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STRUCTURAL STEEL DESIGN

CHAPTER 2

STRENGTH OF WELDED CONNECTIONS

Department of Civil Engineering, University of North Sumatera

Ir. DANIEL RUMBI TERUNA, MT;IP-U HAKI

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Strength of fillet welds

Tensile strength of electrode

material

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Strength of fillet welds

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Strength of fillet welds

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Strength of fillet welds

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Design Strength of fillet welds

The design strength per unit length of a fillet weld is based on the shearresistance through the throat of the weld, as follows:

weldfilletFtR EXXenw 60.075.0

But not greater than shear rupture strength of the base metal:

metalbaseFtR unw 60.075.0

metalbaseofstrengthtensileF

placedisweldwhichalongmaterialbaseofthicknesst

materialelectrodeofstrengthtensileFensionthroateffectivet

u

EXX

e

dim

where

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Design strength of fillet welds

weldfilletFtR EXXenw 5.1sin5.0160.075.0

P

weldallongitudinFtRfor EXXenw 60.075.00

weldtransverseFtRfor EXXenw 5.160.075.090

a transvese weld is 50% stronger than longitudinal weld

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Design tension member with welded end connection

gyn xAxFP 9.01. Yielding on Ag

2. Fracture on Ae

eun xAxFP 75.0 connectionweldedUxAA

connectionboltedUxAA

ge

ne

plateofwidthw

weldallongitudinoflengthL

wLwwhenU

wLwwhenU

wLwhenU

c

c

c

c

5.175.0

5.1287.0

200.1

Where

When a member is asingle plate fastenedby only longitudinalwelds )( wLc

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Design tension member with welded end connection

When preceding item is not applicable

9.01

cL

xU

Where

x

Lc Length of longest longitudinal welds

Connection eccentricity

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Design tension member with welded end connection

3. Block shear rupture

vutu AFAF 6.0

tuvybs AFAFR 6.0

vutu AFAF 6.0

tyvubs AFAFR 6.0

Shear yielding tension fracture

Shear fracture tension yielding

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Design tension member with welded end connection

where

y

u

t

v

F

F

A

A

gross area subject to shear

gross area subject to tension

0,75 for fracture limit state

minimum tensile strength

minimum yield stress

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Example 1. A plate welded 8mm x 200mm welded to a 10 mm gussetplate. Compute the maximum force. ( block shear are not considered)

mm8

mm200

mm2400

mm200

P

mmt

MpacmkgEMpaFMpaF

e

uy

4

420/4200450,300

2

60

Strength of steel plate.

- Yielding on Ag

kNNAFP gyn 43243200016003009.09.0

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Strength of fillet welds

- Fracture on Ae

21200160075.0 mmUAA ge

kNxAxFP eun 405120045075.075.0

- Strength of fillet weld

For longitudinal weld

1. Weld fracture

mmNxxxFtR EXXenw /756)42060.0(475.060.075.0

2. Shear rupture of the member alongside a weld

mmNxtFR un /16208)45060.0(75.060.075.0

governsfractureweldRR nwn ,since

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Strength of fillet welds

For transverse weld

1. Weld fracture

mmNmmNxxFtR EXXenw /1134/7565.15.160.075.0

2. Tension rupture of the gusset plate alongside of weld

mmNtFR gussetun /337510)450(75.075.0

governsfractureweldRR nwn ,since

For the fillet weld group, the design strength is

kNNxxxLmmR wnw 389389680200)1134(240)756(2/

Thus, the maximum force of steel plate connection is 389 kN

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Strength of fillet weldsExample 2. A pair of steel angle is welded to 9mm thick gusset plate as

shown in figure below . A36 is used for steel angle and gusset plate. Find thedimension of angle if the connection is loaded 420kN axial force, (2). designthe thickness of weld.

MpacmkgE

MpaFMpaF uy

490/4900

360,250

2

70

uPe

1L

2L

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Using equilibrium equations to find 21 PandP

nwR

PL

11

nwR

P

L

2

2

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1. Yielding on Ag

2. Fracture on Ae

eun xAxFP 75.0

85.0Uestimate

2

155636075.0 mmP

A u

e

21830mmU

AA eg 690902, xxLTry

0x 0x

0y

0y

(min)(max)

yc

xc

cmcccmrcmr

cmrrcmA

yx

yxg

42.2,75.1,47.3

75.2,50.10 002

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3. Design of weld

kNPcP ux 54.153)2/(

99

1

2/uPxc

1L

2L

xc9

1

P

2P

kNPc

P ux 46.56)2/(9

2

mmttandmmtuse e 4707.06

4. Strength of longitudinal weld

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weld fracture

mmNxxxFtR

EXXenw /882)49060.0(475.060.075.0

shear rupture of base metal (angle)

mmNxtFR un /9726)36060.0(75.060.075.0

governsfractureweldRR nwn ,since

mmR

PL

nw

1751.174882

15354011

min2

2 627.61882

54460 LmmRPLnw

mmtL 244min

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Yielding on Ag

2. Fracture on Ae

)(6.6291166236075.075.0 okPkNxxAxFP ueun

9.090.098.0175

42.2

11 UuseL

x

U

21166

9.0

1050mm

U

AA

g

e

4. Check the strength of angle

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uPxc

1L

3L xch

1P

2P

2L

3P

)( 32 PPh

cP u

x

nwRxLP 33