Vol2_Section10

8/10/2019 Vol2_Section10

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Section 10 - Deck Beams and Supporting Deck Structures B 10 - 1

Section 10

Deck Beams and Supporting Deck Structures

A. General

1. Definitions

k = material factor according to Section 2, B.2.

= unsupported span [m] according to Section 3,

C.

e = width of deck supported, measured from centre

to centre of the adjacent unsupported fields [m]

p = deck load pD, pDAor pL [kN/m2], according

to Section 4, B. and C.c = 0,55

= 0,75 for beams, girders and transverses which

are simply supported on one or both ends.

Ps = pillar load

= P A + Pi[kN]

A = load area for one pillar [m2]

Pi = load from pillars located above the pillar

considered [kN]

s

= degree of slenderness of the pillar

= 0,2s

is

ReH

E

s = length of the pillar [cm]

is = radius of gyration of the pillar

=Is

As[cm]

= 0,25 ds for solid pillars of circular cross

section

= 0,25 for tubular pillarsd2

a d2

i

Is = moment of inertia of the pillar [cm4]

As = sectional area of the pillar [cm2]

ds = pillar diameter [cm]

da = outside diameter of pillar [cm]

di = inside diameter of pillar [cm].

ma = factor according to Section 9, A.1.2

2. Permissible stresses

Where the scantlings of girders not forming part of the

longitudinal hull structure, or of transverses, deck beams,

etc. are determined by means of strength calculations the

following stresses are not to be exceeded:

b = [N/mm2]

150

k

= [N/mm2]

100

k

v = [N/mm2]2 32

180

k

3. Buckling strength

In order to achieve adequate buckling strength of the

orthotropic plate panels of the strength deck as per Section.3,

F.2. it may be necessary to strengthen the transverse deck

beams within 0,6Lamidships for the purpose of increasing

the moment of inertia. For this purpose the design stresses

according to Section 5, D.1. and the stresses due to local

loads are to be considered.

B. Deck Beams and Girders

1. Transverse deck beams and deck longitudinals

The section modulus Wdand shear area Adof transverse

deck beams and of deck longitudinals between 0,25 Hand

0,75 Habove base line is to be determined by the following

formula:

Wd = c a p .2. k [cm3].

Ad = (1 - 0,817 ma) 0,05 a p k [cm2],

2. Deck longitudinals in way of the upper and lower

hull flange

The section modulus of deck longitudinals of decks locatedbelow 0,25 Hand/or above 0,75 Hfrom base line is to be

calculated according to Section 9, B.

3. Attachment

3.1 Transverse deck beams are to be connected to the

frames by brackets according to Section 3, D.2.

3.2 Deck beams crossing longitudinal walls and girders

may be attached to the stiffeners of longitudinal walls and

the webs of girders respectively by welding without

brackets.

3.3 Deck beams may be attached to hatchway coamingsand girders by double fillet welds where there is no

constraint. The length of weld is not to be less than 0,6 x

depth of the section.


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Section 10 - Deck Beams and Supporting Deck Structures C10 - 2

3.4 Where deck beams are to be attached to hatchway

coamings and girders of considerable rigidity (e.g. box

girders), brackets are to be provided.

3.5 Within 0,6 Lamidships, the arm lengths of the beam

brackets in single deck ships are to be increased by 20%.

The scantlings of the beam brackets need, however, not

be taken greater than required for the Rule section modulus

of the frames.

3.6 Regarding the connection of deck longitudinals to

transverses and bulkheads, Section 9, B.1. is to be observed.

4. Girders and transverses

4.1 The section modulus W and shear area Aware not

to be less than:

W = c e2 p k [cm3].

Aw = 0,05 p e k [cm2].

4.2 The depth of girders is not to be less than 1/25 of

the unsupported span. The web depth of girders scalloped

for continuous deck beams is to be at least 1,5 times the

depth of the deck beams.

Scantlings of girders of tank decks are to be determined

according to Section 12, B.3.

4.3 Where a girder does not have the same section

modulus throughout all girder fields, the greater scantlings

are to be maintained above the supports and are to be

reduced gradually to the smaller scantlings.

4.4 End attachments of girders at bulkheads are to be

so dimensioned that the bending moments and shear forces

can be transferred. Bulkhead stiffeners under girders are

to be sufficiently dimensioned to support the girders.

4.5 Face plates are to be stiffened by tripping brackets

according to Section 3, H. 2.5. At girders of symmetrical

section, they are to be arranged alternately on both sides

of the web.

4.6 For girders in line of the deckhouse sides under thestrength deck, see Section 16, A.3.2.

4.7 For girders forming part of the longitudinal hull

structure and for hatchway girders see E.

5. Supporting structure of windlasses and chain

stoppers

5.1 For the supporting structure under windlasses and

chain stoppers, the following permissible stresses are to

be observed:

b = [N/mm

2

]

200

k

= [N/mm2]

120

k

v = [N/mm2]2 32

220

k

5.2 The acting forces are to be calculated for 80% and

45% respectively of the rated breaking load of the chain

cable, i.e.:

S for chain stoppers80%

S for windlasses 80%, where chain stoppers

are not fitted.

for windlasses 45%, where chain stoppers

are fitted.

See also Rules for Machinery Installations, Volume III,

Section 14, D. and Rules for Materials, Volume V,

Section 12, Table.12.7.

C. Pillars

1. General

1.1 Structural members at heads and heels of pillars as

well as substructures are to be constructed according to

the forces they are subjected to. The connection is to be

so dimensioned that at least 1 cm2cross sectional area is

available for 10 kN of load.

Where pillars are affected by tension loads doublings are

not permitted.

1.2 Pillars in tanks are to be checked for tension. Tubular

pillars are not permitted in tanks for flammable liquids.

1.3 For structural elements of the pillars' transverse

section, sufficient buckling strength according to Section.3,

F. has to be verified. The wall thickness of tubular pillars

which may be expected to be damaged during loading and

unloading operations is not to be less than:

tw = 4,5 + 0,015 da [mm] for da 300 mm

tw = 0,03 da [mm] for da> 300 mm

da = outside diameter of tubular pillar in [mm]

1.4 Pillars also loaded by bending moments have to be

specially considered.

2. Scantlings

The sectional area of pillars is not to be less than:

As req = [cm2]10

Ps

p

p = permissible compressive stress.

=

SR

eH


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Section 10 - Deck Beams and Supporting Deck Structures E 10 - 3

= reduction factor

=1

2 s2

= 0,5 1 np

(s 0,2)

s2

np = 0,34 for tubular and rectangular pillars

= 0,49 for open sections

S = safety factor

= 2,00 in general

= 1,66 in accommodation area

D. Cantilevers

1. General

1.1 In order to withstand the bending moment arising

from the load P, cantilevers for supporting girders, hatchway

coamings, engine casings and unsupported parts of decks

are to be connected to transverses, web frames, reinforced

main frames, or walls.

1.2 When determining the scantlings of the cantilevers

and the aforementioned structural elements, it is to be taken

into consideration that the cantilever bending moment

depends on the load capacity of the cantilever, the loadcapacity being dependent on the ratio of rigidity of the

cantilever to that of the members supported by it.

1.3 Face plates are to be secured against tilting by

tripping brackets fitted to the webs at suitable distances

(see also Section 3, H.2.).

1.4 Particulars of calculation, together with drawings

of the cantilever construction are to be submitted for

approval.

2. Permissible stresses

2.1 When determining the cantilever scantlings, the

following permissible stresses are to be observed:

.1 Where single cantilevers are fitted at greater

distances:

bending stress:

b = [N/mm2].

125

k

shear stress:

= [N/mm

2

].

80

k

.2 Where several cantilevers are fitted at smaller

distances (e.g. at every frame):

bending stress:

b = [N/mm2].

150

k

shear stress:

= [N/mm2]100

k

equivalent stress:

v = = [N/mm2].2 32

180

k

.3 The stresses in web frames are not to exceed the

values specified in .1 and .2 above.

E. Hatchway Girders and Girders Forming Partof the Longitudinal Hull Structure

1. The scantlings of longitudinal and transverse

hatchway girders are to be determined on the basis of

strength calculations. The calculations are to be based upon

the deck loads calculated according to Section 4, B. and.C.

2. The hatchway girders are to be so dimensioned that

the stress values given in Table 10.1 will not be exceeded.

Table 10.1 Maximum stress values for hatchway

girder

Longitudinal coaming

and girders of the

strength deck

All other

hatchway

girders

upper and lower flanges :

= [N/mm2]

150

k = [N/mm

2]

150

kdeck level:

= [N/mm2]

70

k

3. For continuous longitudinal coamings the combined

stress resulting from longitudinal hull girder bending and

local bending of the longitudinal coaming is not to exceed

the following value:

L+ [N/mm2]

200

k

= local bending stress in the ship's longitudinal

direction

L = design longitudinal hull girder bending stress

according to Section 5, E.4.

4. The equivalent stress is not to exceed the following

value:


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Section 10 - Deck Beams and Supporting Deck Structures E10 - 4

v = [N/mm2]0,8

L

450

230

k

for L< 90 m

= [N/mm2]

230

k

for L 90 m

= 2x

2

y x y 32

x = L+

y = stress in the ship's transverse direction at

intersection points with transverse members

= shear stress

max = [N/mm2].

90

k

The individual stresses and y are not to exceed150/k [N/mm

2].

5. The requirements regarding buckling strength

according to A.3. are to be observed.

6. Weldings at the top of hatch coamings are subject

to special approval.

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