6. Steel Joint Design (Tension Splices)

STRUCTURAL STEELWORK & TIMBER DESIGN - ECS328 STEEL JOINT DESIGN NOV13 – MAC14 MA.T

Clause

Remarks TENSION SPLICES CONNECTION (BOLTED CONNECTION)

1. JOINT DETAILS AND SECTION OF PROPERTIES

Table 3.1 EC3:1:1

COVER PLATE, 290 × 140 × 6mm thk, S275 Depth, hp Width, bp Thickness, tp Yield Strength, fyp Ultimate Strength, fup

290 mm 140 mm 6 mm 275 N/mm2 430 N/mm2

Direction of Load Transfer Number of bolts row, n1 Plate Edge to first bolt row, e1 Pitch between bolts row, p1

4 35 mm 70 mm

Direction to perpendicular to load transfer Numbers of vertical lines of bolts, n2 Plate Edge to first bolt line, e2 Gauge, p2

2 35 mm 70 mm

BOLTS, NON PRELOAD, M20 CLASS 4.6 BOLTS

Table 3.1 EC3:1:8

Gross Section of Bolts, A (un-threaded portion) Tensile Stress Area, As (threaded portion) Diameter of shank, d Diameter of Holes, do Yield Strength, fyb Ultimate Strength, fub

1   

314 mm2 245 mm2 20 mm 22 mm 240 N/mm2 400 N/mm2

STRUCTURAL STEELWORK & TIMBER DESIGN - ECS328 STEEL JOINT DESIGN NOV13 – MAC14 MA.T

2. POSITIONING OF HOLES FOR BOLTS Minimum and maximum spacing and end and edge distance for bolts and rivets are given in Table 3.3 Minimum

Maximum

End distance, e1

= 1.2 do = 1.2 (22) = 26.4mm

= 4tp + 40mm = 4(6) + 40mm = 64 mm

Edge distance, e2

= 1.2 do = 1.2 (22) = 26.4mm

= 4tp + 40mm = 4(6)+ 40mm = 64 mm

Spacing, p1

= 2.2 do = 2.2 (22) = 48.4mm

= smaller of 14t or 200mm = 14(6) = 84 mm

Spacing, p2

= 2.4 do = 2.4 (22) = 52.8mm

= smaller of 14t or 200mm = 14(6) = 84 mm

Table 3.3 EC3:1:8

Since - 26.4mm < 35mm < 64mm .: End distance, e1 satisfied - 26.4mm < 35mm < 64mm .: Edge distance, e2 satisfied - 48.4mm < 70mm < 84mm .: Spacing, p1 satisfied - 52.8mm < 70mm < 84mm .: Spacing, p2 satisfied 3. BOLTED CONNECTION Table 3.4 EC 3:1:8

Shear Resistance Of Bolt Group For this example, we assume that the shear plane passes through un-threaded portion of the bolt. Hence, gross section of bolt A =314mm2 and for bolt class 4.6, αv = 0.6 Fv,Rd = (αv fub A ) / γM2 = (0.6 x 400 x 314) / 1.25 = 60.29 kN All four bolts are in double shear. Hence, shear resistance of single bolt, Fv,Rd of connection is Fv,Rd = 60.29 kN x 2 = 120.58 kN

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STRUCTURAL STEELWORK & TIMBER DESIGN - ECS328 STEEL JOINT DESIGN NOV13 – MAC14 MA.T

Hence, shear resistance of bolt group, Vv,Rd Vv,Rd = Fv,Rd x n =120.58 kN x 4 =482.32 kN Table 3.4 EC 3:1:8

Bearing Resistance Of Bolt Group Bearing failure will tend to take place in the cover plates since they are thinner Fb,Rd = (k1 αb fu d t ) / γM2 Where αb is the smallest of αd , fub/fup , 1.0 For end bolts αd = e1/3do = 35/3(22) = 0.53 For inner bolts αd = (p1/3do) – (1/4) = (70/3(22)) – (1/4) = 0.81 fub/fup = 400/430 = 0.93 .: smallest αd = αb = 0.53 And k1 for edge bolts is smallest of: (2.8e2/d0) – 1.7) , (1.4(p2/do) – 1.7 and 2.5 (2.8e2/d0) – 1.7 = (2.8(35)/22) – 1.7 = 2.75 (1.4(p2/do) – 1.7 = (1.4(70/22) – 1.7 = 2.75 And k1 for inner bolts is smallest of: (1.4(p2/do) – 1.7 or 2.5 (1.4(p2/do) – 1.7 = (1.4(70/22) – 1.7 = 2.75 .: smallest k1 = 2.5

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STRUCTURAL STEELWORK & TIMBER DESIGN - ECS328 STEEL JOINT DESIGN NOV13 – MAC14 MA.T

.: Fb,Rd = (k1 αb fup d tp ) / γM2 = (2.5 x 0.53 x 430 x 20 x 6) / 1.25 = 54.7 kN All four bolts are in double shear plane. Hence, bearing resistance of single bolt, Fb,Rd of connection is Fb,Rd = 54.7 kN x 2 = 109.4 kN Bearing Resistance of bolt Groups, Vb,Rd Vb,Rd = Fb,Rd x 4 =109.4 kN x 4 = 437.6 kN

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STRUCTURAL STEELWORK & TIMBER DESIGN - ECS328 STEEL JOINT DESIGN NOV13 – MAC14 MA.T

TENSION SPLICES CONNECTION (WELDED CONNECTION) Two S275 steel plates are connected using fillet weld with E35 electrodes, as shown in figure below. Determine the maximum load F that can be applied, based on the strength of the fillet weld. Given that the throat thickness is 4mm.

RESISTANCE OF WELDED CONNECTIONS 4.5.3.3

Fw,Rd = fvwd α (eq. 4.3)

4.5.3.3(2)

fvwd = (fu/√3) / (βwγM2) (eq.4.4)

4.5.3.3(3)

fu = nominal ultimate tensile strength of weaker part joined = 430 N/mm2

4.5.3.2(6) Table 4.1

Correlation factor, βw for fillet welds steel grade S275 = 0.85 .: fvwd = (fu/√3) / (βwγM2) (eq.4.4) = (430/√3) / (0.85 x 1.25) = 233.9 N/mm2 .: Fw,Rd = fvwd α (eq. 4.3) = 233.9 N/mm2 x 4mm = 935.6 N/mm Weld length, L = hp - 2α = 80 mm - 8mm = 72 mm .: Vw,Rd = 935.6 N/mm x 72 mm x 2 = 134.73 kN

 

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