1. Connection

2. Introduction General definition:
Connections or joints are used to transfer the forces supported by a structural member to other parts of the structure or to the supports.
EN definitions;
Connection consists of fasteners such as bolts, pin, rivets or weld and the local member elements connected by these fasteners
A joint consists of the zone in which the members are connected and includes the connection as well as the portions of the member or members at the joint needed to facilitate the action being transferred.
The arrangement of a joint is usually chosen to suit
The type of action (force and/or moment)
The type of member such as tension or compression member, beam or beam-column being connected.

3. Types of connections
For buildings designed to resist essentially static loading, including wind loads, it will normally be sufficient to design connections to resist forces that primarily act in one direction only
Connection between members of roof truss
Truss to column
Beam to column
Column to base
Splice joint beam to beam
Splice joint column to column 1 2 6 3 4 5

4. Joints configurations
Single sided beam to column connection

5. Double sided beam to column connection
Beam to beam joints

6. Beam slices
Braced connection

7. Column base

8. Other type of connection commonly used for design recommendation
Three connections type used in the present design recommendations to connect a beam to a column or a beam to a beam
Header plate connections
Main component: a steel plate, a filled weld on both sides of the supported beam web and two single or two double vertical bolt lines

9. 2. Fin plate connections
Main component: a fin plate, a filled weld on both sides of the plate and a single or double vertical bolt line.

10. 3. Web cleat connections
Characteristic by two web cleats and three single or double vertical bolt lines (two on the supporting element and one on the supported member)

11. 4. Other simple connections
Other type of beam to column connections are considered as hinges.
Nowadays EC3 part 1-8 classified them as semi-rigid

12. Bolts connection
Bolt mainly used in connection to resist shear on the surface of plates and tensile force along the axis of the bolts.
Shank
Thread
(tensile area)
Bolt head
Bolt dia

13. Bolt may transfer loads by shear and bearing, by friction plates and clamped together or by tension
The use of bolts often facilitates the assembly of a structure, as only very simple tools are required.
Shear and bearing joint
Preloaded friction-grip joint
Tension joint

14. Bolt type
Two classes of bolt: normal bolts and high strength bolts (preload bolts)
Only non-preload cover
Their design geometrical and mechanical characteristic are given in Table below:
Table 1 : Bolts area
d (mm) 8 10 12 14 16 18 20 22 24 27 30
A (mm2) 50 78
113
154
201
254
314
380
452
573
707
As (mm2) 36 58 84
115
157
192
245
303
353
459
561
Table 2 : Nominal values of the yield strength fyb and the ultimate tensile strength fub for bolts (Table 3.1 EC3-1-8)
Bolt class
4.6
4.8
5.6
5.8
6.8
8.8
10.9
fyb (N/mm2)
240
320
300
400
480
640
900
fub (N/mm2)
500
600
800
1000

15. Black hexagon bolt which is usually specified in two strength grades:
Common bolt :
Black hexagon bolt which is usually specified in two strength grades:
Grade 4.6 ( mild steel ) , yield stress 240N/mm2
Grade 8.8 ( high strength steel ) yield stress 640 N/mm2
HSFG bolt (high strength friction grip)
Specified in Grade 8.8 and grade 10.9
Current bolt development:
Blind bolt fastener:
Lindapter Hollobolt
Ultra Twist bolt
Flowdrill

16. Bolt :Geometric consideration
Hole size
for bolts ups to and including diameters of 24mm, the clearance should be 2mm and above 24 mm should be 3 mm.
Table 11 in EN gives nominal clearances for bolts and pin (mm)
Normal clearance holes, as given for ordinary bolts, are usually used for preloaded bolting assemblies but it is permissible to use oversize, short or long slotted holes, provided standard hardened washers are used over the holes in the outer plies and not just under turn part.
The assessment of the slip resistance is affected when oversize or slotted holes are used. The constant ks (Table 3.6 EC3-1-8), which is 1.0 for bolts in clearance holes, is educed to depending on the length slotted hole and its orientation to the direction of load transfer.

17. Nominal bolt or pin diameter d (mm)
Table 3 : Nominal clearances for bolts and pins (mm) (Extract from Table 11 of EN )
Nominal bolt or pin diameter d (mm) 12 14 16 18 20 22 24
27 and over
Normal round holes a
1 b c 2 3
Oversize round holes 4 6 8
Short slotted holes (on the length) d 10
Long slotted holes (on the length) d
1,5 d
a For application such as towers and masts the nominal clearance for normal round holes shall be reduced by 0,5 mm unless otherwise specified.
b For coated fasteners, 1 mm nominal clearance can be increased by the coating thickness of the fastener.
c Bolts with nominal diameter 12 and 14 mm, or countersunk bolts may also be used in 2 mm clearance holes under conditions given in EN
d For bolts in slotted holes the nominal clearance across the width shall be the same as the clearance on diameter specified for normal round holes.

18. Spacing of fasteners, end and edge distance
The maximum spacing requirement is to ensure that the section of plate between bolts does not buckle when it is in compression.
The requirement for minimum spacing is to ensure that local crushing in the wake of a bolt does not affect any adjacent bolt.
Lifting of the edges are prevented by specifying a maximum edge distance. Specifying minimum edge distance may prevent edge splitting or tearing.
Spacing requirement is covered fully in Clause 3.5 of EN
Minimum bolt spacing and edge and end distances are as below, where do is the fastener (bolt) hole diameter. These values are defined in Table 6.4 or in Table 3.3 of EC3-1-8.
Minimum spacing of bolts in the direction of load transfer p1=2.2do
Minimum end distance in the direction of load transfer e1=1.2do

19. Structures made of steels according to EN 10025-5
Table 4 : Minimum and maximum spacing, end and edge distance (Table 3.3 of EC3-1-8)
Distance and spacing, See figure 1
Minimum
Maximum 1) 2) 3)
Structures made of steels according to EN except steel acc. to EN
Structures made of steels according to EN
Steel exposed to the weather or other corrosive influence
Steel not exposed to the weather or other corrosive influence
Steel upon unprotected
End distance e1
1,2do
4t + 40 mm
The larger of 18t or 125 mm
Edge distance e2
Spacing p1
2,2do
The smaller of 14t or 200 mm
The smaller of 14tmin or 175 mm
Spacing p2
2,4do

20. Maximum values for spacing, edge and end distance are unlimited, except in the following cases:
For compression members in order to avoid local buckling and to prevent corrosion in exposed members and
For exposed tension members to prevent corrosion
The local buckling resistance of the plate in compression between the fasteners should be calculated according to EN as column-like buckling by using 0.6pi as buckling length. Local buckling between fasteners need to be checked if p1/t is smaller the 9ε. The edge distance should not exceed the maximum to satisfy local buckling requirements for an outstand element in the compression members, see EN the end distance is not effected by this requirement
t is the thickness of the thinner outer connected part
Figure 1 : Symbols for end and edge distance and spacing of fasteners (Figure3.1 of EC3-1-8)

21. Principle of load transmission
Shear
In this case the load is transmitted into and out of the bolts by bearing on the connected plates. The forces in the bolts are transmitted by transverse shear

22. Tension force
In the case of moment loading (M) only, the tension part of the load is transmitted by axial tension in the bolt

23. Combined tension and shear force
In the case of combined moment (M) and transverse loading (V), the bolts may be required to transmit a combination of transverse shear and axial tension.
In Figure below, the bolts A transmit transverse shear, while the bolts B transmit a combination of shear and tension or shear and compression
Bolts that are not preloaded to a predetermined preload, may be called "non-preloaded bolts" or "ordinary bolts". In case of a shear connection (in Figure)these bolts are also called "bearing type" bolts

24. Spliced joint
The principal action on a bolt in a splice joint of the type shown in Figure is shearing on its cross-sectional plane caused by bearing between opposing plates in the joint.
The elastic distribution of these bearing stresses and the stresses produced in the bolt are complex. However, for fully developed plastic conditions, the distribution of shear stress is effectively uniform so that the shear strength is the product of the cross-section area of the bolt in the shear plane and the shear strength of the material

25. Modes of failure Bolt shear Plate shear or tear-out Bolt bearing
Plate bearing
Bolt tension failure
Tension on net section

26. Design resistance of bolt
BS EN assign bolted connections to one of five categories:
Category A: Bearing-type
No preloading is required and the resistance is the less of the design shear or bearing resistance
Category B: Slip resistant at serviceability limit state
Preloading is sufficient to ensure that slip does not occur under serviceability loading but at the ultimate limit state the bolt acts as a category A bearing type
Category C: Slip resistance at ultimate limit state
The design slip resistance should be greater than the design ultimate shear load.
Category D: Non-preload bolts loaded in tension, which are not suitable in connections where the tensile loading fluctuates.
Category E: Preloaded bolts loaded in tension, which require controlling tightening.

27. EC3-1-8 requires the design shear force Fv,Ed to be limited by
Non-preloaded structural bolting assemblies have to resist force in shear and bring or tension, or combination of these
Shear
The resistance Fv of a bolt in shear depends on the shear strength of bolt ( of tensile strength fub) and the area A of the bolt in a particular shear plane (either gross area or tensile stress area through the threads As , as appropriate)
EC3-1-8 requires the design shear force Fv,Ed to be limited by
The shear resistance per shear plane , Fv,Rd, is given by
( Table 3.4 EC3-1-8)

28. Where the shear plane passes through the threaded portion of the bolt ( A is the tensile area of the bolt As)
For class 4.6, 5.6 and 8.8
αv = 0,6
For class 4.8, 5.8and 6.8 and 10.9
αv = 0,5
Where the shear plane passes through the unthreaded portion of the bolt ( A is the gross section of the bolt)
In preloaded shear connection, shear force is resist by friction until the slip occurs. The slip resistance, Fs,Rd is given by:
(Clause of EC3-1-8)

29. Table 5 : Values of ks (Table 3.6 of EC3-1-8)
Where ; ks is given in Table 5 ( Table 3.6 of EC3-1-8) n is the number of friction surfaces. μ is the slip factor which may obtained from tests conducted in accordance with standard from Table 18 of BS EN or Table 3.7 of EC3-1-8 (reproduced here as Table 6) Fp,C is the preloading force, which for class 8.8 and 10.9 bolts with controlled tightening, My be taken as 0.7 fub As
Table 5 : Values of ks (Table 3.6 of EC3-1-8)
Description ks
Bolts in normal holes
1,0
Bolts in either oversized holes or short slotted holes with the axis of the slot perpendicular to the direction of load transfer
0,85
Bolts in long slotted holes with the axis of the slot perpendicular to the direction of load transfer.
0,7
Bolts in short slotted holes with the axis of the slot parallel to the direction of load transfer.
0,76
Bolts in long slotted holes with the axis of the slot parallel to the direction of load transfer
0,63

30. Table 6: slip factors (Extract from Table 18 of EN1090-2)
Surface treatment
Class
Slip factor μ
Surface blasted with shot or grit with loose rust removed, not pitted A
0,50
Surface blasted with shot or grit
spray-metallized with a aluminium or zinc based product;
With alkali-zinc silicate paint with a thickness of 50 μm to 80 μm B
0,40
Surface cleaned by wire-brushing or flame cleaning, with loose rust removed C
0,30
Surface as rolled D
0,20

31. i.e. end, edge and pitch distances
Bearing
Controlled by either deformation of the bolt or the bearing resistance of the plates or section through which the bolt pass, and is a function of the position of the bolt holes.
i.e. end, edge and pitch distances
For bearing the resistance is given by
Where αb is the smallest of αd , fub/fu or 1.0
fu is the ultimate tensile strength of the connected parts and ( with reference to Figure 1):
(Table 3.4 of EC3-1-8)

32. In the direction of load transfer,
Where αb is the smallest of αd ; fub/fu ; 1.0
Perpendicular to the direction of load transfer k1, is the smaller of:

33. Verification
for the situation in which bearing failure occurs in the bolt rather than the plate
for situation in which bearing failure of the plate ( where a bolt bears against part of the surface of bolt hole through the plate)

34. Tension
The resistance of a bolt in tension depends on the tensile strength fub of the bolt and the minimum cross-sectional area of the threaded length of the bolt, the design force is limited to
The design tension resistance , Ft,Rd of bolt is given in EC3-1-8 Table 3.4 as;
where ;
As is the tensile area of bolt
k2 = 0.9 (Except for countersunk bolts, where k2 = 0.63

35. Combination shear and tension
Non- preloaded bolt which are subjected to both tension and shear should satisfy the following relationship;
This expression allows a bolt fully loaded in tension to also resist shear forces up to approximately 30% of the design resistance
Preloaded bolts in friction grip connections that are also subjected to externally applied tension should satisfy (Clause 3.9.2)
For category B connection (slip resistance at SLS)
For a category C connection ( slip resistance at ULS)
(Table 3.4 of EC3-1-8)

36. Packing and long joints
Special provision are made when using oversize or slotted holes or countersunk bolts.
Where bolts transmit load in shear and bearing and pass through packing of total thickness tp
The design shear resistance should be reduced by a factor βp given by
Figure 4 : Fasteners through packing
But βp ≤ 1.0

37. Provisions are also given for
injection bolts ( Clause of EN3-1-8)
bolts groups in bearing( Clause 3.7 of EN3-1-8)
Long joints ( Clause 3.8 of EN )
For long joints, the design resistance of all fasteners should be reduced by multiplying by the reduction factor βLf
Where Lj is the distance between the centres of the end bolts in joint

38. Example 6.1 : Bolt in single shear
Problem : Calculate the strength of the bolts in the lap slice shown below assuming the use of M20 Grade 4.6 bolts in 22 mm clearance holes and Grade S275 plate.

39. Shear resistance per bolt, Fv,Rd:
Solution:
1) Shear resistance
Bolts are in single shear and it is assumed that the shear plane passes through the threaded portion of the bolts:
αv=0.6
fub = 400 N/mm2
A=As = 245 mm2
M2=1.25
Shear resistance per bolt, Fv,Rd:
Table 3.1 of EC3-1-8/ISO 898

40. 2) Bearing resistance
Bearing resistance per bolt , Fb,Rd:
From geometry : p1 = 60 mm, e1 = 40 mm, e2 = 40 mm, do = 22 mm
From EN , fu of plate (Grade S275, t>3 mm) = 410 N/mm2.
For end bolts,
For inner bolts,
For edge bolts, k1 is the smaller of

41. fub/fu = 400/410 = 0.98
αb is the smallest of αd ; fub/fu ; 1.0
For end bolts αb = 0.61 and the inner bolts αb = 0.66
Therefore for end bolts,
And, for inner bolt
 Clearly the resistance of the joint is controlled by the strength in shear. Therefore, the resistance of the tension splice as governed by the shear resistance of the bolts = 3 x 47.0 = 141 kN.

42. Example 6.2: Bolt in double shear
Problem : Calculate the strength of the bolts in the lap slice shown below assuming the use of M20 Grade 4.6 bolts in 22 mm clearance holes and Grade S275 plate

43. Solution: 1) Shear resistance Bolts are in double shear and it is assumed that two shear plane passes through the threaded portion of the bolts: αv=0.6 fub = 400 N/mm2 A=As = 245 mm2 M2=1.25 Shear resistance per bolt, Fv,Rd:

44. 2) Bearing resistance
Bearing resistance per bolt , Fb,Rd:
From geometry : p1 = 60 mm, e1 = 40 mm, e2 = 40 mm, do = 22 mm
From EN , fu of plate (Grade S275, t>3 mm) = 410 N/mm2.
For end bolts,
For inner bolts,
For edge bolts, k1 is the smaller of

45. fub/fu = 400/410 = 0. 98 αb is the smaller of : αd ; fub/fu ; 1
fub/fu = 400/410 = 0.98 αb is the smaller of : αd ; fub/fu ; 1.0 For end bolts αb = 0.61 and the inner bolts αb = 0.66 Therefore for end bolts, And, for inner bolt  Clearly the resistance of the joints is controlled by the strength in shear. Therefore, the resistance of the tension splice as govern by the shear resistance of the bolts = 3 x 94.0 = 282 kN.

46. Verify the connection in Figure below is adequate
   
Given:
2 Nos 100 x 65 x 8 
Bolt 20 mm dia Grade 4.6
Bolt holes 22 mm dia
Steel Grade S275
Permanent load (tension) = 85 kN
Variable load (tension) = 95 kN
Splice plate 95 x 50

47. Eccentric connection (bracket connetions)
Generally these types of connections are used to resist applied moment and shear. Usually these kinds of connection are commonly used when the applied load is not located in the column axis

48. There are two principle types of eccentrically loaded connection
Moment at 90o to plane of connection (Direct shear and tension)
Moment in plane of connection ( direct shear and torsion)

49. Moment in plane of connection (direct shear and torsion)
Suppose force in each bolt due to moment is F1, F2, F3,…Fn with the distance of r1,r2,r3…rn respectively.
Therefore :
Applied moment Mi = Pe
Resistance Moment of bolts
Mr = F1r1+F2r2+F3r3
But F1 α r1, F2 α r2 or F1 = kr1, F2 = kr2 -z z -y y e P

51. The bolt size is then determined from the maximum load on bolt

52. Example 6.3: Shear and Torsion
Problem: Determine the suitable bolt size
155mm
P=100kN
200kN

53. Solution:
Load due to shear,
Load due to moment,

54. Resultant load
4) Try bolt 16mm dia grade 4.6
Shear resistance per bolt,
 fv,Rd >fr,Ed, ok
5) Other checking if necessary
Limit shear force, Fv,Rd = 30.1 12.5 kN ok
Limit bearing strength,

55. Moment at 90o to the plane of connection (Bolt in shear and tension)
For this kind of connection there are several checks need to be carried out to ensure the adequacy of the connection
Tension resistance (Table 3.4 of EC3-1-8)
where : k2=0,63 for countershank bolt, otherwise k2=0,9.
Shear resistance per shear plane (Table 3.4 of EC31-8)
Combined shear and tension (Table 3.4 of EC3-1-8)

56. Method of analysis
Approximate analysis (assumption)
Centre of rotation is assumed at the bottom bolt of group
The tension force vary linearly
The applied shear is distributed equally to each bolt

57. Note: For more accurate method analysis, the applied moment is assumed resisted by the bolt in tension as well as by an area the bottom of the bracket in compression. The area approximately covers about h/7 from the bottom of the bracket

58. Example 6.4: Eccentricity connection ( Bolt in shear and tension)
Problem: Determine the suitable bolt size

59. Solution:
Force due to direct shear
Force due to moment
Try bolt 20 mm dia. Grade 4.6
3) Carry out the verification

60. i) Ft,Ed < Ft,Rd i. e. 27. 6 kN < 70
i) Ft,Ed < Ft,Rd i.e kN < 70.5 kN ok ii) Fv,Ed < Fv,Rd i.e kN < 47 kN ok iii)

61. Material properties of bolt

62. Figure 3 : Typical butt weld configurations
Welds connection
Welds
Welding is essential in the fabrication of steel structures
Good design leads to cost effective fabrications that can be made to required standards by the use of coordinated specifications, which provide means for quantitative control of weld quality
Advantages : Neat, More efficient, No holes to be punched or drilled etc
In EC3 various type of weld are considered: filled welds, filled welds all around, butt welds, plug welds and flare groove welds
Typical butt weld configuration (a) Partial penetration weld (b) one side with permanent backing (c) grinding or gouging the second side to sound metal and welding to completion from second side
Figure 2 :Typical fillet weld configurations for (a) T-Joints, (b) lap joint, (c) corner joints
Figure 3 : Typical butt weld configurations

63. Welds connection (clause 4 EN 1993-1-8)
Design information is provided for welds covering material thicknesses in excess of 4 mm.
For structural hollow sections this limit is reduced to 2.5 mm (specific guidance being provided in Section 7 of EN
** for thinner materials, reference should normally be made to part 1.3 of the code.
Typical butt weld configuration (a) Partial penetration weld (b) one side with permanent backing (c) grinding or gouging the second side to sound metal and welding to completion from second side

64. Welds: Geometric considerations Fillet Welds
Effective throats
The usual geometrical restrictions that the included angle be between 60o and 120o. The throat thickness of fillet welds is given in Table 6.7
Table 6.7 : Throat thickness of fillet welds
Angle between fusion faces (degrees)
Factor ( to be applied to leg length)
60 to 90
91 to 100
101 to 106
107 to 113
114 to 120
0.7
0.65
0.6
0.55
0.5

65. Welds: Geometric considerations Fillet Welds
Effective throats thickness
Figure 4.3 (EN ) indicates how the effective weld thickness should be measured; this should not be less than 3 mm.

66. Welds: Geometric considerations Fillet Welds

67. Welds: Geometric considerations Fillet Welds

68. Effective length (fillet welds)
The effective length of a fillet weld is the actual length less twice the throat thickness to allow for the starting and stopping of the weld.
Should not be less than 30mm or less than six times the throat thickness (then it can be considered as load carrying)
When a fillet welds terminates at the end or edge of a plate it should be returned continuously round the corner for a distance of twice the leg length.
Intermittent filled welds are laid in short length with gaps between as specified in EC3-1-8 Figure 4.1.
Seldom use because of corrosion problem and the possibility of dynamic load which may cause failure due to fatigue or brittle fracture

69. Design strength of Weld
In this study only Filled welded is considered.
Other important detail in design strength
In fillet welded joints which are subjected to compression forces should not be assume, unless provision is made to ensure it, that the parent metal surfaces are in bearing contact
Should design to carry the whole of the load.
Single-sided fillet welds should not be used in cases where there is a moment about the longitudinal axis
Ideally should not be used to transmit tension

70. Design of fillet weld
There are three type consider in design welded connection
Direct shear
Shear an torsion
Shear and bending
Two methods are permitted for the design of fillet welds:
Directional method
Forces transmitted by unit length of weld
Simplified method
Only longitudinal shear is considered

71. Directional method
Normal and shear stresses of the form in Figure 6.19 ( Figure 4.5 of EC3-1-8) are assumed, in which :
σ is the normal stress perpendicular to the throat
σ is the normal stress parallel to the axis of the throat
 is the shear stress perpendicular to the axis of the weld
 is the shear stress parallel to the axis of the weld

72. σ is assumed not to influence the design resistance, while σ,  and  must satisfy the pair of conditions given by equation
[σ2+3(2+2)]0.5
where:
fu is the nominal ultimate strength of the weaker part joined ( see Table 6.8)
βw is a factor (between 0.8 and 1.0) depending on the steel type (see Table 4.1 of EN )

73. Table 6. 8 : Design resistance of fillet weld (Extract from Table 4
Table 6.8 : Design resistance of fillet weld (Extract from Table 4.1 of En and Table 7 of EN )
Steel Grade
Thickness of the Jointed part weaker (mm)
Ultimate strength , fu (N/mm2)
Correlation factor βw
S 235
tp  3
360
0,8
3 tp  100
S 275
430
0,85
410
S 355
510
0,9
470

74. Simplified method
At all points along its length, the resultant of all forces per unit length transmitted by the weld (Fw,ed) must not exceed the design weld resistance per unit length (Fw,Rd), where this is simply the product of the design shear strength fvw,d and the throat thickness, a.
The value of fvw,d should be taken as
Where :
fu and βw are defined in section ( or (6) of EC3-1-8)

75. Example 6.5: Design resistance of fillet weld ( simplified method)
Problem: Calculate the design strength of fillet weld if the thickness of the part used is 10 mm thick and the steel grade used s355 (EN 10025).
Solution:
The design shear strength of fillet weld,

76. Example 6.6: Welded connection (Direct shear)
Problem:
A 150 x 20 mm thick tie in Grade S275 steel carrying factored load of 400 kN require a splice within its length. Design a suitable arrangement using single sided cover plate and fillet weld.
400 kN
Cover plate

77. Solution:
Cover plate used should be less than 150 mm. Given Fw,Ed = 400 kN. Try cover plate 100 x 20 mm and try size 8 mm weld
Throat thickness, a = 0.7s = 0.7 x 8 = 5.6 mm
Design shear strength of weld:
From Table 6.8, fu = 410 N/mm2 and βw = 0.85
2) The design resistance of the weld per unit length (i.e. per mm run)
Fw,Rd = fvw,d.a = 223 x 5.6 = 1248 N/mm = 1.25 kN/mm

78. Minimum length required = 400/1.25 = 320 mm
3) Total resistance
Minimum length required = 400/1.25 = 320 mm
The required length = (2 x 8) + (2 x 8) = 352 mm ( let say 360 mm)
 Total resistance of weld = 1.25 x 360 = 450 kN (>400 kN) ok
Duplicate the same size at the other side.
400 kN

79. Example 6.7: Welded connection (direct shear)
Problem :
Design fillet welds for direct shear connection. Use steel grade S275.
P = 500 kN
2 nos 65 x 50 x 6 mm
50 mm
65 mm
yb=21.1 mm
yt=43.9 mm

80. Solution : Load for 1 angle section, Fw,Ed = 500/2 = 250 kN Try size 8 mm fillet weld Throat thickness, a = 0.7s = 0.7 x 8 = 5.6 mm 1) Design shear strength of weld: From Table 6.8 fu = 410 N/mm2 and βw = ) The design resistance of the weld pe unit length ( i.e per mm run) Fw,Rd = fvw,d.a = 223 x 5.6 = 1248 N/mm = 1.25 kN/mm minimum length required = 250/1.25 = 200 mm

81. 3) The weld length may be arranged in two ways
Balanced the weld on each sides:
Length : 200 x 43.9/65 = 135 mm
Add 2s = 16 mm ;
required length = = 151 mm, say = 155 mm
The other side length = 200 – 135 = 65 mm
Add 2s = 16 mm;
required length = = 81 mm, say = 85 mm
85 mm
155 mm

82. ii. Weld placed across the end of angle
Total required length of weld = 200 mm
Taking moment about L2;
ML2 = (L1 x 65) + (65 x 32.5) = 200 x 21.1
L1 = 32.4 mm + 2s = 48.4 mm, say = 50 mm
L2 = (200 – 65 – 32.4 ) + 2s = mm,
say = 120 mm L1 L2
65 mm
50 mm
120 mm
65 mm

83. Eccentric connection of weld
Shear and torsion
Load acted at the plane of weld group
Shear and bending
Load acted perpendicular to weld group P P

84. Shear and torsion

86. Example 6.8: Eccentric connection (Shear and Torsion)
Problem:
Determine the size of the fillet weld. Use steel Grade S275 and Electrode E35. Design a critical position, A.

89. Note: For structural use of steel minimum size of 6 mm is normally used

90. Shear and bending
Load 90o to the plane of weld group , i.e. Bracket connection

91. Many assumptions made to analyse the force
Many assumptions made to analyse the force. There two method assumption used in design weld connection of shear and bending.
i) Assumed rotation occurs at x-x
Direct shear,
Due to moment ,
Resultant,
Weld size will then be determined

92. 2 ) Assumed rotation occur at x1-x1
Weld at flange to resist moment
Weld at web to resist shear
Direct shear,
Determine weld size at web (Pw=0.75pw)
Due to moment,
Determine weld size at flange

93. Example 6.9: Welded connection (Shear and bending
Problem:
determine the suitable size of weld