Chapter-6b Welded Connection CENG417
Chapter-6b Welded Connection CENG417
Chapter-6b Welded Connection CENG417
Weld
Connection
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Types of Welds
Full penetration BUTT weld in Full penetration Partial penetration
which there is a complete
penetration and fusion of weld
and parent metal throughout
the thickness of the joint. Butt joint
Types of Welds
A FILLET weld is a weld of approximately
triangular cross-section applied to the surface
profile of the plates. No edge preparation is
needed.
Therefore, fillet welds are usually cheaper than
butt welds.
Fillet Weld Butt Weld
Slot Weld
Corner joint Lapped joint
Electrodes
Plug Weld
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Fillet Weld
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sw
Parent metal
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½ volume of weld
Direction that
weld is laid
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Simple method
PW = a pw (shear capacity per unit length of weld), BS Cl 6.8.7.3
Directional method
PL = a pw (longitudinal shear capacity per unit length of weld), BS Cl 6.8.7.3
a = effective throat size
L = effective weld length
pw = design strength of weld
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Transverse Plane PT
Simple method
PW = a pw (shear capacity per unit length of weld), BS Cl 6.8.7.3
Directional method
PT = K a pw (transverse shear capacity per unit length of weld), BS Cl 6.8.7.3
1.5
K 1.25
1 cos 2
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Comparison of Fillet Weld Under
Longitudinal and Transverse Shear Load
PW or PT Throat Line
θ = 45º
θ = 45º
PW or PL
a
1.5
K=1.25 =1.25
1+cos2450
Simple Method Assume equal L in both loading conditions
PW = a pw
Directional Method
PL = a pw For the same weld, its transverse
PT = K a pw = 1.25PL shear capacity is higher.
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1st deposit
2nd deposit
Example 6.8
Given S275 steel with E35 electrode. Area of tie, A = 100×8 = 800mm2. Design the
weld such that the connection fails by tensile rupture of the tie.
Simple Method
F < L a pw ⇒ a > F/(L pw)
amin = 220/(200x220x10-3) = 5mm ⇒ s = 1.4a = 7mm (Use 7.0mm weld minimum)
Example 6.9
Given S275 steel with E35 electrode. Area of tie, A = 100×8 = 800mm2. Design using s = 6 mm welds
such that the connection fails by tensile rupture of the tie.
Simple Method
F < (100+2beff) a pw ⇒ beff > F/(2a pw) - 50
beff = 220/(2x0.924) - 50 = 69mm ⇒ b = beff + s = 75mm (Use b = 75mm)
Directional method
F < 100K a pw + 2beff a pw ⇒ beff > F/(2a pw) - 50K
beff = 220/(2x0.924) - 50x1.25 = 56.5mm ⇒ b = beff + s = 62mm (Use b = 65 mm)
Example 6.10
Design the connection between angle (50x50x5) and gusset plate shown. Use steel grade S275 and
electrode E35.
8 mm
50x50x5
L
1
36
14 F
(DL 60 kN
L2 & LL 40 kN)
Gusset plate, t=8 mm
Solution:
Assume 5 mm welding leg length fillet weld but not less than 3 mm [cl. 6.7.2]
Factored load = 1.460+1.640 = 148 kN
Load on one angle (Fu) = 148/2 = 74 kN
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l1
F1
36 1 mm
14
A A 74 kN
F2
l2
F1 and F2 can be arranged, so that Fu can pass through the centroid of the angle
to avoid eccentricity
MA-A = 0; 36F1 =14F2…………………...(i)
Fx-x = 0, F1+F2 =74 …………………...(ii)
Solving these two Equations, F1 = 20.72 kN and F2 = 53.27 kN
14
A A 74 kN
F2
l2
F1 = 50 0.753 = 37.65 kN
96.81
l e ( new )
2 128.57 mm
0.753
l practical
l S e
[cl. 6.8.2]
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l 1
practical
l S 50 5 55 mm
1
e
l 2
practical
l S 128.57 5 133.57 mm 135 mm
e
2
55 mm
l1e S
10 Cl. 6.7.2
10
l2e S
135 mm
Weld detail
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Mz = 0.1(100+120–cx)kNm
160 x Corner weld around
160 x
the back of plate
cx
cx
120 B A
Geometrical properties of the weld group
Assume a minimum weld of > 2s around the corners Iyy= (160)(362) + 2(1203/12)
Length of weld, L = (160 + 120 + 120) = 400 mm2, + 2(120)(242)
Center of welding length, Take moment about AB line, = 0.63×106 mm4
xc =[12060+12060]/400 = 36 mm Polar moment of inertia of the weld
Moment of inertia of welding, group,
Ixx= 1603/12+ (120802)2 =1.88106 mm4 Ip = Ixx + Iyy = 2.51×106 mm4
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100kN
Maximum stresses occur in weld furthest from the C.G of C D
the weld group (at point B or D),
At D, shear due to torsion, FT =Mr D/ Ip y FS
FT
rD FR
rD =(842+802)0.5 =116 mm;
FT =MrD / Ip = (18.4103)116 / = 2.51×106 β Mz = 18.4kNm
x
= 0.85036 kN/mm 160
At D, shear due to direct shear, FS=100/400 cx
=0.25 kN/mm
=tan-1 (80/84)=43.60280 A B
FR F S
2
FT2 2 FS FT cos
FR = 1.0457 kN/mm
Simple method
pw = 220N/mm2 regardless of the class of electrode used since S275 steel is used (Table 37)
Directional method
S275 steel
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Simple method
pw = 220N/mm2 regardless of the class of electrode used since S275 steel is used (Table 37)