Connection

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 1993-1-8 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.

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

Joints configurations Single sided beam to column connection

Double sided beam to column connection Beam to beam joints

Beam slices Braced connection

Column base

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

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.

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)

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

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

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

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

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

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 1090-2 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 0.85-0.63 depending on the length slotted hole and its orientation to the direction of load transfer.

Nominal bolt or pin diameter d (mm) Table 3 : Nominal clearances for bolts and pins (mm) (Extract from Table 11 of EN 1090-2) 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 1993-1-8. 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.

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 1993-1-8 . 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

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 10025 except steel acc. to EN 10025-5 Structures made of steels according to EN 10025-5 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

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 1993-1-1 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 EN1993-1-1. 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)

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

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

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

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

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

Design resistance of bolt BS EN 1993-1-8 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.

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)

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 3.9.1 of EC3-1-8)

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 1090-2 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

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

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)

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:

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)

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

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)

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

Provisions are also given for injection bolts ( Clause 3.6.2 of EN3-1-8) bolts groups in bearing( Clause 3.7 of EN3-1-8) Long joints ( Clause 3.8 of EN 1993-1-8) 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

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.

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

2) Bearing resistance Bearing resistance per bolt , Fb,Rd: From geometry : p1 = 60 mm, e1 = 40 mm, e2 = 40 mm, do = 22 mm From EN10025-2, 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

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.

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

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:

2) Bearing resistance Bearing resistance per bolt , Fb,Rd: From geometry : p1 = 60 mm, e1 = 40 mm, e2 = 40 mm, do = 22 mm From EN10025-2, 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

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.

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

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

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)

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

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

Example 6.3: Shear and Torsion Problem: Determine the suitable bolt size 2@70mm 3@100mm 155mm P=100kN 200kN

Solution: Load due to shear, Load due to moment, 2@70mm 3@100mm

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,

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)

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

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

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

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

i) Ft,Ed < Ft,Rd i. e. 27. 6 kN < 70 i) Ft,Ed < Ft,Rd i.e. 27.6 kN < 70.5 kN ok ii) Fv,Ed < Fv,Rd i.e. 13.8 kN < 47 kN ok iii)

Material properties of bolt

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

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 1993-1-8. ** 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

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

Welds: Geometric considerations Fillet Welds Effective throats thickness Figure 4.3 (EN 1993-1-8) indicates how the effective weld thickness should be measured; this should not be less than 3 mm.

Welds: Geometric considerations Fillet Welds

Welds: Geometric considerations Fillet Welds

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

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

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

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

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 1993-1-8)

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 1993-1-8 and Table 7 of EN10025-2) 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

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 6.5.2.1 ( or 4.5.3.2(6) of EC3-1-8)

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,

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

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

Minimum length required = 400/1.25 = 320 mm 3) Total resistance Minimum length required = 400/1.25 = 320 mm The required length = 320 + (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

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

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 = 0.85 2) 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

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 = 135 + 16 = 151 mm, say = 155 mm The other side length = 200 – 135 = 65 mm Add 2s = 16 mm; required length = 65 + 16 = 81 mm, say = 85 mm 85 mm 155 mm

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 = 118.6 mm, say = 120 mm L1 L2 65 mm 50 mm 120 mm 65 mm

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

Shear and torsion

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.

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

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

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

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

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