than the thickness of the shell plating at aft part according to Ch 9, Sec 2.

Regarding dimensions and welding, [10.1.1] is to be comply with.

Reason for the Rule Clarification: Editorial correction is made to be in line with IACS UR S10 (Refer to KC 569)

10. Rudder coupling flanges

10.1.3

≥ 30°

R ≥ 100 mm

≤ 8

mmfinal machining

after welding

a

R ≥ 45 mm

2 m

m

R 8

ab

= ÷ 15

13

b

D

≥ 30°

R ≥ 100 mm

≤ 8

mmfinal machining

after welding

a

R ≥ 45 mm

2 m

m

R 8

ab

= ÷ 15

13

bD

Figure 21 Welded joint between rudder stock and coupling flange


51

31 to

ba

=


PAGE 39 OF 40

CHAPTER 11 –CONSTRUCTION AND TESTING

SECTION 2 WELDING

2. Types of welded connection

2.6 Fillet welds

Table 1 Categories of fillet welds

Category Kinds of fillet welds

As-built thickness of abutting plate, t, in

mm (1)

Leg length of fillet weld, in mm (2)

Length of fillet welds, in

mm

Pitch, in mm

F0 Double continuous weld t 0.7t - -

t ≤ 10 0.5t + 1.0 - - 10 ≤ t < 20 0.4t + 2.0 - - F1 Double

continuous weld 20 ≤ t 0.3t + 4.0 - - t ≤ 10 0.4t + 1.0 - -

10 ≤ t < 20 0.3t + 2.0 - - F2 Double continuous weld

20 ≤ t 0.2t + 4.0 - - t ≤ 10 0.3t + 1.0

10 ≤ t < 20 0.2t + 2.0 F3 Double continuous weld

20 ≤ t 0.1t + 4.0 - -

t ≤ 10 0.5t + 1.0 10 ≤ t < 20 0.4t + 2.0 F4 Intermittent weld

20 ≤ t 0.3t + 4.0 75 300

(1) t is as-built thickness of the thinner of two connected members (2) Leg length of fillet welds is made fine adjustments corresponding to the corrosion addition tC specified

in Ch 3, Sec 3, Tab 1 as follows: + 1.0 mm for 5>Ct

+ 0.5 mm for 45 >≥ Ct

+ 0.0 mm for 34 >≥ Ct

- 0.5 mm for 3≤Ct

(3) The weld sizes are to be rounded to the nearest half millimeter. Reason for the Rule Clarification: Editorial correction is made for clarification of the weld size in order to harmonize the CSR for double hull oil tanker. (Refer to KC ID 507)

2.6.2 Intermittent welds Where double continuous fillet welds in lieu of intermittent welds are applied, leg length of fillet welds is to be

of category F2 F3.



PAGE 40 OF 40

It is a typo. As its application is limited to weld connection of the secondary member not importance structural members, the lowest double continuous category, e.g., F3, was originally intended in lieu of the intermittent weld. (Refer to KC ID 508)

Common Structural Rules for Bulk Carriers Rule Change Notice 3

Page 1 of 15


Rule Change Notice 3 (Ch 8 Sec 2, 2.3 Equivalent notch stress range)

Notes: (1) These Rule Changes enter into force on 12 September 2008.




Rule Change Notice 3 Common Structural Rules for Bulk Carriers

Page 2 of 15

For technical background for Rule Changes in this present document, reference is made to separate document Technical Background for Rule Change Notice 3

Chapter 8 Fatigue Check of Structural Details

Section 2 – FATIGUE STRENGTH ASSESSMENT

2. Equivalent notch stress range

2.3 Equivalent notch stress range

2.3.1 Equivalent notch stress range The equivalent notch stress range, in N/mm2, for each loading condition is to be calculated with the following

formula:

jequivfjeq K ,, σσ ∆=∆

where:

∆σequiv , j : Equivalent hot spot stress range, in N/mm2, in loading condition “j” obtained by [2.3.2].

Kf : Fatigue notch factor defined in Tab 1.

Table 1: Fatigue notch factors Kf

Subject KfNot Grinding

Without weld grinding

Grinding With weld grinding (not applicable for

ordinary stiffeners and boxing fillet welding*1)

Butt welded joint 1.25 1.10 Fillet welded joint 1.30 1.15 *2 Non welded part 1.00 -

Note: *1 Boxing fillet welding is defined as a fillet weld around a corner of a member as an extension of the principal weld. *2 This is applicable for deep penetration welding, or full penetration welding only. In case where grinding is performed, full details regarding grinding standards including the extent, smoothness particulars, final welding profiles, and grinding workmanship as well as quality acceptance criteria are to be submitted to the Society for approval. It is preferred that any grinding is carried out by rotary burrs, is to extend below plate surfaces in order to remove any toe defects and ground areas are to have sufficient corrosion protection. Such treatments are to procedure smooth concave profiles at weld toes with the depth of these depressions penetrating into plate surfaces to at least 0.5mm below the bottom of any visible undercuts. The depth of any grooves produced is to be kept to a minimum and, in general, kept to a maximum of 1mm. Under no circumstances is grinding depth to exceed 2mm or 7 % of plate gross thickness, whichever is smaller. Grinding has to extend to 0.5 longitudinal spacing or 0.5 frame spacing at the each side of hot spot locations.

Common Structural Rules for Bulk Carriers Rule Change Notice 3

Page 3 of 15

2.3.2 Equivalent hot spot stress range The equivalent hot spot stress range, in N/mm2, is to be calculated for each loading condition with the following

formula:

jWjmeanjequiv f ,,, σσ ∆⋅=∆

where:

fmean , j : Correction factor for mean stress :

• for hatch corners fmean , j = 0.77

• for primary members and longitudinal stiffeners connections, fmean , j corresponding to the condition

“j” taken equal to:

( )⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛

∆−

+=−

25.0

,

,4

, 410ln

21,0max,4.0max

jW

jmjmeanf

σσ

σm ,1 : Local hot spot mean stress, in N/mm2, in the condition “1”, obtained from the following formulae:

• If eHW R5.26.0 1, ≥∆σ :

1,1, 18.06.0 Wm σσ ∆−=∆

• If eHW R5.26.0 1, <∆σ :

1,1, 6.0 WeHm R σσ ∆−= for 1,1,6.0 meanreseHW R σσσ −−>∆

resmeanm σσσ += 1,1, for 1,1,6.0 meanreseHW R σσσ −−≤∆

σm , j : Local hot spot mean stress, in N/mm2, in the condition “j”, obtained from the following formulae:

• If eHjW R≥,24.0 σ :

jWjjm ,)1(, 18.0 σσ ∆−=≠

• If eHjW R<,24.0 σ :

jWeHjjm R ,)1(, 24.0 σσ ∆+−=≠ for jmeanmeanmeHjW R ,1,1,,24.0 +−+>∆ σσσ

jmeanmeanmjjm ,1,1,)1(, σσσσ +−=≠ for jmeanmeanmeHjW R ,1,1,,24.0 σσσσ +−+≤∆

σmean , j : Structural hot spot mean stress, in N/mm2, corresponding to the condition “j”

σres : Residual stress, in N/mm2, taken equal to: obtained from the following formulae:

{ }4,3,2,1,max , == jjresres σσ

eHres R25.0=σ for stiffener end connection

Rule Change Notice 3 Common Structural Rules for Bulk Carriers

Page 4 of 15

0=resσ for non welded part and primary members(cruciform joint or butt weld)

{ }[ ]

{ }[ ]⎪⎪⎩

⎪⎪⎨

⎧

<+−−+−

≥−−++−

=

0for 24.024.0,max,min

0for 6.06.0,min,max

,

,,,,0

,

,,,,0

,

jmean

jWjmeanjWjmeanreseHeH

jmean

jWjmeanjWjmeanreseHeH

jres RR

RR

σσ∆σσ∆σσ

σσ∆σσ∆σσ

σ

⎩⎨⎧

=part non weldedfor0

joint weldedfor25.00

eHres

Rσ

Common Structural Rules for Bulk carriers Technical Background for Rule Change Notice 3

Page 5 of 15


Technical Background for Rule Change Notice 3

(Ch 8 Sec 2, 2.3 Equivalent notch stress range)



Technical Background for Rule Change Notice 3 Common Structural Rules for Bulk Carriers

Page 6 of 15

Technical Background for the Changes Regarding Equivalent notch stress range: 1. Reason for the Rule Change in Ch 8 Sec 2 2.3: As specified in Appendix 1, almost all damages are occurred in ballast hold. The reasons that the majority of damage caused by cracks occurs in ballast holds are as follows. Structural members in ballast holds are subject to high internal pressure due to ballast water. However, since they are subject to relatively low external pressure, high tensile stresses (both the mean stress and stress range are large) are placed on those structural members susceptible to low fatigue life such as lower stool connections and bilge knuckle connections as shown in Fig. 3.1, while, the stresses placed on structural members in cargo holds that are other than ballast holds are relatively small or compressive even in cases where their value is large. Therefore, the majority of damage caused by cracks occurs in ballast holds. In the case of bilge knuckle connections in ballast holds under heavy ballast conditions, since the sum of the tensile mean stress and 0.6 times stress range are greater than ReH, the term 0resσ does not affect any formula specified in CH 8 Sec 2 [2.3.2] of the current CSR (See the background for the treatment of residual stress specified in Appendix 2. This means that any fatigue assessment results for structural members such as those bilge knuckle connections in which damage occurs are not affected by the value of residual stress. On the other hand, with respect to those structural members in empty and loaded holds that are other than ballast holds, excessive compressive mean stresses or the mean stresses in four loading conditions are compressive or relatively low. Therefore, any fatigue assessments performed according to current rules give results which are far from our experience that less damage caused by cracks of primary members (bilge knuckles and lower stools) in empty and loaded holds other than ballast holds occur

The reasons for obtaining such results are due to the assumptions that (1) the tensile residual stresses are generated after any excessive compressive loads are removed, and (2) the existence of initial weld residual stresses of 0.25 ReH.

In some cases, the weld residual stress is released due to certain reasons for the primary members. The factors which are the cause of stress release are (i) assembly process (ii) tank test (iii) internal and external loads etc. And we obtained the remark that the weld residual stress is released even if the large compressive load is applied

Based on the above knowledge, the calculation formula of the equivalent hot spot stress range is corrected to make weld residual stress zero except the case for ordinary stiffener. Moreover, it is also known that when excessive compression loads are imposed on the welded structure and then removed, it does not lead to production of tensional residual stress. This knowledge has been reflected in the formula.

However, the assumption of initial weld residual stress is kept for longitudinal stiffeners, because longitudinal stiffeners penetrate transverse webs at so many locations that the estimation should be left on the safer side.

Furthermore, the stress concentration at the hot spots subjected to fatigue strength assessment can be mitigated by grinding as can the stress concentration in primary members. As the CSR for tankers reflects this information, the effects of stress mitigation by grinding have been included in the assessment of primary members except the connection of side frames which the boxing fillet welds are adopted, considering the actual and practical construction procedure. 2. Summary of the Rule Change 2.1 Improvement of the calculation of the equivalent hot spot stress range of primary members to include weld residual stress and excessive compressive stress (1) The current assumption of the initial weld residual stress is to be applied to the fatigue strength

assessment for longitudinal stiffeners.

Common Structural Rules for Bulk Carriers Technical Background for Rule Change Notice 3

Page 7 of 15

eHres R25.0=σ for ordinary stiffener

(2) As the effects of weld residual stress do not need to be considered for primary members, the assumption of the initial weld residual stress is to be added in a similar way to the current assumption for non welded parts in which the residual stress does not exist.

0=resσ , (for non welded part and primary members (cruciform and butt weld) 2.2 Consideration of the effects of grinding

In the calculation of hot spot stress, the coefficient for the grinding effect is to be defined with reference to the ‘International Institute of Welding (IIW) Recommendation of IIW “Fatigue design welded joint and component”’ and added to Ch8 Sec2 Table1.

According to the post welds improvements specified in “IIW Recommendations on Post Weld Improvements of Steel and Aluminum Structures, XIII-1965-00, 2004”, grinder finishing for the purpose of removing any undercut and /or smoothing any welding beads is recommended to be carried out.

The recommended practice for grinder finishing is to the plate surface to a depth of at least 0.5mm from the bottom of the visible undercut but not to exceed 1.0mm.

According to the results of experiments specified in several technical papers, the grinder effect on fatigue life is estimated to have a value of 1.3. If a value of 1.0 is used for those surfaces that are not subjected to grinder finishing then this is an improvement.

According to “IIW Recommendations for Fatigue Design of Welded Joints and Components, 2004, IIW Document XIII-1965-03/XV-1127-03” the grinder effect value is to be taken as 1.25 in order to be on the safe side. For example, (extract of IIW Rec.) No. 511

Two-sided fillets, toe ground: 100MPa Fillet weld(s) as welded : 80MPa (100/80=1.25)

The recommended value is based on the results of experiments that used specimens in well

controlled conditions. Considering that any actual grinding work on structures is not so well controlled, we feel that, to

be even more on the safe side, the grinder effect value should be even further lowered to 1.15 as proposed in Rule Change Notice 3.

Table 1 Fatigue notch factors Kf

Subject KfNot Grinding

Without weld grinding

Grinding With weld grinding

(not applicable and boxing fillet welding*1)

Butt welded joint 1.25 1.10 Fillet welded joint 1.30 1.15*2 Non welded part 1.00 -

Note: *1 Boxing fillet welding is defined as a fillet weld around a corner of a member as an extension of the principal weld. *2 This is applicable for deep penetration welding, or full penetration welding only. However, to avoid any risk of root cracking, the application of this technique is limited to deep penetration welding or full penetration welding. Furthermore, in order to ensure the effects of the grinding, procedures specified by the International Institute of Welding have been added to the Rules. 3. Effects due to this change


Page 8 of 15

To see the effects of the change to the calculation formulae of the equivalent hot spot stress range for primary members, the fatigue strength assessment of the connections of the inner bottom plate with the bilge hopper sloping plate and the lower stool side plate was carried out. For reference, all the lower stool side plates have slanted configuration.

Table 3.1 Considerable ships and cargo holds Type of ship Type of cargo holds A Cape (DSS) 170K Ballast hold Empty hold Loaded hold B Cape (SSS) 180K Ballast hold Loaded hold C Panamax (SSS) 82K Ballast hold Empty hold D Panamax (SSS) 110K Ballast hold Loaded hold E Handymax (SSS) 57K Ballast hold Empty hold The equivalent hot spot stress range and mean stress obtained by FEA are shown in Figure 3.1 The following cumulative fatigue damage was calculated from the above equivalent hot spot stress range and mean stress. (1) The cumulative fatigue damage according to the current CSR (2)(a) The cumulative fatigue damage according to the corrected formulae in 2.1 (“mod_1” in

Figure 3.2) (b) The cumulative fatigue damage according to the corrected formulae in 2.1 with the effect of

grinding in 2.2 (“mod_1(G) in Figure 3.2) The results of the cumulative fatigue damage are shown in Figure 3.2. From the results in Figure 3.2, the following can be said about the corrected formulae in 2.1. (1) There is no effect on the cumulative fatigue damage at the fatigue assessment points in ballast

holds where there was high tensional mean stress. (2) In cargo holds other than ballast holds, the cumulative fatigue damage at the fatigue assessment

points was less than that of the current CSR, when there was compressive or low tensional mean stress and the hot spot stress range was large.

(3) The relative tendency of the cumulative fatigue damage at the fatigue assessment points in ballast holds and other holds was consistent with the damage record specified in the Appendix.

(4) The cumulative fatigue damage with grinding was about 60% of that without grinding. 4. Impact on scantlings

Since the results of the fatigue strength assessment depend on various countermeasures such as grinding, additional reinforcement, inset plate or local thickness increase, and other fabrication improvements, the scantling impact due to this change cannot be estimated directly. However, the correction of the calculation formulae mitigates the excessive result on fatigue damage in cargo holds other than ballast holds, where less fatigue cracks have been found in the damage record.


Page 9 of 15

Fig. 3.1 Hot spot stress range and hot spot mean stress

A (DSS Cape)

-1065

-710

-355

0

355

710

1065

Heav

y

Hom

o

Norm

al Alt

Heav

y

Hom

o

Alt

Norm

al

Heav

y

Hom

o

Alt

Norm

al Alt

Hom

o

Heav

y

Norm

al

Heav

y

Hom

o

Alt

Norm

al Alt

Hom

o

Norm

al

Heav

y

Hom

o

Norm

al

Heav

y

Alt

Hom

o

Heav

y

Alt

Norm

al

Hom

o

Heav

y

Alt

Norm

al

Bilge(Ballast)

Lstool_Aft(Ballast)

Lstool_Fore(Ballast)

Bilge(Loaded)

Lstool_Aft(Loaded)

Lstool_Fore(Loaded)

Bilge(Empty)

Lstool_Aft(Empty)

Lstool_Fore(Empty)

Str

ess

(N/m

m2)

max

min

mean

B (SSS Cape)

-1065

-710

-355

0

355

710

1065

Heav

y

Hom

o

Norm

al

Alt

Heav

y

Hom

o

Norm

al

Alt

Heav

y

Hom

o

Alt

Norm

al

Alt

Hom

o

Heav

y

Norm

al

Hom

o

Alt

Norm

al

Heav

y

Heav

y

Hom

o

Alt

Norm

al

Bilge (Ballast) Lstool_Aft (Ballast) Lstool_Fore(Ballast)

Bilge (Loaded) Lstool_Aft (Loaded) Lstool_Fore(Loaded)

Str

ess

(N

/m

m2)

max

min

mean

Fig. 3.1 Hot spot stress range and hot spot mean stress (continued)

C (SSS Panamax)

-1065

-710

-355

0

355

710

1065

Heav

y

Hom

o

Norm

al

Alt

Heav

y

Hom

o

Norm

al

Alt

Heav

y

Hom

o

Alt

Norm

al

Heav

y

Hom

o

Alt

Norm

al

Hom

o

Heav

y

Norm

al

Alt

Hom

o

Alt

Norm

al

Heav

y

Hom

o

Alt

Norm

al

Heav

y

Bilge (Ballast) Lstool_Fore(Ballast)

Lstool_Aft(Ballast)

Bilge (Ballast) Bilge (Empty) Lstool_Aft(Empty)

Lstool_Fore(Empty)

Str

ess

(N

/mm

2)

max

min

mean


Page 10 of 15

D (SSS Panamax)

-1065

-710

-355

0

355

710

1065

Heav

y

Hom

o

Norm

al Alt

Heav

y

Hom

o

Alt

Norm

al

Heav

y

Hom

o

Alt

Norm

al Alt

Hom

o

Norm

al

Heav

y

Hom

o

Alt

Heav

y

Norm

al

Hom

o

Alt

Norm

al

Heav

y

Bilge (Ballast) Lstool_Aft (Ballast) Lstool_Fore(Ballast)

Bilge (Loaded) Lstool_Aft(Loaded)

Lstool_Fore(Loaded)

Str

ess

(N/m

m2)

max

min

mean

E (SSS Handymax)

-1065

-710

-355

0

355

710

1065

Heavy

Alt

Hom

o

Norm

al

Heavy

Alt

Hom

o

Norm

al

Heavy

Hom

o

Alt

Norm

al

Hom

o

Norm

al

Heavy

Alt

Hom

o

Alt

Heavy

Norm

al

Hom

o

Alt

Norm

al

Heavy

Bilge (Ballast) Lstool_Aft(Ballast)


Bilge (Empty) Lstool_Aft(Empty)

Lstool_Fore(Empty)

Str

ess

(N/m

m2)

max

min

mean

*"Lstool_Aft" and "Lstool_Fore" mean the lower stool of the aft end and fore end of the cargo hold.


Page 11 of 15

Fig. 3.2 Cumulative fatigue damage

A (DSS Cape)

0

0.5

1

1.5

2

Bilge(Ballast)

Lstool_Aft(Ballast)


Bilge(Loaded)

Lstool_Aft(Loaded)

Lstool_Fore(Loaded)

Bilge(Empty)

Lstool_Aft(Empty)

Lstool_Fore(Empty)

Cum

ula

tive

fat

igue d

amag

e CSR-B

mod_1

mod_1(G)

B (SSS Cape)

0

0.5

1

1.5

2

2.5

3




Lstool_Fore(Loaded)

Cum

ula

tive

fat

igue d

amag

e CSR-B

mod_1

mod_1(G)

C (SSS Panamax)

0

0.5

1

1.5

2

2.5

3

3.5

4

Bilge (Ballast) Lstool_Fore(Ballast)

Lstool_Aft(Ballast)

Bilge (Ballast) Bilge (Empty) Lstool_Aft(Empty)

Lstool_Fore(Empty)

Cum

ula

tive

fat

igue d

amag

e CSR-B

mod_1

mod_1(G)


Page 12 of 15

Fig. 3.2 Cumulative fatigue damage (Continued)

D (SSS Panamax)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5




Lstool_Fore(Loaded)

Cum

ula

tive

fat

igue d

amag

e CSR-B

mod_1

mod_1(G)

E (SSS Handymax)

0

0.5

1

1.5

2



Bilge (Empty) Lstool_Aft (Empty) Lstool_Fore(Empty)

Cum

ula

tive

fat

igue

dam

age CSR-B

mod_1

mod_1(G)

*"Lstool_Aft" and "Lstool_Fore" mean the lower stool of the aft end and fore end of the cargo hold.


Page 13 of 15

Appendix 1 Damage record The members and locations specified in Ch 8 Sec 1 of CSR for Bulk Carriers are those that have a potential risk of fatigue damage regardless of the type of hold or damage frequency. We surveyed damage data of the primary members listed below that require fatigue strength assessment in order to comprehend the exact risk of fatigue damage: • Connections between inner bottom plating and sloping and/or vertical plate of lower stool

(IB/slant of LS) • Connections between inner bottom plating and sloping plate of hopper tank

(IB/sloping of BH) • Connections between inner hull plating and sloping plate of hopper tank

(IS/sloping of BH) • Connections between transverse bulkhead and sloping plate of lower stool (TB/LS) • Connections between transverse bulkhead and sloping plate of upper stool (TB/US) • Connections between hold frames and sloping plate of lower wing tank (HF/BH) • Connections between hold frames and sloping plate of upper wing tank (HF/TST) The survey was carried out according to the following conditions.

(1) Crack damage data reported between 1996 and 2007 in the 3015 ships constructed between 1958 and 2007

(2) Damage that occurred due to design, fatigue, or unknown causes (3) For hold frames, damage of ships complying with IACS S12 (1992) Damage data is classified by the type of hold (ballast hold and cargo hold) and the number of

cases of damage is normalized by the number of classified holds per a ship. The results are given in Table A1.

Table A1 Number of cases of damage * Ballast hold Cargo hold

(No. of cases of damage / No. of cargo holds)

IB/slant of LS 365 0 IB/sloping of BH 173 0.4 IS/sloping of BH 9 0 TB/LS 92 0.2 TB/US 63 0.5 HF/BH 15 0 HF/TST 31 0 Total 748 1.1 Note * The number of cases of damage per cargo hold is the quotients of number of cargo damage divided by number of cargo holds.

As given in Table A1, the damage to members in ballast hold is 99.8% of the total number of the case of damage for primary members and the damage to holds other than ballast hold is 0.2%. About 72% of damage occurred at the connection between inner bottom plating and the sloping plate of the hopper tank and between inner bottom plating and the sloping and/or the vertical plate of the lower stool.

Common Structural Rules for Bulk carriers Technical Background for Rule Change Notice 3

Page 14 of 15

Appendix 2 Technical Background for the treatment of mean stress and residual stress 1. It is well and widely known that any initial residual stresses (σres), which are tensile and have magnitudes that are normally close to the yield stresses of materials, exist in welded joints (hot spots) or their periphery thereof.

In cases where loads are imposed onto hot spots and stresses at such hot spots reach locally yield stresses, any initial residual stresses are relaxed after the removal of such loads. This phenomenon is called the shake-down effect. This shake-down effect occurs in those perfectly elasto plastic models introduced in the Rules.

Furthermore, it is also known that static mean stresses (structural mean stresses) influence the fatigue strengths.

The effect of any mean stresses influencing the fatigue strengths can be evaluated by the sum of any residual stresses and structural mean stresses.

Since the S-N curves with slopes equal to 3, as given by UK-HSE standards, express fatigue strengths of welded structures in those cases where residual welds close to the yield stresses of materials exists, it cannot be used to evaluate the effects of mean stresses. 2. The relaxation of any initial residual stresses at hot spots can be evaluated by using shake-down models based on the assumptions of perfectly elasto plastic models. Those loads to be considered are hydrostatic loads (structural mean stresses) and hydrodynamic loads induced by waves.

Since those stress ranges due to hydrodynamic loads induced by waves are random variables in which wave heights are subject to the Gaussian process, any stresses contributing to shake-down effects depend on the periods of duration in navigating under specific loading conditions.

Assuming that ships are imposed upon by significant hydrodynamic pressure only in cases where such ships are at sea, these periods of duration for one loading condition can be set to about 10 days (105 cycles).

In this case, the magnitude of any stress ranges Sσ dominating mean stress conditions during this period can be expressed by 596.0 σ∆ (Ref. SNAJ 190, November 2001), where 5σ∆ is defined as the maximum stress range corresponding to these 105 cycles loads.

In those fatigue strength assessment procedures specified in the Rules, reference stresses correspond to 104 cycle loads. In cases where 5σ∆ is defined as the maximum stress range corresponding to 105 cycles loads, the relationship between 5σ∆ and 4σ∆ is:

45 25.1 σσ ∆=∆ Then, we can get the following relationship：

45 2.196.0 σσσ ∆=∆=S The model regarding initial residual stresses resσ , mean stresses meanσ and Sσ can be

illustrated as given in Fig. A1 and maxσ is used, in order to evaluate any shake-down effects. From the relationship illustrated by the above figure, we can get the following equation:

4max 6.05.0 σσσσσσσ ∆++=++= meanresSmeanres

3. As specified above, shake-down effects are to be considered in cases where the maxσ exceeds the yield stress of material (ReH). In such cases, any considered mean stresses can be expressed by the following equation:

46.0 σσ ∆−= eHm R In those cases where meanresS σσσ ++5.0 is less than ReH:

resmeanm σσσ +=


Page 15 of 15

The above cases are applicable to “Condition 1” which is defined the condition in which maximum stress is the largest on the tension side among the loading conditions “homogeneous”, “alternate” “normal ballast” and “heavy ballast”

According to experience as well as some studies regarding fatigue damages of side longitudinals in single hull tankers, initial weld residual stresses for welded joints such as longitudinals are conservatively given the value of 0.25 ReH.

Fig. A1 Illustration of the relationship of resσ , meanσ and Sσ

4. However, in the cases of fatigue strengths of any of the welded joints of primary members, initial residual stress values of 0.25 ReH are too conservative considering the tendency of fatigue damage, especially, in those cases where mean stresses of all loading conditions are compressions.

In the case of weld joints of primary members, any residual stresses after removal of applied loads can be still evaluated by the following equation in order to consider shake-down effects.

11' meanmres σσσ −= Where,

1mσ : the mean stress of the “Condition 1” considered the shake-down effect

1meanσ : the structural mean stress in the “Condition 1”. However, in cases where 1meanσ is a compression, 'resσ should be taken to equal 0 considering the damage tendencies of the welded joints of primary members. 5. In conclusion, the treatment of residual stresses of primary members is to be changed as specified by this Rule Change Notice 3.

0

resσ

42.1 σσ ∆=Smeanσ

46.0 σ∆

maxσ

COMMON STRUCTURAL RULES FOR BULK CARRIERS RULE CHANGE NOTICE NO.1

PAGE 1 OF 171

Common Structural Rules for Bulk Carriers, July 2008

Rule Change Notice No. 1 January 2009

Notes: (1) These Rule Changes enter into force on 1 July 2009. Copyright in these Common Structural Rules for Bulk Carriers is owned by:



RULE CHANGE NOTICE NO.1 COMMON STRUCTURAL RULES FOR BULK CARRIERS

PAGE 2 OF 171

Table of Contents Rule Change Notice No.1-1 (Hull Girder Strength) …………………...…………………3 Technical Background for Rule Change Notice No.1-1(Hull Girder Strength)…………19

Rule Change Notice No.1-2 (Hatch Covers) ………………………………………....…31 Technical Background for Rule Change Notice No.1-2 (Hatch Covers) …………..…...35

Rule Change Notice No.1-3 (Steel Coil) …………………………………….…….……41 Technical Background for Rule Change Notice No.1-3 (Steel Coil) ……..…………….51

Rule Change Notice No.1-4 (Minimum Scantling, Side Frame and Grab) ………..……71 Technical Background for Rule Change Notice No.1-4

(Minimum Scantling, Side Frame and Grab) ………....79 Rule Change Notice No.1-5 (Direct Strength Analysis) ………………………..……….83 Technical Background for Rule Change Notice No.1-5 (Direct Strength Analysis) ...….89

Rule Change Notice No.1-6 (Fatigue Check for Longitudinals) …...………………...…97 Technical Background for Rule Change Notice No.1-6

(Fatigue Check for Longitudinals) ……...…...………119 Rule Change Notice No.1-7 (Corrosion Additions) …...……………………………….133 Technical Background for Rule Change Notice No.1-7 (Corrosion Additions) …....….139

Rule Change Notice No.1-8 (Corrugated Bulkhead) ……...………………………..….143 Technical Background for Rule Change Notice No.1-8 (Corrugated Bulkhead) ......….163

Rule Change Notice No.1-9 (Main Engine Foundation) ……………....………………167 Technical Background for Rule Change Notice No.1-9 (Main Engine Foundation) … 169

COMMON STRUCTURAL RULES FOR BULK CARRIERS RULE CHANGE NOTICE NO.1-1

PAGE 3 OF 171


Rule Change Notice No.1-1 (Hull Girder Strength)




RULE CHANGE NOTICE NO.1-1 COMMON STRUCTURAL RULES FOR BULK CARRIERS

PAGE 4 OF 171

For technical background for Rule Changes in this present document, reference is made to separate document Technical Background for Rule Change Notice No.1-1.

CHAPTER 5 HULL GIRDER STRENGTH

Section 1 YIELDING CHECK

2. Hull girder stresses

2.2 Shear stresses

2.2.2 Simplified calculation of shear stresses induced by vertical shear forces The shear stresses induced by the vertical shear forces in the calculation point are obtained, in N/mm2, from the

following formula:

( ) δετtI

SQQQY

CWVSW Δ−+=1

where:

t : Minimum net thickness, in mm, of side and inner side plating, as applicable according to Tab 1

δ : Shear distribution coefficient defined in Tab 1

( )SWQsgn=ε

ΔQC : Shear force correction (see Fig 2) at the section considered. The shear force correction is to be

considered independently forward and aft of the transverse bulkhead for the hold considered. , which

The shear force correction takes into account, when applicable, the portion of loads transmitted by the

double bottom girders to the transverse bulkheads:

• for ships with any non-homogeneous loading conditions, such as alternate hold loading conditions

and heavy ballast conditions carrying ballast in hold(s):

LCHH

C TB

MQ ρα −=Δl mhLC

HHC T

BMQ ,ρα −=Δl

for each non-homogeneous loading condition

• for other ships and homogeneous loading conditions:

ΔQC = 0

0

055.138.1bl

+=ϕ , to be taken not greater than 3.7

0

0

00

2b

bgl

l

ϕα

+=


PAGE 5 OF 171

l0 , b0 : Length and breadth, respectively, in m, of the flat portion of the double bottom in way of the hold

considered; b0 is to be measured on the hull transverse section at the middle of the hold

lH : Length, in m, of the hold considered, measured between the middle of the transverse corrugated

bulkheads depth

BH : Ship’s breadth, in m, measured at the level of inner bottom on the hull transverse section at the middle

of the hold considered

M : Total mass of cargo, in t, in the hold of the section considered Mass, in t, in the considered section.

• Adjacent cargo hold is loaded in a non homogeneous loading condition for the condition under

consideration

M is to include the total mass in the hold and the mass of water ballast in double bottom tank,

bounded by side girders in way of hopper tank plating or longitudinal bulkhead.

• Other cases

M is the total mass in the hold.

TLC TLC,mh : Draught, in m, measured vertically on the hull transverse section at the middle of the hold

considered, from the moulded baseline to the waterline in the loading condition considered.

Figure 2: Shear force correction ΔQC


Corrected shear force

Shear force obtained as specified in Ch 4, Sec 3

ΔQC FCQ _Δ ECQ _Δ ΔQC=ραTLC

Bulkhead Bulkhead

Bulkhead

FCQ _Δ : shear force correction for the full hold

ECQ _Δ : shear force correction for the empty hold


PAGE 6 OF 171

Table 1: Shear stresses induced by vertical shear forces Ship typology Location t, in mm δ Single side ship Sides tS 0,5

Sides tS ( )φ−15.0 Double side ship

Inner sides tIS φ5.0

where: tS, tIS : Minimum net thicknesses, in mm, of side and inner side, respectively

tSM, tISM : Mean net thicknesses, in mm, over all the strakes of side and inner side , respectively. They are calculated

as Σ(li ti) / Σli, where li and ti are the length, in m, and the net thickness, in mm, of the ith strake of side

and inner side.

φ : Coefficient taken equal to: SM

ISM

tt

25.0275.0 +=φ

2.2.3 Shear stresses in flooded conditions of BC-A or BC-B ships

This requirement applies to BC-A or BC-B ships, in addition to [2.2.1] and [2.2.2].

The shear stresses, in the flooded conditions specified in Ch 4, Sec 3, are to be obtained at the calculation any

point, in N/mm2, from the following formula:

( ) δετt

SQQQY

CFWVFSW ΙΔ−+= ,,1

)(sgn ,FSWQ=ε

ΔQC : Shear force correction, to be calculated according to [2.2.2],where the mass M is to include the mass

of the ingressed water in the hold considered is to be added to M and where the draught TLC TLC,mh is to

be measured up to the equilibrium waterline.

t : Net thickness, in mm, of the side plating.

5. Permissible still water bending moment and shear force

5.1 Permissible still water bending moment and shear force stresses

5.1.3 Permissible still water shear force - Simplified calculation

Where the shear stresses are obtained through the simplified procedure in [2.2.2], the permissible positive or

negative still water shear force in intact condition at any hull transverse section is obtained, in kN, from the

following formula:

WVCY

P QQS

tk

Q −⎟⎠⎞

⎜⎝⎛ Δ+

Ι=

δε 120

where:

( )SWQsgn=ε

δ : Shear distribution coefficient defined in Tab 1


PAGE 7 OF 171

t : Minimum net thickness, in mm, of side and inner side plating, as applicable according to Tab 1

ΔQC : Shear force corrections defined in [2.2.2], to be considered independently forward and aft of the

transverse bulkhead.

A lower value of the permissible still water shear force may be considered, if requested by the Shipbuilder.


PAGE 8 OF 171

Appendix 1 - HULL GIRDER ULTIMATE STRENGTH

Symbols For symbols not defined in this Appendix, refer to Ch 1, Sec 4.

IY : Moment of inertia, in m4, of the hull transverse section around its horizontal neutral axis, to be

calculated according to Ch 5, Sec 1, [1.5.1]

ZAB, ZAD : Section moduli, in m3, at bottom and deck, respectively, defined in Ch 5, Sec 1, [1.4.2].

ReHs : Minimum yield stress, in N/mm2, of the material of the considered stiffener.

ReHp : Minimum yield stress, in N/mm2, of the material of the considered plate.

As : Net sectional area, in cm2, of stiffener, without attached plating

Ap : Net sectional area, in cm2, of attached plating


2.1 Simplified method based on a incremental-iterative approach

2.1.1 Procedure The curve M-χ is to be obtained by means of an incremental-iterative approach, summarised in the flow chart in

Fig 1.

In this approach, the ultimate hull girder bending moment capacity MU is defined as the peak value of the curve

with vertical bending moment M versus the curvature χ of the ship cross section as shown in Fig 1. The curve is

to be obtained through an incremental-iterative approach.

Each step of the incremental procedure is represented by the calculation of the bending moment Mi which acts on

the hull transverse section as the effect of an imposed curvature χi.

For each step, the value χi is to be obtained by summing an increment of curvature Δχ to the value relevant to the

previous step χi-1.This increment of curvature corresponds to an increment of the rotation angle of the hull girder

transverse section around its horizontal neutral axis.

This rotation increment induces axial strains ε in each hull structural element, whose value depends on the

position of the element. In hogging condition, the structural elements above the neutral axis are lengthened,

while the elements below the neutral axis are shortened. Vice-versa in sagging condition.

The stress σ induced in each structural element by the strain ε is to be obtained from the load-end shortening

curve σ-ε of the element, which takes into account the behaviour of the element in the non-linear elasto-plastic

domain.

The distribution of the stresses induced in all the elements composing the hull transverse section determines, for

each step, a variation of the neutral axis position, since the relationship σ-ε is non-linear. The new position of the

neutral axis relevant to the step considered is to be obtained by means of an iterative process, imposing the

equilibrium among the stresses acting in all the hull elements.


PAGE 9 OF 171

Once the position of the neutral axis is known and the relevant stress distribution in the section structural

elements is obtained, the bending moment of the section Mi around the new position of the neutral axis, which

corresponds to the curvature χi imposed in the step considered, is to be obtained by summing the contribution

given by each element stress.

The main steps of the incremental-iterative approach described above are summarised as follows (see also Fig

1):

Step 1 Divide the transverse section of hull into stiffened plate elements.

Step 2 Define stress-strain relationships for all elements as shown in Tab 1

Step 3 Initialize curvature χ1 and neutral axis for the first incremental step with the value of incremental

curvature (curvature that induces a stress equal to 1% of yield strength in strength deck) as:

NzE

R

D

eH

−=Δ=

01.01 χχ

where:

zD : Z co-ordinate, in m, of strength deck at side, with respect to reference co-ordinate defined in Ch

1, Sec 4, [4]

Step 4 Calculate for each element the corresponding strain εi = χ zi εi = χ (zi-zNA) and the corresponding stress

σi

Step 5 Determine the neutral axis zNA_cur at each incremental step by establishing force equilibrium over the

whole transverse section as:

ΣAi σi = ΣAj σj (i-th element is under compression, j-th element under tension)

Step 6 Calculate the corresponding moment by summing the contributions of all elements as:

( )∑ −= curNAiiUiU zzAM _σ

Step 7 Compare the moment in the current incremental step with the moment in the previous incremental

step. If the slope in M-χ relationship is less than a negative fixed value, terminate the process and

define the peak value of MU. Otherwise, increase the curvature by the amount of Δχ and go to Step 4.

2.1.3 Modeling of the hull girder cross section Hull girder transverse sections are to be considered as being constituted by the members contributing to the hull

girder ultimate strength.

Sniped stiffeners are also to be modeled imaginarily, taking account that they doesn’t contribute to the hull

girder strength.

The structural members are categorized into an ordinary stiffener element, a stiffened plate element or a hard

corner element.

The plate panel including web plate of girder or side stringer is idealized into either a stiffened plate element, an

attached plate of an ordinary stiffener element or a hard corner element.

The plate panel is categorized into the following two kinds:

- longitudinally stiffened panel of which the longer side is in the longitudinal direction, and

- transversely stiffened panel of which the longer side is in the perpendicular direction to the longitudinal

direction.


PAGE 10 OF 171

• Hard corner element

Hard corner elements are sturdier elements composing the hull girder transverse section, which collapse

mainly according to an elasto-plastic mode of failure (material yielding); they are generally constituted by

two plates not lying in the same plane.

The extent of a hard corner element from the point of intersection of the plates is taken equal to 20tp on

transversely stiffened panel and to 0.5s on a longitudinally stiffened panel. (See Fig 6)

where:

tp : Gross offered thickness of the plate, in mm

s : Spacing of the adjacent longitudinal stiffener, in m

Bilge, sheer strake-deck stringer elements, girder-deck connections and face plate-web connections on large

girders are typical hard corners.

• Ordinary stiffener element

The ordinary stiffener constitutes an ordinary stiffener element together with the attached plate.

The attached plate width is in principle:

- equal to the mean spacing of the ordinary stiffener when the panels on both sides of the stiffener are

longitudinally stiffened, or

- equal to the width of the longitudinally stiffened panel when the panel on one side of the stiffener is

longitudinally stiffened and the other panel is of the transversely stiffened. (See Fig 6)

• Stiffened plate element

The plate between ordinary stiffener elements, between an ordinary stiffener element and a hard corner

element or between hard corner elements is to be treated as a stiffened plate element. (See Fig 6)

Figure 6: Extension of the breadth of the attached plating and hard corner element

The typical examples of modeling of hull girder section are illustrated in Figs 7 and 8.

Notwithstanding the foregoing principle these figures are to be applied to the modeling in the vicinity of upper

deck, sheer strake and hatch side girder.

s 1 s3

s 2 -(s1 +s )/2

s 3

s 2- s 1- s３/2 s 1=Min(20tp,s 2/2)

s 1 s3

s 2 -(s1 +s 3 )/2

s2 s3

s 2- s 1- s３/2

Stiffened plate element

s 1=Min(20tp,s 2/2)

Hard corner element

4

s4/2

Ordinary stiffener element

(Transversely stiffened panel)

(Longitudinally stiffened panel) (Transversely

stiffened panel)

s2 (Longitudinally stiffened panel)

(Longitudinally stiffened panel)


PAGE 11 OF 171

s1

s1/2

s2

s2/2 s2/2

s3

s3/2s3/2

: Ordinary stiffener element

s1/2

s 4

s 4/2

s 4/2

: Hard corner

s 6/2

s 6s 7

s 8

s 6/2

s 7/2

s 7/2

s 8/2

s 8/2

s1

s1/2

s2

s2/2 s2/2

s3

s3/2s3/2

: Ordinary stiffener element

s1/2

s 4

s 4/2

s 4/2

: Hard corner

s 6/2

s 6s 7

s 8

s 6/2

s 7/2

s 7/2

s 8/2

s 8/2

Figure 7: Extension of the breadth of the attached plating and hard corner element

Figure 8: Examples of the configuration of stiffened plate elements, ordinary stiffener elements and hard corner elements on a hull section

element

Hard corner element

Ordinary stiffener element

Stiffened plate element


PAGE 12 OF 171

(Note)

(1) In case of the knuckle point as shown in Fig 9, the plating area adjacent to knuckles in the plating with an

angle greater than 30 degrees is defined as a hard corner. The extent of one side of the corner is taken equal

to 20tp on transversely framed panels and to 0.5s on longitudinally framed panels from the knuckle point.

Figure 9: The case of plating with knuckle point

(2) Where the plate members are stiffened by non-continuous longitudinal stiffeners, the non-continuous

stiffeners are considered only as dividing a plate into various elementary plate panels.

(3) Where the opening is provided in the stiffened plate element, the openings are to be considered in

accordance with Ch 5 Sec 1, [1.2.7], [1.2.8] and [1.2.9].

(4) Where attached plating is made of steels having different thicknesses and/or yield stresses, an average

thickness and/or average yield stress obtained by the following formula are to be used for the calculation.

sststt 2211 +

= , ts

stRstRR eHpeHp

eHp222111 +

=

Where,

ReH1, ReH2, t1, t2, s1, s2 and s are shown in Fig 10.

Figure 10: Element with different thickness and yield strength


2.2.1 Stiffened plate element Plating panels and ordinary stiffeners element

Stiffened plate element Plating panels and ordinary stiffener, element composing the hull girder transverse

sections may collapse following one of the modes of failure specified in Tab 1.

s1 s2 s

t1 t2 ReHp1 ReHp2

Knuckle point

α

Knuckle pointKnuckle point

α


PAGE 13 OF 171

• Where the plate members are stiffened by non-continuous longitudinal stiffeners, the stress of the element is

to be obtained in accordance with [2.2.3] to [2.2.7], taking into account the non-continuous longitudinal

stiffener.

In calculating the total forces for checking the hull girder ultimate strength, the area of non-continuous

longitudinal stiffener is to be assumed as zero.

• Where the opening is provided in the stiffened plate element, the considered area of the stiffened plate

element is to be obtained by deducting the opening area from the plating in calculating the total forces for

checking the hull girder ultimate strength. The consideration of the opening is in accordance with the

requirement in Ch 5 Sec 1, [1.2.7] to [1.2.9].

• For stiffened plate element, the effective breadth of plate for the load shortening portion of the stress-strain

curve is to be taken as full plate breadth, i.e. to the intersection of other plate or longitudinal stiffener – not

from the end of the hard corner element nor from the attached plating of ordinary stiffener element, if any.

In calculating the total forces for checking the hull girder ultimate strength, the area of the stiffened plate

element is to be taken between the hard corner element and the ordinary stiffener element or between the

hard corner elements, as applicable.

Table 1: Modes of failure of stiffened plate element plating panel and ordinary stiffeners element

Element Mode of failure Curve σ−ε defined in

Lengthened stiffened plate element transversely framed plating panel or ordinary stiffeners element

Elasto-plastic collapse [2.2.3]

Shortened ordinary stiffeners element Beam column buckling

Torsional buckling

Web local buckling of flanged profiles

Web local buckling of flat bars

[2.2.4]

[2.2.5]

[2.2.6]

[2.2.7]

Shortened stiffened plate element transversely framed plating panel

Plate buckling [2.2.8]

2.2.2 Hard corners element Hard corners are sturdier elements composing the hull girder transverse section, which collapse mainly

according to an elasto-plastic mode of failure (material yielding). These elements are generally constituted of

two plates not lying in the same plane. Bilge, sheer strake-deck stringer elements, girder-deck connections and

face plate-web connections on large girders are typical hard corners.

The relevant load-end shortening curve σ-ε is to be obtained for lengthened and shortened hard corners

according to [2.2.3].


PAGE 14 OF 171

2.2.3 Elasto-plastic collapse of structural elements The equation describing the load-end shortening curve σ-ε for the elasto-plastic collapse of structural elements

composing the hull girder transverse section is to be obtained from the following formula, valid for both positive

(shortening) and negative (lengthening) strains (see Fig 2):

σ = Φ ReH σ = Φ ReHA

where:

ReHA : Equivalent minimum yield stress, in N/mm2, of the considered element, obtained by the following

formula

sp

seHspeHpeHA AA

ARARR

++

=


Φ = -1 for 1−<ε

Φ = ε for 11 ≤≤− ε

Φ = 1 for 1>ε

ε : Relative strain, equal to:

Y

E

εεε =

εE : Element strain

εY : Strain at yield stress in the element, equal to:

E

ReHY =ε

EReHA

Y =ε

Figure 2: Load-end curve σ-ε for elasto plastic collapse

2.2.4 Beam column buckling The equation describing the load-end shortening curve σCR1-ε for the beam column buckling of ordinary


pStif

pEStifCCR stA

tbAΦ

1010

11 +

+= σσ

pS

pESCCR AA

AAΦ

+

+= 11 σσ

where:

ReHA

-ReHA


PAGE 15 OF 171




εσ

σ 11

EC = for εσ

21eH

ER

≤ εσ21eHB

ER

≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

11 4

1E

eHeHC

RRσ

εσ for εσ21eH

ER

>

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

11 4

1E

eHBeHBC

RRσ

εσ for εσ21eHB

ER

>

ReHB : Equivalent minimum yield stress, in N/mm2, of the considered element, obtained by the following

formula

sEspEpE

sEseHspEpEeHpeHB lAlA

lARlARR

++

=1

1

ApE1 : Effective area, in cm2, equal to

pEpE tbA 11 10=

lpE : Distance, in mm, measured from the neutral axis of the stiffener with attached plate of width bE1 to the

bottom of the attached plate

lsE : Distance, in mm, measured from the neutral axis of the stiffener with attached plate of width bE1 to

the top of the stiffener



42

21 10−=

lAI

EE

EE πσ



EE

sbβ

=1 for 0.1>Eβ


ER

ts eH

pE

εβ 310=

ER

ts eHp

pE

εβ 310=

AE ApE : Net sectional area, in cm2, of ordinary stiffeners with attached shell plating of width bE, equal to:

pEpE tbA 10=


PAGE 16 OF 171


sbEE

E ⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

25.125.2ββ

for 25.1>Eβ


Figure 3: Load-end shortening curve σCR1-ε for beam column buckling

2.2.5 Torsional buckling The equation describing the load-end shortening curve σCR2-ε for the flexural-torsional buckling of ordinary

stiffeners composing the hull girder transverse section is to be obtained according to the following formula (see

Fig 4).

pStiff

CPpCStiffCR stA

stAΦ

10102

2 ++

=σσ

σ ps

CPpCsCR AA

AAΦ

++

=σσ

σ 22

where:


AStiff : Net sectional area of stiffener, in cm2, without attached plate


εσ

σ 22

EC = for εσ

22eH

ER

≤ εσ22eHs

ER

≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

22 4

1E

eHeHC

RRσ

εσ for εσ22eH

ER

>

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

22 4

1E

eHseHsC

RRσ

εσ for εσ22eHs

ER

>




eHEE

CP R⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

25.125.2ββ

σ eHpEE

CP R⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

25.125.2ββ

σ for 25.1>Eβ

eHCP R=σ eHpCP R=σ for 25.1≤Eβ



PAGE 17 OF 171

Figure 4: Load-end shortening curve σCR2-ε for flexural-torsional buckling

2.2.6 Web local buckling of ordinary stiffeners made of flanged profiles The equation describing the load-end shortening curve σCR3-ε for the web local buckling of flanged ordinary

stiffeners composing the hull girder transverse section is to be obtained from the following formula:

ffwwp

ffwwepEeHCR tbthst

tbthtbΦR

++

++= 3

3

3 10

10σ

ffwwp

eHsffwweeHppECR tbthst

RtbthRtbΦ

++++

= 3

3

3 10)(10

σ

where


bE : Effective width, in m, of the attached shell plating, defined in [2.2.4]

hwe : Effective height, in mm, of the web, equal to:

www

we hh ⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

25.125.2ββ

for 25.1>wβ

wwe hh = for 25.1≤wβ

ER

th eH

w

ww

εβ =

ER

th eHs

w

ww

εβ =


2.2.7 Web local buckling of ordinary stiffeners made of flat bars The equation describing the load-end shortening curve σCR4-ε for the web local buckling of flat bar ordinary


PStiff

CStiffCPPCR stA

AstΦ

1010 4

4 ++

=σσ

σ sp

CsCPpCR AA

AAΦ

++

= 44

σσσ

where:


AStiff : Net sectional area of stiffener, in cm2, without attached plate



εσ

σ 44

EC = for εσ

24eH

ER

≤ εσ24eHs

ER

≤


PAGE 18 OF 171

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

44 4

1E

eHeHC

RRσ

εσ for εσ24eH

ER

>

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

44 4

1E

eHseHsC

RRσ

εσ for εσ24eHs

ER

>


4 160000 ⎟⎟⎠

⎞⎜⎜⎝

⎛=

w

wE h

tσ


Figure 5: Load-end shortening curve σCR4-ε for web local buckling



⎪⎪⎩

⎪⎪⎨

⎧

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟⎟

⎠

⎞⎜⎜⎝

⎛−Φ

= 2

225 1111.025.125.2min

EEEeH

eH

CR ssR

ΦR

βββσ

ll

⎪⎪⎩

⎪⎪⎨

⎧

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎠⎞

⎜⎝⎛ −+⎟⎟

⎠

⎞⎜⎜⎝

⎛−Φ

= 2

225 1111.025.125.2min

EEEeHp

eHp

CR ssR

ΦR

βββσ

ll

where:


ER

ts eH

pE

εβ 310= E

Rts eHp

pE

εβ 310=

s : plate breadth, in m, taken as the spacing between the ordinary stiffeners

l : longer side of the plate, in m.

COMMON STRUCTURAL RULES FOR BULK CARRIERS TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1

PAGE 19 OF 171


Technical Background for Rule Change Notice No.1-1

(Hull Girder Strength)



TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-1 COMMON STRUCTURAL RULES FOR BULK CARRIERS

PAGE 20 OF 171

Technical Background for the Changes Regarding Hull Girder Strength 1. Reason for the Rule Change in: 1.1 Chapter 5, Section 1, [2.2.2], [2.2.3] and [5.1.3] These changes are made to clarify the requirements (Refer to KC ID 353, 453 and 459). The way to consider any shear force corrections forward and aft of transverse bulkheads is specified in [2.2.2] and [5.1.3]. It is specified that the total mass M in those holds loaded in non-homogeneous loading conditions deadweight such as water ballast and fuel oil tank in double bottom, bounded by side girders in way of hopper tank plating or longitudinal bulkhead. In addition, the symbol “TLC” defined in Chapter 1 Section 4, [2.1.1] is defined differently in Chapter 5 Section 1. 1.2 Chapter 5, Appendix 1, Symbols, [2.1.1], [2.1.3], [2.2.1] to [2.2.8] These changes are made to clarify the requirements (Refer to KC ID 499, 519 and 520). The position and extent of the hard corners is specified in order to provide the equivalent definition of hard corners used in the CSR for Bulk Carriers regarding hull girder ultimate strength calculations to the one used in the CSR for Oil Tankers. The calculation method is specified for those cases where any attached plating and stiffeners are made of steels having different yield stresses and/or thicknesses. The way to consider non-continuous stiffeners for the hull girder ultimate strength calculation is specified. In cases where attached plating and stiffeners are made of steel having different yield stresses, load end shortening curves are to be separately calculated for the stiffeners and the attached plates, i.e. the method is similar to the “weighted average method on area” in consideration of the net area of stiffeners and attached plates because this approach is very simple and easy to understand. However, as described in Annex 1, this approach sometimes give a smaller ultimate strength in comparison to the results attained from a 3D non-linear FEA in cases where the yield stress of stiffeners is smaller than that of any attached plates. This is because the area of such attached plates is greater than that of the stiffeners. Normally, such a case is scarcely found in actual designs. From the results of 3D non-linear FEA, it has been found that any underestimation of the load end shortening curves for beam column buckling of such stiffened panels can be resolved by considering the first moment of such stiffened panels. In addition, load end shortening curves for modes of failure other than beam column buckling can be evaluated by using the yield stress of stiffeners and attached plates, respectively. 2. Summary of Rule Changes 2.1 Chapter 5, Section 1, [2.2.2], [2.2.3] and [5.1.3] The shear force correction is to be considered independently forward and aft of transverse bulkheads for any hold considered. In addition, the total mass M may include masses of water ballast in double bottoms tanks, bounded by side girders in way of hopper tank plating or longitudinal bulkheads, if such spaces are loaded for the non-homogeneous loading condition considered. Finally, the symbol “TLC” is changed to “TLC_mh”


PAGE 21 OF 171

2.2 Chapter 5, Appendix 1, [2.1.1], [2.1.3], [2.2.1] to [2.2.8] 2.2.1 Chapter 5, Appendix 1, Symbols and [2.1.1] (1) Definitions of necessary symbols are added in order to evaluate stiffened panels in cases where any attached plating and stiffeners are made of steel having different stresses. (2) Editorial correction in [2.1.1] is made. 2.2.2 Ch 5 Appendix 5 [2.1.3] The new paragraph [2.1.3] is added for the modelling of hull girder cross sections. The extent of hard corner elements from corners is taken equal to 20tp on transversely framed panels and to 0.5s on longitudinally framed panels. In cases where attached plating is made of steels having different thicknesses and/or yield stresses, average thickness and/or average yield stress are to be used in calculations. 2.2.3 Ch 5 Appendix 5, [2.2.1] to [2.2.8] The provisions regarding the definition of hard corners specified in [2.2.2] are shifted to a new paragraph [2.1.3]. In addition, the ways to calculate the load-end shortening curves of the following cases are explained: in cases where attached plating and stiffener are made of steels having different yield stresses; in cases where plate members are stiffened by non-continuous longitudinal stiffeners; in cases where openings are provided in stiffened plate elements; and, in cases where stiffened plate elements are provided. 3. Impact on Scantling

3.1 Chapter 5, Section 1, [2.2.2], [2.2.3] and [5.1.3] There is no change in terms of steel weight by comparing that before and after the proposed rule change. 3.2 Chapter 5, Appendix 1, [2.1.1], [2.1.3], [2.2.1] to [2.2.8] There is no change in terms of steel weight by comparing that before and after the proposed rule change.


PAGE 22 OF 171

Annex 1: Evaluation method of the load end shortening curve for stiffened panel where the attached plate and stiffener are made of

steel having different yield stresses 1. Introduction

The evaluation methodology of hull girder ultimate strength in CSR-BC is based on Smith’s method. In cases where any attached plates and stiffeners are made of steel having different yield stresses,

the procedures and formulae for load end shortening curves are not described in the current Rules. The following two methods to deal with such elements were considered. (1) Using lower yield stresses. (2) Considering plate elements and stiffener elements to be separate elements, and calculating the

load-end shortening curves for the stiffener and the attached plating separately as follows: For stiffeners: by adding attached plating having the same yield stress as the stiffener and then

determining the shortening curve and the stress to be applied to the stiffener only.

For attached plating: by adding a stiffener having the same yield stress as the attached plating and then determining the shortening curve and the stress to be applied to the attached plating only.

Finally, load end shortening curves for stiffened panels can be obtained by adding the load end shortening curve for the stiffener to the load end shortening curve for the attached plating and dividing the sum by the total area of the stiffened panel.

This method is called “Method A”. It has been confirmed that any load end shortening curve obtained by this method is nearly equal to that obtained by using the average yield stress considering areas of any stiffeners and attached plates.

It is obvious that the method specified in (1) above gives a conservative load end shortening curve

because the higher yield strengths of stiffeners or panels is not taking into account. On the other hand, because Method A is simple and easy to understand, this method has been indicated in the IACS KC DB 520 as a practicable approach to evaluate the load end shortening curves of stiffened panels with different yield stresses between attached plates and stiffeners

However, there are some cases where Method A may give inadequate values of the load end

shortening curves of stiffened panels of different materials used for the attached plate and the stiffener. Specifically, in cases where stiffened panel elements consist of attached plates of HT36 and

stiffeners of HT 32, the load end shortening curves of such elements are sometimes overestimated in comparison to the results of 3D non-linear FEAs (FEA). On the contrary, in cases where elements consist of attached plates of HT32 and stiffeners of HT36, the load end shortening curves of such stiffened panel elements are sometimes underestimated in comparison to the results of FEA.

Although stiffeners with yield stresses lower than that of attached plates are rarely used in actual ship design, any underestimated result obtained by Method A should be resolved.

Since the areas of attached plates are larger than that of stiffeners in most cases, the load end shortening curve of the stiffened panel obtained by method A is affected by the yield strength of the attached plating. However, in reality, the yield stress of the stiffener has great impact on its load end shortening curve if beam-column buckling takes place, the parameters other than the areas of stiffeners and attached plates should be considered to accurately estimate the load end shortening curves of stiffened panels of attached plates and stiffeners having different yield stresses

In order to reduce the dependency on the areas of attached panels, the first moment of stiffened panels instead of the areas of attached plates and stiffeners are considered.

This method is called “Method B”. For example, using Method B, load end shortening curves of beam column buckling are calculated

in the following manner:


PAGE 23 OF 171

. Equivalent yield stress ReHB of the stiffened panel can be expressed by the following formula:

sEspEpE

sEseHspEpEeHpeHB lAlA

lARlARR

++

=1

1

The load end shortening curve for the beam column buckling is obtained from the following formula:

pS

pESCCR AA

AAΦ

++

= 11 σσ

where:

Φ andε : defined in [2.2.3], Ch 5 Appendix 1 of the Rules.


εσ

σ 11

EC = for εσ

21eHB

ER

≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

11 4

1E

eHBeHBC

RRσ

εσ for εσ21eHB

ER

>

ApE1 : Effective area, in cm2, equal to pE tb 110


42

21 10−=

lAI

EE

EE πσ



EE

sbβ

=1 for 0.1>Eβ


E

Rts eHp

pE

εβ 310=

Attached plate

Stiffener

ReHp : yield stress of the attached plate

ReHs : yield stress of the stiffener

As

ApE

Neutral Axis

lsE

lpE

bE1

bE1 : effective width of the attached plate

ApE : area of the attached plate with effective breadth bE1.

As : area of the stiffener

lsE : distance to the top of the stiffener from the neutral axis of the stiffened panel having the attached plate with bE1

lpE : distance to the bottom of the attached plate from the neutral axis of the stiffened panel having the attached plate with bE1


PAGE 24 OF 171

ApE : Net sectional area, in cm2, of attached shell plating of width bE, equal to:

pEpE tbA 10=


sbEE

E ⎟⎟⎠

⎞⎜⎜⎝

⎛−= 2

25.125.2ββ

for 25.1>Eβ


3D non-linear FEAs are carried out for the purpose of verifying the accuracy of the ultimate strength of stiffened panels obtained by Method B as well as Method A. 2. FEA

96 cases of the collapse analyses of the stiffened panels with non-linear FEM have been performed. The scantlings of stiffened plates analysed are listed in Table 1. As seen in Fig.1, the stiffened panels are modelled in the range of double span – double bay. Periodical continuous conditions are imposed along the edges of the model in the longitudinal and transverse directions. The material properties used in the analyses are as follows:

Young’s Modulus : E = 206000 N/mm2 Poisson’s Ratio: n = 0.3 Strain Hardening Rate: Η’=0 Case 1 : 315 N/mm2 for attached plate and 315 N/mm2 for stiffener Case 2 : 315 N/mm2 for attached plate and HT 355 N/mm2for stiffener (Different material case) Case 3 : 355 N/mm2 for attached plate and HT 315 N/mm2 for stiffener (Different material case) Case 4 : 355 N/mm2 for attached plate and 355 N/mm2 for stiffener

Table 1 Scantling and yield strength of each analysis case

Stiffener Attached plate

Type Size (mm) Length a (mm)

Breadth b (mm)

Aspect ratio (a/b)

Thickness tp (mm)

10 15 20

2400 800 3.0

25 10 15 20

Angle 250x90x12/16

4000 800 5.0

25 10 15 20

3600 900 4.0

25 10 15 20

T-bar 400x120x13/18

5400 900 6.0

25 10 15 20 2400 800 3.0

25 10

Flat-bar 300x15

4000 800 5.0 15


PAGE 25 OF 171

20 25

Fig.1 Model of stiffened panel

3. Verification results of the two methods

The results of the FEA, method A and Method B analyses are shown in Fig. 2 to Fig. 7. In these figures, FEA results are indicated by a line, the results of Method A and Method B are indicated by symbols.

Generally, it was found that there is good agreement between the results obtained by both methods and those by FEA from these figures except those cases where the plate thickness is 10mm.

However, considering the actual thickness of hull transverse members, both methods can be used for the evaluation of ultimate strength.

Fig. 2 Comparison on ultimate strength (Angle a/b=3.0)


PAGE 26 OF 171

Fig. 3 Comparison on ultimate strength (Angle a/b=5.0)

Fig. 4 Comparison on ultimate strength (T-bar a/b=4.0)

Fig. 5 Comparison on ultimate strength (T-bar a/b=6.0)


PAGE 27 OF 171

Fig. 6 Comparison on ultimate strength (Flat-bar a/b=3.0)

Fig. 7 Comparison on ultimate strength (Flat-bar a/b=5.0)

In order to discuss the accuracy of the results of Method A and Method B, a ratio obtained by

dividing the results of both methods into that of FEA is given in Fig. 8 to Fig. 13. Here, we call attention to the results of Case 2 and Case 3 in cases where any attached plates and

stiffeners are made of steels having different yield stresses. The ultimate strengths of all of the calculation conditions in Case 3 evaluated by Method A always

are greater than those in Case 3. In addition, the error (difference) becomes greater in those cases where the thickness of the attached

plate with large aspect ratio becomes greater. This is because the ultimate strength of the stiffened panels is strongly affected by the yield strengths of attached plates.

On the other hand, the error of any results obtained by Method B seems to be smaller than those obtained by Method A, and any tendencies obtained by Method A cannot be observed in the results obtained by Method C.


PAGE 28 OF 171

Fig. 8 Comparison on accuracy of estimation method (Angle a/b=3.0)

Fig. 9 Comparison on accuracy of estimation method (Angle a/b=5.0)

Fig. 10 Comparison on accuracy of estimation method (T-bar a/b=4.0)


PAGE 29 OF 171

Fig. 11 Comparison on accuracy of estimation method (T-bar a/b=6.0)

Fig. 12 Comparison on accuracy of estimation method (Flat-bar a/b=3.0)

Fig. 13 Comparison on accuracy of estimation method (Flat-bar a/b=5.0)

For the purpose of confirming the accuracy of any results obtained by Method A and Method B,

average values and coefficients of variation (COV) are calculated and those results are given in Figure 14 and 15.


PAGE 30 OF 171

Fig. 14 Averages of Ultimate Strength in Each Case Fig. 15 Coefficients of Variation in Each Case From Figure 15, it is obvious that the variance of any results obtained by method B is small. This means the accuracy of any results obtained by Method B is higher than those results obtained by Method A. 4. Conclusion

Two methods to estimate the ultimate strength of stiffened panels in cases where attached plates and stiffeners are made of steel having different yield stresses are considered.

One is Method A, where the yield stress used in the estimation of beam-column buckling is calculated so as to be the weighted average value of the yield stresses of the stiffener and the attached plating according to their area.

The other is method B, where the yield stress in the estimation of beam-column buckling is set to the weighted average value of the yield stresses of the stiffener and the attached plating according to the product of their areas and their distances from the neutral axis.

In order to evaluate the accuracy of the ultimate strength of the stiffened panel obtained by both methods, the results obtained by both methods are compared to those obtained by 3D non-linear FEAs.

From these comparison works, the following findings are obtained. (1) The method A is very simple and practicable, but it may overestimated the ultimate strength in

the case that the yield strength of the stiffener is lower than that of the attach plating (2) Method B is not as simple and practicable as Method A, but it gives more accurate ultimate

strength values for stiffened panels in comparison to those obtained by Method A.

Therefore, in cases where attached panels and stiffeners are made of steel having different yield stresses, Method B should be used for the evaluation of the load end shortening curve thereof. The text in the RCP is based on this.


PAGE 31 OF 171


Rule Change Notice No.1-2 (Hatch Covers)





PAGE 32 OF 171


CHAPTER 9 OTHER STRUCTURES

Section 5 HATCH COVERS

Symbols

For symbols not defined in this Section, refer to Ch 1, Sec 4.

pS : Still water pressure, in kN/m2, defined in [4.1]

pW : Wave pressure, in kN/m2, defined in [4.1]

pC : Pressure acting on the hatch coaming, in kN/m2, defined in [6.2]

FS, FW : Coefficients taken equal to:

FS = 0 and FW = 0.9 for ballast water loads on hatch covers of the cargo ballast hold

FS = 1.0 and FW = 1.0 in other cases

s : Length, in m, of the shorter side of the elementary plate panel

l : Length, in m, of the longer side of the elementary plate panel

bp : Effective width, in m, of the plating attached to the ordinary stiffener or primary supporting member,

defined in [3]

w : Net section modulus, in cm3, of the ordinary stiffener or primary supporting member, with an attached

plating of width bp

Ash : Net shear sectional area, in cm2, of the ordinary stiffener or primary supporting member

m : Boundary coefficient for ordinary stiffeners and primary supporting members, taken equal to:

m = 8 , in the case of ordinary stiffeners and primary supporting members simply supported at both

ends or supported at one end and clamped at the other end

m = 12 , in the case of ordinary stiffeners and primary supporting members clamped at both ends

tC : Total corrosion addition, in mm, defined in [1.4]

σa , τa : Allowable stresses, in N/mm2, defined in [1.5]

1. General

1.5 Allowable stresses

1.5.1 Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 15(6) and 16(5))

The allowable stresses σa and τa, in N/mm2, are to be obtained from Tab 2.


PAGE 33 OF 171

Table 2 Allowable stresses, in N/mm2

Members of Subjected to σa, in N/mm2 τa, in N/mm2

Weathertight hatch cover 0.80 ReH 0.46 ReH Pontoon hatch cover

External pressure, as defined in Ch 4, Sec 5, [2][5.2.1] 0.68 ReH 0.39 ReH

Weathertight hatch cover and pontoon hatch cover

Other loads, as defined in Ch 4 ,Sec 5, [5.1.1] and Ch 4, Sec 6, [2]

0.90 ReH 0.51 ReH

5. Strength check

5.2 Plating

5.2.3 Critical buckling stress check The compressive stress σ in the hatch cover plating, induced by the bending of primary supporting members,

parallel to the direction of ordinary stiffeners is to comply with the following formula:

188.0

CSσσ ≤

where:

S : Safety factor defined in Ch 6, Sec 3

σC1 : Critical buckling stress, in N/mm2, taken equal to:

11 EC σσ = for 21eH

ER

≤σ

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

11 4

1E

eHeHC

RRσ

σ for 21eH

ER

>σ

2

1 10006.3 ⎟

⎠⎞

⎜⎝⎛=

stEEσ

t : Net thickness, in mm, of plate panel

The compressive stress σ in the hatch cover plating, induced by the bending of primary supporting members,

perpendicular to the direction of ordinary stiffeners is to comply with the following formula:

288.0

CSσσ ≤

where:

S : Safety factor defined in Ch 6, Sec 3

σC2 : Critical buckling stress, in N/mm2, taken equal to:

22 EC σσ = for 22eH

ER

≤σ

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

22 4

1E

eHeHC

RR

σσ for

22eH

ER

>σ

2

2 10009.0 ⎟⎟

⎠

⎞⎜⎜⎝

⎛=

sE s

tEmσ


PAGE 34 OF 171

m : Coefficient taken equal to:

1.1

1.21

22

+⎥⎥

⎦

⎤

⎢⎢

⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+=

ψs

sscm

l

t : Net thickness, in mm, of plate panel

ss : Length, in m, of the shorter side of the plate panel

ls : Length, in m, of the longer side of the plate panel

ψ : Ratio between smallest and largest compressive stress


c = 1.3 when plating is stiffened by primary supporting members

c = 1.21 when plating is stiffened by ordinary stiffeners of angle or T type

c = 1.1 when plating is stiffened by ordinary stiffeners of bulb type

c = 1.05 when plating is stiffened by flat bar

c = 1.30 when plating is stiffened by ordinary stiffeners of U type. The higher c value but not greater

than 2.0 may be taken if it is verified by buckling strength check of panel using non-linear FEA and

deemed appropriate by the Society.

An averaged value of c is to be used for plate panels having different edge stiffeners.

In addition, Tthe bi-axial compression stress in the hatch cover plating, when calculated by means of finite

element analysis, is to comply with the requirements in Ch 6, Sec 3.

5.3 Ordinary stiffeners

5.3.2 Minimum net thickness of web The web net thickness of the ordinary stiffener, in mm, is to be not less than the minimum values given in [5.2.2]

4mm.

5.4 Primary supporting members

5.4.2 Minimum net thickness of web The web net thickness of primary supporting members, in mm, is to be not less than the minimum values given

in [5.2.2] 6mm.


PAGE 35 of 171



(Hatch Covers)




PAGE 36 OF 171

Technical Background for the Change Regarding Hatch Covers 1. Reason for the Rule Changes 1.1 Symbols

To consider the internal pressure due to ballast water in ballast hold, the load combination coefficients are introduced in Symbols. The rule change is made to clarify the application of the symbols Fs and Fw. 1.2 Table 2 Allowable stresses

According to ILLC and IACS UR S21, the external pressure is only external wave pressure acting on the hatch cover. However, as the pressure is referred to Ch 4 Sec 5 [2] which are mentioned not only the wave pressure on exposed deck but also other distributed load and concentrated loads. This rule change is made according to the answer in KC ID 537 in order to be in line with ILLC and IACS UR S21. 1.3 “5.2.3 Critical buckling stress” 1.3.1 Application of buckling check

When the bi-axial compression stress in the hatch cover plating calculated by means of finite element analysis, buckling check is to be carried out in accordance with the requirement in Ch 6 Sec 3. This check is alternative check to the buckling check using the compression stress obtained by a grillage analysis as specified in IACS UR S21. This rule change is made according to the answer in KC ID 477 in order to be in line with IACS UR S21. 1.3.2 “c” or “F1” factor for ordinary stiffener of U type

There are many hatch covers stiffened by ordinary stiffener of U type. As the ordinary stiffener of U-type has the merit of being more resistant to rotational effect than other ordinary stiffener of flat bar, angle type or T type. However, the coefficient “c” is taken equal to 1.05 to 1.2 corresponding to the type of stiffener. Regarding this issue, the interpretation is made according to the results as shown in Annex 1. 1.4 5.3.2 Minimum thickness of ordinary stiffener and 5.4.2 Minimum thickness of Primary supporting member

The definition of the web minimum thickness of ordinary stiffeners and primary supporting members was linked to the minimum requirements for the hatch cover plating, as defined in URS 21 and ILLC Reg. 16 (5.b). These rules contain no requirement for minimum web thickness for ordinary stiffeners and primary supporting members. But the rules for hatch covers of CSR-BC should have such a minimum requirement, comparable to the approach for the ship structure.

The reason is the change to the net thickness concept, which has not taken into account for the stiffeners. Hatch cover manufactures demand that the minimum net thickness of ordinary stiffeners plus the corrosion margin of 2mm has not to be greater than the well proven gross thickness of 6mm.

In addition, the relation to the distance between ordinary stiffeners (tmin = 10s) is only valid for the hatch cover plating.

The rule change is made in accordance with the answer in KC ID 535. 2. Summary of the Rule Change 2.1 Symbols

The use of the coefficients Fs=0 and Fw=0.9 are limited for hatch covers of the ballast hold in case scantling check is done against the ballast water pressure.


PAGE 37 OF 171

2.2 Table 2

The reference is changed to Ch 4 Sec 5 [5.2.1] from Ch 4 Sec 5 [2] and clarification of “other load” is made. 2.3 “5.2.3 Critical buckling stress” 2.3.1 Application of buckling check

The used stress for buckling check is clarified as follows. For uni-axial compression stress, the stress is obtained by a grillage analysis. For bi-axial compression stress, the stresses are obtained by a FEA

2.3.2 “c” or “F1” factor for ordinary stiffener of U type According to the results specified in Annex 1, the coefficient “c” for ordinary stiffener of U-

type can be taken to higher value than 1.3. However, “c” value depends on the aspect ratio as shown in Annex 1. Therefore, the coefficient “c” is taken equal to 1.3 as a minimum, but the higher value may be used if it is verified by buckling strength check of panel using non-linear FEA and deemed appropriate by the Society.

In addition, the treatment of the different edge stiffeners is added according to Table 1 in Ch 6 Sec 3. 2.4 “5.3.2 Minimum thickness of web of ordinary stiffener” and “5.4.2 Minimum thickness of Primary supporting member” (1) The relation to the distance between ordinary stiffeners (tmin = 10s) is only valid for the hatch

cover plating. Therefore this requirement is deleted the reference to the minimum thickness of hatch cover plate for ordinary stiffeners and primary supporting.

(2) In addition to the change, described in (1) above, the minimum net web thickness of ordinary stiffener of 6mm has been changed to 4mm.

(3) In addition to the change, described in (2) above, the minimum net thickness of 6mm is specified in the requirement for web of primary supporting member, but the value is the same as the current Rule.

3. Effects and impact on scantling due to this definition 3.1 Items in 2.1, 2.2 and 2.3.1 mentioned above As the rule change is only made for the clarification, there is no scantling impact due to these changes. 3.2 Items in 2.3.2 mentioned above

Regarding the U-type stiffeners, the coefficient “c” is to be an appropriate value deemed by the Society because the factor of such stiffeners are not defined in CSR and IACS UR S21. The minimum value is newly defined by this rule change although the used value still depends on the discretion of the Society. Therefore, the scantling impact due to this change can not be estimated. 3.3 Item in 2.4

The minimum web thickness for ordinary stiffeners and primary supporting members is decreased.

The impact on scantling can not be estimated in general. Depending on the hatch cover type, the hatch cover size and loads, different design criteria determine the dimensions of the structure. One manufacturer estimates the weight increase when using the current CSR approach with 40% for ordinary stiffeners (KC-ID. 535).


PAGE 38 OF 171

Annex 1: Technical Background for the Changes regarding F1 factor for transverse compressed plate fields in buckling check of

hatch cover plating 1. Reason for the Rule Change in Ch 9 Sec 5 [5.2.3]

It was requested to make an interpretation for the factor “c” in case of U-type stiffener in buckling assessment of hatch covers. The factor “c” considers the torsion stiffness of the longitudinal stiffener of an elementary plate panel under transverse compression loads. The following values are given in the URS 11:

c = 1.3 when plating is stiffened by primary supporting members

c = 1.21 when plating is stiffened by ordinary stiffeners of angle or T type

c = 1.1 when plating is stiffened by ordinary stiffeners of bulb type

c = 1.05 when plating is stiffened by flat bar

The intention of this RC is to make a proposal for the “c” factor for U-type stiffener 2. Summary of the Rule Change

The derivation of the “c”-factor for U-type stiffeners based on nonlinear FE-analyses should be treated as a future development, because this work is beyond the capability of CSR PT1. CSR PT1 proposes to make a comparison study to estimate a F1 value by comparing the buckling load case (BLC) 9 (clamped edges) with the reference BLC 2 (simply supported).

Both buckling load cases BLC 2 and BLC 9 are theoretical cases and the real boundary

condition of the U-Profile is in between these extreme cases. As a short term solution we propose to use the mean buckling reduction factor κy value of both BLC's to estimate the “c”-factor for U-type stiffeners.

The following diagrams show the buckling reduction factors of BLC 1 and 9 together with

the mean value and the “c”-factors as a function of c = κy(9) / κy(1) and c = κy(mean) / κy(1) for different plate thicknesses and aspect ratios.


PAGE 39 OF 171

Influence of longitudinal stiffeners with high torsional stiffness of the buckling behaviour of

transverse loaded plate panels (t=25mm)

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

1 2 3 4 5 6 7 8 9 10

alpha

kapp

a, F

1

kappa BLC2kappa BLC 9c=f(BLC2,9)kappa meanc_mean



0,0

0,5

1,0

1,5

2,0

2,5

3,0

1 2 3 4 5 6 7 8 9 10

alpha

kapp

a, F

1



PAGE 40 OF 171



0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

1 2 3 4 5 6 7 8 9 10

alpha

kapp

a, F

1


The diagrams show the following dependencies • With decreasing thickness the “c” factor increases • With decreasing thickness the range of a constant “c” factor increases

Different hatch cover designs show aspect ratios between 3 and 8 with a majority of ratios between 3 and 6. The plate thickness is typically below 10mm. For these parameter ranges a “c” factor of 2.0 may be assumed.

To be in line with the simple definitions of “c” in URS 11 a constant “c” value of 1.3 can be used regardless of the thickness and aspect ratio. The diagrams leads to the assumption, that a higher value might be possible, taking the aspect ratio and plate thickness into account. But this has to be verified as a future development for CSR-BC.

3. Effects and impact on scantling due to this definition

The highest value for “c”, given in the URS 11 is 1.3 for primary supporting members. Higher values are not allowed by IACS up to now. Defining a constant value of 1.3 for U-type stiffeners regardless of plate field aspect ratios or thicknesses, we do not change the result of the plate buckling check for hatch covers and this definition has no impact on scantling.

With the selection of a higher “c” value for such kind of stiffeners, the buckling strength of hatch cover plating, stiffened with U-type stiffeners increases with respect to transverse loaded plate fields.


PAGE 41 OF 171


Rule Change Notice No.1-3 (Steel Coil)





PAGE 42 OF 171


CHAPTER 4 DESIGN LOADS

Section 2 SHIP MOTION AND ACCELERATIONS

2. Ship absolute motions and accelerations

2.1 Roll

2.1.1 The roll period TR, in s, and the single roll amplitude θ, in deg, are given by:

GMkT r

R3.2

=

( )( )πθ

75025.025.19000

+

−=

BkfT bpR

where:

kb : Coefficient taken equal to:

kb = 1.2 for ships without bilge keel

kb = 1.0 for ships with bilge keel

kr : Roll radius of gyration, in m, in the considered loading condition. When kr is not known, the values

indicated in Tab 1 may be assumed.

GM : Metacentric height, in m, in the considered loading condition. When GM is not known, the values

indicated in Tab 1 may be assumed.

Table 1: Values of kr and GM Loading condition kr GM

(Alternate or homogeneous loading) 0.35B 0.12B Full load condition Steel coil loading 0.42B 0.24B

Normal ballast condition 0.45B 0.33B Heavy ballast condition 0.40B 0.25B


PAGE 43 OF 171

CHAPTER 6 HULL SCANTLING

Section 1 PLATING


2.7 Inner bottom loaded by steel coils on a wooden support

2.7.1 General The net thickness of inner bottom, bilge hopper sloping plate and inner hull for ships intended to carry steel

coils is to comply with [2.7.2] to [2.7.4].

The provision is determined by assuming Fig 2 as the standard means of securing steel coils. In case where steel

coils are lined up two or more tier, formulae in [2.7.2] and [2.7.3] can be applied to the case that only lowest tier

of steel coils is in contact with hopper sloping plate or inner hull plate. In other cases, scantlings of plate

thickness are calculated by direct strength analysis or other procedures.

Figure 2: Inner bottom loaded by steel coils

2.7.1 bis1 Accelerations In order to calculate the accelerations, the following coordinates are to be used for the centre of gravity.

scGx − = 0.75 lH forward of aft bulkhead, where the hold of which the mid position is located forward from

0,45L from A.E.


PAGE 44 OF 171

scGx − = 0.75 lH afterward of fore bulkhead, where the hold of which the mid position is located afterward from

0,45L from A.E.

4h

scGBy ε=−

( )22

311 1sc

DBscGdnhz

⎭⎬⎫

⎩⎨⎧

−++=−

where:

ε : 1.0 when a port side structural member is considered , or -1.0 when a starboard side structural member

is considered.

Bh : breadth in m, at the mid of the hold, of the cargo hold at the level of connection of bilge hopper plate

with side shell or inner hull

dsc : diameter of steel coils, in m

hDB : height of inner bottom, in m

lH : Cargo hold length, in m

Vertical acceleration aZ, in m/s2,.are to be calculated by the formulae defined in Ch 4, Sec 2, [3.2] and tangential

acceleration aR due to roll, in m/s2 .is to be calculated by the following formula.

22_

22

180Ry

Ta SCG

RR +⎟⎟

⎠

⎞⎜⎜⎝

⎛=

ππθ

where:

θ, TR and R: as defined in Ch 4 Sec 2, [3.2].

2.7.2 Inner bottom plating The net thickness of plating of longitudinally framed inner bottom is to be not less than the value obtained, in

mm, from the following formula:

( )YP

ZR

FagKtλ+

= 1

( ) ( )( ){ }YP

zZRZP

RFaCCgKt

λθ +Φ

=coscos

1

where:

K1 : Coefficient taken equal to:

( )( )2

222

22

1 22'2'73.07.1

KsKsKs

Kll

lll

+−−−

=

Za : Vertical acceleration, in m/s2, defined in Ch 4, Sec 2, [3.2] [2.7.1 bis1]

Φ : Single pitch amplitude, in deg, defined in Ch 4, Sec 2, [2.2]

θ : Single roll amplitude, in deg, defined in Ch 4, Sec 2, [2.1]

CZP,CZR : Load combination factor defined in Ch 4, Sec 4, [2.2]


PAGE 45 OF 171


3

21

nnWnKF S= for 102 ≤n and 53 ≤n

SS l

lWnKF 1= for 102 >n or 53 >n

Pλ : Coefficient defined in Tab 6

KS : Coefficient taken equal to:

KS = 1.4 when steel coils are lined up in one tier with a key coil

KS = 1.0 in other cases

W : Mass of one steel coil, in kg

1n : Number of tiers of steel coils

2n : Number of load points per elementary plate panel of inner bottom (See Figs 3 and 4), taken equal to.

When 53 ≤n , 2n can be obtained from Tab 3 according to the values of n3 and Sll /

• in case of steel coils loaded as shown in Fig 3, n2 is obtained from Tab 3 according to the values of

n3 and l/lS

• in case of steel coils loaded as shown in Fig 4, n2 = n3

3n : Number of dunnages supporting one steel coil

Sl : Length of a steel coil, in m

K2 : Coefficient taken equal to:

33.2'137.1222

2 +⎟⎠⎞

⎜⎝⎛ −⎟

⎠⎞

⎜⎝⎛+⎟

⎠⎞

⎜⎝⎛+−=

l

ll

ll sssK

l’ : Distance, in m, between outermost load points per elementary plate panel of inner bottom plate in ship

length, taken equal to: (See Figs 3 and 4). When 102 ≤n and 53 ≤n , l’ can be obtained from Tab 4

according to the values of l, lS, n2 and n3. When 102 >n or 53 >n , l’ is to be taken equal to l.

• in case of steel coils loaded as shown in Fig 3, l’ is obtained from Tab 4 according to the values of

l, lS, n2 and n3

• in case of steel coils loaded as shown in Fig 4, l’ is the actual value.

2.7.3 Bilge hHopper sloping plate and inner hull plateing The net thickness of plating of longitudinally framed bilge hopper sloping plate and inner hull is to be not less

than the value obtained, in mm, from the following formula:

( )[ ]YP

Y

RFag

Ktλ

θθθ ′+−= 121

1sincos

RyFa

Ktp

hopper

λ'

1=


PAGE 46 OF 171

where:

K1 : Coefficient defined in [2.7.2]

1θ hθ : Angle, in deg, between inner bottom plate and bilge hopper sloping plate or inner hull plateing

2θ : Single roll amplitude, in deg, defined in Ch 4, Sec 2, [2.1]

Ya : Transverse acceleration, in m/s2, defined in Ch 4, Sec2, [3.2]

hswayYSXGYGhhscG

RYRhopper aCCCgR

yaCa θθθθ sin)cos()cos(tansin _1 +Φ−+⎟

⎟⎠

⎞⎜⎜⎝

⎛−−= −

aR : tangential acceleration defined in [2.7.1 bis1].

asway : Transverse acceleration due to sway, in m/s2, defined in Ch 4, Sec 2, [2.4]

CXG, CYS, CYR, CYG: Load combination factors defined in Ch 4, Sec 4, [2.2]

yG_sc : Centre of gravity in transverse direction, in m, defined in [2.7.1 bis1]

R : Coefficient defined in Ch 4 Sec 2, [3.2.1]

F ′ : Force, in kg, taken equal to:

3

2

nCWn

F k=′ for 102 ≤n and 53 ≤n

S

k llWCF =' for 102 >n or 53 >n ,

Pλ : Coefficient defined in Tab 6

W, n2, n3, Φ and θ : As defined in [2.7.2]

kC : Coefficient taken equal to:

Ck = 4.03.2 when steel coils are lined up two or more tier, or when steel coils are lined up one tier

and key coil is located second or third from bilge hopper sloping plate or inner hull plate

Ck = 2.52.0 for other cases

Figure 3: Loading condition of steel coils (Example of 42 =n , 33 =n )

Inner bottom

Floor Bottom

Steel coil Dunnage

n2 and ℓ’ are given by Tables 3 and 4


PAGE 47 OF 171

Figure 4: Loading condition of steel coils (Example of 32 =n , 33 =n )

2.7.4 Where the number of load points per elementary plate panel n2 is greater than 10 and/or the number of dunnages

n3 is greater than 5, the inner bottom may be considered as loaded by a uniform distributed load. In such a case,

the thickness of the inner bottom plating is to be obtained according to [3.2.1]. (void)

Inner bottom

Floorℓ'

Bottom

Steel coil Dunnage


PAGE 48 OF 171

Table 3: Number n2 of load points per elementary plate panel

n2 n3 = 2 n3 = 3 n3 = 4 n3 = 5

1 5.00 ≤<Sl

l 33.00 ≤<Sl

l 25.00 ≤<Sl

l 2.00 ≤<Sl

l

2 2.15.0 ≤<Sl

l 67.033.0 ≤<Sl

l 5.025.0 ≤<Sl

l 4.02.0 ≤<Sl

l

3 7.12.1 ≤<Sl

l 2.167.0 ≤<Sl

l 75.05.0 ≤<Sl

l 6.04.0 ≤<Sl

l

4 4.27.1 ≤<Sl

l 53.12.1 ≤<Sl

l 2.175.0 ≤<Sl

l 8.06.0 ≤<Sl

l

5 9.24.2 ≤<Sl

l 87.153.1 ≤<Sl

l 45.12.1 ≤<Sl

l 2.18.0 ≤<Sl

l

6 6.39.2 ≤<Sl

l 4.287.1 ≤<Sl

l 7.145.1 ≤<Sl

l 4.12.1 ≤<Sl

l

7 1.46.3 ≤<Sl

l 73.24.2 ≤<Sl

l 95.17.1 ≤<Sl

l 6.14.1 ≤<Sl

l

8 8.41.4 ≤<Sl

l 07.373.2 ≤<Sl

l 4.295.1 ≤<Sl

l 8.16.1 ≤<Sl

l

9 3.58.4 ≤<Sl

l 6.307.3 ≤<Sl

l 65.24.2 ≤<Sl

l 0.28.1 ≤<Sl

l

10 0.63.5 ≤<Sl

l 93.36.3 ≤<Sl

l 9.265.2 ≤<Sl

l 4.20.2 ≤<Sl

l

Table 4: Distance between load points in ship length direction per elementary plate panel of inner bottom

n3 n2 2 3 4 5 1 Actual breadth of dunnage 2 0.5lS 0.33lS 0.25lS 0.2lS 3 1.2lS 0.67lS 0.50lS 0.4lS 4 1.7lS 1.20lS 0.75lS 0.6lS 5 2.4lS 1.53lS 1.20lS 0.8lS 6 2.9lS 1.87lS 1.45lS 1.2lS 7 3.6lS 2.40lS 1.70lS 1.4lS 8 4.1lS 2.73lS 1.95lS 1.6lS 9 4.8lS 3.07lS 2.40lS 1.8lS

10 5.3lS 3.60lS 2.65lS 2.0lS


PAGE 49 OF 171

Section 2 ORDINARY STIFFENERS


2.5 Ordinary stiffeners of inner bottom loaded by steel coils on a wooden support

2.5.1 General The requirements of this sub-article apply to the ordinary stiffeners located on inner bottom plate, bilge hopper

sloping plate and inner hull plate when loaded by steel coils on a wooden support (dunnage), as indicated in Fig

2 of Ch 6, Sec 1.

In case where steel coils are lined up two or more tier, formulae in [2.5.2] and [2.5.3] can be applied to the case

that only lowest tier of steel coils is in contact with hopper sloping plate or inner hull plate. In other cases,

scantlings of net section modulus and net shear section area are calculated by direct strength analysis or other

procedures.

2.5.2 Ordinary stiffeners located on inner bottom plating The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of single span ordinary stiffeners

located on inner bottom plating are to be not less than the values obtained from the following formulae:

( )YS

Z

RFag

Kwλ83+

=

( ) 310sin

5 −+=

φτ a

Zsh

FagA

( ) ( )[ ]YS

ZZRZPR

FaCCgKw

λθ

⋅⋅+⋅Φ⋅

=8

coscos3

( ) ( )[ ] 310sin

)coscos5 −⋅+⋅Φ⋅=

φτθ

a

ZZRZPsh

FaCCgA

where:

K3 : Coefficient defined in Tab 1. When 2n is greater than 10, 3K is to be taken equal to 2l/3

Za : Vertical acceleration, in m/s2, defined in Ch 4, Sec2, [3.2] Ch 6, Sec 1, [2.7.1 bis1]

Φ : Single pitch amplitude, in deg, defined in Ch 4, Sec 2, [2.2]

θ : Single roll amplitude, in deg, defined in Ch 4, Sec 2, [2.1]

CZP,CZR : Load combination factor defined in Ch 4, Sec 4, [2.2]

F : Force, in kg, defined in Ch 6, Sec 1, [2.7.2]

Sλ : Coefficient defined in Tab 3

φ : Angle, in deg, defined in [3.2.3].


PAGE 50 OF 171

2.5.3 Ordinary stiffeners located on bilge hopper sloping plate or inner hull plateing The net section modulus w , in cm3, and the net shear sectional area shA , in cm2, of single span ordinary

stiffeners located on bilge hopper sloping plate and inner hull plate are to be not less than the values obtained

from the following formulae:

( )[ ]YS

Y

RFag

Kwλ

θθθ8

'sincos 1213

+−=

310sinsin'5 −=

φϕτ a

Ysh

FaA

YS

hopper

RFa

Kwλ8

'3=

310sin

'5 −=φτ a

hoppersh

FaA

where:

K3 : Coefficient defined in Tab 1. When 102 >n , 3K is taken equal to 2l/3.

θ1, θ2 : Angles, in deg, defined in Ch 6, Sec 1, [2.7.3]

hθ : Angle, in deg, between inner bottom plate and bilge hopper sloping plate or inner hull plate

aY : Transverse acceleration, in m/s2, defined in Ch 4, Sec 2, [3.2]

hoppera : Acceleration, in m/s2, defined in Ch 6 Sec 1, [2.7.3]

'F : Force, in kg, defined in Ch 6, Sec 1, [2.7.3]

Sλ : Coefficient defined in Tab 3

φ : Angle, in deg, defined in [3.2.3]

φ : Angle, in deg, between inner bottom plating and hopper sloping plate or inner hull plating.

l' : Distance, in m, between load points per elementary plate panel of inner bottom plate in ship length,

sloping plate or inner hull plating, as defined in Ch 6, Sec 1, [2.7.2].

l′ : Distance, in m, between outermost load points per elementary plate panel in ship length

Table 1 : Coefficient K3

n2 1 2 3 4 5 6 7 8 9 10

3K l l

ll

2'−

l

ll

32 2'

− l

ll

95 2'

− l

ll

2

2'−

l

ll

157 2'

− l

ll

94 2'

− l

ll

73 2'

− l

ll

125 2'

− l

ll

2711 2'

−

2.5.4 Where the number of load points per elementary plate panel n2 is greater than 10 and/or the number of dunnages

n3 is greater than 5, the inner bottom may be considered as loaded by a uniform distributed load. In such a case,

the scantling of the inner bottom ordinary stiffeners is to be obtained according to [3.2.3]. (void)


PAGE 51 OF 171



(Steel Coil)




PAGE 52 OF 171

Technical Background for the Change Regarding Scantling Formula for Steel Coil Loading 1. Background of Rule change regarding steel coil loading 1.1 Addition of GM and kr value for steel coil loading to the note of Table 1 in Ch 4, Sec 2,

[2.1.1] Roll radius of gyration ( rk ) and metacentric height ( GM ) in the considered loading condition is

used for the calculation of the parameters regarding the ship’s absolute motion and accelerations. When these values are not known, the default values specified in Table 1 in Ch 4, Sec 2, [2.1.1] may be assumed in the current CSR.

However, these default values specified in the Table do not correspond to the steel coil loading condition because the steel coil load is normally concentrated near the inner bottom. The rule change is made to set the GM value based on the actual design values given in Table 1 and the averaged values of GM and kr is about 0.24B and 0.42B, respectively.

Table 1 Actual GM Value

B 32.26 32.26 31.00 29.40 23.00 19.60 23.50 23.70Actual GM 8.05 7.76 8.34 7.99 4.39 4.12. 4.95 5.10GM = X*B 0.245 0.241 0.269 0.272 0.191 0.210 0.211 0.215B 27.00 26.00 23.50 24.50 24.40 23.70 27.0 23.700Actual GM 6.88 6.38 4.95 5.78 4.93 5.06 6.89 5.10GM = X*B 0.255 0.245 0.211 0.236 0.202 0.214 0.255 0.215B 23.50 22.30 27.00 27.00 32.26 32.26 27.20 32.26Actual GM 4.95 4.65 6.89 6.93 9.30 9.11 6.12 9.14GM = X*B 0.211 0.209 0.255 0.257 0.288 0.282 0.225 0.283

The GM and kr value for steel coil loading are newly added to Table 1 in Ch 4, Sec 2, [2.1.1] as

a default value. 1.2 Modification of the requirements in Ch 6, Sec 1, [2.7.1] and Ch 6, Sec 2, [2.5.1]

The 3rd sentence and the 4th sentence in Ch 6, Sec 1, [2.7.1] and the 2nd sentence and the 3rd sentence in Ch 6, Sec 2, [2.5.1] are deleted due to the following reasons. (a) As the term of the acceleration in the scantling formula is revised in order to accommodate any

loading pattern of steel coil as mentioned in Annex 1, the limitation of the rule application regarding the loading pattern is not necessary.

(b) In addition, CSR does not permit overruling the scantling determined by the prescriptive requirement by FEA.

1.3 Clarification of the treatment of centre of gravity for steel coil loading

If the actual centre of gravity in steel coil loaded condition is known, it is better to use the actual one in calculating the acceleration. Therefore, this treatment has been added to the text. If the actual centre of gravity is not known, the standard value of the centre of gravity is needed. Then the centre of gravity ( )zyx ,, is set up ( )( )( )22311,4, 1 SCDBh dnhBholdmid −++− ε as a conservative manner, where Bh is defined as a breadth of the cargo hold and ε is 1.0 when a port side structural member is considered, or -1.0 when a starboard side structural member is considered.


PAGE 53 OF 171

1.4 Amendment of the formulae for plating and ordinary stiffeners of inner bottom, bilge hopper and inner hull In the current formulae for inner bottom plating and ordinary stiffeners (inner bottom

longitudinals), load cases H and F are only considered but the load cases R and P is not considered. The rule change is made to consider the all load cases.

The current formulae for plating and ordinary stiffeners of bilge hopper and inner hull give the excessive scantling due to the account of gravity acceleration in duplicate and conservative coefficient kC . In addition, formula for shear area of the ordinary stiffeners is modified. 1.5 Amendment of the treatment which the number of load points per elementary plate panel is greater than 10 and/or the number of dunnages is greater than 5.

In the current requirements, the number of load points per elementary plate panel 2n is greater than 10 and/or the number of dunnages 3n is greater than 5, the scantling of plating and ordinary stiffeners may be checked by the formulae based on uniform distributed loads. However, this assumption is inappropriate because the scantling formula for steel coil is based on the line load which is transformed from the concentrated loads due to steel coil acting on the most severe locations of an elementary plate panel. Even if the number of load points becomes larger than 10, this assumption for the load model should be kept.

Therefore, the texts of Ch 6, Sec 1, [2.7.4] and Ch 6, Sec 2, [2.5.4] are deleted. Furthermore, in order to clarify the treatment where the number of load points per elementary

plate panel is greater than 10 and/or the number of dunnages is greater than 5, the relevant text is revised.

The technical backgrounds of these modifications are described in Annex 1. 2. Summary of Rule Changes 2.1 Ch 4, Sec 2, Table 1

The GM and kr values are added to Table 1 as averaged values based on the investigation results of actual ships’ data. 2.2 Ch 6, Sec 1, [2.7.1]

The 3rd and the 4th sentences are deleted. 2.3 Ch 6, Sec 1, [2.7.2], [2.7.3], [2.7.4]

The new paragraph [2.7.1 bis1] is added for calculating the acceleration and the paragraph [2.7.4] is deleted. The tangential acceleration due to roll is added.

222

2180

RyT

a SCR

R +⎟⎟⎠

⎞⎜⎜⎝

⎛=

ππθ

Where,

yG_SC: Centre of gravity in transverse direction, in m, is taken equal to 4

hscG

By ε=−

R: Coefficient defined in Ch 4 Sec 2, [3.2.1] of the Rules TR: Roll period, in s, defined in Ch 4, Sec 2, [2.1.1] of the Rules Bh: breadth in m, at the mid of the hold. In order to consider the acceleration of pitch, although the effect is very small because the hold

length is relative short, the definition of xG_SC is added as follows. scGx − = 0.75 lH forward of aft bulkhead, where the hold of which the mid position is located forward

from 0,45L from A.E.


PAGE 54 OF 171

scGx − = 0.75lH afterward of fore bulkhead, where the hold of which the mid position is located afterward from 0,45L from A.E The backgrounds of these modifications are described in Annex 1 2.4 Ch 6, Sec 1, [2.7.2]

The scantling formula for load cases H and F is revised in order to consider all load cases. In addition, the interpretation of the case where n2>10 or n3>5 is added.

( ) ( )( ){ }YP

zZRZPR

FaCCgKtλ

θ +⋅Φ=

coscos1

Where,

For n2<=10 and n3<=5, 3

21

nnWnKF S=

For n2>10 or n3>5 S

S llWnKF 1=

Definitions of all symbols are specified in the Rule text. 2.5 Ch 6, Sec 1, [2.7.3]

In the current formula, the gravity component is accounted in duplicate because the acceleration “ay” contains the component of gravity acceleration. The formula is corrected to consider the gravity acceleration component correctly and to correspond to the all load case. In addition, the coefficient ck is changed based on the experimental data.

RyFa

Ktp

hopper

λ'

1=

Where,

For n2<=10 and n3<=5, 3

2'n

CWnF k=

For n2>10 or n3>5 S

k llWCF ='

hswayYSXGYGhhSCG

RYRhopper aCCCgR

yaCa θθϑθ sin)cos()cos(tansin _1 +Φ−+⎟

⎟⎠

⎞⎜⎜⎝

⎛−−= −

Definitions of all symbols are specified in the Rule text. 2.6 Ch 6, Sec 1, [2.7.4]

As the interpretation of the cases where n2>10 and/or n3>5 are added to the renumbered paragraph [2.7.3], the paragraph [2.7.4] is deleted. 2.7 Ch 6, Sec 2, [2.5.1]

The 2nd and the 3rd sentences are deleted. 2.8 Ch 6, Sec 2, [2.5.2] and [2.5.3]

The formulae for all load cases are provided as similar to the revision of the scantling formula for plating in Ch 6 Sec 1. 2.9 Ch 6, Sec 2, [2.5.4]

As the interpretation of the cases where n2>10 and/or n3>5 are added to the paragraph [2.5.3], this paragraph is deleted.


PAGE 55 OF 171

3. Scantling impact due to modifications For scantling of inner bottom plating and ordinary stiffeners there is less impact due to this

modification. For thickness of bilge hopper sloping plate and inner hull plate and section modulus of ordinary

stiffeners, the conservative scantling required by the current requirement is improved by this modification.

Details of the calculation for scantling impact due to these modifications are described in Annex 2.


PAGE 56 OF 171

Annex 1: Background of the formulae for steel coil loading Ch 6, Sec 1 2.7 Inner bottom loaded by steel coils on a wooden support 2.7.1 General 2.7.1a In dimensioning the plating and ordinary stiffeners, static and dynamic loads due to dry

bulk cargoes and liquid acting on the plating and ordinary stiffeners are considered as uniformly distributed loads. On the other hand, as steel coils are loaded on a wooden support (dunnage) provided on the inner bottom plating and bilge hopper plating, the concentrated loads due to steel coils act on the plating through the dunnage. However, as the location of concentrated loads and the distance between concentrated loads depend on the loading pattern and size of dunnage, it is assumed that the concentrated load is transformed to a line load with a small breadth (hereinafter referred to as “rectangular load”) which acts on the most severe conditions (load point and distance between load points). Based on this assumption, the specific formulae for dimensioning the plating and ordinary stiffeners under steel coil loading are introduced in the Rules separately from those based on uniformly distributed loads.

2.7.1b The specific requirements for plating are specified in Ch 6 Sec 1 [2.7.2] and [2.7.3], and those for ordinary stiffeners are specified in Ch 6 Sec 2 [2.5.2] and [2.5.4].

2.7.1c The technical background of loads due to steel coils is common for plating and ordinary stiffeners.

2.7.1d These requirements are based on the assumption that steel coils are loaded on a wooden support and secured in the standard manner. These assumptions are given in Figure 2 in Ch 6 Sec 1.

2.7.2 Inner bottom plating 2.7.2a Load model

Steel coils are usually secured to each other by means of steel wires. Heavier steel coils are loaded with one or two tiers, and lighter ones are loaded with two or more tiers. Examples of steel coil loading are shown in Figs.1 and 2.

Inner bottom plating

Bilge hoppersloping plating

key coil



(A) with key coil (B) without key coil

Fig.1 Loading conditions of one tier



Fig.2 Loading conditions of two tiers


PAGE 57 OF 171

The load due to steel coils acts on an elementary plate panel as a concentrated load through dunnages. However, it is difficult to treat concentrated loads directly because the location of concentrated loads and the distance between concentrated loads depend on the loading pattern and size of dunnage. Then, the following assumptions regarding the loads due to steel coils are considered. (1) Loads due to steel coils act along a centreline of a plate panel. (2) A rectangular load instead of concentrated loads is used in order to be on the safer

side considering the interaction between concentrated loads.

l

l

s

l

l'


FloorFloor

z

x

x

y

dunnage

Steel coil

Elementary plate panel

Fig.3 Convert concentrated loads to rectangular loads

As it is the most severe when loads act on the inner bottom vertically, the vertical acceleration is considered for the scantling formula of inner bottom structures. The position of the centre of gravity is given by the following.

x direction: (i) for the hold of which the mid position is located forward of 0.45L from A.E.: XG_SC = 0.75 lH forward of aft bulkhead, and (ii) for the hold of which the mid position is located afterward of 0.45L from A.E.: XG_SC= 0.75 lH afterward of fore bulkhead, where lH is a cargo hold length

y direction: 4hBε , measured from the centreline z direction: ( )( ) 22311 SCDB dnh −++ Where,

SCd : The diameter, in m, of steel coil DBh : The height, in m, of double bottom

Bh: breadth, in m, at the mid of the hold


PAGE 58 OF 171

Inner bottomplating

Bottom plating

hDB

dSC2

3

dSC2

hDB

dSC2

dSC2

32

Fig.4 The height of steel coils

2.7.2b Structural model As mentioned in 2.7.2a, the rectangular load acts along the centreline of the panel. Its length 'l is determined by the panel length l , the length of a steel coil Sl , the number of load points 2n and the number of dunnages supporting one steel coil 3n , and its width

s3.0 is derived from dunnage width based on the actual loading data. Of course, the axial stress due to hull girder bending is considered in addition to the lateral rectangular load due to the steel coils. An elementary plate panel is collapsed like Fig.5. The boundary conditions of an elementary plate panel are that all sides are considered fixed.

l

sl'

0.3s

Fig.5 Rectangular load and collapsed mode 2.7.2c Number of load points and distances between load points in ship length direction per

elementary plate panel Tables 3 and 4 in Ch 6, Sec 1 of the Rules give the standard number of load points and distances between load points in ship length direction for the case of 102 ≤n and/or

53 ≤n . For other cases, the current treatment as noted in Ch 6, Sec 1, [2.7.4] stipulates that loads due to steel coils are considered as a uniform distribution load and the scantling of plating is obtained according to Ch 6, Sec 1, [3.2.1]. However, it is considered that the scantlings of plating and ordinary stiffeners under steel coil loads are treated separately from those for distributed loads. Therefore, the instruction in Ch 6, Sec 1, [2.7.4] is not appropriate and it has been deleted. Instead a line load at panel centreline is assumed throughout the panel length.


PAGE 59 OF 171

The calculation results are shown in Table 1. In this calculation, the coefficient 3n is changed from 3 to 6, the coefficient 2n is derived from the same procedure gotten from Tables 3 and 4 in Ch 6, Sec 1 of the Rules. The calculation results according to the generic formula for plating and ordinary stiffener specified in Ch 6, Sec 1, [3.2.1] and Sec 2, [3.2.3] of the Rules are calculated by assuming that the loads due to steel coils are treated as uniformly distributed loads defined as (Wl/ls). It is found from this result that the required net thickness and net section modulus for uniform load is greater than those for load model specified in the Rules. In order to eliminate this difference between the case of n2>10 and/or n3>5 and the case of n2<=10 and n3<=5, the treatment of the case n2>10 and/or n3>5 is added to the Rules and current paragraphs [2.7.4] of Ch 6 Sec 1 and [2.5.4] of Ch 6, Sec 2 are deleted.

Table 1 Comparison of required scantlings

Line load according to Ch 6, Sec 1, [2.7.2] and Sec 2, [2.5.2]

Uniform load according to Ch 6, Sec 1, [3.2.1]

l (m) 2.4 2.4 2.4 2.4 2.4 s (m) 0.8 0.8 0.8 0.8 0.8

n1 2 2 2 2 - n2 5 6 7 9 - n3 3 4 5 6

ls (m) 1.5 1.5 1.5 1.5 l’ (m) 1.53 1 1.45 1 1.40 1 1.53 1

W (kg) 15000 15000 15000 15000 F (kg) 50000 45000 42000 45000 45000(n2=6)

tnet_req (mm) 15.8 15.4 15.0 15.0 17.5 wnet_req (cm3) 391 400 399 401 432

2.7.2d Coefficient KS

When steel coils are lined up in one tier with a key coil as shown in Fig.1 (A), two coils support a key coil. However, it is known that half of the weight of a key coil does not act on the supporting coil due to the frictional resistance between steel coils. In order to investigate the effect of the frictional resistance between steel coils, parametric experiments were carried out by the Shipbuilding Research Association of Japan. If the force due to steel coils is expressed by the following formula, the effect of frictional resistance ( SK ) is given in Table 2.

3

21

nnWnKF S=

Where, W : Mass of one steel coil, in kg

1n : Number of tier of steel coils 2n : Number of load points per elementary panel

n : Number of dunnages supporting steel coil


PAGE 60 OF 171

Table 2 Coefficient SK derived from experiments results

1/2 1/3 1/63-3 1.40 1.36 1.343-6 1.36 1.41 1.43

a/DPosition ofkey coil (m-n)

This result shows that the effect of the frictional resistance depends on the diameter of steel coils and distance between the centres of coils. The average value is 1.38, and therefore SK is taken to equal to 1.4 to be on the safe side.

2.7.2e Coefficient K1 and K2

The coefficients 1K and 2K are derived from the principle of virtual work based on material physics.

2.7.2f Formula for required thickness of inner bottom plating

Finally, the scantling formula for inner bottom plating is given as follows. ( ) ( )( ){ }

YP

zZRZP

RFaCCgKt

λθ +Φ

=coscos

1

Where,

For n2<=10 and n3<=5, 3

21

nnWnKF S=

For n2>10 or n3>5 S

S llWnKF 1=

2.7.3 Bilge hopper sloping plate and inner hull plate 2.7.3a Load model

The load model for hopper sloping and inner hull plating is very complex because the loads are supported by the inner bottom directly or by other steel coils as shown in Fig.6.




Inner hullplating

Fig.6 The examples of steel coil loading conditions

The force due to steel coils for bilge hopper sloping plate and inner hull plate is expressed by the following formula considering the effect of frictional resistance between steel coils and the support by the inner bottom.

3

2'n

CWnF k=

Where, W , 2n and 3n are specified in 2.7.2d.

kC : The coefficient specified in 2.7.3c.


PAGE 61 OF 171

This load model is the same for the inner bottom. Although the vertical component of the load is supported by the inner bottom directly or by other coils, only Ck is considered to derive the loads acting on the side wall. As specified in 2.7.3c, the coefficient Ck is introduced based on the experiments. This coefficient Ck is based on the component of the load in the transverse direction.

Therefore, the component of the load in transverse direction is only considered in the scantling formula for bilge hopper plate and inner hull plate. In the original formula specified in the current Rule text, it was considered that the equivalent design wave (EDW) “R” was dominant in the bilge hopper sloping plate or inner hull plate. However, as the acceleration in transverse direction specified in Ch 4 Sec 2, [3.2.1] includes the static component due to roll angle, the static component due to gravity acceleration is counted in duplicate. Therefore, the term related to the transverse acceleration in scantling formula for load case R is revised. In addition, in order to cover all load cases, the term related to the acceleration in the scantling formula is revised as follows, considering the load combination factors.

hswayYSXGYGhhSCG

RYRhopper aCCCgR

yaCa θθθθ sin)cos()cos(tansin _1 +Φ−+⎟

⎟⎠

⎞⎜⎜⎝

⎛−−= −

Where: yrolla swaya : Acceleration due to roll and sway, in m/s2, defined in Ch.4 Sec.2 [3.2]

Ra : Tangential roll acceleration, in m/s2. (See Fig. 7) 22

22

180Ry

Ta scG

RR +⎟⎟

⎠

⎞⎜⎜⎝

⎛= −

ππθ

scGy − : Centre of gravity of steel coils in transverse direction, in m. (see Fig, 7) R : Coefficient defined in Ch. 4 Sec. 2 [3.2.1]. (see Fig.7)

RT : Roll period, in s, defined in Ch 4, Sec 2, [2.1]

g : Gravity acceleration, in m/s2

hθ : Angle, in degrees, between inner bottom plating and bilge hopper sloping plate or inner hull plate. (see Fig. 7)

θ : Single roll amplitude, in degrees, defined in Ch 4, Sec 2, [2.1] CYG, CYR, CYS, CXG: Load combination factors defined in Ch 4, Sec 4, [2.2]


PAGE 62 OF 171

CLθh

Centre of gravity

θh

aR

RyG-sc

Fig.7 Definition of the acceleration aR

2.7.3b Structural model

The structural model for bilge hopper sloping plating and inner hull plating is the same for inner bottom plating.

2.7.3c Coefficient Ck

In order to determine the coefficient kC specified in 2.7.3a, experiments were performed by the Shipbuilding Research Association of Japan. According to the report, the experiments were carried out under the following conditions specified in (a) to (d) and as shown in Fig.8.

Key coilDunnage Side shell

Strain gauge

m n

aD

Note: m and n is the number of coils counted from the key coil.

Fig.8 Experiment device and loading condition of steel coils

(a) Steel coils were loaded with one tier with key coil (b) Roll angle was 20 degree (c) Roll period was 60 seconds (d) Position of key coil was changed (“m” in Fig.8 was changed from 1 to 8)

In addition, a theoretical analysis was tried and the results are shown in Fig. 9. According to the results shown in Fig. 9, the following outcomes were obtained.


PAGE 63 OF 171

i) The Ck value is obtained from the loads on side wall based on the force in transverse direction.

ii) The kC value strongly depends on the location of the key coil. iii) The effect of the diameter of steel coils and the length between the gravity centre of

steel coils is relatively small compared to the effect of the location of the key coil. iv) The calculation results match the experimental results well. v) In order to be on the safe side, 2.3=kC is an appropriate value when the key coil is

located second or third from the side shell and 0.2=kC is appropriate in other cases.

kC : Coefficient taken to equal: 2.3=kC when steel coils are lined up in two or more tiers, or steel coils are lined up

in one tier and the key coil is located second or third from the bilge hopper sloping plating or inner hull plating

0.2=kC for other cases

Calculation

Roll angle = 20 (deg)

m-n

3.2

Ck

Fig.9 Experimental results

2.7.4 2.7.4a The current text is deleted. Ch 6, Sec 2 2.5 Ordinary stiffeners of inner bottom loaded with steel coils on a wooden support 2.5.1 General 2.5.1a Same as specified in 2.7 for plating. 2.5.2 Ordinary stiffeners located on inner bottom plating 2.5.2a Load model

As the structural model for plating is based on the plastic theory, it is too complex to treat the concentrated load. Therefore, a rectangular load is considered in the requirement for plating mentioned in Ch 6, Sec 1, [2.7.2]. On the other hand, the structural model for ordinary stiffeners is based on the simple elastic beam theory. Therefore, the load model for ordinary stiffeners is based on concentrated loads due to steel coils acting through the dunnage.


PAGE 64 OF 171

The calculation of acceleration is based on the same assumption for plating. The parameter and coefficients are also the same for plating. According to the similar reason specified in 2.7.2c, Ch 6, Sec 2, [2.5.4] has been deleted.


Structural model of ordinary stiffeners is based on the simple beam theory with the boundary condition that both ends of beams are fixed.

2.5.2c Coefficient K3

The coefficient 3K is derived from the ratios of moments at ends of ordinary stiffeners against 12 =n when load points of the concentrated loads are located evenly between 'l as shown in Fig.10 When 2n is over 10, the coefficient 3K is 2/3.

l'

l'

n2=1 n2=2

l'

n2=3 n2=4

PP/2 P/2

P/3 P/3 P/3 P/4 P/4 P/4 P/4

Fig.10 Load points on an ordinary stiffener

2.5.3 Ordinary stiffeners located on hopper sloping plate or inner hull plating 2.5.3a Load model

The concentrated load is considered as specified in 2.5.2a and the acceleration due to roll motion is considered as specified in 2.7.3a of Ch 6, Sec 1.


Structural model of an ordinary stiffener is specified in 2.5.2b. 2.5.4 2.5.4a This item is deleted.


PAGE 65 OF 171

Annex 2: Scantling impact due to modifications Ramification studies

In order to quantify the impact due to the modification of the scantling formula for plating and ordinary stiffeners, ramification studies were performed using the following 6 ships listed in Table 2-1.

The data of the steel coils listed in Table 2-2 taken from the loading manuals of the considered ships was used for the ramification study.

Table 2-1 Principal dimensions of subject ships Pre-CSR ship CSR ship

Ship 1 Ship 2 Ship 3 Ship 4 Ship 5 Ship 6 Handy max Small Small Handymax Handymax Handy

Table 2-2 Data of steel coils

Ship 1 Ship 2 Ship 3 Ship 4 Ship 5 Ship 6 W (kg) 15000 20000 15000 20000 15000 15000

Sl (m) 1.5 1.8 1.5 1.5 1.5 1.5Number of tiers 2 1 1 2 2 2Key coil not used used used Not used Not used Not used

1. Scantling changes at inner bottom structures

Where the number of load points is not greater than 10 and/or number of dunnages is not

greater than 5, the scantling formulae for inner bottom plating and ordinary stiffeners are not changed by the Rule Change proposal 3. However, as the calculation point of acceleration is modified and the default value of GM and rk are newly added, the scantling impact calculations were carried out in order to grasp the changes.

Calculation results are shown in Figs.2-1 to 2-3. These results show that the required scantlings are not that different between the current CSR and the modification because the vertical acceleration in EDW “H” which is dominant for the scantlings of inner bottom plating and longitudinals is not affected by the y- and z- coordinate of the gravity centre. For reference, the required thickness of inner bottom plating was increased by 3 to 4mm compared to that of pre-CSR designs because the corrosion additions specified in CSR are larger by 3 to 4 mm than those used in Pre-CSR designs.

Regarding inner bottom longitudinals, the difference between the required section modulus and the actual one of pre-CSR designs varies largely depending on the design. The required shear area is smaller than the actual one of pre-CSR designs.

On the other hand, as the offered scantlings of inner bottom structure for CSR design ships are greater than those determined by the requirement for steel coil loading, they may be determined by the requirement other than that for steel coil loading. Therefore, there is no scantling impact for inner bottom plate and longitudinals due to his change. 2. Scantling changes at bilge hopper and inner hull structures 2.1 Scantlings of plating

Required gross thicknesses of bilge hopper sloping plating are shown in Fig.2-4. This figure shows that the modification improves the formula by providing the appropriate thickness compared to that of inner bottom plating.


PAGE 66 OF 171

For reference, the required thicknesses of bilge hopper sloping plating was increased by 3 to 4mm compared to those of pre-CSR designs because the corrosion additions specified in CSR are larger by 3 to 4mm than those used in the pre-CSR designs.

For CSR ships, the thicknesses of bilge hopper plating are determined by the requirement for steel coil loading, but, the scantling of longitudinal attached to the hopper sloping plate may be determined by the requirement other than that for steel coil loading. As a result, only thickness of hopper sloping plate according to the proposed formula becomes that similar to inner bottom plating and decreased about 4mm for these example cases.

If the thicknesses of hopper sloping plate would be determined by the proposed requirement for steel coil loading, the total steel weight is decreased about 20 tons for ship 5 and 15 tons for ship 6 by this change.

2.2 Scantlings of ordinary stiffeners 2.2.1 Section modulus

Required net section moduli of ordinary stiffeners attached to bilge hopper sloping plating are shown in Fig. 2-5. This figure shows that the modification improves the formula by providing the appropriate section modulus compared to that of inner bottom longitudinals.

Regarding the bilge hopper longitudinal, the difference between the required section modulus and actual one of Pre-CSR designs varies largely depending on the design.

For CSR ships, the scantlings of longitudinal attached to hopper sloping plate become about 60% of those required current rules in terms of section modulus by this change. Therefore, the final scantlings of the longitudinal may be determined by other requirements.

If the scantling of longitudinals would be determined by the proposed formula, the steel weight will be decreased about 4 tons for ship 5 and 2 tons for ship 6 by this change.

2.2.2 Section area

Required net section areas of ordinary stiffeners fitted to the bilge hopper sloping plating are shown in Fig.2-6. The required section area according to modified formulae is larger than those of current CSR. This increase is caused by the correction of a mistake in the formula.

For reference, the required shear area according to the modified formula is smaller than the actual one of both pre-CSR designs and CSR ships.


PAGE 67 OF 171

0

5

10

15

20

25

30G

ross

Thi

ckne

ss (m

m)

ActualCSRModification

Ship 1 Ship 2 Ship 3 Ship 4 Ship 5 Ship 6

Fig.2-1 Comparison of gross thickness of inner bottom plate

0

200

400

600

800

1000

1200

Net

Sec

tion

Mod

ulus

(cm

3 )



Fig. 2-2 Comparison of net section moduli of inner bottom longitudinals


PAGE 68 OF 171

0

5

10

15

20

25

30

35

40

45

50N

et S

ectio

n A

rea

(cm

2 )



Fig.2-3 Comparison of net section area of inner bottom longitudinals

0

5

10

15

20

25

30

35

40

Gro

ss T

hick

ness

(mm

)



Fig. 2-4 Comparison of gross thickness of bilge hopper sloping plate


PAGE 69 OF 171

0

200

400

600

800

1000

1200N

et S

ectio

n M

odul

us (c

m3 )



Fig.2-5 Comparison of net section moduli of longitudinals attached to bilge hopper sloping plate

0

5

10

15

20

25

30

35

40

45

50

Net

Sec

tion

Are

a (c

m2 )



Fig.2-6 Comparison of net section area of longitudinals attached to bilge hopper sloping plate


PAGE 70 OF 171


PAGE 71 OF 171


Rule Change Notice No.1-4 (Minimum Scantling, Side Frame

and Grab)





PAGE 72 OF 171


Chapter 6 HULL SCANTLING

Section 2 ORDINARY STIFFENERS


2.2 Minimum nNet thicknesses of webs of ordinary stiffeners

2.2.1 Minimum net thicknesses of webs of oOrdinary stiffeners other than side frames of single side bulk carriers The net thickness of the web of ordinary stiffeners, in mm, is to be not less than the greater of:

• t = 3.0 + 0.015L2

• 40% of the net required offered thickness of the attached plating, to be determined according to Ch.6, Sec.1.

and is to be less than 2 times the net offered thickness of the attached plating

2.2.2 Minimum net thicknesses of sSide frames of single side bulk carriers The net thickness of side frame webs within the cargo area, in mm, is to be not less than the value obtained from the following formula: tMIN = 0.75α (7 + 0.03L) where: α : Coefficient taken equal to:

α = 1.15 for the frame webs in way of the foremost hold

α = 1.00 for the frame webs in way of other holds.

2.2.3 Maximum net thickness of web of ordinary stiffener The net thickness of the web of ordinary stiffeners, in mm, is to be less than 2 times the net offered thickness of the attached plating.

3. Yielding check

3.3 Strength criteria for side frames of single side bulk carriers

3.3.1 Net section modulus and net shear sectional area of side frames The net section modulus w, in cm3, and the net shear sectional area Ash , in cm2, of side frames subjected to

lateral pressure are to be not less, in the mid-span area, than the values obtained from the following formulae:

( ) 32

10125.1YS

WSm Rm

sppw

λα

l+=


PAGE 73 OF 171

( )⎟⎠

⎞⎜⎝

⎛ −+=

l

lll B

a

WSSsh

sppA

2sin

51.1

φτα

where:

αm : Coefficient taken equal to:

αm = 0.42 for BC-A ships

αm = 0.36 for other ships

λS : Coefficient taken equal to 0.9

l : Side frame span, in m, defined in Ch 3, Sec 6, Fig 19, to be taken not less than 0.25D

αS : Coefficient taken equal to:

αS = 1.1 for side frames of holds specified to be empty in BC-A ships

αS = 1.0 for other side frames

lB : Lower bracket length, in m, defined in Fig 7

ps, pw : Still water and wave pressures, in kN/m², in intact conditions calculated as defined in [1.3] and

[1.4.2].

l l

Figure 7 Side frame lower bracket length

In addition to the above provision, for side frames of holds intended to carry ballast water in heavy ballast

condition, the net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, all along the span of

side frames subjected to lateral pressure in holds intended to carry ballast water are to be in accordance with

[3.2.3], l being the span of the side frame as defined in Ch.3 Sec.6 [4.2], with consideration to brackets at ends.

3.3.3 Lower bracket of side frame In addition, aAt the level of lower bracket as shown in Ch 3, Sec 6, Fig 19, the net section modulus of the frame

and bracket, or integral bracket, with associated shell plating, is to be not less than twice the net section modulus

w required for the frame mid-span area obtained from [3.3.1].

In addition, for holds intended to carry ballast water in heavy ballast condition, the net section modulus w, in

cm3, at the level of lower bracket is to be not less than twice the greater of the net sections moduli obtained from

[3.3.1] and [3.2.3].


PAGE 74 OF 171

The net thickness tLB of the frame lower bracket, in mm, is to be not less than the net thickness of the side frame

web plus 1.5 mm.

Moreover, the net thickness tLB of the frame lower bracket is to comply with the following formula:

• for symmetrically flanged frames: kth

LB

LB 87≤

• for asymmetrically flanged frames : kth

LB

LB 73≤

The web depth hLB of lower bracket may be measured from the intersection between the sloped bulkhead of the

hopper tank and the side shell plate, perpendicularly to the face plate of the lower bracket (see Ch 3, Sec 6,

Fig 22).

For the 3 side frames located immediately abaft the collision bulkhead, whose scantlings are increased according

to [3.3.2], when tLB is greater than 1.73tw, the thickness tLB may be taken as the value t’LB obtained from the

following formula:

( ) 312'

wLBLB ttt =

where tw is the net thickness of the side frame web, in mm, corresponding to Ash determined in accordance to

[3.3.1].

The flange outstand is not to exceed 12k0.5 times the net flange thickness.

3.3.4 Upper bracket of side frame In addition, aAt the level of upper bracket as shown in Ch 3, Sec 6, Fig 19, the net section modulus of the frame

and bracket, or integral bracket, with associated shell plating, is to be not less than twice the net section modulus

w required for the frame mid-span area obtained from [3.3.1].

In addition, for holds intended to carry ballast water in heavy ballast condition, the net section modulus w, in

cm3, at the level of upper bracket is not to be less than twice the greater of the net sections moduli obtained from

[3.2.3] and [3.3.1].

The net thickness tUB of the frame upper bracket, in mm, is to be not less than the net thickness of the side frame

web.


PAGE 75 OF 171


Section 1 FORE PART

4. Scantlings


4.3.3 The net thickness of the web of ordinary stiffeners, in mm, is to be not less than the greater of:

• t = 3.0 + 0.015L2

• 40% of the net offered required thickness of the attached plating, to be determined according to [4.2] and

[5.2].

and is to be less than twice the net offered thickness of the attached plating.

The net dimensions of ordinary stiffeners are to comply with the requirement in Ch 6, Sec 2, [2.2.2] and [2.3].


PAGE 76 OF 171

Section 2 AFT PART

4. Scantlings


4.2.3 The net thickness of the web of ordinary stiffeners, in mm, is to be not less than the greater of:

• t = 3.0 + 0.015L2

• 40% of the net offered required thickness of the attached plating, to be determined according to [4.1].

and is to be less than twice the net offered thickness of the attached plating.

The net dimensions of ordinary stiffeners are to comply with the requirement in Ch 6, Sec 2, [2.2.2] and [2.3].


PAGE 77 OF 171

CHAPTER 12 ADDITIONAL CLASS NOTATIONS

Section 1 GRAB ADDITIONAL CLASS NOTATION

2. SCANTLINGS

2.1. Plating

2.1.1

The net thickness of plating of inner bottom, lower strake of hopper tank sloping plate, and transverse lower stool plating, transverse bulkhead plating and inner hull up to a height of 3.0m above the lowest point of the from inner bottom, excluding bilge wells, is to be taken as the greater of the following values:

• t , as obtained according to requirements in Ch 6 and Ch 7

• tGR , as defined in [2.1.2] and [2.1.3].

2.1.2

The net thickness tGR, in mm, of the inner bottom plating is to be obtained from the following formula:

( ) skMt GRGR 5028.0 +=

2.1.3

The net thickness tGR, in mm, within the lower 3 m of hopper tank sloping plate, and of transverse lower stool, transverse bulkhead plating and inner hull up to a height of 3.0m above the lowest point of the inner bottom, excluding bilge wells, is to be obtained from the following formula:

( ) skMt GRGR 4228.0 +=


PAGE 78 OF 171


PAGE 79 OF 171



(Minimum Scantling, Side Frame and Grab)




PAGE 80 OF 171

Technical Background for the Changes Regarding Scantling Requirement for Ordinary stiffener, Side Frame and Grab 1. Reason for the Rule Change: 1.1 Ch 6, Sec 2, [2.2]

The current CSR requires the minimum thickness of webs of ordinary stiffeners is not to be less than 40% of the net offered thickness of the attached plating. However, there are some cases where the thickness of plating is increased due to buckling check of the plating and hull girder strength check and so on. In such cases, the thickness of web of ordinary stiffener is determined by the increased offered thickness of the attached plating and sometimes scantling of the angle type stiffener is remarkable large in order to satisfy with this requirement. This rule change is made to avoid such cases. (KC ID 213).

In addition, the maximum thickness of webs of ordinary stiffeners is mentioned in [2.2.1],

although the title of this requirement is minimum thickness requirement. This requirement is based on the consideration of the proportion of thickness

between the attached plating and webs of ordinary stiffener. Accordingly, [2.2] will be modified to be applicable both on minimum and maximum thickness, as follows: • Title of [2.2] should be “Net thicknesses of webs of ordinary stiffeners” • Title of [2.2.1] should be “Minimum net thicknesses of webs of ordinary stiffeners other than side frames of single side bulk carriers” • Title of [2.2.2] should be “Minimum net thicknesses of side frames of single side bulk carriers”

• New [2.2.3] with the following title: “Maximum net thickness of web of ordinary stiffener”. 1.2 Ch 6 Sec 2, [3.3.1]

This change is made to clarify the requirement by specifying the extent of the span to use and the calculation point for still water and wave pressures (refer to KC ID 216 and 217). It specifies also that the requirements of Ch6. Sec2 [3.2.3] are to be asserted along the whole span of the frames for holds intended to carry ballast water in heavy ballast condition (KC ID 356). 1.3 Ch 6 Sec 2, [3.3.3]

This change is made to clarify the requirement by specifying the requirements to be met for side frame’s lower bracket in holds intended to carry ballast water in heavy ballast condition (KC ID 356). 1.4 Ch 6 Sec 2, [3.3.4]

This change is made to clarify the requirement by specifying the requirements to be met for side frame’s upper bracket in holds intended to carry ballast water in heavy ballast condition (KC ID 356). 1.5 Ch 9 Sec 1, [4.3.3] and Sec 2, [4.2.3] The requirements in Ch 9 Sec 1, [4.3.3] and Sec 2 [4.2.3] are same required in Ch 6 Sec 2, [2.2.1].


PAGE 81 OF 171

1.6 Ch 12 Sec 1, [2.1] This change is made to clarify the requirement by specifying the areas concerned by this

calculation (refer to KC ID 313 and 544). 2. Summary of Rule Changes 2.1 Ch 6, Sec 2, [2.2.1], [2.2.3], Ch 9 Sec 1, [4.3.3] and Sec 2, [4.2.3] (1) The “net offered thickness” is changed to “net required thickness” and the required

thickness is determined according to Ch 6 Sec 1. (2) The maximum net offered thickness is deleted from the requirement in [2.2.1] and the

formula with the same meaning are added to new paragraph [2.2.3]. (3) The requirements in Ch 9 Sec 1, [4.3.3] and Sec 2, [4.2.3] are revised in order to be same

for Ch 6 Sec 2, [2.2.1]. 2.2 Ch 6, Sec 2, [3.3.1] (1) The definition of the pressures for side frames is added. (2) For side frames in ballast hold, the scantling check is carried out as an ordinary stiffener

with span defined in Ch 3 Sec 6 [4.2]. 2.3 Ch 6, Sec 2, [3.3.3] and [3.3.4]

For lower and upper brackets of side frame in ballast hold, the net section modulus at the level of brackets of side frame is to be not less than twice of the net section moduli obtained by the requirements for both side frames and ordinary stiffeners. 2.4 Ch 12 Sec 1, [2.1]

Inner hull up to a height of 3.0m from the lowest point of inner bottom is applied to this requirement. 3. Impact on Scantling 3.1 Ch 6, Sec 2, [2.2.1], [2.2.3], Ch 9 Sec 1, [4.3.3] and Sec 2, [4.2.3]

Regarding the minimum thickness requirement of webs of ordinary stiffeners, the scantling impact depends on the stiffener type used. If the angle type stiffener is used, the scantling is decrease by this change but steel weight decrease is negligible.

3.2 Ch 6 Sec 2 [3.3.1], [3.3.3] and [3.3.4]

There is no change in terms of the steel weight by comparing that before and after the proposed Rule change. 3.3 Ch 12 Sec 1, [2.1]

For double side skin bulk carrier having the height of the bilge hopper tanks less than 3.0m or hybrid bulk carrier with cargo hold without hopper tank, it is considered that the thickness of inner hull may be increased by this rule change. However, as there is no CSR ships with such design, the scantling impact cannot be compared that before and after the proposed Rule change.


PAGE 82 OF 171


PAGE 83 OF 171


Rule Change Notice No.1-5 (Direct Strength Analysis)




RULE CHANGE NOTICE NO.1-5 COMMON STRUCTURAL RULES FOR BULK CARIIERS

PAGE 84 OF 171


CHAPTER 7 DIRECT STRENGTH ANALYSIS

Section 2 GLOBAL STRENGTH FE ANALYSIS OF CARGO HOLD STRUCTURES

2. Analysis model

2.2 Finite element modeling

2.2.4 When orthotropic elements are not used in FE model:

• mesh size is to be equal to or less than the representative spacing of longitudinal stiffeners or transverse side

frames

• stiffeners are to be modeled by using rod and/or beam/bar elements

• where a double hull is fitted, webs of primary supporting members are to be divided by at least three

elements height-wise. However, for transverse primary supporting members inside hopper tank and top side

tank, which are less in height than the space between ordinary longitudinal stiffeners, two elements on the

height of primary supporting members are accepted.

• where no double hull construction is fitted, side shell frames and their end brackets are to be modeled by

using shell elements for web and shell/beam/rod elements for face plate. Webs of side shell frames need not

be divided along the direction of depth

• aspect ratio of elements is not to exceed 1:4.

An example of typical mesh is given in App 1.

2.3 Boundary conditions

2.3.1 Both ends of the model are to be simply supported according to Tab 1 and Tab 2. The nodes on the longitudinal

members at both end sections are to be rigidly linked to independent points at the neutral axis on the centreline

as shown in Tab 1. The independent points of both ends are to be fixed as shown in Tab 2.

Table 1: Rigid-link of both ends

Translational Rotational Nodes on longitudinal members at both ends of the model Dx Dy Dz Rx Ry Rz

All longitudinal members RL RL RL - - - RL means rigidly linked to the relevant degrees of freedom of the independent point


PAGE 85 OF 171

Table 2: Support condition of the independent point

Translational Rotational Location of the independent point

Dx Dy Dz Rx Ry Rz Independent point on aft end of model - Fix Fix - Fix - - Independent point on fore end of model Fix Fix Fix Fix - -

3. Analysis criteria

3.2 Yielding strength assessment

3.2.1 Reference stresses Reference stress is Von Mises equivalent stress at the centre of a plane element (shell or membrane) or axial

stress of a line element (bar, beam or rod) obtained by FE analysis through considering hull girder loads

according to [2.5.4] or [2.5.5].

Where the effects of openings are not considered in the FE model, the reference stresses in way of the openings

are to be properly modified with adjusting shear stresses in proportion to the ratio of web height and opening

height.

Where elements under assessment are smaller than the standard mesh size specified in [2.2.4] or [2.2.5], the

reference stress may be obtained from the averaged stress over the elements within the standard mesh size.

3.4 Deflection of primary supporting members The relative deflection, δmax in mm, in the outer bottom plate obtained by FEA is not to exceed the following

criteria:

The maximum relative deflection between the double bottom and the forward (or afterward) transverse bulkhead

obtained from the FE analysis is not to exceed the following criteria:

150maxil

≤δ

where:

maxδ : Maximum relative deflection, in mm, obtained by the following formula, and not including secondary

deflection between the double bottom and the forward (or afterward) transverse bulkhead, in mm

),max( 21max BB δδδ =

where, δB1 and δB2 are shown in Fig 3.

il : Length or breadth of the flat part of the double bottom, in mm, whichever is the shorter.


PAGE 86 OF 171

Figure 3: Definition of relative deflection

δB1

δB2

li

δB1

δB2

li

δB2δB1

li

δB2δB1

li


PAGE 87 OF 171

Section 3 DETAILED STRESS ASSESSMENT

1. General

1.1 Application

1.1.1 This Section describes the procedure for the detailed stress assessment with refined meshes to evaluate highly

stressed areas of primary supporting members.

Where the global cargo hold analysis of Sec 2 is carried out using a model complying with the modelling criteria

of Sec 2, [2.2.4], the areas listed in Tab 1 are to be refined at the locations whose calculated stresses exceed 95%

for non-orthotropic elements or 85 % for orthotropic element but do not exceed 100% of the allowable stress as

specified in Sec 2, [3.2.3].


PAGE 88 OF 171


PAGE 89 OF 171


Technical Background for Rule Change Notice No.1-5 (Direct Strength Analysis)




PAGE 90 OF 171

Technical Background for the Changes Regarding the Direct Strength Analysis: 1. Reason for the Rule Change: 1.1 Ch 7, Sec 2, [2.2.4] and [3.2.1]

In a transverse ring in bilge hopper tank, there are some cases where the web height is smaller than the space between ordinary stiffeners. Where the web is divided by three elements, the element size is relative small. In addition, the element sometimes becomes smaller so that the aspect ratio of element does not exceed 1:4. It is not considered that such smaller elements are appropriate for applying the global strength analysis of cargo hold structures.

Therefore this rule change is made to clarify the requirements according to the interpretation in KC ID 149. 1.2 Ch 7, Sec 2, Table 2

The boundary condition in FEA, which restricts rotation along x-axis at fore end of FE model but allow free rotation at aft end, specified in Table 2. However, this boundary condition may cause unexpected warping deformation under beam sea condition because the one end of FE model is rotated about x-axis. It has been noticed that the stress level induced by the warping deformation is sometimes unreasonable severe, especially, in case of smaller bulk carrier as handy size and Panamax BCs.

This rule change is an interim solution made to avoid the unexpected rotation in FEA due to this boundary condition. (Refer to KC ID 340).

A definitive agreement on boundary conditions has later to be made through further studies that will use same basis in order to make effective comparisons and impact evaluations. 1.3 Ch 7, Sec 2, [3.2.1]

Stress level of all elements in FE model should be within the allowable criteria specified in the Rules, in principle. However, the elements having relative small size are often used in FEA. In this case, the averaged stresses among these elements are normally used where deemed reasonable by the Society.

This change is made to clarify the requirements for such a case.(Refer to KC ID 340) 1.4 Ch 7, Sec 2, [3.4]

The maximum relative deflection is not clear in the current text. In order to clarify the relative deflection, which does not include the deflection of

ordinary stiffeners, the editorial correction is made and new figure which gives a definition of the deflection of the outer bottom plate is added. 1.5 Ch 7, Sec 3, [1.1.1]

This rule change is made to clarify the requirement for the application of the detailed stress assessment. (Refer to KC ID 341)


PAGE 91 OF 171

2. Summary of Rule Change 2.1 Ch 7, Sec 2, [2.2.4]

Considering the actual design for the transverses in bilge hopper or topside tank, the height of transverse web is smaller than the spacing between longitudinals. In order to avoid the smaller mesh size in such structural members as far as practicable, the rule change is so made that two shell elements can be accepted. 2.2 Ch 7, Sec 2, [2.3.1] Table 2

As an interim solution the rotational boundary condition RX of independent point on at end of model is changed to “Fix” from “-“. 2.3 Ch 7, Sec 2, [3.2.1] Reference stresses

Where the cargo hold FE model includes the smaller mesh size than the standard mesh size specified in the Rules, the reference stress can be obtained from the averaged stress over the elements within the standard mesh size. 2.4 Ch 7, Sec 2 [3.4] Deflection of primary supporting members

In order to clarify the definition of the relative deflection of outer bottom structure, the figure is added in the text and the relevant texts are modified. 2.5 Ch 7, Sec 3, [1.1]

Where the stresses calculated according to the global strength analysis of cargo hold structures specified in Ch 7 Sec 2 exceed 95% for non-orthotropic elements or 85% for orthotropic elements but not exceed allowable stress, detailed stress analysis specified in Sec 3 is required. 3. Impact on Scantling 3.1 Impact on scantling due to the change in Ch 7, Sec 2, [2.2.4], [3.2.1], [3.4] and Sec 3, [1.1]

As these rule changes specified in 2.1, 2.3, 2.4 and 2.5 above are made for the clarification, there is no scantling impact due to these changes. 3.2 Impact on scantling due to the changes in Ch 7, Sec 2, Table 2 regarding the correction of the boundary conditions

The cargo hold FEA using the boundary condition specified in the current text gives too unreasonable stress in cross deck.

Due to the unreasonable stresses, the required thickness for cross deck may be than that for upper deck plating.

For example, the required thickness for cross deck is 22.5mm (AH32) and 15mm (AH32) for upper deck according to KC ID 343.

From the engineering point of view, this result caused by the boundary condition which gives unrealistic warping effect in FE model obviously.

Therefore, the scantling impact due to this change is not carried out. However, the unreasonable and excessive stresses around the hatch opening and in cross

deck are improved drastically by this modification. The details of the effect due to the modification of the boundary condition are mentioned in Annex 1.


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Annex 1: Details of the effect due to the modification of the boundary conditions

1. FE Analysis and results

In order t to examine the effect due to the modification of the boundary condition regarding the rotational restriction Rx along x-axe, the FE analysis for one Handy max buck carrier is carried out as a typical example.

Applied boundary condition is given in Table 1-1.

Table 1-1 Applied boundary condition (1) Case-1 Boundary condition as per CSR

Translational Rotational Independent Point Dx Dy Dz Rx Ry Rz

Aft End of Model - Fx Fix - - - Fore End of Model Fix Fix Fix Fix - - (2) Case-2 Modified boundary condition

Translational Rotational Independent Point Dx Dy Dz Rx Ry Rz

Aft End of Model - Fx Fix Fix - - Fore End of Model Fix Fix Fix Fix - -

Applied loading condition and load case are full load homogeneous condition and EDW “P1”. As the effect due to the boundary condition is mainly appeared in the stresses of structures around the hatch opening and cross deck under beam sea condition, the calculated stresses in cross deck and deformations for full load condition under beam sea (P1) as a typical example. The sampling point of the stress of cross deck is shown in Fig. 1-1.

Fig. 1-1 Sampling Point

1

2

6

7

8

4

5

3

14

15

9

10

11

12

13

16 C.L

P

S


PAGE 93 OF 171

The stresses of the sampling points for case 1 and case 2 are shown in Table 1-2. The stress level in cross deck is given in Figure 1-2 and the deformation of the FE model is given in Fig. 1-3.

Table 1-2 Stresses at the sampling points in Cross Deck in full load condition under beam sea (P1)

σallowable σe (N/mm2) σallowable σe (N/mm2) ID

(N/mm2) Case-1 (CSR)

Case-2 (Modified)

ID(N/mm2) Case-1

(CSR) Case-2

(Modified) 1 326 41 229 9 326 439 224 2 235 103 145 10 235 213 141 3 235 165 137 11 235 153 134 4 326 145 109 12 326 201 132 5 235 195 168 13 235 249 174 6 326 246 94 14 326 108 68 7 235 167 112 15 235 103 91 8 235 144 153 16 235 205 150


PAGE 94 OF 171

(1) Case -1

Fig-5 Deformation (Case-2 / Boundary Condition of CSR)

Fig. 1-2 Stress level in the cross deck in full load condition under beam sea (P1)

NG

(1) Case 1

(2) Case 2


PAGE 95 OF 171

(1) Case 1

(2) Case 2 Fig. 1-3 Deformation for FE model at the full load condition under beam sea (P1)


PAGE 96 OF 171

2. Conclusion

According to Fig 1-3(1), the deformation of FE model is warped unreasonably due to the boundary condition that is the aft end of FE model is free. Hence, the stress distribution in cross deck forward the mid hold of FE model is different from that of afterward the mid hold and the stress value in cross deck seems to be excessive as shown in Fig 1-2(1) and Table 1-1. On the other hand, the deformation of FE model for case 2 is not observed the unreasonable warp because the rotational restriction of both ends of FE model is applied, as shown in Fig 1-3(2). Hence, the stress distribution in forward cross deck forward the mid hold of FE model is similar to that afterward the mid hold and excessive stress values are not appeared in cross deck as shown in Fig. 1-2(2) and Table 1-1.

Then, it is concluded that (1) The boundary in current text gives excessive and unreasonable results. (2) The corrected boundary condition does not give excessive and unreasonable results.

In order to evaluate the FEA results properly, the incorrect boundary condition should be revised to avoid the unreasonable warping deformation in FE model.


PAGE 97 OF 171


Rule Change Notice No.1-6 (Fatigue Check for Longitudinals)





PAGE 98 OF 171


CHAPTER 4 DESIGN LOADS

Section 5 EXTERNAL PRESSURES

2. External pressures on exposed decks

2.1 General 2.1.1 The external pressures on exposed decks are to be applied for the local scantling check of the structures on

exposed deck but not applied for fatigue strength assessment.

If a breakwater is fitted on the exposed deck, no reduction in the external pressures defined in [2.2] and [2.3] is

allowed for the area of the exposed deck located aft of the breakwater.


PAGE 99 OF 171

Section 6 INTERNAL PRESSURES AND FORCES

2. Lateral pressure due to liquid

2.1 Pressure due to liquid in still water 2.1.3 For fatigue strength assessment, the liquid pressure in still water pBS, in kN/m2, is given by the following formula.

)( zzgp TOPLBS −= ρ

If the pBS is negative, pBS is to be taken equal to 0.

Where the considered load point is located in the fuel oil, other oils or fresh water tanks, liquids are assumed to be fulfilled up to the half height of the tanks and zTOP is taken to the Z coordinate of the liquid surface at the upright condition


PAGE 100 OF 171

CHAPTER 8 FATIGUE CHECK OF STRUCTURAL DETAILS

Section 1 GENERAL CONSIDERATION

1. General

1.3 Subject members

1.3.1 Fatigue strength is to be assessed, in cargo hold area, for members described in Tab 1, at the considered

locations.

Table 1: Members and locations subjected to fatigue strength assessment

Members Details Connection with sloping and /or vertical plate of lower stool Inner bottom plating Connection with sloping plate of hopper tank

Inner side plating Connection with sloping plate of hopper tank Connection with sloping plate of lower stool

Transverse bulkhead Connection with sloping plate of upper stool

Hold frames of single side bulk carriers Connection to the upper and lower wing tank Connection of longitudinal stiffeners with web frames and transverse bulkhead Ordinary stiffeners in double side space Connection of transverse stiffeners with stringer or similar

Ordinary stiffeners in upper and lower wing tank

Connection of longitudinal stiffeners with web frames and transverse bulkhead

Ordinary stiffeners in double bottom Connection of longitudinal stiffeners with floors and floors in way of lower stool or transverse bulkhead

Hatch corners Free edges of hatch corners

3. Loading

3.1 Loading condition

3.1.1 The loading conditions to be considered are defined in Tab 2 depending on the ship type. The standard loading

conditions illustrated in Ch 4, App 3 are to be considered.


PAGE 101 OF 171

Table 2: Loading conditions

Full load condition Ballast condition Ship type Homogeneous Alternate Normal ballast Heavy ballast

BC-A

BC-B ---

BC-C ---


PAGE 102 OF 171

Section 4 STRESS ASSESSMENT OF STIFFENERS

1. General

1.1 Application

1.1.1 Hot spot stress ranges and structural hot spot mean stresses of longitudinal stiffeners are to be assessed in line

with the requirements of this Section.

1.1.2 The hot spot stress ranges and structural hot spot mean stresses of longitudinal stiffeners are to be evaluated at

the face plate of the longitudinal considering the type of longitudinal end connection and the following locations.

(1) Transverse webs or floors other than those at transverse bulkhead of cargo hold or in way of stools, such that

additional hot spot stress due to the relative displacement may not be considered. These longitudinal end

connections are defined in Tab 1. When transverse webs or floors are watertight, the coefficients Kgl and Kgh

as defined in Tab 2 are to be considered instead of those defined in Tab 1

(2) Transverse webs or floors at transverse bulkhead of cargo hold in way of stools, such that additional hot spot

stress due to the relative displacement should be considered. These longitudinal end connections are defined

in Tab 2. When transverse webs or floors at transverse bulkhead of cargo hold or in way of stools are not

watertight, the coefficients Kgl and Kgh as defined in Tab 1 are to be considered instead of those defined in

Tab 2.

2. Hot spot stress range

2.3 Stress range according to the simplified procedure

2.3.1 Hot spot stress ranges The hot spot stress range, in N/mm2, due to dynamic loads in load case “i” of loading condition “(k)” is to be


( ) ( ))(2,)(2,2)(2,1)(2,)(1,)(1,2)(1,1)(1,)(, kidkiWkiWkiGWkidkiWkiWkiGWkiW σσσσσσσσσ +−+−+−+=Δ

where

σGW , i1(k), σGW , i2(k) : Stress due to hull girder moment, defined in [2.3.2]

σW1 , i1(k), σW1 , i2(k) : Stress σLW ,i j(k) , σCW ,i j (k) and σLCW , i j (k) due to hydrodynamic or inertial pressure when the

pressure is applied on the same side as the ordinary stiffener depending on the considered

case

σW2 , i1(k), σW2 , i2(k) : Stress σLW , i j(k) , σCW , i j (k) and σLCW , i j (k) due to hydrodynamic or inertial pressure when the

pressure is applied on the side opposite to the stiffener depending on the considered case

σLW , i1(k), σLW , i2(k) : Stresses due to wave pressure, defined in [2.3.3]

σCW , i1(k), σCW , i2(k) : Stresses due to liquid pressure, defined in [2.3.4]

σLCW , i1(k), σLCW , i2(k) : Stresses due to dry bulk cargo pressure, defined in [2.3.5]


PAGE 103 OF 171

σd , i1(k), σd , i2(k) : Stress due to relative displacement of transverse bulkhead or floor in way of stools,

defined in [2.3.6].

2.3.2 Stress due to hull girder moments The hull girder hot spot stress, in N/mm2, in load case “i1” and “i2” for loading condition “(k)” is to be obtained

from the following formula:

( ) ( )2,1)(,,,,)(, =−⋅= jCCK kWHjiWHjiWVjiWVghkjiGW σσσ

where:

Kgh : Geometrical stress concentration factor for nominal hull girder stress depending on the detail of end

connection as defined in Tab 1. Kgh is given in Tab 1 and Tab 2 for the longitudinal end connection

specified in [1.1.2](1) and [1.1.2](2), respectively.

The stress concentration factor can be evaluated directly by the FE analysis.

CWV , i1 , CWV , i2 , CWH , i1 , CWH , i2 : Load combination factors for each load case defined in Ch 4, Sec 4, [2.2]

σWV , i1 , σWV , i2 , σWH , (k) : Nominal hull girder stresses, in N/mm2, defined in Sec 3, [2.2.2]

2.3.3 Stress due to wave pressure The hot spot stress, in N/mm2, due to the wave pressure in load case “i1” and “i2” for loading condition “(k)” is

to be obtained from the following formula:

( )2,11012

661

32

22

)(,)(,

)(, =⎟⎟⎠

⎞⎜⎜⎝

⎛+−

= jw

xxspCKK ff

kjiWkjiNEsgl

kjiLW

lll

σ

( )2,11012

661

32

22

)(,

)(, =⎟⎟⎠

⎞⎜⎜⎝

⎛+−

= jw

xxspKK ff

kjiCWsgl

kjiLW

lll

σ

⎪⎩

⎪⎨⎧

≥

<=

5.0;

5.0;2

)(1,)(1,

)(1,)(1,)(1,)(1,

kiNEkiW

kiNEkiWkiNEkiCW Cp

CpCp

⎪⎩

⎪⎨⎧

≥−

<=

5.0;)12(

5.0;0

)(2,)(2,)(2,

)(2,)(2,

kiNEkiWkiNE

kiNEkiCW CpC

Cp

where:

pW , i j(k) : Hydrodynamic pressure, in kN/m2, specified in Ch 4, Sec 5, [1.3], [1.4] and [1.5] , with fp = 0.5, in

load case “i1” and “i2” for loading condition “(k)”. When the location of the considered member is

above the waterline, the hydrodynamic pressure is to be taken as the pressure at waterline.

Kgl : Geometrical stress concentration factor for stress due to lateral pressure depending on the detail of end

connection as defined in Tab 1. Kgl is given in Tab. 1 and Tab. 2 for the longitudinal end connection

specified in [1.1.2] (1) and [1.1.2] (2), respectively

The stress concentration factor can be evaluated directly by the FE analysis when the detail of end

connection is not defined in Tab 1.


PAGE 104 OF 171

Ks : Geometrical stress concentration factor due to stiffener geometry

322

10112

)(1 −

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+−

⎥⎥⎦

⎤

⎢⎢⎣

⎡ −+=

a

b

fb

fs w

wbb

wbat

K

a , b : Eccentricity, in mm, of the face plate as defined in Fig 1. For angle profile, “b” is to be taken as half

the net actual thickness of the web.

tf, bf : thickness and breadth of face plate, in mm, respectively, as defined in Fig 1

wa , wb : Net section modulus in A and B respectively(see Fig.1), in cm3, of the stiffener about the neutral axis

parallel to Z axis without attached plating.

CNE , i j(k) : Correction factor for the non linearity of the wave pressure range in load case “i1” and “i2” of loading

condition “(k)”

( )

⎪⎪⎪⎪

⎩

⎪⎪⎪⎪

⎨

⎧

−≤

−>

⎥⎥⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢⎢⎢

⎣

⎡

⎟⎟⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜⎜⎜

⎝

⎛

−

+−−

= −

g

pTz

g

pTz

g

pg

pTz

C

WLkjiWkLC

WLkjiWkLC

WLkjiW

WLkjiWkLC

kjiNE

ρ

ρ

ρ

ρ

),(,)(

),(,)(

5.2

5.21),(,

),(,)(

)(,

for0.1

for

5.0ln

exp

TLC(k) : Draught, in m, of the considered loading condition “(k)”

pW , i j(k) , WL : Hydrodynamic pressure, in kN/m2, at water line in load case “i1” and “i2” of loading condition “(k)”

z : Z co-ordinate, in m, of the point considered

s : Stiffener spacing, in m

l : Span, in m, to be measured as shown in Fig 2. The ends of the span are to be taken at points where the

depth of the end bracket, measured from the face plate of the stiffener is equal to half the depth of the

stiffener.

xf : Distance, in m, to the hot spot from the closest end of the span l (see Fig 2)

w : Net section modulus, in cm3, of the considered stiffener. The section modulus w is to be calculated

considering an effective breadth se, in m, of attached plating obtained from the following formulae:

( )

⎪⎪

⎩

⎪⎪

⎨

⎧

−>

−≤

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛ −⋅

=

3/116for67.0

3/116for

23/11

6sin67.0

ss

sss

sel

llπ


PAGE 105 OF 171

X

Z

b a

bf

B Atf

hw

tw

tp

O

bp

X

Z

b a

bf

B Atf

hw

tw

tp

O

bp

Figure 1: Sectional parameters of a stiffener

l

l

l

Trans.Trans.

dd/2d/2

xf

hot spot

l

Figure 2: Span and hot spot of longitudinal stiffeners


PAGE 106 OF 171

2.3.4 Stress due to liquid pressure The hot spot stress, in N/mm2, due to the liquid pressure in load case “i1” and “i2” for loading condition “(k)” is

to be obtained from the following formula:

( )2,11012

661

32

22

)(,)(,

)(, =⋅⎟⎟

⎠

⎞

⎜⎜

⎝

⎛+−

= jw

xxspCKK ff

kjiBWkjiNIsgl

kjiCW

lll

σ

where:

pBW , i j(k) : Inertial pressure, in kN/m2, due to liquid specified in Ch 4, Sec 6, [2.2], with fp = 0.5, in load case “i1”

and “i2” for loading condition “(k)”. Where the considered location is located in fuel oil, other oil or

fresh water tanks, no inertial pressure is considered for the tank top longitudinals and when the

location of the considered member is above the liquid surface in static and upright condition, the

inertial pressure is to be taken at the liquid surface line.

CNI , i j(k) : Correction factor for the non linearity of the inertial pressure range due to liquid in load case “i1” and

“i2” for loading condition “(k)”

( )

⎪⎪⎪⎪⎪

⎩

⎪⎪⎪⎪⎪

⎨

⎧

−≤

−>

⎥⎥⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢⎢⎢

⎣

⎡

⎟⎟⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜⎜⎜

⎝

⎛

−

+−−

= −

g

pzz

g

pzz

g

pg

pzz

C

SFkjiBWSF

SFkjiBWSF

SFkjiBW

SFkjiBWSF

kjiNI

ρ

ρ

ρ

ρ

),(,

),(,

5.2

5.21),(,

),(,

)(,

for0.1

for

5.0ln

exp

zSF : Z co-ordinate, in m, of the liquid surface. In general, it is taken equal to “ztop” defined in Ch 4 Sec 6.

If the considered location is located in fuel oil, other oil or fresh water tanks, it may be taken as the

distance to the half height of the tank. In general, it is taken as the distance to the top of the tank. In

case of fuel oil tank, it may be taken as the distance to the half height of the tank

z : Z co-ordinate, in m, of the point considered

pBW , i j(k) , SF : Inertial pressure due to liquid, in kN/m2, taken at the liquid surface in load case “i1” and “i2” for

loading condition “(k)”. In calculating the inertial pressure according to Ch 4 Sec 6, [2.2.1], x and y

coordinates of the reference point are to be taken as liquid surface instead of tank top.

Kgl, Ks : the stress concentration factor defined in [2.3.3]

2.3.6 Stress due to relative displacement of transverse bulkhead or floor in way of transverse bulkhead or stool For longitudinal end connection specified in [1.1.2] (2), tThe additional hot spot stress, in N/mm2, due to the

relative displacement in the transverse direction perpendicular to the attached plate between the transverse

bulkhead or floor in way of stools and the adjacent transverse web or floor in load case “i1” and “i2” for loading

condition “(k)” is to be obtained from the following formula.

( )2,1""point for ""point for

)(,)(,

)(,)(,)(, =

⎩⎨⎧

++

=−−−−

−−−− jfKKaKK

kjifdAfdAkjifdFfdF

kjiadAadAkjiadFadFkjid σσ

σσσ

where:

a , f : Suffix which denotes the location considered as indicated in Tab 12.


PAGE 107 OF 171

A , F : Suffix which denotes the direction, forward (F) and afterward (A), of the transverse web or floor

where the relative displacement is occurred as indicated in Tab 12.(see Fig 3)

σdF-a , i j(k) , σdA-a , i j(k) , σdF-f , i j(k) , σdA-f , i j(k) : Additional stress at point “a” and “f ”, in N/mm2, due to the

relative displacement between the transverse bulkhead or floors in way of stools and the forward (F)

and afterward (A) transverse web or floor respectively in load case “i1” and “i2” for loading condition

“(k)”

( )5)(,

)(, 1015.119.3 −

− ⎟⎟

⎠

⎞

⎜⎜

⎝

⎛−

+=

A

fA

AFFAFA

FAkjiFkjiadF

x

IIwIEI

llll

δσ

( )5

3)(,)(,

)(, 109.0

15.119.3 −

− ⎥⎥

⎦

⎤

⎢⎢

⎣

⎡−⎟

⎟

⎠

⎞

⎜⎜

⎝

⎛−

+=

AA

fAAkjiA

A

fA

AFFAAA

FAkjiAkjiadA

w

xEIx

IIwIEI

lllll

δδσ

( )5

3)(,)(,

)(, 109.0

15.119.3 −

− ⎥⎥

⎦

⎤

⎢⎢

⎣

⎡−⎟

⎟

⎠

⎞

⎜⎜

⎝

⎛−

+=

FF

fFFkjiF

F

fF

AFFAFF

FAkjiFkjifdF

w

xEIx

IIwIEI

lllll

δδσ

( )5)(,

)(, 1015.119.3 −

− ⎟⎟

⎠

⎞

⎜⎜

⎝

⎛−

+=

F

fF

AFFAAF

FAkjiAkjifdA

x

IIwIEI

llll

δσ

δF , i j(k) , δA , i j(k) : Relative displacement, in mm, in the transverse direction perpendicular to the attached plate

between the transverse bulkhead or floor in way of stools and the forward (F) and afterward (A)

transverse web or floor in load case “i1” and “i2” for loading condition “(k)” (see Fig 3)

(a) For longitudinals penetrating floors in way of stools

Relative displacement is defined as the displacement of the longitudinal in relation to the line

passing through the stiffener end connection at the base of the stool measured at the first floor

forward (F) or afterward (A) of the stool.

(b) For longitudinals other than (a)

Relative displacement is defined as the displacement of the longitudinal in relation to its original

position measured at the first forward (F) or afterward (A) of the transverse bulkhead.

Where the stress of the face of longitudinal at the assessment point due to relative displacement is

tension, the sign of the relative displacement is positive.

IF , IA : Net moment of inertia, in cm4, of forward (F) and afterward (A) longitudinal

KdF-a , KdA-a , KdF-f , KdA-f : Stress concentration factor for stiffener end connection at point “a” and “f “ subject

to relative displacement between the transverse bulkhead and the forward (F) and afterward (A)

transverse web or floors in way of stool respectively as defined in Tab 12. The stress concentration

can be evaluated directly by the FE analysis when the detail of end connection is not defined in Tab

12.

lF , lA : Span, in m, of forward (F) and afterward (A) longitudinal to be measured as shown in Fig 2

xfF , xfA : Distance, in m, to the hot spot from the closest end of lF and lA respectively (see Fig 2).


PAGE 108 OF 171

Trans.T.BHDTrans.

a f

ForeAft

A F

δFδA

Trans. Trans.T. BHD

Aft Fore

lA lF

a f

IA IF

δFδA

Trans. Trans.T. BHD

Aft Fore

δFδA

Trans. Trans.T. BHD

Aft Fore

lA lF

a f

IA IF

Figure 3 Relative displacement between the transverse bulkhead and the transverse web or floor Definition of the relative displacement (Example of the side longitudinal)

3. Hot Spot Mean Stress

3.3 Mean stress according to the simplified procedure

3.3.1 Hot spot mean stresses The structural hot spot mean stress, in N/mm2, in loading condition “(k)” regardless of load case “i” is to be


)(,)(,2)(,1)(,)(, kdSkSkSkGSkmean σσσσσ +−+=

where

σGS , (k) : Stress due to still water hull girder moment, defined in [3.3.2]

σS1 , (k) : Stress due to static pressure when the pressure is applied on the same side as the ordinary stiffener

depending on the considered case, with consideration of the stresses defined in [3.3.3] to [3.3.5]

σS2 , (k) : Stress due to static pressure when the pressure is applied on the side opposite to the stiffener

depending on the considered case, with consideration of the stresses defined in [3.3.3] to [3.3.5]

σLS , (k) : Stress due to hydrostatic pressure, defined in [3.3.3]

σCS , (k) : Stress due to liquid pressure in still water, defined in [3.3.4]

σLCS , (k) : Stress due to dry bulk cargo pressure in still water, defined in [3.3.5]

σdS , (k) : Stress due to relative displacement of transverse bulkhead in still water, defined in [3.3.6].


PAGE 109 OF 171

3.3.2 Stress due to still water hull girder moment The hot spot stress due to still water bending moment, in N/mm2, in loading condition “(k)” is to be obtained

with the following formula:

( ) 3)(,)(, 10−−

=Y

kSghkGS I

NzMKσ

where:

MS , (k) : Still water vertical bending moment, in kN.m, defined in Sec 3, [3.2.2].

3.3.3 Stress due to hydrostatic and hydrodynamic pressure The hot spot stress due to hydrostatic and hydrodynamic pressure, in N/mm2, in loading condition “(k)” is to be

obtained with the following formula:

32

22

)(,

)(, 1012

661

w

xxspKK ff

kSsgl

kLS

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛+−

=ll

l

σ

32

22)(2,)(1,

)(,

)(, 1012

661

2⋅

⎟⎟⎠

⎞⎜⎜⎝

⎛+−

⎭⎬⎫

⎩⎨⎧ +

+

=w

xxs

pppKK ffkiCWkiCW

kSsgl

kLS

lll

σ

where:

pS , (k) : Hydrostatic pressure, in kN/m2, in loading condition “(k)” specified in Ch 4, Sec 5, [1.2].

pCW , i j(k): Corrected hydrodynamic pressure, in kN/m2, according to [2.3.3], with fp = 0.5, in load case “i1” and

“i2” for loading condition “(k)”

i : Suffix which denotes the load case specified in Sec 2 [2.1.1], when calculating the mean stress, "I" is

to be used.

3.3.4 Stress due to liquid pressure in still water The structural hot spot mean stress due to liquid pressure, in N/mm2, in loading condition “(k)” is to be obtained

with the following formula:

32

22

)(,

)(, 1012

661

w

xxspKK ffkCSsgl

kCS

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛+−

=ll

l

σ

where: pCS ,(k) : Liquid pressure in still water, in kN/m2, in loading condition “(k)” specified in Ch 4, Sec 6, [2.1].

Where the considered location is located in fuel oil, other oil or fresh water tanks, dAP and PPV defined

in Ch 4 Sec 6 are to be taken equal to 0 and zTOP specified in Ch 4 Sec 6, [2.1] is to be taken equal to

zSF specified in [2.3.4].


PAGE 110 OF 171

Table 1: Stress concentration factors for the stiffener end connection

Stress concentration factors Structural type Assessed

point Collar plate Bracket size

Kgl Kgh KdF KdA

watertight ----- 1.5 1.1 1.15 1.5 A

non-watertight ----- 1.65 1.1 ----- -----

1

F watertight ----- 1.1 1.05 1.55 1.05

dw ≤ d<1.5dw 1.45 1.1 1.15 1.4 watertight

1.5dw ≤ d 1.4 1.05 1.15 1.35

dw ≤ d<1.5dw 1.55 1.1 ----- ----- A

non-watertight 1.5dw ≤ d 1.5 1.05 ----- -----

dw ≤ d<1.5dw 1.1 1.05 1.15 1.1

2

F watertight

1.5dw ≤ d 1.05 1.05 1.1 1.05


1.5dw ≤ d 1.35 1.05 1.05 1.3

dw ≤ d<1.5dw 1.5 1.1 ----- ----- a


dw ≤ d<1.5dw 1.05 1.05 1.1 1.05

3

f watertight

1.5dw ≤ d 1.05 1.05 1.05 1.05

dw ≤ d<1.5dw 1.1 1.05 1.05 1.25 a watertight

1.5dw ≤ d 1.05 1.05 1.05 1.2


1.5dw ≤ d 1.3 1.05 1.3 1.05

dw ≤ d<1.5dw 1.4 1.1 ----- -----

4

f non-

watertight 1.5dw ≤ d 1.4 1.05 ----- -----

dw ≤ d<1.5dw 1.1 1.05 1.05 1.2 a watertight

1.5dw ≤ d 1.05 1.05 1.05 1.15


1.5dw ≤ d 1.3 1.05 1.5 1.05

dw ≤ d<1.5dw 1.35 1.1 ----- -----

5

f non-

watertight 1.5dw ≤ d 1.35 1.05 ----- -----


PAGE 111 OF 171

Table 1: Stress concentration factors for the stiffener end connection (continued)



Kgl Kgh KdF KdA


1.5dw ≤ d 1.05 1.05 1.05 1.05

dw ≤ d<1.5dw 1.15 1.05 ----- ----- a


dw ≤ d<1.5dw 1.05 1.05 1.1 1.05

6

f watertight

1.5dw ≤ d 1.05 1.05 1.05 1.05


1.5dw ≤ d 1.05 1.05 1.05 1.15

dw ≤ d<1.5dw 1.15 1.05 ----- ----- a


dw ≤ d<1.5dw 1.05 1.05 1.05 1.05

7

f watertight

1.5dw ≤ d 1.05 1.05 1.05 1.05


1.5dw ≤ d 1.05 1.05 1.05 1.1

dw ≤ d<1.5dw 1.1 1.1 ----- ----- a


dw ≤ d<1.5dw 1.05 1.05 1.1 1.05

8

f watertight

1.5dw ≤ d 1.05 1.05 1.05 1.05

a watertight ----- 1.4 1.05 1.05 1.75

9

f watertight ----- 1.6 1.05 1.7 1.05

a watertight ----- 1.3 1.05 1.05 1.75

10

f watertight ----- 1.55 1.05 1.3 1.05


PAGE 112 OF 171

Table 1: Stress concentration factors for the stiffener end connection (continued)



Kgl Kgh KdF KdA

a watertight ----- 1.1 1.05 1.05 1.2

11

f watertight ----- 1.75 1.05 1.4 1.05

a watertight ----- 1.1 1.05 1.05 1.2

12

f watertight ----- 1.3 1.05 1.05 1.05

a watertight ----- 1.05 1.05 1.05 1.15

13

f watertight ----- 1.95 1.05 1.55 1.05

a watertight ----- 1.05 1.05 1.05 1.15

14

f watertight ----- 1.7 1.05 1.15 1.05


PAGE 113 OF 171

Table 1: Stress concentration factors for non-watertight longitudinal end connection at transverse webs or floors other than transverse bulkheads or floors in way of stools

Stress concentration factors Bracket type Assessed point Bracket size

Kgl Kgh 1

a ----- 1.65 1.1

dw ≤ d < 1.5dw 1.55 1.1 2

a

1.5dw ≤ d 1.5 1.05

dw ≤ d < 1.5dw 1.5 1.1 3

a

1.5dw ≤ d 1.45 1.05

dw ≤ d < 1.5dw 1.4 1.1 4

f

1.5dw ≤ d 1.4 1.05

dw ≤ d < 1.5dw 1.35 1.1 5

f

1.5dw ≤ d 1.35 1.05

dw ≤ d < 1.5dw 1.15 1.05 6

a

1.5dw ≤ d 1.1 1.05

A

A F

F

A F

F A

A F

F A


PAGE 114 OF 171

Table 1: Stress concentration factors for non-watertight longitudinal end connection at transverse webs or floors other than transverse bulkheads or floors in way of stools (continued)


Kgl Kgh

dw ≤ d < 1.5dw 1.15 1.05 7

a

1.5dw ≤ d 1.1 1.05

dw ≤ d < 1.5dw 1.1 1.1 8

a

1.5dw ≤ d 1.05 1.05

9

a d ≤ 2h 1.45 1.1

10

a d ≤ 2.5h 1.35 1.1

a

1.15 1.1 11

f

d1 ≤ 2h and

h ≤ d2 1.85 1.1

a

1.15 1.1 12

f

d1 ≤ 2.5h and

h ≤ d2 1.35 1.1

a

1.1 1.1 13

f

d1 ≤ 2h and

h ≤ d2 2.05 1.1

a

1.1 1.1 14

f

d1 ≤ 2.5h and

h ≤ d2 1.8 1.1

A F

A F

A F

A F

A F

A F

A F

A F

Tripping bracket

Tripping bracket

Tripping bracket

Tripping bracket

Tripping bracket

Tripping bracket


PAGE 115 OF 171

Table 2: Stress concentration factors for watertight longitudinal end connection at transverse bulkheads and floors in way of stools

Stress concentration factors Bracket type Assessed

point Bracket size Kgl Kgh KdF KdA

a ----- 1.5 1.1 1.15 1.5

1

f ----- 1.1 1.05 1.55 1.05

dw ≤ d<1.5dw 1.45 1.1 1.15 1.4 a 1.5dw ≤ d 1.4 1.05 1.15 1.35

dw ≤ d<1.5dw 1.1 1.05 1.15 1.1

2

f 1.5dw ≤ d 1.05 1.05 1.1 1.05

dw ≤ d < 1.5dw 1.4 1.1 1.1 1.35 a 1.5dw ≤ d 1.35 1.05 1.05 1.3

dw ≤ d<1.5dw 1.05 1.05 1.1 1.05

3

f 1.5dw ≤ d 1.05 1.05 1.05 1.05

dw ≤ d<1.5dw 1.1 1.05 1.05 1.25 a 1.5dw ≤ d 1.05 1.05 1.05 1.2

dw ≤ d < 1.5dw 1.3 1.1 1.35 1.05

4

f 1.5dw ≤d 1.3 1.05 1.3 1.05

dw ≤ d < 1.5dw 1.1 1.05 1.05 1.2 a 1.5dw ≤ d 1.05 1.05 1.05 1.15

dw ≤ d < 1.5dw 1.3 1.1 1.55 1.1

5

f 1.5dw ≤ d 1.3 1.05 1.5 1.05

dw ≤ d < 1.5dw 1.1 1.05 1.05 1.1 a 1.5dw ≤ d 1.05 1.05 1.05 1.05

dw ≤ d < 1.5dw 1.05 1.05 1.1 1.05

6

f 1.5dw ≤ d 1.05 1.05 1.05 1.05

A F

A F

A F

A F

A F

A F


PAGE 116 OF 171

Table 2: Stress concentration factors for watertight longitudinal end connection at transverse bulkheads and floors in way of stools (continued)


Kgl Kgh KdF KdA

dw ≤ d<1.5dw 1.1 1.05 1.05 1.2 a 1.5dw ≤ d 1.05 1.05 1.05 1.15

dw ≤ d < 1.5dw 1.05 1.05 1.05 1.05

7

f 1.5dw ≤ d 1.05 1.05 1.05 1.05

dw ≤ d<1.5dw 1.1 1.1 1.05 1.15 a 1.5dw ≤ d 1.05 1.05 1.05 1.1

dw ≤ d < 1.5dw 1.05 1.05 1.1 1.05

8

f 1.5dw ≤ d 1.05 1.05 1.05 1.05

a 1.4 1.05 1.05 1.75

9

f

d ≤ 2h

1.6 1.05 1.7 1.05

a 1.3 1.05 1.05 1.75

10

f

d ≤ 2.5h

1.55 1.05 1.3 1.05

a 1.1 1.05 1.05 1.2

11

f

d1 ≤ 2h

and h ≤ d2

1.75 1.05 1.4 1.05

a 1.1 1.05 1.05 1.2

12

f

d1 ≤ 2.5h and

h ≤ d2 1.3 1.05 1.05 1.05

a 1.05 1.05 1.05 1.15

13

f

d1 ≤ 2h and

h ≤ d2 1.95 1.05 1.55 1.05

A F

A F

A F

A F

A F

A F

A F

Tripping bracket

Tripping bracket

Tripping bracket

Tripping bracket

Tripping bracket


PAGE 117 OF 171

a 1.05 1.05 1.05 1.15

14

f

d1 ≤ 2.5h and

h ≤ d2 1.7 1.05 1.15 1.05

A F Tripping bracket


PAGE 118 OF 171


PAGE 119 OF 171



(Fatigue Check for Longitudinals)




PAGE 120 OF 171

Technical Background for the Changes Regarding Fatigue Check for Longitudinals 1. Reason for the Rule Change in: 1.1 Chapter 4, Section 5, [2.1.1]

Since the external pressures on exposed deck are set up in order to check the local scantling considering the effect on green water and are not referenced in the pressures specified in Ch 8 Sec 4, [2.3.3], the clarification is made that these pressures are not necessary to consider for the fatigue check. 1.2 Chapter 4, Section 6, [2.1.3]

For fatigue strength assessment, the filling height of liquid in the tank is to consider the average one because the fatigue strength of the structures is dominant to the most frequent condition in the representative loading condition. Generally, for water ballast tanks, the most frequent condition is assumed that the upper surface of liquid matches to upper level of the tank according to KC ID 359.

1.3 Chapter 8, Section 1, Table 1 and [3.1.1] These changes are made in order to clarify the requirements. 1.4 Chapter 8, Section 4, [2.3.3] and [3.3.3]

To consider the nonlinear relation between wave pressure and wave height, the correction factor of the pressure range is specified in Ch8 Sec4 [2.3.3] of the current CSR. This correction factor is introduced to define an equivalent linear long term distribution of stress range which gives a fatigue damage equivalent to the damage according to the nonlinear distribution of stress range. However, the consideration of this nonlinearity on the evaluation of mean stress was not included.

This consideration is naturally necessary to consider the nonlinear effect of wave pressure on the fatigue damage of side longitudinals. Consequently, Ch8 Sec4 [2.3.3] is to be modified so that this consideration can be taken into account. And Ch8 Sec4 [3.3.3] is also to be modified so that the mean stress considering the nonlinear effect can be evaluated.

1.5 Chapter 8, Section 4, [2.3.4] and [3.3.4]

The interpretation is added to the text for the case where the considered locations are located in fuel oil tank, other oil tank or fresh water tank, according to KC ID 359.

1.6 Chapter 8, Section 4, [2.3.6]

The clarification is made for the relative displacement according to the answer in KC ID 342. 1.7 Chapter 8, Section 4, Table 1

The table gives the stress concentration factors for representative stiffener end connections. However, some types of stiffener end connection not defined in the table are used for non watertight transverses and size of bracket was not defined in the table.

The modification of the table is made to clarify the application of the types of stiffener end connections and the size of bracket based on the investigation result of actual ship design, according to KC IDs 255, 256, 257, 258 and 259. 2. Summary of Rule Change 2.1 Chapter 4, Section 5, [2.1.1] The sentence regarding the external pressure on exposed deck is added to the paragraph [2.1.1].


PAGE 121 OF 171

2.2 Chapter 4, Section 6, [2.1.3] The new paragraph [2.1.3] regarding the liquid pressure in still water is added. 2.3 Chapter 8, Section 1, Table 1 and [3.1.1] The word “floors in way of lower stool” is added to the details for ordinary stiffener in double bottom in Table 1 and the sentence regarding standard loading condition for fatigue strength assessment is added to [3.1.1]. 2.4 Chapter 8, Section 4, [2.3.3] and [3.3.3] In order to consider the nonlinearity on the evaluation of mean stress, the formulae are modified as follows. (1) [2.3.3]

( )2,11012

661

32

22

)(,)(,

)(, =⎟⎟⎠

⎞⎜⎜⎝

⎛+−

= jw

xxspCKK ff

kjiWkjiNEsgl

kjiLW

lll

σ

( )2,11012

661

32

22

)(,

)(, =⎟⎟⎠

⎞⎜⎜⎝

⎛+−

= jw

xxspKK ff

kjiCWsgl

kjiLW

lll

σ

⎪⎩

⎪⎨⎧

≥−

<=

⎪⎩

⎪⎨⎧

≥

<=

5.0;)12(

5.0;0

5.0;

5.0;2

)(2,)(2,)(2,

)(2,)(2,

)(1,)(1,

)(1,)(1,)(1,)(1,

kiNEkiWkiNE

kiNEkiCW

kiNEkiW

kiNEkiWkiNEkiCW

CpC

Cp

Cp

CpCp

(2) [3.3.3]

32

22

)(,

)(, 1012

661

w

xxspKK ff

kSsgl

kLS

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛+−

=ll

l

σ

32

22)(2,)(1,

)(,

)(, 1012

661

2⋅

⎟⎟⎠

⎞⎜⎜⎝

⎛+−

⎭⎬⎫

⎩⎨⎧ +

+

=w

xxs

pppKK ffkiCWkiCW

kSsgl

kLS

lll

σ

In addition, the texts referring to Table 1 and Table 2 are changed according to the modification of these tables. The background of these formulae is given in Annex 1. 2.5 Chapter 8, Section 4, [2.3.4] and [3.3.4]

Where the considered locations are located in fuel oil tank, other oil tank or fresh water tank, ZSF may be taken as the distance to the half height of the tank.

In addition, where the hydrostatic pressure of the considered member located in fuel oil tank, other oil tank or fresh water tank is calculated according to Ch 4 Sec 6 [2.1.1], dAP and PPV defined in Ch 4 Sec 6 are to be taken equal to 0.

2.6 Chapter 8, Section 4, [2.3.6] The text on the definition of relative displacement is added.


PAGE 122 OF 171

2.7 Chapter 8, Section 4 Table 1 The current Table 1 is divided into two tables. One is for stress concentration factor for non-watertight longitudinal end connection and the other is for stress concentration factor for watertight longitudinal connection. In addition, the bracket size is added based on the actual design. 3. Effect due to this change 3.1 Clarification of the rules specified in 2.1, 2.2, 2.4 and 2.5 As these changes are made for clarification, there is no scantling impact due to this clarification. 3.2 Chapter 8, Section 4, [2.3.3] and [3.3.3]

The effect on assessed fatigue damage due to the modification was examined. Sample ships are listed in Table G1. Fatigue damages of side longitudinal stiffener with as-built scantling according to the current rule and the modified proposal were assessed and compared in Figs. 1(a) and (b).

Assessed fatigue damages are well improved to agree with the current experiences that the side longitudinal stiffeners were hardly fatigue damaged.

Table 1: List of Examined Ships

Vessel ID D1 D2 D3 S1 S3 S7Type Cape Handymax Handymax Cape Handymax Cape

Lpp (Rule) 275.48 178.48 178.29 275.00 182.85 286.91 B 45.00 32.20 31.00 45.00 32.26 50.00 D 24.30 16.50 16.50 24.40 17.80 24.10

Max. 17.80 11.68 11.66 17.93 12.45 17.88 Homo. 17.80 11.68 11.66 17.93 12.45 17.88

Alt. 17.80 11.68 11.66 17.93 12.45 17.88 N.B. 7.59 5.87 6.19 8.06 5.02 7.01 H.B. 9.78 7.91 8.67 9.14 8.02 8.92

d

NA 10.56 6.16 6.08 11.31 7.00 10.67

D1

0

5

10

15

20

25

0.0 0.5 1.0 1.5 2.0 2.5

Fatigue Dam age

Vertical Location (m)

C urrent

M odified

D2

0

5

10

15

0.0 1.0 2.0 3.0 4.0 5.0

Fatigue Dam age


C urrent

M odified

D3

0

5

10

15

0.0 1.0 2.0 3.0 4.0

Fatigue Dam age


C urrent

M odified

Fig. 1(a) Comparison of Fatigue Damages of DSS BCs


PAGE 123 OF 171

S1

0

5

10

15

20

25

0.0 1.0 2.0 3.0

Fatigue Dam age


C urrent

M odified

S3

0

5

10

15

0.0 1.0 2.0 3.0 4.0

Fatigue Dam ageVertical Location (m)

C urrent

M odified

S7

0

5

10

15

20

25

0.0 2.0 4.0 6.0

Fatigue Dam age


C urrent

M odified

Fig. 1(b) Comparison of Fatigue Damages of SSS BCs

3.3 Scantling impact due to the change in Chapter 8, Section 4, [2.3.3] and [3.3.3] 3.3.1 Procedure for impact calculation (1) Original scantlings of side longitudinals are checked by the requirement of Ch 6, Sec 2 of the

Rules. If the original scantlings do not meet the requirement of Ch 6, Sec 2, the modified scantlings are considered.

(2) Fatigue check for the longitudinals with modified scantlings is carried out by the current CSR. (3) Scantling impact in terms of sectional area due to fatigue check is evaluated. (4) Fatigue check for the longitudinal with the modified scantling is carried out by the proposed

requirement. (5) Scantling impact in terms of sectional area due to the proposed fatigue check requirement is

evaluated. 3.3.2 Scantling impact due to proposed fatigue check requirement

The scantling impact in terms of sectional area of longitudinal is evaluated according to the procedure mentioned above for D1 ship and S1 ship for an example and the results are given in Table 2 and 3.

Table 2 Scantling impact of side longitudinals for D1 ships Current Rule Proposed Rule ID Scantling impact

according to the requirement in Ch 6 Sec 2

Cumulative fatigue damage

Scantling effect due to fatigue check



Scantling impact due to modification

1 (Upper) 0.0% 1.25 0.0% (IA to T-type) 0.79 0.0% (T-type to IA) 0.0% 2 0.0% 0.64 0.0% 0.45 0.0% 0.0% 3 0.0% 1.09 +2.3% 0.62 -2.3% -2.3% 4 0.0% 0.94 0.0% 0.50 0.0% 0.0% 5 0.0% 0.94 0.0% 0.27 0.0% 0.0% 6 0.0% 1.25 +9.3% 0.11 -9.3% -9.3% 7 0.0% 1.92 +23.7% 0.39 -23.7% -23.7% 8 0.0% 2.21 +20.6% 0.45 -20.6% -20.6% 9 0.0% 2.35 +23.9% 0.48 -23.9% -23.9% 10 0.0% 1.85 +13.7% 0.49 -13.7% -13.7% 11 0.0% 1.15 +4.9% 0.41 -4.9% -4.9% 12 0.0% 0.95 0.0% 0.34 0.0% 0.0% 13 0.0% 0.61 0.0% 0.23 0.0% 0.0% 14 0.0% 0.23 0.0% 0.04 0.0% 0.0% 15 0.0% 0.16 0.0% 0.04 0.0% 0.0% 16 0.0% 0.17 0.0% 0.05 0.0% 0.0% 17 0.0% 0.18 0.0% 0.06 0.0% 0.0% 18 0.0% 0.39 0.0% 0.40 0.0% 0.0% 19 0.0% 0.53 0.0% 0.55 0.0% 0.0% 20 0.0% 0.08 0.0% 0.09 0.0% 0.0% 21(Lower) 0.0% 0.62 0.0% 0.65 0.0% 0.0% Average 0.0% - 4.3% up - -4.3% -4.3%


PAGE 124 OF 171

Table 2 Scantling impact of side longitudinals for S1 ships

Current Rule Proposed Rule ID Scantling impact according to the requirement in Ch 6 Sec 2





Scantling impact due to modification

1 (Upper) +8.4% 0.64 0.0% 0.52 0.0% 0.0% 2 +5.8% 0.54 0.0% 0.42 0.0% 0.0% 3 +27.9% 0.81 0.0% 0.54 0.0% 0.0% 4 +23.8% 0.74 0.0% 0.45 0.0% 0.0% 5 +28.0% 0.76 0.0% 0.53 0.0% 0.0% 6 +29.0% 1.21 +5.3% 1.21 +5.3% 0.0% 7 +26.5% 1.10 +3.2% 1.10 +3.2% 0.0% 8 +26.5% 1.20 +6.2% 1.20 +6.2% 0.0% 9 +30.9% 1.54 +17.0% 1.54 +17.0 0.0% 10(Lower) +30.9% 1.33 +12.1% 1.33 +12.1% 0.0% Average 23.8% up - +4.4% - +4.4% 0.0%

For double side skin bulk carrier whose side structure is longitudinal frame system, scantlings

of a few side longitudinals located below the load water line are affected by the rule change proposal.

For singe side skin bulk carriers, fatigue check result for side longitudinals in top side tank located above load water line are affected by the rule change proposal, however, there is no scantling impact due to the rule change proposal where side longitudinals have the scantlings satisfied with the requirements of Ch 6, Sec 2.

4．Technical Background Technical backgrounds of nonlinear effect on wave pressure and stress concentration factor of longitudinal end connection are described in Annex 1 and Annex 2, respectively.


PAGE 125 OF 171

Annex 1: Technical background of nonlinear effect on wave pressure 1. Current Treatment of mean stress

In the current rule, correction factor for the non linearity of the wave pressure range is introduced to define an equivalent linear long term distribution of stress range which gives a fatigue damage equivalent to the damage according to the nonlinear distribution of stress range. Fig. 1-1 shows the calculated correction factor in accordance with the distance from the base line.

Fig. 1-1 Correction Factor for Non Linearity of the Wave Pressure Range By multiplying this correction factor by the linear wave pressures for wave crest and wave

trough conditions, wave pressure range considering non linear effect can be obtained from the difference of both pressures. In the current rule, because the mean value of the fluctuating pressure is evaluated as the mean of the pressures for wave crest and wave trough conditions, negative pressure will work at the position above water line as shown in Fig. 1-2.

Fig. 1-2 Current Condition of Fluctuating Non Linear Pressure

2. Correct Treatment of Mean Stress Since the negative pressure is not acting at the position above waterline due to the wave

fluctuation, the actual fluctuation of nonlinear pressure is illustrated as Fig. 1-3.


PAGE 126 OF 171

Fig. 1-3 Actual Condition of Fluctuating Non Linear Pressure

In order to reflect above mentioned condition of fluctuating nonlinear pressure, the equation

specified in Ch 8, Sec 4, [2.3.3] is to be modified as below:

( )

( )⎩⎨⎧

≥−<

=

⎩⎨⎧

≥<

=

=⋅⎟⎟

⎠

⎞

⎜⎜

⎝

⎛+−

=

5.0;125.0;0

5.0;5.0;2

2,11012

661

)(2,)(2,)(2,

)(2,)(2,

)(1,)(1,

)(1,)(1,)(1,)(1,

32

22

)(,

)(,

kiNEkiWkiNE

kiNEkiCW

kiNEkiW

kiNEkiWkiNEkiCW

ffkjiCWsgl

kjiLW

CpCC

p

CpCpC

p

jw

xxspKK

lll

σ

According to this modification, the evaluated wave induced stress condition of the stiffeners can

be illustrated as Fig. 1-4. The magnitude of stress range hold same as the one by current rule. Only the evaluation of mean stress considering the non linearity of the wave pressure has been improved.

0

45

- 10 -5 0 5 10 15 20

LWL

Stress Range

NegativeMean Stress

Fig. 1-4 Wave induced Stress Condition along Ship Side

In order to take the nonlinear fluctuating pressure condition into account in the evaluation of

mean stress, the equation specified in Ch 8, Sec 4, [3.3.3] is to be modified as below:


PAGE 127 OF 171

3

2

22)(2,)(1,

)(,

)(, 1012

661

2⋅

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛+−

⎭⎬⎫

⎩⎨⎧ +

+

=w

xxs

pppKK ffkiCWkiCW

kSsgl

kLS

lll

σ

If fluctuating pressure is linear, )(,)(2,)(1,

)(, 2 kSkiCWkiCW

kS ppp

p =+

+ , then, above equation would

be same as the current equation.


PAGE 128 OF 171

Annex 2: Technical background of stress concentration factors for the stiffeners end connection

SCFs(Stress Concentration Factors) in Table 1 of Ch 8, Sec 4, CSR for Bulker are the ratio of the

hot spot stress obtained by the very fine FE analysis to the nominal stress calculated by the simple formulae. 1. FE analysis

Considering difference of the stiffener end connection detail, following 2 kinds of hot spot stress are calculated for each detail Nos.1-14.

σgl_hotspot : hot spot stress due to out-of-plane load σdF_hotspot, σdA_hotspot : hot spot stress due to forced displacement

1.1 Analysis model

The T type longitudinal stiffener with shell penetrating Transverse Bulkhead is considered. According to each detail number in Table 1 of Ch 8, Sec 4, CSR for Bulker, the hot spot stresses (position ‘a’ and position ‘f’) at stiffener end connection are calculated.

Fig. 2-1 shows the analysis model and the size of stiffener. Fig. 2-2 shows the stiffener end connection of each detail No.

(a) Analysis model

Stiffener Size (mm) h tw wf Tf S ts 500 12.5 150 22 850 18

Moment of inertia I= 99,482 (cm4) Section modulus Z= 2,507 (cm3) Span length l0= 5,000 (mm)

(b) Stiffener shape and size

Fig. 2-1 Analysis model and Stiffener details


PAGE 129 OF 171

Flat Bar Part

detail no a/b b/h R1/b

c/d d/h R2/d

r（mm）

1 1.0 0.4 30 3 0.4 1.0 0.7 50 4 1.0 0.4 1.0 0.7 50 5 1.0 0.4 1.0 0.7 1.3 50 6 0.36 1.1 1.0 0.7 50 7 0.4 1.0 0.7 1.0 0.7 50 8 0.4 1.0 0.7 1.0 0.7 1.3 50

Tripping Bracket Part detail no a/b b/h e/b R1/b c/d d/h R2/d r(mm)

9 0.29 1.4 50 10 0.33 1.2 1.5 0.75 50 11 0.29 1.4 1.0 1.0 50 12 0.33 1.2 1.5 0.75 1.0 1.0 50 13 0.29 1.4 1.0 0.9 1.22 50 14 0.33 1.2 1.5 0.75 1.0 0.9 1.22 50

Fig. 2-2 Stiffener end connection of each detail number 1.2 Loads a) Out-of-plane loading

A certain out-of-plane uniformly distributing load is loaded, which makes the nominal stress of stiffener end connection 200N/mm2 in tension side at l0=5m, xf=0. Fig. 2-3 shows the loading condition of a). Considering the bracket size (shown in Fig. 2-2), the hot spot stress of stiffener end connection, σgl_hotspot, is analyzed for each detail No.

b) Forced displacement Forced displacement (23.7mm) is added to the position (A) or (E) in Fig. 2-1, which makes also the nominal stress of stiffener end connection 200N/mm2 in tension side at l0=5m, xf=0. Considering the bracket size, the hot spot stresses of stiffener end connection, σdF_hotspot, σdA_hotspot, are analyzed for each detail No (shown in Fig. 2-2).

Fig. 2-3 Loading condition

b

b


PAGE 130 OF 171

1.3 Boundary condition

The boundary conditions at each position in each analysis load condition are shown in Table 2-1. In this Table, (a) means out-of-plane loading, and the others mean forced displacement. The position (A) to (E) is shown in Fig. 2-1.

Table 2-1 Boundary condition Position Load condition ( A ) ( B ) ( C ) ( D ) ( E )

(a) Complete restraint Symmetry Complete

restraint Y: Rotation

restraint Complete restraint

(b1) Y: Forced displacement Symmetry Complete


restraint Complete restraint

(b2) Complete restraint Symmetry Complete


restraint Y: Forced

displacement 2. Simple beam formulae

The beam model shown in Fig. 2-1 and Fig. 2-2 is considered as well as FE analysis, whose nominal stress of the stiffener end connection is set 200N/mm2 in tension side at l0=5m, xf=0 by out-of-plane load or forced displacement. Considering the effect of modified span length (lf) and change of hot spot position by xf specified in Ch 8, Sec 4, CSR for Bulker, following 2 kinds of modified nominal stress are calculated for each detail No.1-14.

σgl_nominal : modified nominal stress due to out-of-plane load σdF_nominal, σdA_nominal : modified nominal stress due to forced displacement

a) Out-of-plane loading Considering the bracket size (shown in Fig. 2-2), the modified nominal stress, σgl_nominal, for each detail No is calculated according to the following equation.

)0.5,/200(66

1 02

020

2

0

2

00min mlmmN

lx

lx

ll fff

alnogl ==⎟⎟⎠

⎞⎜⎜⎝

⎛+−⎟⎟

⎠

⎞⎜⎜⎝

⎛=− σσσ

b) Forced displacement Considering the bracket size (shown in Fig. 2-2), the modified nominal stresses, σdF_nominal, σdA_nominal, are calculated according to the following equations. The value of relative displacement (δF, δA) is 23.7mm.

52min_ 1015.1195.1 −

− ⎟⎟

⎠

⎞

⎜⎜

⎝

⎛−=

f

fA

f

FalnoadF l

x

wlEIδσ

53

52min_ 10

9.01015.1195.1 −−

− −⎟⎟

⎠

⎞

⎜⎜

⎝

⎛−=

f

fAA

f

fA

f

AalnoadA wl

xEIlx

wlEI δδσ

53

52min_ 10

9.01015.1195.1 −−

− −⎟⎟

⎠

⎞

⎜⎜

⎝

⎛−=

f

fAF

f

fF

f

FalnoadF wl

xEIlx

wlEI δδσ

52min_ 1015.1195.1 −

− ⎟⎟

⎠

⎞

⎜⎜

⎝

⎛−=

f

fF

f

AalnofdA l

x

wlEIδσ

Usually, the dimension and the length of the stiffener fitted at fore of transverse bulkhead is the same of those fitted at after of transverse bulkhead, but there are some cases where they are different between fore part and after part. Then, taking into account the cases of af ll ≠ and


PAGE 131 OF 171

FA II ≠ in order to generalize to the formula mentioned above, the equations specified in 3.3.6 of Ch 8, Sec 4, CSR for Bulker can be obtained. 3. Results and SCF calculation

Table 2-2 shows the hot spot stress obtained by FE analysis and the modified nominal stress calculated by simple formulae.

As the values of SCFs for web stiffener connection depend on the analytical model, boundary condition, definition of hot spot stress, etc., each classification society specifies the different SCFs. In CSR for Bulker, in order to set up the single SCFs, we decided that the SCFs for Kgl_in detail No. 1 to 8 specified in BV rule were used. (See Table 2-2) The other SCFs in detail No. 1 to 8 were obtained by multiplying the ratio (5) in Table 2 by the value calculated by FEA. For SCFs for tripping brackets connections in detail No. 9 to 14, the averaged ratio (5) in Table 2 which is equal to 0.83 was considered.

Furthermore, the modified SCFs value obtained by multiplying the SCFs specified in Table 2 by the correction factor is modified by the following manner. (a) Minimum value is set to 1.05 (b) All values are expressed by 0.05 unit

Finally, SCFs of each detail No. can be obtained as shown in Table 2-3 whose values are used for Table 1 of Ch 8, Sec 4, CSR for Bulker.

Table 2-3 Stress concentration factor

detail No.

point Kgl KdF KdA detail No.

point Kgl KdF KdA

point 'a' 1.50 1.15 1.50 9 point 'a' 1.40 1.05 1.75 1 point 'f' 1.10 1.55 1.05 point 'f' 1.60 1.70 1.05 point 'a' 1.35 1.05 1.30 10 point 'a' 1.30 1.05 1.75 3 point 'f' 1.05 1.05 1.05 point 'f' 1.55 1.30 1.05 point 'a' 1.05 1.05 1.20 11 point 'a' 1.10 1.05 1.20 4 point 'f' 1.30 1.30 1.05 point 'f' 1.75 1.40 1.05 point 'a' 1.05 1.05 1.15 12 point 'a' 1.10 1.05 1.20 5 point 'f' 1.30 1.50 1.05 point 'f' 1.30 1.05 1.05 point 'a' 1.05 1.05 1.05 13 point 'a' 1.05 1.05 1.15 6 point 'f' 1.05 1.10 1.05 point 'f' 1.95 1.55 1.05 point 'a' 1.05 1.05 1.15 14 point 'a' 1.05 1.05 1.15 7 point 'f' 1.05 1.05 1.05 point 'f' 1.70 1.15 1.05 point 'a' 1.05 1.05 1.10 8 point 'f' 1.05 1.10 1.05

PA

GE 132 O

F 171

T

ECH

NIC

AL B

AC

KG

RO

UN

D FO

R R

ULE C

HA

NG

E NO

TICE N

O.1-6 C

OM

MO

N S

TRU

CTU

RA

L RU

LES FOR

BU

LK C

AR

RIER

S

Table 2-2 Stress obtained by FE analysis or simple formulae

Detail No. point

σgl_hot (1)

σgl_nom (2)

NK’s SCF (3) =(1)/(2)

BV’s SCF (4)

Ratio (5) (=(4)/(3))

Modified SCF σdF_hot (6)

σdF_nom (7)

NK’s SCF (6)/(7)

Modified SCF σdA_hot (8)

σdA_no

m (9)

NK’s SCF (8)/(9)

Modified SCF

point 'a' 297.7 184.3 1.62 1.5 0.93 1.50 205.5 167.1 1.23 1.14(1.23*0.93) 270.1 167.1 1.62 1.50(1.62*0.93) 1 point 'f' 217.5 184.3 1.18 1.09(1.18*0.93) 280.5 167.1 1.68 1.55(1.68*0.93) 150.3 167.1 0.90 0.83(0.90*0.93) point 'a' 299.8 179.1 1.67 1.35 0.81 1.35 223.7 172.0 1.30 1.05(1.30*0.81) 272.4 172.0 1.58 1.28(1.58*0.81) 3 point 'f' 122.6 129.0 0.95 0.77(0.95*0.81) 200.5 158.4 1.27 1.02(1.27*0.81) 170.8 162.3 1.05 0.85(1.05*0.81) point 'a' 175.6 136.5 1.29 1.03(1.29*0.80) 200.2 174.6 1.15 0.92(1.15*0.80) 253.6 171.7 1.48 1.12(1.40*0.80) 4 point 'f' 275.8 169.6 1.63 1.30 0.80 1.30 295.7 181.6 1.63 1.30(1.63*0.80) 210.1 181.6 1.16 0.93(1.16*0.80) point 'a' 150.5 123.3 1.22 1.03(1.22*0.84) 190.9 163.7 1.17 0.99(1.17*0.84) 214.6 159.4 1.35 1.13(1.35*0.84) 5 point 'f' 271.3 176.7 1.54 1.30 0.84 1.30 311.0 174.3 1.78 1.51(1.78*0.84) 210.0 174.3 1.20 1.01(1.20*0.84) point 'a' 184.5 123.9 1.49 1.10 0.74 1.10 226.3 190.0 1.19 0.88(1.19*0.74) 268.5 186.8 1.44 1.07(1.44*0.74) 6 point 'f' 155.3 123.9 1.25 0.93(1.25*0.74) 255.3 186.8 1.37 1.01(1.37*0.74) 208.8 190.0 1.10 0.81(1.10*0.74) point 'a' 182.9 132.1 1.38 1.05 0.76 1.05 209.9 179.7 1.17 0.88(1.17*0.76) 264.0 176.8 1.49 1.13(1.49*0.76) 7 point 'f' 129.3 116.7 1.11 0.84(1.11*0.76) 206.8 171.7 1.20 0.91(1.20*0.76) 188.1 176.1 1.07 0.81(1.07*0.76) point 'a' 151.0 119.1 1.27 1.05 0.83 1.05 194.7 168.3 1.16 0.96(1.16*0.83) 219.8 163.9 1.34 1.11(1.34*0.83) 8 point 'f' 129.9 122.6 1.06 0.88(1.06*0.83) 206.0 165.0 1.25 1.03(1.25*0.83) 181.3 169.1 1.07 0.89(1.07*0.83) point 'a' 311.9 200.0 1.56 1.30(1.56*0.83) 198.5 154.0 1.29 1.07(1.29*0.83) 320.6 154.0 2.08 1.73(2.08*0.83) 9 point 'f' 106.5 55.5 1.92 1.60(1.92*0.83) 253.5 119.3 2.12 1.76(2.12*0.83) 135.4 129.2 1.05 0.87(1.05*0.83) point 'a' 312.2 200.0 1.56 1.29(1.56*0.83) 193.8 154.0 1.26 1.05(1.26*0.83) 323.0 154.0 2.10 1.74(2.10*0.83) 10 point 'f' 42.8 22.9 1.87 1.55(1.87*0.83) 169.8 109.4 1.55 1.29(1.55*0.83) 121.6 122.2 1.00 0.83(1.00*0.83) point 'a' 150.6 113.9 1.32 1.10(1.32*0.83) 189.0 186.3 1.01 0.84(1.01*0.83) 263.7 182.0 1.45 1.20(1.45*0.83) 11 point 'f' 161.3 77.4 2.08 1.73(2.08*0.83) 282.7 167.7 1.69 1.40(1.69*0.83) 182.0 176.1 1.03 0.85(1.03*0.83) point 'a' 152.7 113.9 1.34 1.11(1.34*0.83) 192.2 186.3 1.03 0.85(1.03*0.83) 263.2 182.0 1.45 1.20(1.45*0.83) 12 point 'f' 69.2 44.7 1.55 1.29(1.55*0.83) 178.6 153.3 1.17 0.97(1.17*0.83) 147.8 165.8 0.89 0.74(0.89*0.83) point 'a' 116.6 113.7 1.03 0.85(1.03*0.83) 167.9 162.4 1.03 0.85(1.03*0.83) 219.0 157.3 1.39 1.15(1.39*0.83) 13 point 'f' 159.3 67.5 2.36 1.96(2.36*0.83) 267.8 142.3 1.88 1.56(1.88*0.83) 172.4 151.7 1.14 0.95(1.14*0.83) point 'a' 119.0 113.7 1.05 0.87(1.05*0.83) 172.1 162.4 1.06 0.88(1.06*0.83) 219.3 157.3 1.39 1.15(1.39*0.83) 14 point 'f' 70.2 34.9 2.01 1.67(2.01*0.83) 176.1 130.3 1.35 1.12(1.35*0.83) 143.8 143.1 1.00 0.83(1.00*0.83)

Note: (1) For detail No. 2, the ratio is taken to 0.93. (2) For detail No. 9-14, the coefficient 0.83 is the average value obtained from the ratios for detail No. 1 to 8.


PAGE 133 OF 171


Rule Change Notice No.1-7 (Corrosion Additions)





PAGE 134 OF 171


CHAPTER 3 STRUCTURAL DESIGN

PRINCIPLES

Section 3 CORROSION ADDITIONS

1. Corrosion additions

1.2 Corrosion addition determination

1.2.1 Corrosion additions for steel The corrosion addition for each of the two sides of a structural member, tC1 or tC2, is specified in Tab 1.

The total corrosion addition tC, in mm, for both sides of the structural member is obtained by the following

formula:

reserveCCC tttRoundupt ++= )( 215.0

For an internal member within a given compartment, the total corrosion addition tC is obtained from the

following formula:

reserveCC ttRoundupt += )2( 15.0

where tC1 is the value specified in Tab 1 for one side exposure to that compartment.

When a structural member is affected by more than one value of corrosion addition (e.g. a plate in a dry bulk

cargo hold extending above the lower zone), the scantling criteria are generally to be applied considering the

severest value of corrosion addition applicable to the member.

In addition, the total corrosion addition tC is not to be taken less than 2 mm, except for web and face plate of

ordinary stiffeners.


PAGE 135 OF 171

Table 1: Corrosion addition on one side of structural members

Corrosion addition, tC1 or tC2 in mm Compartment

Type Structural member BC-A or BC-B ships with L ≥ 150 m

Other

Within 3m below the top of tank (3) 2.0 Face plate of

primary members Elsewhere 1.5 Within 3 m below the top of tank (3) 1.7

Ballast water tank (2)

Other members Elsewhere 1.2 Upper part (4) 2.4 1.0 Lower stool: sloping plate, vertical plate and top plate 5.2 2.6 Transverse

bulkhead Other parts 3.0 1.5 Upper part (4) Webs and flanges of the upper end brackets of side frames of single side bulk carriers

1.8 1.0

Webs and flanges of lower brackets of side frames of single side bulk carriers

2.2 1.2

Other members

Other parts 2.0 1.2

Continuous wooden ceiling 2.0 1.2

Dry bulk cargo hold (1)

Sloped plating of hopper tank, inner bottom plating No continuous wooden ceiling 3.7 2.4

Horizontal member and weather deck (5) 1.7 Exposed to atmosphere Non horizontal member 1.0 Exposed to sea water (7) 1.0 Fuel oil tanks and lubricating oil tanks (2) 0.7 Fresh water tanks 0.7

Void spaces (6) Spaces not normally accessed, e.g. access only through bolted manholes openings, pipe tunnels, etc. 0.7

Dry spaces Internal of deck houses, machinery spaces, stores spaces, pump rooms, steering spaces, etc. 0.5

Other compartments than above 0.5 Notes (1) Dry bulk cargo hold includes holds, intended for the carriage of dry bulk cargoes, which may carry water

ballast. (2) The corrosion addition of a plating between water ballast and heated fuel oil tanks is to be increased by

0.7 mm. (3) This is only applicable to ballast tanks with weather deck as the tank top .This is not to be applied to

structural members of inner bottom and located below inner bottom. (4) Upper part of the cargo holds corresponds to an area above the connection between the top side and the

inner hull or side shell. If there is no top side, the upper part corresponds to the upper one third of the cargo hold height.

(5) Horizontal member means a member making an angle up to 20° as regard as a horizontal line. (6) The corrosion addition on the outer shell plating in way of pipe tunnel is to be considered as water ballast

tank. (7) Outer side shell between normal ballast draught and scantling draught is to be increased by 0.5 mm.


PAGE 136 OF 171


Section 4 SUPERSTRUCTURES AND DECKHOUSES

Symbols For symbols not defined in this Section, refer to Ch 1, Sec 4.

L2 : Rule length L, but to be taken not greater than 300 m

pD : Lateral pressure for decks, in kN/m2, as defined in [3.2.1]

pSI : Lateral pressure for sides of superstructures, in kN/m2, as defined in [3.2.3]

k : Material factor, defined in Ch 3, Sec 1, [2.2]

s : Spacing, in m, of ordinary stiffeners, measured at mid-span along the chord

l : Span, in m, of ordinary stiffeners, measured between the supporting members, see Ch 3, Sec 6, [4.2]

tC : Corrosion addition, defined in Ch 3, Sec 3


c = 0.75 for beams, girders and transverses which are simply supported on one or both ends

c = 0.55 in other cases

ma : Coefficient taken equal to:

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎠⎞

⎜⎝⎛−=

2

4204.0ll

ssma , with 1≤l

s

4. Scantlings

4.1 Side plating of non-effective superstructures

4.1.1 The gross thickness, in mm, of the side plating of non-effective superstructures is not to be less than the greater

of the following values:

CSI tkpst += 21.1 5.121.1 += SIkpst

kLt 8.0=

4.2 Deck plating of non-effective superstructures

4.2.1 The gross thickness, in mm, of deck plating of non-effective superstructures is not to be less than the greater of

the following values:

CD tkpst += 21.1 5.121.1 += Dkpst


PAGE 137 OF 171

( ) kLt 02,05.5 +=

where L is not to be taken greater than 200 m.

4.2.2 Where additional superstructures are arranged on non-effective superstructures located on the freeboard deck,

the gross thickness required by [4.2.1] may be reduced by 10%.

4.2.3 Where plated decks are protected by sheathing, the gross thickness of the deck plating according to [4.2.1] and

[4.2.2] may be reduced by tC 1.5mm. However, such deck plating is not to be less than 5 mm.

Where a sheathing other than wood is used, attention is to be paid that the sheathing does not affect the steel. The

sheathing is to be effectively fitted to the deck.

4.5 Decks of short deckhouses

4.5.1 Plating The thickness, in mm, of weather deck of short deckhouses and is not to be less than:

Ctkst += 8 5.18 += kst

For weather decks of short deckhouses protected by sheathing and for decks within deckhouses, the gross

thickness may be reduced by tC 1.5mm. However, such deck plating is not to be less than 5 mm.

5. Superstructure end bulkheads and deckhouse walls

5.3 Scantlings

5.3.2 Plate thickness The gross thickness of the plating, in mm, is not to be less than the greater of the values obtained from the

following formulae:

Ctkpst += Α9.0 5.19.0 += Αkpst

kL

t ⎟⎠

⎞⎜⎝

⎛ +=100

0.5 2min , for the lowest tier

kL

t ⎟⎠

⎞⎜⎝

⎛ +=100

0.4 2min , for the upper tiers, without being less than 5.0 mm.


PAGE 138 OF 171


PAGE 139 OF 171



(Corrosion Additions)




PAGE 140 OF 171

Technical Background for Changes Regarding Corrosion Additions: 1. Reason for the Rule Change 1.1 Note (3) in Table 1 of Ch 3, Sec 3:

The corrosion additions for structural members located within 3m below the top of the tank are enhanced considering the high temperature effect where the tank top is exposed. Moreover, in the upper part of the bilge hopper tank not connected to the topside tank, the corrosion additions of structural members in such locations are enhanced considering the possible effect due to flushing in an air and water mixture environment as specified in KC ID 206.

Hence, the note (3) of Table 1 of the Rules is provided so that the enhanced corrosion addition is applicable to the structural members in the upper part of the bilge hopper tank.

However, this effect was not evaluated by the statistical thickness measurement data. In order to evaluate this effect, the corrosion diminutions of the structural members in the upper

part and other parts of the bilge hopper tank not connected to the topside tank are re-examined using the statistical data which is used for setting up the corrosion additions specified in CSRs.

In the statistical data, 6 ships from among 108 ships have bilge hopper tanks not connected to the topside tank. The difference of thickness diminution between the structural members in the upper and lower parts of the bilge hopper tank is given in Table 1.

Table 1 Difference of thickness diminution of structural members in bilge hopper tank

. Average (mm) 95 percentile value (mm)

(Upper) – (Lower) (Upper) – (Lower) A (21-years) -0.14 -0.9 B (16-years) -0.20 -0.8 C (8-years) 0.10 0.1 C (16-years) 0.00 0.0 D (12-years) -0.04 -0.4 E (11-years) -0.07 -0.4 F (9-years) 0.00 -0.1

The results in Table 1 show that the thickness diminution of structural members in the upper

part of the bilge hopper tank is rather small compared to those in the lower part. Therefore, the note (3) of Table 1 of the Rules should be revised according to this result. 1.2 Ch 9, Sec 4 According to the requirements in Ch 3, Sec 2, [2.1.1] and Ch 9, Sec 4, [1.2.1], the scantlings of structural members in superstructures and deckhouses are gross. However, corrosion additions based on the net scantling approach specified in Ch 3, Sec 1, [2.2] are referred in “Symbols” and required thickness formula. This was not the intention of these requirements which come from GL rules. 2. Summary of the Rule Change 2.1 Note (3) in Table 1 of Ch 3, Sec 3

The structural members located within 3m below the top of the tank where the tank top is exposed to the weather deck is applicable to the enhanced corrosion additions specified in Table 1 of the Rules.


PAGE 141 OF 171

2.2 Ch 9, Sec 4 In all required thickness formulae, “tc” is changed to the absolute value, i.e., 1.5mm. In addition, the word “thickness” is changed to “gross thickness” for clarification. 3. Impact on scantlings 3.1 Note (3) in Table 1 of Ch 3, Sec 3 As the corrosion additions on one side of structural members within 3m below the top of the bilge hopper tank is changed to 1.2mm from 1.7mm, thicknesses of side shell and sloping plate and scantlings of longitudinals and transverses within 3m of the bilge hopper tank are reduced accordingly. 3.2 Ch 9, Sec 4 The gross thicknesses in superstructures and deckhouses are reduced by 0.5mm.


PAGE 142 OF 171


PAGE 143 OF 171


Rule Change Notice No.1-8 (Corrugated Bulkhead)





PAGE 144 OF 171


CHAPTER 3 STRUCTURAL DESIGN

PRINCIPLES

Section 6 STRUCTURAL ARRANGEMENT PRINCIPLES

6. Double bottom

6.4 Floors

6.4.2 Floors in way of transverse bulkheads Where transverse bulkhead is provided with lower stool, solid floors are to be fitted in line with both sides of

lower stool. Where transverse bulkhead is not provided with lower stool, solid floors are to be fitted in line with

both flanges of the vertically corrugated transverse bulkhead or in line of plane transverse bulkhead.

The net thickness and material properties of the supporting floors and pipe tunnel beams are to be not less than

those required for the bulkhead plating or, when a stool is fitted, of the stool side plating.


10.4 Corrugated bulkheads

10.4.2 Construction The main dimensions a, R, c, d, t, ϕand sC of corrugated bulkheads are defined in Fig 28.

The bending radius is not to be less than the following values, in mm:

R = 3.0t

where :

t : As-built thickness, in mm, of the corrugated plate.

The corrugation angle ϕ shown in Fig 28 is to be not less than 55°.

The thickness of the lower part of corrugations is to be maintained for a distance from the inner bottom (if no

lower stool is fitted) or the top of the lower stool not less than 0.15lC.

The thickness of the middle part of corrugations is to be maintained for a distance from the deck (if no upper

stool is fitted) or the bottom of the upper stool not greater than 0.3lC.

The section modulus of the corrugations in the remaining upper part of the bulkhead is to be not less than 75% of

that required for the middle part, corrected for different minimum yield stresses.

When welds in a direction parallel to the bend axis are provided in the zone of the bend, the welding procedures

are to be submitted to the Society for approval.


PAGE 145 OF 171

a

c

sC

tw

d

tf

o55≥ϕR

Figure 28: Dimensions of a corrugated bulkhead

10.4.5 Structural arrangements The strength continuity of corrugated bulkheads is to be ensured at the ends of corrugations.

Where corrugated bulkheads are cut in way of primary supporting members, attention is to be paid to ensure

correct alignment of corrugations on each side of the primary member.

Where vertically corrugated transverse bulkheads or longitudinal bulkheads are welded on the inner bottom

plate, floors or girders are to be fitted in way of flanges of corrugations, respectively and the net thickness and

materials of floors and girders are to be not less than those adjacent corrugation face plate.

In general, the first vertical corrugation connected to the boundary structures is to have a width not smaller than

typical width of corrugation flange.

Where stools are fitted at the lower part of transverse bulkheads, the net thickness of adjacent floors is to be not

less than that of the stool plating.

10.4.6 Bulkhead stools Plate diaphragms or web frames are to be fitted in bottom stools in way of the double bottom longitudinal girders

or plate floors, as the case may be.

Brackets or deep webs are to be fitted to connect the upper stool to the deck transverse or hatch end beams, as

the case may be.

The continuity of the corrugated bulkhead with the stool plating is to be adequately ensured. In particular, upper

strake of the lower stool is to be of the same net thickness and yield stress as those of the lower strake of the

bulkhead.

10.4.7 Lower stool The lower stool, when fitted, is to have a height in general not less than 3 times the depth of the corrugations.

The net thickness and material of the stool top plate are to be not less than those required for the bulkhead

plating above. The thickness and material properties of the upper portion of vertical or sloping stool side plating

within the depth equal to the corrugation flange width from the stool top are to be not less than the required

flange plate thickness and material to meet the bulkhead stiffness requirement at the lower end of the corrugation.

The ends of stool side ordinary stiffeners, when fitted in a vertical plane, are to be attached to brackets at the

upper and lower ends of the stool.

The distance d from the edge of the stool top plate to the surface of the corrugation flange is to be in accordance

with Fig 30.


PAGE 146 OF 171

The stool bottom is to be installed in line with double bottom floors or girders as the case may be, and is to have

a width not less than 2.5 times the mean depth of the corrugation.

The stool is to be fitted with diaphragms in line with the longitudinal double bottom girders or floors as the case

may be, for effective support of the corrugated bulkhead. Scallops in the brackets and diaphragms in way of the

connections to the stool top plate are to be avoided.

Where corrugations are cut at the lower stool, corrugated bulkhead plating is to be connected to the stool top

plate by full penetration welds. The stool side plating is to be connected to the stool top plate and the inner

bottom plating by either full penetration or deep penetration welds. The supporting floors are to be connected to

the inner bottom by either full penetration or deep penetration weld.

Figure 30: Permitted distance, d, from the edge of the stool top plate to the surface of the corrugation flange

10.4.8 Upper stool

The upper stool, when fitted, is to have a height in general between two and three times the depth of corrugations.

Rectangular stools are to have a height in general equal to twice the depth of corrugations, measured from the

deck level and at the hatch side girder.

The upper stool of transverse bulkhead is to be properly supported by deck girders or deep brackets between the

adjacent hatch end beams.

The width of the upper stool bottom plate is generally to be the same as that of the lower stool top plate. The

stool top of non-rectangular stools is to have a width not less than twice the depth of corrugations.

The thickness and material of the stool bottom plate are to be the same as those of the bulkhead plating below.

The thickness of the lower portion of stool side plating is to be not less than 80% of that required for the upper

part of the bulkhead plating where the same material is used.

The ends of stool side ordinary stiffeners when fitted in a vertical plane, are to be attached to brackets at the

upper and lower end of the stool.

The stool is to be fitted with diaphragms in line with and effectively attached to longitudinal deck girders

extending to the hatch end coaming girders or transverse deck primary supporting members as the case may be,

for effective support of the corrugated bulkhead.

Scallops in the brackets and diaphragms in way of the connection to the stool bottom plate are to be avoided.


PAGE 147 OF 171

10.4.9 Alignment At deck, if no upper stool is fitted, two transverse or longitudinal reinforced beams as the case may be, are to be

fitted in line with the corrugation flanges.

At bottom, if no lower stool is fitted, the corrugation flanges are to be in line with the supporting floors or

girders.

The weld of corrugations and floors or girders to the inner bottom plating are to be full penetration ones. The

thickness and material properties of the supporting floors or girders are to be not less than those of the

corrugation flanges. Moreover,

Tthe cut-outs for connections of the inner bottom longitudinals to double bottom floors are to be closed by collar

plates. The supporting floors or girders are to be connected to each other by suitably designed shear plates.

Stool side plating is to be aligned with the corrugation flanges. Lower stool side vertical stiffeners and their

brackets in the stool are to be aligned with the inner bottom structures as longitudinals or similar, to provide

appropriate load transmission between these stiffening members.

Lower stool side plating is not to be knuckled anywhere between the inner bottom plating and the stool top plate.

10.4.13 Section modulus at the lower end of corrugations

(void)

a) The section modulus at the lower end of corrugations (Fig 31 to Fig 35) is to be calculated with the

compression flange having an effective flange width bef not larger than that indicated in [10.4.10].

b) Webs not supported by local brackets

Except in case e), if the corrugation webs are not supported by local brackets below the stool top plate (or

below the inner bottom) in the lower part, the section modulus of the corrugations is to be calculated

considering the corrugation webs 30% effective.

c) Effective shedder plates

Provided that effective shedder plates, as defined in [10.4.11], are fitted (see Figs 31 and 32), when

calculating the section modulus of corrugations at the lower end (cross sections 1 in Figs 31 and 32), the area

of flange plates may be increased by the value obtained, in cm2, from the following formula:

SHfSH ttaI 5.2= without being taken greater than 2.5atf,

where:

a : Width, in m, of the corrugation flange (see Fig 28)

tSH : Net shedder plate thickness, in mm

tf : Net flange thickness, in mm.

d) Effective gusset plates

Provided that effective gusset plates, as defined in [10.4.12], are fitted (see Figs 33 to 35), when calculating

the section modulus of corrugations at the lower end (cross-sections 1 in Figs 33 to 35), the area of flange

plates may be increased by the value obtained, in cm2, from the following formula:

fGG thI 7=

where:

hG : Height, in m, of gusset plates (see Figs 33 to 35), to be taken not greater than (10/7)SGU


PAGE 148 OF 171

SGU : Width, in m, of gusset plates

tf : Net flange thickness, in mm

e) Sloping stool top plate

If the corrugation webs are welded to a sloping stool top plate which has an angle not less than 45° with the

horizontal plane, the section modulus of the corrugations may be calculated considering the corrugation

webs fully effective. For angles less than 45°, the effectiveness of the web may be obtained by linear

interpolation between 30% for 0° and 100% for 45°.

Where effective gusset plates are fitted, when calculating the section modulus of corrugations the area of

flange plates may be increased as specified in d) above. No credit may be given to shedder plates only.

hGshedder plate

①

lower stool

Figure 31: Symmetrical shedder plates (void)

hG

shedder plate

①

lower stool

Figure 32: Asymmetrical shedder plates (void)


PAGE 149 OF 171

hG

lower stool

gusset plate

①

Figure 33: Symmetrical gusset/shedder plates (void)

hG

gusset plate

①

lower stool

Figure 34: Asymmetrical gusset/shedder plates (void)


PAGE 150 OF 171

hG①==

lower stool

Figure 35: Asymmetrical gusset/shedder plates (void)

10.4.14 Section modulus at sections other than the lower end of corrugations (void)

The section modulus is to be calculated with the corrugation webs considered effective and the compression

flange having an effective flange width, bef, not larger than that obtained in [10.4.10].

10.4.15 Shear area (void)

The shear area is to be reduced in order to account for possible non-perpendicularity between the corrugation

webs and flanges. In general, the reduced shear area may be obtained by multiplying the web sectional area by

(sin ϕ), ϕ being the angle between the web and the flange (see Fig 28).


PAGE 151 OF 171

CHAPTER 6 HULL SCANTLING

Section 1 PLATING

3. Strength check of plating subjected to lateral pressure

3.2 Plating thickness

3.2.3 Net thickness of the corrugations of transverse vertically corrugated watertight bulkheads separating cargo holds for flooded conditions The net plate thickness t, in mm, of transverse vertically corrugated watertight bulkheads separating cargo holds

is to be not less than that obtained from the following formula:

eHRpst 05.19.14=

p : Resultant pressure, in kN/m2, as defined in Ch 4, Sec 6, [3.3.7]

s : plate width, in m, to be taken equal to the width of the corrugation flange or web, whichever is greater.

For built-up corrugation bulkheads, when the thicknesses of the flange and web are different:

• the net thickness of the narrower plating is to be not less than that obtained, in mm, from the following

formula:

eHN R

pst 05.19.14=

s : plate width, in m, of the narrower plating

• the net thickness of the wider plating is not to be less than the greater of those obtained, in mm, from the

following formulae:

eHW R

pst 05.19.14=

22462

NPeH

W tR

pst −=

where:

tNP : Actual net thickness of the narrower plating, in mm, to be not taken greater than:

eHNP R

pst 05.19.14=

s : plate width, in m, to be taken equal to the width of the corrugation flange or web, whichever is greater.

The net thickness of the lower part of corrugations is to be maintained for a distance from the inner bottom (if no

lower stool is fitted) or the top of the lower stool not less than 0.15lC, where lC is the span of the corrugations,

in m, to be obtained according to Ch 3, Sec 6, [10.4.4]. The net thickness is also to comply with the requirements

in [3.2.1], Sec 2, [3.6.1 & 3.6.2], and Sec 3, [6].


PAGE 152 OF 171

The net thickness of the middle part of corrugations is to be maintained for a distance from the deck (if no upper

stool is fitted) or the bottom of the upper stool not greater than 0.3lC. The net thickness is also to comply with

the requirements in [3.2.1] and Sec 2, [3.6.1& 3.6.2].

Figure 5: Parts of Corrugation

3.2.3 bis1 Net thickness of lower stool and upper stool The net thickness and material of the stool top plate of lower stool are to be not less than those for the corrugated

bulkhead plating above required by [3.2.3].

The net thickness and material of the upper portion of vertical or sloping stool side plating of lower stool within

the depth equal to the corrugation flange width from the stool top are to be not less than the flange plate at the

lower end of the corrugation required by [3.2.3], as applicable, whichever is the greater.

The net thickness and material of the stool bottom plate of upper stool are to be the same as those of the

bulkhead plating below required by [3.2.3], as applicable, whichever is the greater.

The net thickness of the lower portion of stool side plating is to be not less than 80% of the upper part of the

bulkhead plating required by [3.2.3], as applicable, whichever is the greater, where the same material is used.

The net thicknesses of lower stool and upper stool are to be not less than those required by [3.2.1], [3.2.2] and

[3.2.4].

3.2.3 bis2 Net thickness of supporting floors of corrugated bulkhead The net thickness and material of the supporting floors and pipe tunnel beams of corrugated bulkhead, when no

stool is fitted, are to be not less than those of the corrugation flanges required by [3.2.3]

When a lower stool is fitted, the net thickness of supporting floors are to be not less than that of the stool side

plating required by the first sentence of [3.2.2].


PAGE 153 OF 171

3.2.4 Testing conditions The plating of compartments or structures as defined in Ch 4, Sec 6, [4] is to be checked in testing conditions. To

this end, its net thickness is to be not less than the value obtained, in mm, from the following formula:

Y

Tra R

pscct05.1

8.15=


PAGE 154 OF 171

Section 2 ORDINARY STIFFENERS 2. General requirements 2.1 Corrugated bulkhead (void) 2.1.1 (void)

Unless otherwise specified, the net section modulus and the net shear sectional area of a corrugation are to be not

less than those obtained for an ordinary stiffener with s equal sC, as defined in Fig 2.

a

c

sC

tw

d

tf

o55≥ϕR

Figure 2: Corrugated bulkhead (void)

3. Yielding check

3.2 Strength criteria for single span ordinary stiffeners other than side frames of single side bulk carriers

3.2.4 Net section modulus of corrugated bulkhead of ballast hold for ships having a length L

less than 150m

The net section modulus w, in cm3, of corrugated bulkhead of ballast hold for ships having a length L less than

150m subjected to lateral pressure are to be not less than the values obtained from the following formula:

( ) 32

10YS

CWS

Rmspp

Kwλ

l+=

where:

K : Coefficient given in Tab 4 and 5, according to the type of end connection. When dH < 2.5d0 , both

section modulus per half pitch of corrugated bulkhead and section modulus of lower stool at inner

bottom are to be calculated.

sC : Half pitch length, in m, of the corrugation, defined in [2.1.1] Ch 3, Sec 6, Fig 28

λ : Length, in m, between the supports, as indicated in Fig 6

λS : Coefficient defined in Tab 3.

The effective width of the corrugation flange in compression is to be considered according to Ch3, Sec 6,

[10.4.10] when the net section modulus of corrugated bulkhead is calculated.


PAGE 155 OF 171

Table 4: Values of K, in case 05.2 dd H ≥

Upper end

Lower end Supported by girders

Welded directly to deck

Welded to stool efficiently supported by ship structure

Supported by girders or welded directly to decks or inner bottoms 0.83 1.25 1.25

Welded to stool efficiently supported by ship structure 1.25 1.00 0.83

Upper end support

Supported by girders Welded directly to deck Welded to stool efficiently

supported by ship structure

1.25 1.00 0.83

Table 5: Values of K, in case 05.2 dd H <

Upper end support Supported by girders Connected to deck Connected to stool Section modulus of corrugated bulkhead 0.83 0.71 0.65

Section modulus of stool at bottom 0.83 1.25 1.13

Upper end support Section modulus of

Supported by girders Connected to Deck Connected to stool

Corrugated bulkhead 0.83 0.71 0.65

Stool at bottom 0.83 1.25 1.13

dH dH

l

eA

d0

( )BdAe 2/1 0−=

B

05.2 ddH ≥ 05.2 ddH <

l

eA

d0

B

Figure 6: Measurement of l


PAGE 156 OF 171

3.2.6 Bending capacity and shear capacity of the corrugations of transverse vertically corrugated watertight bulkheads separating cargo holds for flooded conditions (void) The bending capacity and the shear capacity of the corrugations of watertight bulkheads between separating

cargo holds are to comply with the following formulae:

31095.0

5.0eH

MLE RMWW ≥+

2eHR

≤τ

where:

M : Bending moment in a corrugation, to be obtained, in kN.m, from the following formula:

M = FlC / 8

F : Resultant force, in kN, to be calculated according to Ch 4, Sec 6, [3.3.7]

lC : Span of the corrugations, in m, to be obtained according to Ch 3, Sec 6, [10.4.4]

WLE : Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the lower end of the

corrugations according to Ch 3, Sec 6, [10.4.13], without being taken greater than the value obtained from


32

, 105.0

⎟⎟⎠

⎞⎜⎜⎝

⎛ −+=

eH

GCGGGMLE R

pshhQWW

WG : Net section modulus, in cm3, of one half pitch corrugation, to be calculated in way of the upper end of

shedder or gusset plates, as applicable, according to Ch 3, Sec 6, [10.4.1413]

Q : Shear force in a corrugation, to be obtained, in kN, from the following formula:

Q = 0.8F

hG : Height, in m, of shedders or gusset plates, as applicable (see Ch 3, Sec 6, Fig 31 to Fig 35)

pG : Resultant pressure, in kN/m2, to be calculated in way of the middle of the shedders or gusset plates, as

applicable, according to Ch 4, Sec 6, [3.3.7]

sC : Spacing of the corrugations, in m, to be taken according to Fig 2

WM : Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the mid-span of corrugations

according to Ch 3, Sec 6, [10.4.14], without being taken greater than 1.15WLE

τ : Shear stress in the corrugation, in N/mm2, to be obtained from the following formula:

shAQ10=τ

Ash : Shear area, in cm2, calculated according to Ch 3, Sec 6, [10.4.15].

3.2.7 Net section modulus and net shear sectional area of single span ordinary stiffeners under testing conditions The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of single span ordinary stiffeners

subjected to testing are to be not less than the values obtained from the following formulae:

32

1005.1 Y

T

mRsp

wl

=

φτ sin05.15

a

Tsh

spA

l=


PAGE 157 OF 171

where:

φ : Angle, in deg, defined in [3.2.3].

3.6 Scantlings of transverse vertically corrugated watertight bulkheads separating cargo holds for flooded conditions

3.6.1 Bending capacity and shear capacity of the corrugations of transverse vertically corrugated watertight bulkheads separating cargo holds The bending capacity and the shear capacity of the corrugations of watertight bulkheads between separating

cargo holds are to comply with the following formulae:

31095.0

5.0eH

MLE RMWW ≥+

2eHR

≤τ

where:

M : Bending moment in a corrugation, to be obtained, in kN.m, from the following formula:

M = FlC / 8

F : Resultant force, in kN, to be calculated according to Ch 4, Sec 6, [3.3.7]

lC : Span of the corrugations, in m, to be obtained according to [3.6.2]

WLE : Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the lower end of the

corrugations according to [3.6.2], without being taken greater than the value obtained from the

following formula:

32

, 105.0

⎟⎟⎠

⎞⎜⎜⎝

⎛ −+=

eH

GCGGGMLE R

pshhQWW

WG : Net section modulus, in cm3, of one half pitch corrugation, to be calculated in way of the upper end of

shedder or gusset plates, as applicable, according to [3.6.2]

Q : Shear force at the lower end of a corrugation, to be obtained, in kN, from the following formula:

Q = 0.8F

hG : Height, in m, of shedders or gusset plates, as applicable (see Fig 11 to Fig 15)

pG : Resultant pressure, in kN/m2, to be calculated in way of the middle of the shedders or gusset plates, as

applicable, according to Ch 4, Sec 6, [3.3.7]

sC : Spacing of the corrugations, in m, to be taken according to Ch 3, Sec 6, Fig 28

WM : Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the mid-span of

corrugations according to [3.6.2] without being taken greater than 1.15WLE

τ : Shear stress in the corrugation, in N/mm2, to be obtained from the following formula:

shA

Q10=τ

Ash : Shear area, in cm2, calculated according to the followings.

The shear area is to be reduced in order to account for possible non-perpendicular between the

corrugation webs and flanges. In general, the reduced shear area may be obtained by multiplying the


PAGE 158 OF 171

web sectional area by (sin ϕ), ϕ being the angle between the web and the flange (see Ch 3, Sec 6, Fig

28).

The actual net section modulus of corrugations is to be calculated according to [3.6.2].

The net section modulus of the corrugations upper part of the bulkhead, as defined in Sec 1, Fig 5, is

to be not less than 75% of that of the middle part complying with this requirement and Sec 1, [3.2.1],

corrected for different minimum yield stresses.

3.6.2 Net Section modulus at the lower end of corrugations a) The net section modulus at the lower end of corrugations (Fig 11 to Fig 15) is to be calculated with the

compression flange having an effective flange width bef not larger than that indicated in Ch 3, Sec 6, [10.4.10]

b) Webs not supported by local brackets

Except in case e), if the corrugation webs are not supported by local brackets below the stool top plate (or

below the inner bottom) in the lower part, the section modulus of the corrugations is to be calculated

considering the corrugation webs 30% effective.

c) Effective shedder plates

Provided that effective shedder plates, as defined in Ch 3, Sec 6, [10.4.11] are fitted (see Fig 11 and Fig 12),

when calculating the section modulus of corrugations at the lower end (cross sections 1 in Fig 11 and Fig 12),

the net area of flange plates may be increased by the value obtained, in cm2, from the following formula:

SHfSH ttaI 5.2= without being taken greater than 2.5atf,

where:

a : Width, in m, of the corrugation flange (see Ch 3, Sec 6, Fig 28)

tSH : Net shedder plate thickness, in mm

tf : Net flange thickness, in mm.

d) Effective gusset plates

Provided that effective gusset plates, as defined in Ch 3, Sec 6, [10.4.12], are fitted (see Fig 13 to Fig 15),

when calculating the net section modulus of corrugations at the lower end (cross-sections 1 in Fig 13 to Fig

15), the area of flange plates may be increased by the value obtained, in cm2, from the following formula:

IG = 7hGtf

where:

hG : Height, in m, of gusset plates (see Fig 13 to Fig 15), to be taken not greater than (10/7)SGU

SGU : Width, in m, of gusset plates

tf : Net flange thickness, in mm

e) Sloping stool top plate

If the corrugation webs are welded to a sloping stool top plate which has an angle not less than 45° with the

horizontal plane, the section modulus of the corrugations may be calculated considering the corrugation webs

fully effective. For angles less than 45°, the effectiveness of the web may be obtained by linear interpolation

between 30% for 0° and 100% for 45°.

Where effective gusset plates are fitted, when calculating the net section modulus of corrugations the net area

of flange plates may be increased as specified in d) above. No credit may be given to shedder plates only.


PAGE 159 OF 171

hG

shedder plate

①

lower stool

hG

lower stool

gusset plate

①hG

gusset plate

①

lower stool

Figure 11: Symmetrical shedder plates Figure 12: Asymmetrical shedder plates

Figure 13: Symmetrical gusset/shedder plates

Figure 14: Asymmetrical gusset/shedder plates

h G shedder plate

①

lower stool


PAGE 160 OF 171

hG①==

lower stool

Figure 15: Asymmetrical gusset/shedder plates

3.6.3 Stiffeners in lower stool and upper stool The net section modulus of stiffeners in lower stool and upper stool is to be greater of the values obtained from

the following formula or required by [3.2.5].

32

1016 YsR

pswαλ

l=

Where,

p : Pressure, in kN/m2, as defined in Ch 4 Sec 6, [3.3.7]

α and sλ : defined in [3.2.5]


PAGE 161 OF 171

Section 3 BUCKLING & ULTIMATE STRENGTH OF ORDINARY STIFFENERS AND STIFFENED PANELS

6. Transverse vertically corrugated watertight bulkhead in flooded condition 6.1 General 6.1.1 Shear buckling check of the bulkhead corrugation webs The shear stress τ, calculated according to Ch 6, Sec 2, [3.6.1 3.2.6], is to comply with the following formula:

τ ≤ τC

where:

τC : Critical shear buckling stress to be obtained, in N/mm2, from the following formulae:

EC ττ = for 32

eHE

Rτ ≤

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

E

eHeHC

RR

ττ

341

3 for

32eH

ER

>τ

τE : Euler shear buckling stress to be obtained, in N/mm2, from the following formula: 2

3109.0 ⎟

⎠

⎞⎜⎝

⎛=c

tEk w

tEτ

kt : Coefficient, to be taken equal to 6.34

tW : Net thickness, in mm, of the corrugation webs

c : Width, in m of the corrugation webs (see Ch 3, Sec 6, Fig 28Ch 6, Sec 2, Fig 2).


PAGE 162 OF 171


PAGE 163 OF 171



(Corrugated Bulkhead)




PAGE 164 OF 171

Technical Background for the Changes regarding Corrugated Bulkhead: 1. Reason for the Rule Change:

There are paragraphs in Ch 3, Sec 6, [10.4] and Ch 6, Sec 1 & 2 where requirements are

specified to transverse vertically corrugated watertight bulkheads separating cargo holds. However, there are obscure scantling requirements in their application.

It is due to that; - the scantling requirements are included in both chapters which incurs confusion to the

user, and - the application of the requirements is not clearly identified especially for flooded

condition although it was the original intention that IACS UR S18 requirements were to be incorporated explicitly.

The rule change is prepared in order to resolve this issue by; - shifting the scantling requirements in Ch 3, Sec 6, [10.4] to the appropriate paragraphs in

Ch 6, Sec 2, and - collecting together the scantling requirements for flooded conditions in the new

paragraph to be in line with IACS UR S18 requirements, and - only requirements to structural arrangement being remained in Ch 3, Sec 6, [10.4], and - clarifying the cross reference of the related paragraphs. The answers or interpretations in KC IDs 332, 354, 450 and 580 are taken into

consideration for preparation of this rule change. In addition, the thickness requirement in Ch 3, Sec 6, [6.4.2] is shifted to Ch 6, Sec 1.

2. Summary of Rule Change 2.1 Ch 3, Sec 6, [6.4.2] and Ch 6, Sec 1, [3.2.3 bis2]

The thickness requirement in Ch 3, Sec 6, [6.4.2] is shifted to Ch 6, Sec 1, [3.2.3 bis2] with partly modification. 2.2 Ch 3 Sec 6, [10.4.2] “Construction” and Ch 6 Sec 1 [3.2.3]

The scantling requirements in Ch 3, Sec 6, [10.4.2] are deleted and shifted to Ch 6, Sec 1, [3.2.3]. Further in Ch 6, Sec 1, [3.2.3], taking account of the answer in KC ID 332,

- “net” scantling basis is clarified, and - the definition of λc is added, - it is clarified that the net thickness of lowest part of corrugation is to comply with the

requirements in [3.2.1], Ch 6, Sec 2, [3.6.1] & [3.6.2] and Ch 6, Sec 3, [6], and, - it is clarified that the net thickness of middle part of corrugation is to comply with the

requirements in [3.2.1], Ch 6 and Sec 2, [3.6.1 & 3.6.2] 2.3 Ch 3, Sec 6, [10.4.5], [10.4.6] and [10.4.7], Ch 6, Sec 1, [3.2.3 bis1] and [3.2.4]

The scantling requirements in Ch 3, Sec 6, [10.4.5], [10.4.6] and [10.4.7] are deleted and shifted to Ch 6, Sec 1, [3.2.3 bis1], and “net” scantling basis is clarified and in line with the answer in KC ID 450 the shifted rule text is modified.

Taking account of the answer in KC ID 332, it is clarified that the required corrugation flange net plate thickness is according to [3.2.3] or [3.2.4].


PAGE 165 OF 171

2.4 Ch 3, Sec 6, [10.4.8] Upper stool and Ch 6, Sec 1, [3.2.3 bis1] The scantling requirements are deleted and shifted to Ch 6, Sec 1 [3.2.3 bis1] and “net”

scantling basis is clarified. Taking account of the answer in KC ID 332, it is clarified that the bulkhead plating below

the upper stool bottom plating and upper part of the bulkhead plating are according to [3.2.3] or [3.2.4]. 2.5 Ch 3, Sec 6, [10.4.9] Alignment and Ch 6, Sec 1, [3.2.3 bis2]

The scantling requirements in Ch 3, Sec 6, [10.4.9] are deleted and shifted to Ch 6, Sec 1, [3.2.3 bis2], considering the consistency with the requirement in Ch 3, Sec 6, [6.4.2] and “net” scantling basis is clarified. 2.6 Ch 3, Sec 6, [10.4.13] Section modulus at the lower end of corrugations and Ch 6, Sec 2, [3.6.2]

The requirement in Ch 3, Sec 6, [10.4.13] is deleted and shifted to the new paragraph Ch 6, Sec 2, [3.6.2] since it is only related to the scantling requirements for flooded condition. Further in the new paragraph figure nos. are corrected from “31 thru 35” to “11 thru 15” accordingly and the cross references in the text are modified. 2.7 Ch 3, Sec 6, [10.4.14] Section modulus at sections other than the lower end of corrugations and Ch 3, Sec 6, [10.4.15] Shear area

The requirement in Ch 3, Sec 6, [10.4.14] is deleted and shifted to the new paragraph Ch 6, Sec 2, [3.6.2] (a).

The requirement in Ch 3, Sec 6, [10.4.15] is deleted and shifted to the new paragraph Ch 6, Sec 2, [3.6.1]. 2.8 Ch 6, Sec 2, [2.1.1]

Figure 2 is only applicable when section modulus of corrugated bulkhead is investigated according to Ch 6, Sec 2, [3.2.4]. Figure 2 is same as Ch 3, Sec 6, and Figure 28. In order to avoid user’s misinterpretation Ch 6, Sec 2, [2.1.1] is deleted together with Figure 2. 2.9 Ch 6, Sec 2, [3.2.4], Tables 4 and 5

The definition of the effective width of the corrugation flange is added and Tables 4 and 5 are clarified. 2.10 Ch 6, Sec 2, [3.2.6], Bending capacity and shear capacity of the corrugations of transverse vertically corrugated watertight bulkheads separating cargo holds for flooded conditions and [3.6]

This paragraph is deleted and shifted to the new paragraph Ch 6, Sec 2, [3.6.2] so that all requirements related to flooded condition are unified together in the new paragraph Ch 6, Sec 2, [3.6] and the paragraph Ch 6, Sec 2, [3.6] is newly provided so that the UR S18 requirements can be clearly collected and identified therein. In addition, for determining the net section modulus of stiffeners in lower stool and upper stool, as it is necessary to consider the pressure specified in Ch 4, Sec 6, [3.3.7] which comes from IACS UR S18, the new paragraph [3.6.3] is added. 2.11 Ch 6, Sec 3, [6.1.1]

The reference is changed, according to the modification of Ch 6, Sec 2.


PAGE 166 OF 171

3. Impact on Scantling Since the subject revisions to the text are:

a) the clarification of the text in line with the original intention, or b) the clarification of the texts. For a) it is not necessary to perform impact study. For b) it is not possible to perform impact study because the basis is not identified clearly.


PAGE 167 OF 171


Rule Change Notice No.1-9 (Main Engine Foundation)





PAGE 168 OF 171



Section 3 MACHINERY SPACE

7. Main machinery seating

7.2 Minimum scantlings

7.2.1 The net scantlings of the structural elements in way of the internal combustion engine seatings are to be obtained

from the formulae in Tab 2. However, the net cross-sectional area of each bedplate of the seatings may be

determined by the engine manufacturers, provided the information regarding permissible foundation stiffness

considering the engine characteristics and engine room arrangement, etc..

Table 2: Minimum scantlings of the structural elements in way of machinery seatings

Scantling minimum value Scantling minimum value Net cross-sectional area, in cm2, of each bedplate of the seatings

Er LnP7040 +

Bedplate net thickness, in mm Bedplates supported by two or more girders:

ErLnP175240 +


Er LnP

1752405 ++

Total web net thickness, in mm, of girders fitted in way of machinery seatings

Bedplates supported by two or more girders:

Er LnP

215320 +


Er LnP

6595 +

Web net thickness, in mm, of floors fitted in way of machinery seatings

Er LnP

4055 +


PAGE 169 OF 171


Technical Background for Rule Change Notice No.1-9 (Main Engine Foundation)



TECHNICAL BACKGROUND FOR RULE CHANGE NOTICE NO.1-9 COMMON STRUCTURAL RULES FOR BULK CARIIERS

PAGE 170 OF 171

Net Thickness of Girder

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 50 100 150 200 250 300Ship's Length (L) (m)

Act

ual /

Req

uire

d


0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0.0 5.0 10.0 15.0 20.0 25.0P/(Nr*Le)

Act

ual /

Req

uire

d


0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 5000 10000 15000 20000Engine power (kW)

Act

ual /

Req

uire

d

Net Area of Seating

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0 50 100 150 200 250 300Ship's Length (L) (m)

Act

ual /

Req

uire

d

Net Area of Seating

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0 5000 10000 15000 20000Engine power (kW)

Act

ual /

Req

uire

d

Net Area of Seating

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0.0 5.0 10.0 15.0 20.0 25.0P/(Nr*Le)

Act

ual /

Req

uire

d

Net Thickness of Seating

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 50 100 150 200 250 300Ship's Length (L) (m)

Act

ual /

Req

uire

d


0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 5000 10000 15000 20000Engine power (kW)

Act

ual /

Req

uire

d


0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0.0 5.0 10.0 15.0 20.0 25.0P/(Nr*Le)

Act

ual /

Req

uire

d

Net Thickness of Floor

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 50 100 150 200 250 300Ship's Length (L) (m)

Act

ual /

Req

uire

d


0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 5000 10000 15000 20000Engine power (kW)

Act

ual /

Req

uire

d


0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0.0 5.0 10.0 15.0 20.0 25.0P/(Nr*Le)

Act

ual /

Req

uire

d

Technical Background for the Changes Regarding Main Engine Foundations 1. Reason for the Rule Change in Ch 9, Sec 3, [7.2] PT1 was requested to make an interpretation for the usage of Table 2 of the Rule (KC-ID 413). The scantling according this table leads to very large scantlings, especially the net cross-sectional area of engine seatings. This was not the intention of these requirements. However, the scantling formula except for cross-sectional area of engine seatings specified in Table 2 of the Rules are considered reasonable according to the investigation results of existing BCs as given in Figure 1 to Figure 4.

Fig.1 Cross-sectional area of engine seating

Fig.2 Net thickness of engine seating

Fig.3 Total net thickness of girders

Fig.4 Net thickness of floors


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From these results, it is necessary to clarify the dealing with the formula for cross-sectional area of engine seatings. In this regard, we considered that it is possible to deal with the drawings supplied by the engine manufactures with information regarding permissible foundation stiffness considering the engine characteristics and engine room arrangement, etc.. 2. Summary of the Rule Change The scantling of the combustion engine foundation is generally determined by not only the results of the calculations or experiments for the required foundation stiffness, derived by the engine manufacturer but also the engine room arrangements. It is not the intention of the CSR for bulk carrier to establish requirements for the combustion engine foundation, which are more severe than the requirements from the engine manufacturer. The following examples give an overview of the scantling impact Therefore, we propose to add the following sentence after the present text of Ch 9, Sec 3, [7.2.1] <Quote> However, the net cross-sectional area of each bedplate of the seatings may be determined by the engine manufacturers, provided the information regarding permissible foundation stiffness considering the engine characteristics and engine room arrangement, etc.. <Unquote> 3. Effects and impact on scantling due to this definition

The following table gives an overview of the scantling impact regarding the cross-sectional

area of engine seatings.

Documents

Csr Bc Corr February 2009