Metal Structures Lecture XI Bolted joints (part II)footbridge.pl/stud/z/se1/lec111.pdf · Frame: •Hinged joint; •Shear joint; ... •Shear joint; •No bolts; •Interactions

Metal Structures

Lecture XI

Bolted joints(part II)

Contents

Technical solutions → #t / 3

Initial assumptions about geometry of different types of joints → #t / 23

Interactions and contact → #t / 32

Examination issues → #t / 92

Technical solutions

There are many different types of bolted joints between different parts and

members of structure. Which solutions of bolted joints are most often used?

Which phenomenons are important for them?

Bracings:

• Hinged joint;

• Shear joint;

• For bolts calculation according to #10 / 71;

• Interactions between bolts and gusset plates → #t;

Photo: Author

Bracings, tie beams, hangers:

• Rigging screw;

• Fixed joint;

• Tension joint;


Photo: Author

Bracings, tie beams:

• Hinged joint;

• Shear joint;


• Interactions between:

• bolts and L section → #t;

• bolts and gusset plate → #t;

Photo: Author

Floor girder:

• Hinged joint;

• Shear joint;

• Connection between secondary and primary beams;

• Bending moment = sherar force ∙ eccentricity;



• bolts and transverse stiffeners → #t;

• bolts and of secondary beam web → #t;

• transverse stiffeners and primary beam → #14;

Photo: Author

Photo: Author

Frame:

• Hinged joint;

• Shear joint;

• Connection between beam and column;

• Bending moment = shear force ∙ eccentricity;



• bolts and gusset plate → #t;

• bolts and beam web → #t;

Frame:

• Fixed joint;

• Shear joint; tension joint;

• Connection between girder and column;

• For shear bolts calculation according to #10 / 71;

• For tension bolts calculation according to #10 / 79;


• bolts and elements of joint → #t, #12;

• differen elements of joint → #t, #12;

Photo: Author

Frame:

• Fixed joint;

• Shear joint;

• Connection between flange / web of beam

and flange plate / web plate;

• For bolts in flange calculation according to

#10 / 71;

• For bolts in web calculations according to

#10 / 73;


• bolts and web / flange / web plate /

flange plate → #t;

• elements of joint → #t;

Photo: Author

Frame:

• Fixed joint;

• Shear joint;

• Connection between flange / web of beam and flange

plate / web plate;

• For bolts in flange calculation according to #10 / 71;

• For bolts in web calculations according to #10 / 73;


• bolts and web / flange / web plate / flange plate

→ #t;

• elements of joint → #t;

• flange plate and web / flange / stiffeners of

column → #t, #12, #14;

Photo: Author

Frame:

• Fixed joint;

• Shear joint;

• Bolts in beam – acording to #t / 11;

• Bolts in column – according to #t / 9

• Interaction between:

• flange cleats and web cleats (L sections) and bolts → #t, #12;

• web / flange of column and cleats →

#t, #12;

Photo: Author

Frame:

• Fixed joint;

• Shear joint;

• For beam – acording to #t / 10;

• For column (welded joint) – interaction

between:

• beam and web / flange / stiffeners of

column → #t / 11;

Photo: Author

Frame:

• Fixed joint;


• Connection between beams;

• For shear bolts calculation according to #10 / 71;

• For tension bolts calculation according to #10 / 79;


• bolts and elements of joint → #t, #12;

• differen elements of joint → #t, #12;

Photo: Author

Brick wall:

• Hinged joint;

• Shear joint;

• No bolts;


• beam and transverse stiffener → #14;

• steel beam and masonry structure → #12;

Photo: Author

Frame:

• Hinged joint;

• Shear joint;

• Connection between beam and column;

• Force acts on bolts = axial force in beam or shear force in column (if exists);



• bolts and flange / bolts and cap plate → #t;

• beam and transverse stiffener → #14;

• different parts of column head → #14;

Photo: Author

Column:

• Hinged joint;

• Shear joint;

• Connection between beam and foundations (concrete);

• Force acts on bolts = shear force in column;



• bolts and base plate → #t;

• base plate shearing → #t;

• contact between base plate and concrete → #12;

Photo: Author

Column:

• Rigid joint;


• Connection between beam and foundations (concrete);

• Shear force acts on bolts = shear force in column;

• Tension force acts on bolts = force caused by bending moment;



• bolts and base plate → #t;

• base plate shearing → #t;

• contact between base plate and concrete → #12;

Photo: Author

Beam-column Beam-beam

Shear joint

Tension joint

Photo: Author

Most often used rigid joints in steel frames:

Imperfections Time of calculations Time of erection

(number of bolts)

Shear joint + / -C D

Tension joint -D C

Photo: Author

There is a little gap between beam and column.

Because of this, beam can be a little longer than

in design project (imperfection +); of course

beam can be a little shorter (imperfection -)

Photo: Author

Because of collision between beam and column,

beam can't be longer (imperfection + impossible).

Beam can be little shorter (imperfection -); in this

situation we must use additional packing plate.

Photo: Author

n = max [5,2 MEd / (h FRd) ; 9]

FRd = shear resistance for category A and B; slip resistance for category C

Initial assumptions about geometry of different types of joints

Number of bolts, web / web plate / gusset plate

Photo: Author

I Method, II Method III Method

1. Initial asumptions of dimensions

Photo: Author

→ #Des 1 / 15

bfp = bf

tf ≤ tfp ≤ 2tf

twp ≤ tw ≤ 2twp

twp ≥ 8 mm

hwp ≈ 0,8 h0

0,8 JI, y ≤ Jfp, y

Jfp, y ≥ 10 Jwp, y

I Method

(there are no actions of low temperatures)

→ #Des 1 / 16

bfp = bf

tf ≤ tfp ≤ 2tf

twp ≤ tw ≤ 2twp

twp ≥ 8 mm

hwp ≈ 0,8 h0

Jf, y ≈ Jfp, y

Jw, y ≈ Jwp, y

II Method

(there are no actions of low temperatures)

→ #Des 1 / 17

III Method

(there are actions of low temperatures

and, additionally,

tfp, Method I / II > tmax)

bfp1 = bf

bfp2 = (bf - 2r - tw) / 2

tfp2 = tmax

bfp1 tfp1 (tf + tfp1) / 2 = 2 bfp2 tfp2 (tf + tfp2) / 2

twp ≤ tw ≤ 2twp

twp ≥ 8 mm

hwp ≈ 0,8 h0

0,8 JI, y ≤ Jfp, y

Jfp, y ≥ 10 Jwp, y

→ #Des 1 / 18

EN 1993-1-10→ #Des 1 / 19

Mfp = MEd J1, y / (J1, y + J2, y)

Mwp = MEd J2, y / (J1, y + J2, y)

Nfp = NEd A1 / (A1 + A2)

Nwp = NEd A2 / (A1 + A2)

Vfp = 0

Vwp = VEd

2. Distribution of cross-sectional forces

Characteristics Method A Method B

A1 Afp Af

A2 Awp Aw

J1,y Jfp,y Jf,y

J2,y Jwp,y Jw,y

→ #Des 1 / 21

Ffp = max (Ffp, top ; Ffp, bottom) =

= | Nfp | / 2 + | Mfp | / x

/ 2

/ 2

Method A B

I x = x1 x = x2

II x = x1 x = x2

III x = x2 x = x2

x1 = h + tfp / 2 + tfp / 2

x2 = h - tf / 2 - tf / 2

Photo: Author

→ #Des 1 / 22

min (t1 ; t2) ≥ max (T1 ; T2)

T1 = 2,0 √ {c Ft,Rd / [fy (2c + d)]}

T2 = 1,67 d 3√ {fub / 1 000 [MPa]}

Tension connection – thickness of end plate (t1) and additional

plate for column flange (t1 = tflange + tplate)

Photo: Author

Type of bolts

Bearin

g resistan

ce

Base p

lates shearin

g

Punch

ing resistan

ce

Pry

ing actio

ns

Plate / flan

ge in

ben

din

g

Web

in ten

sion

t/39-

52

t/72-

74

t/75 t/76-

79

t/80-90

Shear

"normal" A ✓ ✓

preloaded

B ✓ ✓

C ✓ ✓

Ten

sion

"normal" D ✓ ✓ ✓ ✓

preloaded E ✓ ✓ ✓ ✓

Interactions and contact

Bolt-elements

Type of bolts

Net area Instab

ility o

f plate

Slip

-resistant

„Classical” n

et area

Blo

ck tearin

g

Lsectio

nt/56-65 t/53-

54

t/66-

71

Shear

"normal" A ✓ ✓ ✓ ✓

preloaded

B ✓ ✓ ✓ ✓ ✓

C ✓ ✓ ✓ ✓ ✓

Ten

sion

"normal" D

preloaded E

Intercaction / contact elements-elements, bolted joints

Type of bolts

Shear resistan

ce

Ten

sion resistan

ce

Differen

tty

pes

of

interactio

ns

(lec #11, 1

2)

Shear

"normal" A ✓ ✓

preloaded

B ✓ ✓

C ✓

Ten

sion

"normal" D ✓ ✓

preloaded E ✓ ✓

Shear resistance and tension resistance are important for

different categories of joints.

EN 1993-1-8 tab. 3.2

→ #10 / 51

• Punching resistance, prying actions, plate / flange in bending and web in

tension are important for resistance of rigid bolted joints in frames. Calculation

of rigid welded joints in frames are similar. Both ways are resented on lecture

#12;

• Part of column base is welded joint (column - end plate), part is bolted joint

(end plate – concrete). Additionally there must be analysed contact between steel

and concrete. Way of calculations is presented on lecture #12;

• Support on wall is welded joint (stiffeners – beam), additionally there must be

analysed contact between beam and masonry structure. Way of calculations is

presented on lecture #12;

Intercaction / contact elements-elements, bolted, pinned and welded joints

Photo: Author

• Trusses nodes are welded joints. There are contact between part of nodes. Way of

calculations is presented on lecture #14;

• Stiffeners can be used for different reasons (support of slender web, joint with

secondary beam, reinforcement of column-beam joint, reinforcement of beam in

place of support on wall or on column). General rules for calculations are presented

on lecture #14;

• Column head is welded joint and part could be bolted joint. Way of calculations

for both parts is presented on lecture #14;

Intercaction / contact element-element, bolted, pinned and welded joints

(continuation)

Photo: EN 1993-1-8 fig 7.3, 7.4 Photo: Author

• Additional rules for welded joint between L section and plate are presented on

lecture #14;

• Additional rules for welded joint between two I-beam are presented on lecture

#14;

• Additional rules for pin ended members and contact bearing stresses for pins are

presented on lecture #14;

• Bolted joint for R&CHS are presented on lecture #14.

Intercaction / contact element-element, bolted, pinned and welded joints

(continuation)

Connections Joints

Type Resistance Stiffness Resistance

Contact / interaction

between

connections and other

elements

Contact / interaction

between

other elements

Welded EN 1993-1-8

chapter 4

(welds)

Lecture #9EN 1993-1-8

chapter 5 and 6

Lecture #20, #21

No phenomenons EN 1992-1-1 chapter 6

EN 1993-1-5 chapter5, chapter 9

EN 1993-1-8 chapter 4,

chapter 6, chapter 7

EN 1995-1-5 chapter 9

Lecture #12, #14

Bolted EN 1993-1-8

chapter 3

(shanks)

Lecture #10


chapter 6

Lecture #11


chapter 6

Lecture #11, #12

→ #10 / 44

Local deformation or destruction - but no global destruction (block tearing)

Photo: Author

→ Des #1 / 42

Deformation or destruction of plates as

the effect of contact with shank of bolt.

Photo: A. Biegus, Projektowanie konstrukcji stalowych

według Eurokodów, Politechnika Wrocławska

→ Des #1 / 41

Bearing resistance

We assume linear stersses in

calculation model.

Photo: A. Biegus, Projektowanie konstrukcji stalowych

według Eurokodów, Politechnika Wrocławska

Fb,Rd = bb k1 ab fu d tmin / gM2

EN 1993-1-8 tab 3.4, red part is given in bottom part of table.

bb – parameter fo shape of hole → #t / 43

k1 – parameter for phenomenons in direction perpendicular to force → #t / 44, 47, 48

ab – parameter for phenomenons in direction paralell to force → #t / 43, 44, 47, 48

fu – ultimate strength of plate

d – dimension of bolt

tmin – minimum total thickness of plate → #t / 43, 44

gM2 = 1,25

Photo: Author

ab = min (ad ; fub / fu ; 1,0)

tmin = min (St1 ; St2)

bb

Fit bolts

Normal round holes

1,0

Oversized round holes 0,8

Slotted holes 0,6

0,8

EN 1993-1-8 tab 3.4Photo: Author

Bearing resistance: Fb,Rd = k1 ab fu d tmin / gM2

ab = min (ad ; fub / fu ; 1,0)

tmin = min(Sti)

EN 1993-1-8 tab 3.4

Photo: Author

Enge

Inner

min(2,8 e2 / d0 - 1,7 ; 2,5)

min(1,4 p2 / d0 - 1,7 ; 2,5)

k1

Direction perpendicular to force

End

Inner

e1 / 3d0

p1 / 3d0 - 0,25

ad

Direction parallel to force

Photo: AuthorgM2 = 1,25

→ #Des 1 / 50

EN 1993-1-8 tab 3.3

Dimensions Minimum

Maximum

„Normal” steels

Stainless steelsSteel exposed to the

weather / corrosion influences

Not exposed

e1 1,2 d0 4 te, min + 40 mm max(8 te, min ; 125 mm)

e2 1,2 d0 4 te, min + 40 mm max(8 te, min ; 125 mm)

e3 1,5 d0

e4 1,5 d0

p1 2,2 d0 min(14 te, min ; 200 mm) min(14 te, min ; 200 mm) min(14 tmin ; 175 mm)

p1,0 min(14 te, min ; 200 mm)

p1,i min(14 te, min ; 200 mm)

p2 2,4 d0

(1,2 d0 and L ≥ 2,4 d0)

min(14 te, min ; 200 mm) min(14 te, min ; 200 mm) min(14 tmin ; 175 mm)

→ #10 / 24

Index 1 and 2 in symbols e1 e2 p1 p2 - there are no horizontal and vertical

directions, but always paralell (1) and perpendicular (2) to direction of force:

eH eHpH pH

eV

eV

pV

pV

pV

pV

e2e2 p2 p2

e2

e2

p2

p2

e1

e1

p1

p1

p1

p1

e1e1 p1 p1

Photo: Author

E E

I

k1

Inner min(1,4 p2 / d0 - 1,7 ; 2,5)

Enge min(2,8 e2 / d0 - 1,7 ; 2,5)

E

E

I

ad

Inner p1 / 3d0 - 0,25

End e1 / 3d0

k1 ad

EE EE

EE EE

EI EI

IE

IE

IIPhoto: Author

E

E

I

k1

Inner min(1,4 p2 / d0 - 1,7 ; 2,5)

Enge min(2,8 e2 / d0 - 1,7 ; 2,5)

EE I

ad

Inner p1 / 3d0 - 0,25

End e1 / 3d0

k1 ad

EE

EE

EE

EE

EI

EI

IE IE

IIPhoto: Author

One row, separated specification (EN 1993-1-8 (3.2)):

Fb,Rd = min [ bb k1 ab fu d tmin / gM2 ; bb 1,5 fu d tmin / gM2 ] =

= min (k1 ab ; 1,5) ∙ bb fu d tmin / gM2

Photo: EN 1993-1-8 fig. 3.3

Symbols according to #t / 42

Photo: fgg.uni-lj.si

Bearing of iniection bolts:

Fb,Rd, resin = kt ks d tb, resin b fb, resin / gM4

kt - coefficent of limit states → #t / 51

ks - diameter of hollow shape → #t / 51

d - diameter of bolt

tb, resin - effective bearing thickness → #t / 52

b - coefficent of thickness ratio → #t / 52

fb, resin - bearing strength of resin → information from manufactures

gM4 = 1,0

EN 1993-1-8 (3.4)

ULS SLS

kt 1,2 1,0

ks

Fit bolts No space for resin

Normal round holes 1,0

Oversized round holes 1,0 - 0,1 (d0 - d)

Slotted holes 1,0 - 0,05 (l - d0)

l ; d0 ; d [mm]

EN 1993-1-8 3.6.2.2.(5)

EN 1993-1-8 3.6.2.2.(5)

b tb, resin

t1 / t2 ≤ 1,0 1,33

min (t1 ; 1,5d)1,0 ≤ t1 / t2 ≤ 2,0 1,66 - 0,33 (t1 / t2)

t1 / t2 ≥ 2,0 1,0 min (2t2 ; 1,5d)

EN 1993-1-8 tab 3.5

Photo: EN 1993-1-8 fig 3.5

Too big distance between bolts parallel to direction of force (p1)in not recommended.

p1 / t ≥ 9e and compressive force → local buckling of plate

lcr = 0,6 p1

EN 1993-1-8 tab 3.3

More infomation will be presented on lecture #11

Local instability

→ #10 / 29

NEd / (cx NRd) ≤ 1,0

NRd = A fy

A = t ∙ l ; Jx = l ∙ t3 / 12 ; ix = √ (Jx / A) = t / (2 √3)

Lcr = 0,6 p1

cx = cx (Lcr ; ix ; c)

Photo: Author

Net area

Cross-section witout holes for bolts

"Classical" net area Block tearing L section

straight or nearly straight

line;

different cross-sections

(excep L section);

different loads (forces,

bending moment, interactions);

broken line;

flat elements / plates;

olny one force;

additional rules for L section;

axial force;

Photo: EN 1993-1-8 fig. 3.9

Photo: EN 1993-1-8 fig. 3.8

Photo: EN 1993-1-8 fig. 3.1

Force Type Fit

bolts

Normal

round

holes

Oversized round holes Slotted holes

A, B Nu,Rd = 0,9 Anet fu / gM2 (recommendation: Nu,Rd > A fy / gM0)

C Nnet,Rd = Anet fy / gM0

A, B, C Can be neglected

"Classical" net area

EN 1993-1-1 chapter 6

Photo: Author

Force Type Fit

bolts

Normal

round

holes

Oversized round holes Slotted holes

A, B, C Can be neglected Nc, net,Rd = Anet fy / gM2

A, B, C Can be neglected

If 0,9 Acomp, net fu / gM2 ≥ Acomp fy / gM0

then can be neglected

Otherwise Mnet,Rd = Wnet, min fy / gM2

Photo: Author

Veff, 1, Rd = fu Ant / gM2 + fy Anv / (√3 gM0) | 0,5 fu Ant / gM2 + fy Anv / (√3 gM0)

gM0 = 1,00; gM2 = 1,25

Block tearing

EN 1993-1-8 3.10.2

Photo: EN 1993-1-8 fig. 3.8

Example for calculation of net area: flange, flange

plate, web, web plate

Photo: amsd.co.uk

Flange plate, axial force only. According to #t / 55 - 58 we should calculate block tearing

(tension part and shear part), but the smallest area is for red cross-section. According to

bolt category (A, B or C) we calculate

Nu,Rd = 0,9 Anet fu / gM2

or

Nnet,Rd = Anet fy / gM0

Photo: Author

Web plate, bending moment, shear force and, optionally, axial force.

s(Nfp) = Nfp / Anetto

s(Mfp) = Mfp / Wnetto

t(Vfp) = Vfp / Atotal

√{ [s(Nfp) + s(Mfp)]2 + 3[t(Vfp)]

2} ≤ fy

Photo: Author

Web, flange - uniform cross-section, not two separate part. We should analysed

destruction of whole netto cross-section.

Photo: Author

s(Nfp) = Nfp / Anetto

s(Mfp) = Mfp / Wnetto

t(Vfp) = Vfp / (hw tw)

√{ [s(Nfp) + s(Mfp)]2 + 3[t(Vfp)]

2} ≤ fy

Photo: Author

Nu, Rd =

b

p1 / d0 ≤ 2,5 2,5 < p1 / d0 < 5,0 p1 / d0 ≥ 5,0

2 (e1 - 0,5 d0) t fu / gM2

b Anet fu / gM2

0,4 0,4 + 0,12 (p1 / d0 - 2,5) 0,7

0,5 0,5 + 0,08 (p1 / d0 - 2,5) 0,7

L section (axial force)

EN 1993-1-8 3.10.3

Photo: EN 1993-1-8 fig. 3.9

AnetPhoto: Author

Preloaded bolt – special types of bolts; preloading force causes friction; loads can’t be greater than friction.

Slip-resistant

Photo: Author

Type Fs,Rd Condition

Ft,Ed = 0 Ft,Ed ≠ 0

B

ks n m Fp,C / gM3

ks n m [Fp,C - 0,8 Ft,Ed, ser (qk)] / gM3,ser FEd (qk) / Fs,Rd ≤ 1,0

C ks n m [Fp,C - 0,8 Ft,Ed, ser (qk)] / gM3 FEd (q) / Fs,Rd ≤ 1,0

ks - diameter of hollow shape → #t / 68

n - number of friction planes

m - friction coefficent → #t / 69

Fp,C - preloading force → #t / 68

gM3 = 1,25 gM3,ser = 1,10

EN 1993-1-8 (3.7, 3.8a, 3.8b)

Photo: Author

Fp,C = 0,7 fub As

EN 1993-1-8 (3.7)

Type of holes Force ks

Round

Fit 1,0

Normal 1,0

Oversized 0,85

Slotted

Short

0,76

0,85

Long

0,63

0,70

EN 1993-1-8 tab. 3.6 Photo: Author

Class of surface ≠ category of connections

EN 1993-1-8 tab. 3.7

EN 1090-2 tab 18

Class of friction surfaces Slip factor m Surface treatement

A 0,5 Surface blasted with shot or girt with loose rust

removed, not pitted;

B 0,4 Surfaces blasted with shot or girt:

spray-metallized with a aluminum or zinc based

product;

with alkali-zinc silicate paint with a thickness of

50 mm to 80 mm;

C 0,3 Surfaces cleaned by wire-brushing or flame

cleaning, with loose rust removed;

D 0,2 Surfaces as rolled;

Torque spanner for preloaded bolts – we know value of preloaded force.

Photo: narzedzia.pl

Torque moment for preloaded bolts

Mr = km d Fp,C

EN 1090-2 p.8.5.2

km = 0,15 ~ 0,18 according to EN 14 399

Photo: home.jtan.com

By unfortunate coincidence, three completely different things were marked in the same way:

• Grade of bolt: A, B, C (→ 10 / 21);

• Category of bolted connections: A, B, C, D, E (→ 10 / 48);

• Class of friction surfaces: A, B, C, D, E (→ t / 69).

Grade Category

A Rarely used, first of all for B and C

B A, B, C, D, E

C A, D

Category Class of friction

A It doesn't matter for this category

B A, B, C, D, E

C

D It doesn't matter for this category

E

Base plate shearing

Interaction between base plate, anchor bolts and concrete

under shear force (horizontal force).

Photo: Author

Fv, Rd = Ff, Rd + n Fvb, Rd

Ff, Rd = Cf, d Nc, Ed ; Cf, d = 0,2 for compressive force in column

Ff, Rd = 0 for tensile force in column

Type Fvb, Rd

Fit bolts;

Normal round holes

min [shear resistance (lec #10); ab fub As / gM2]

ab = 0,44 - 0,0003 fyb [MPa]

gM2 = 1,25

Oversized round holes;

Slotted short / long holes 0

EN 1993-1-8 6.2.2

Accuracy for steel structures - to 1 mm. Accuracy for concrete structures (also for position of

anchor bolts) - to 10 mm. Diameter of hols for bolts must be very big to enable compensate

imperfection for position of anchor bolts. Of course, for this situation Fvb, Rd = 0. There are

applied additional washers (d0 = d), which can be welded to base plate. Then Fvb, Rd is

calculated as for fit bolts and normal round holes.

Photo: Author

Photo: nees.org

Bp,Rd = 0,6 p dm tp fu / gM2

dm = (D + s) / 2

tp - thickness of plate

fu - strength of plate

gM2 = 1,25

Categories B, C, E → control: Fp,C / Bp,Rd ≤ 1,0

Categories D, E → control: tensile axial force / Bp,Rd ≤ 1,0

EN 1993-1-8 tab. 3.4Photo: Author

Punching resistance

Too big axial force (preloading force) can

destruct plates

Prying actions

Special phenomenon, occured in tension

part of fixed joint.

Photo: Author

Tensile force or bending moment, which acts

on tension part of joint, occurs tensile forces in

bolts.

Generally:

force in bolt = tensile force / number of bolts

Photo: Author

S MA = 0

S MA = P x – (F / 2) (y + x) → P = (F / 2) (y + x) / x

(y + x) / x > 2 → P > F (!!!)

But, if plate and flange begin to deform...

Photo: Author

Lb ≤ Lb* → Prying forces

Lb > Lb* → No prying forces

Lb* = 8,8 m3 As / (Sleff tf

3)

tf – the thickness of the thinnest plate

m, Sleff → #t / 84 ~ #t / 87

When it can occur?

EN 1993-1-8 tab. 6.2

Photo: Author

Flange / plate in bending

Web in tension

Beam and column in tensed part of joint are joined only by bolts. There are local concentration of

stress around bolts; tension in webs of column and beam; bending in column flange and end plate

of beam.

Photo: Author

Calculation model: effective area of stress concentration - effective length

Flange, plate → leff

Web → beff (other symbol, but value the same as for flange / plate leff)

There is possible, that effective areas from two row of bolts would be common. In this situation

we must analysed group of bolts, not separate bolts.

leff

leff

leff

Photo: Author

Circular patterns Non-circular patterns

Generally, breakage of plate / flange is possible by two ways:

There are different values of leff for both. We must calculate leff for both and take into following

consideration less of them.

Photo: Author

Photo: EN 1993-1-8 fig 6.8, 6.10. 6.11

End-plate / beam web

EN 1993-1-8 tab. 6.6

Bolt-row

location

Bolt-row considered individually As part of a group of bolt-rows

Circular leff, cp Non-circular leff, nc Circular Sleff, cp Non-circular Sleff, nc

min (2pmx ;

pmx + w ;

pmx + 2e )

min (4mx + 1,25ex ;

e +2mx + 0,625ex ;

0,5bp ;

0,5w +2mx + 0,625ex )

- -

2pm am pm + p 0,5p + am - 2m - 0,625e

2pm 4m + 1,25e 2p p

2pm 4m + 1,25e pm + p 2m + 0,625e + 0,5p

Photo: Author

Unstiffened column flange /

unstiffened column web

EN 1993-1-8 tab. 6.4

Bolt-row

location



2pm 4m + 1,25p 2p p

min (2pm ;

pm + 2e1 )

min (4m + 1,25e ;

2m + 0,625e + 2e1 )

min (pm + p ;

2e1 + p )

min (2m + 0,625e + 0,5p ;

e1 + 0,5p )

e1 – distance from bolt to end of column’s flange

Photo: Author

Bolt-row

location



2pm am pm + p 0,5p + am - 2m - 0,625e

2pm 4m + 1,25e 2p p

min (2pm ;

pm + 2e1 )

min (4m + 1,25e ;

2m + 0,625e + 2e1 )

min (pm + p ;

2e1 + p )

min (2m + 0,625e + 0,5p ;

e1 + 0,5p )

min (2pm ;

pm + 2e1 )

e1 + am - 2m - 0,625e - -

Stiffened column flange /

stiffened column web

EN 1993-1-8 tab. 6.5

e1 – the least distance from bolt to stiffener

Photo: Author

Flange cleat

leff = ba / 2

Photo: EN 1993-1-8 fig. 6.12

Tensile stress in column web and bending in column flange exist in tensed part of

welded joint, also. Effective length for welded joint are calculated in other way.

Additionally, on this type of joint we must analysed shear of column web, transverse

compression of column web and compression of beam flange and part of web.

These three phenomenon are calculated for bolted and welded connection in the

same way.

Photo: microstran.com.au

Welded joint - other shape of concentration of

stresses than for bolted joint.

Photo: Author

Bolted joint Welded joint

Column web in tension Column web in tension

Beam web in tension

Column flange in bending Column flange in bending

End-plate in bending

Column web in shear

Column web in transverse compression

Beam flange and web in compression

To be continued... Photo: Author

Block of information about bolts is divided between lecture #10, #11 and #12.

Examination issues for these lectures are presented at the end of lecture #12.

Examination issues

Shear (bolted) connections - połączenia (śrubowe) zakładkowe

Tension (bolted) connections - połączenia (śrubowe) doczołowe

Bearing resistance - nośność na docisk

Block tearing - rozerwanie blokowe

Slip-resistant - nośność na poślizg

Punching resistance - nośność na przeciąganie łba

Prying actions - efekt dźwigni

Cleat - nakładka z kątownika

Floor girder - ruszt

Rigging screw - śruba rzymska

Resin - żywica

Elongation length - baza wydłużalności

Grip length - grubość skleszczenia

Circular pattern - kołowy mechanizm zniszczenia

Backing plates - płytki usztywniające

Thank you for attention

© 2016 Tomasz Michałowski, PhD

[email protected]

Documents

Metal Structures Lecture XI Bolted joints (part II)footbridge.pl/stud/z/se1/lec111.pdf · Frame: •Hinged joint; •Shear joint; ... •Shear joint; •No bolts; •Interactions