Timber and Steel Design. Lecture 11. Bolted Connections

Transcription

1 Timber and Steel Design Lecture 11 Bolted Connections Riveted Connections Types of Joints Failure of Joints Bearing & Friction connections Truss Joints Shear and Tension on Bolt S U R A N A R E E UNIVERSITY OF TECHNOLOGY Mongkol JIRAVACHARADET INSTITUTE OF ENGINEERING SCHOOL OF CIVIL ENGINEERING Riveted Connections rivet = round ductile steel bar (shank) with a head at one end d Snap an Flat countersunk d = Shank diameter = Nominal diameter Round countersunk

2 Riveting rocedure Rivets are heated before driving φ hot rivet =φhole φ Head is formed by - Hand hammer - Hydraulic pressure - neumatic pressure On cooling, the rivet shrinks both length and diameter Connected parts become tighter: - Tension in rivet - Compression in plates Friction between plates called clamping action

3 Forms of riveted joints Lap Joint Rivet in single shear f v = / A Eccentricity in lap joint e Undesired bending causes tension in rivets Double riveted lap joint

4 Butt Joint /2 /2 /2 /2 Rivet in double shear f v = /2A Butt joint v.s. Lap joint: - ก ก ก - ก - ก ก Bolted Connections

5 ก ก ก ก /2 W section /2 (a) ก (b) (c) ก (d) ก (e) (f)

6 Failure of Joints Case 1: Shear failure of rivets /2 /2 Single shear in lap joint Double-shear in butt joint Shear stress in rivet exceed the limit Case 2: Shear failure of plates Insufficient edge distance Shearing out Case 3: Tension or Tearing failure of plates Tensile stress at net cross section exceeds tensile strength Case 4: Bearing failure of plate late may be crushed when bearing stress in plate exceeds the limit

7 Bolted Connections /2 /2 Friction from clamping pressure using high strength bolt Beam splice moment connection Bearing-type Connections Shearing Strength: (π / 4)d 2 Fv d ก ก F t (ก.ก./. 2 ) F v (ก.ก./. 2 ) Friction-type Bearing-type A307 1, A325 ( ก ) 3,100 1,200 1,480 A325 ( ก ) 3,100 1,200 2,100 A490 ( ก ) 3,800 1,480 1,970 A490 ( ก ) 3,800 1,480 2,800

8 Threads Excluded from Shear lane or not? Diameter = d Shear planes Bearing stress 2 Bearing Strength Bearing area = d x t Excessive bearing results in shear tear-out failure mode. t Failure surface Failure surface Allowable bearing strength R a : R = bearing area F = d t F a p p d L e For standard or short-slotted holes F p = 1.2 F u R a R a /2 F p LeFu = 1.2F for L u e < 1.5d 2d R a /2 R = 0.5L t F 1. 2d t F a e u u Or R = 0.6L t F 1. 2d t F a c u u For long-slotted holes perpendicular to the load F p = 1.0 F u

9 Spacing and Edge-Distances Requirements Marking for Bolt g s s A307 itch: center-to-center of bolts parallel to axis of member Gage: center-to-center of bolts lines perpendicular to axis of member Edge distance: shortest distance from center of bolt to edge A325 min L e = diameter Distance between bolts: shortest distance between bolts min distance = 3 diameter A490 Spacing and Edge-Distances Requirements L c2 L c1 L c = clear distance, in the direction parallel to the applied load. 2 1 L e = edge-distance to center of the hole s = center-to-center spacing of holes L e s For edge bolts(2), use L c = L e h/2 h = d + 2 mm = hole diameter For other bolts(1), use L c = s h s d (preferably 3d) L e value from AISC Table J3.4 (1.5d - 2d)

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11 11-1 ก ก ก A36, ก ก A ,, ก ก ก, กก 1.5d, ก ก กก 3d 22 mm. bolts 1.0 cm 1.0 cm 30 cm ก ก ก : : ก : ก ก = : A g = 1.0 (30) = A n = 30 2 (2.5) (1.0) = = 0.60 (2.5) (30.0) = 45 = 0.50 (4.0) (25.0) = 50 = 0.25π (2.2) 2 (2.1) (4) = = (1.0) (2.2) (1.2) (4.0) (4) = = A e 11-2 ก ก A ก ก ก ก ก? ก A36 ก ก ก /2 = 40 ton /2 = 40 ton 1.0 cm 1.0 cm ก ก ก : 19 mm. bolts (A = 2.84 cm 2 ) 2.0 cm = 80 ton ก ก ก = 2(2.84)(2.1) = ( ) ก ก ก ก = (2.0)(1.9)(1.2)(4.0) = ก ก ก = 80/11.93 = 7+ ก ก 8 9 ( ก ก )

12 11-3 ก ก V ก 80 ก ก ก A (A= ) ก ก ก ก ก ก ก ก A36 ก ก ก ก W500x128 I x = t f = 1.8 L2x40 L2x40 2 cm 2 cm 45.2 cm 48.8 cm s I = 71, (2 40)(25.4) 2 = 174, q = VQ/I = (80)(2 40)(25.4)/174,226 = 0.93 /. ก ก = (2)(3.8)(2.100) = ( ) ก ก ก = (2)(2.2)(1.8)(1.2)(4.0) = s = 15.96/0.93 = 17. ( 15. c-c) AISC ก s max ก ก ก ก : ก S : 24 = 24(1.8) = > 15. OK 478t 478(1.8) F y f 478/ Fy 30. ก = = > 15. OK 2,500 S max = 30. > OK

13 Slip-critical(Friction-type) Connections ก ก ก ก A325 A490 N N F F ก ก ก ก ( ) ก ก (..) A325 A AISC Specification for Structural Steel Buildings

14 d + 2 mm ( ก ) ( ก ) (ก ) (ก ) d d (d + 2..) (d ) (d + 2..) 2.5 d d + 10 mm (a) Standard d + 2 mm d + 8 mm 2.5 d (c) Short slot d + 2 mm (b) Oversized (d) Long slot ก ก ก - ก ก - ก Gusset plate Gusset plate

15 Truss Joint Double member with a single connector piece, called a gusset plate. Members must have sufficient "bite" into the plate for bolts or weld contact. Converging centerlines enable equilibrium without member moments. ก B ก ก ก A325 ก 19.. ก ก ก ก Ls 75x75x10 2Ls 90x90x10 20 ton A B E 7 ton 1L 50x50x8 1L 50x50x8 D 8 ton ก ก ก A325 ก ก ก : F v = 2,100 กก./. 2 C 28 ton ก ก : F p = 1.2(4,000) = 4,800 กก./. 2

16 AB: = 20 2Ls 75x75x10 ก ก ก ก ก A π π = d F v = = ton ก ก = d 2t F p = 1.9 2(1.0) 4.8= ton ก ก ก = 20/11.91 = Control BC: = 28 2Ls 90x90x10 ก ก ก π π = d F v = = ton ก ก = d 2t F p = 1.9 2(1.0) 4.8= ton ก ก ก = 28/11.91 = Control BD: = 8 1Ls 50x50x8 ก ก ก π π d F v = = = ton ก ก = d t F p = = 7.30 ton ก ก ก = 8/5.95 = Control BE: = 7 1Ls 50x50x8 ก ก ก π π d F v = = = ton ก ก = d t F p = = 7.30 ton ก ก ก = 7/5.95 = Control

17 Detail Drawing A 2Ls 75x75x10 B 2Ls 90x90x10 C 1L 50x50x8 E 1L 50x50x8 D Bolt A mm Gusset plate 20 mm More ckeck for: - Effective area of tension members (0.5F u A e ) - Block shear failure of tension members Timber and Steel Design Lecture 11 Bolted Connections Riveted Connections Types of Joints Failure of Joints Bearing & Friction connections Truss Joints Shear and Tension on Bolt S U R A N A R E E UNIVERSITY OF TECHNOLOGY Mongkol JIRAVACHARADET INSTITUTE OF ENGINEERING SCHOOL OF CIVIL ENGINEERING

18 Riveted Connections rivet = round ductile steel bar (shank) with a head at one end d Snap an Flat countersunk d = Shank diameter = Nominal diameter Round countersunk Riveting rocedure Rivets are heated before driving φ hot rivet =φhole φ Head is formed by - Hand hammer - Hydraulic pressure - neumatic pressure

19 On cooling, the rivet shrinks both length and diameter Connected parts become tighter: - Tension in rivet - Compression in plates Friction between plates called clamping action Forms of riveted joints

20 Lap Joint Rivet in single shear f v = / A Eccentricity in lap joint e Undesired bending causes tension in rivets Double riveted lap joint Butt Joint /2 /2 /2 /2 Rivet in double shear f v = /2A Butt joint v.s. Lap joint: - ก ก ก - ก - ก ก

21 Bolted Connections ก ก ก ก /2 W section /2 (a) ก (b) (c) ก (d) ก

22 (e) (f) Failure of Joints Case 1: Shear failure of rivets /2 /2 Single shear in lap joint Double-shear in butt joint Shear stress in rivet exceed the limit Case 2: Shear failure of plates Insufficient edge distance Shearing out

23 Case 3: Tension or Tearing failure of plates Tensile stress at net cross section exceeds tensile strength Case 4: Bearing failure of plate late may be crushed when bearing stress in plate exceeds the limit Bolted Connections /2 /2 Friction from clamping pressure using high strength bolt Beam splice moment connection

24 Bearing-type Connections Shearing Strength: (π / 4)d 2 Fv d ก ก F t (ก.ก./. 2 ) F v (ก.ก./. 2 ) Friction-type Bearing-type A307 1, A325 ( ก ) 3,100 1,200 1,480 A325 ( ก ) 3,100 1,200 2,100 A490 ( ก ) 3,800 1,480 1,970 A490 ( ก ) 3,800 1,480 2,800 Threads Excluded from Shear lane or not? Diameter = d Shear planes Bearing stress 2

25 Bearing Strength Bearing area = d x t Excessive bearing results in shear tear-out failure mode. t Failure surface Failure surface Allowable bearing strength R a : R = bearing area F = d t F a p p d L e For standard or short-slotted holes F p = 1.2 F u R a R a /2 F p LeFu = 1.2F for L u e < 1.5d 2d R a /2 R = 0.5L t F 1. 2d t F a e u u Or R = 0.6L t F 1. 2d t F a c u u For long-slotted holes perpendicular to the load F p = 1.0 F u Spacing and Edge-Distances Requirements Marking for Bolt g s s A307 itch: center-to-center of bolts parallel to axis of member Gage: center-to-center of bolts lines perpendicular to axis of member Edge distance: shortest distance from center of bolt to edge A325 min L e = diameter Distance between bolts: shortest distance between bolts min distance = 3 diameter A490

26 Spacing and Edge-Distances Requirements L c2 L c1 L c = clear distance, in the direction parallel to the applied load. 2 1 L e = edge-distance to center of the hole s = center-to-center spacing of holes L e s For edge bolts(2), use L c = L e h/2 h = d + 2 mm = hole diameter For other bolts(1), use L c = s h s d (preferably 3d) L e value from AISC Table J3.4 (1.5d - 2d)

27 11-1 ก ก ก A36, ก ก A ,, ก ก ก, กก 1.5d, ก ก กก 3d 22 mm. bolts 1.0 cm 1.0 cm 30 cm ก ก ก : : A g = 1.0 (30) = A n = 30 2 (2.5) (1.0) = = 0.60 (2.5) (30.0) = 45 = 0.50 (4.0) (25.0) = 50 = A e : ก : = 0.25π (2.2) 2 (2.1) (4) = = (1.0) (2.2) (1.2) (4.0) (4) = ก ก = 31.93

28 11-2 ก ก A ก ก ก ก ก? ก A36 ก ก ก /2 = 40 ton /2 = 40 ton 1.0 cm 1.0 cm ก ก ก : 19 mm. bolts (A = 2.84 cm 2 ) 2.0 cm = 80 ton ก ก ก = 2(2.84)(2.1) = ( ) ก ก ก ก = (2.0)(1.9)(1.2)(4.0) = ก ก ก = 80/11.93 = 7+ ก ก 8 9 ( ก ก ) 11-3 ก ก V ก 80 ก ก ก A (A= ) ก ก ก ก ก ก ก ก A36 ก ก ก ก W500x128 I x = t f = 1.8 L2x40 L2x40 2 cm 2 cm 45.2 cm 48.8 cm s I = 71, (2 40)(25.4) 2 = 174, q = VQ/I = (80)(2 40)(25.4)/174,226 = 0.93 /. ก ก = (2)(3.8)(2.100) = ( ) ก ก ก = (2)(2.2)(1.8)(1.2)(4.0) = s = 15.96/0.93 = 17. ( 15. c-c)

29 AISC ก s max ก ก ก ก : ก S : 24 = 24(1.8) = > 15. OK 478t 478(1.8) F y f 478/ Fy 30. ก = = > 15. OK 2,500 S max = 30. > OK Slip-critical(Friction-type) Connections ก ก ก ก A325 A490 N N F F ก ก ก ก ( ) ก ก (..) A325 A

30 AISC Specification for Structural Steel Buildings d + 2 mm ( ก ) ( ก ) (ก ) (ก ) d d (d + 2..) (d ) (d + 2..) 2.5 d d + 10 mm (a) Standard d + 2 mm d + 8 mm 2.5 d (c) Short slot d + 2 mm (b) Oversized (d) Long slot

31 ก ก ก - ก ก - ก Gusset plate Gusset plate Truss Joint Double member with a single connector piece, called a gusset plate. Members must have sufficient "bite" into the plate for bolts or weld contact. Converging centerlines enable equilibrium without member moments.

32 ก B ก ก ก A325 ก 19.. ก ก ก ก Ls 75x75x10 2Ls 90x90x10 20 ton A B E 7 ton 1L 50x50x8 1L 50x50x8 D 8 ton ก ก ก A325 ก ก ก : F v = 2,100 กก./. 2 C 28 ton ก ก : F p = 1.2(4,000) = 4,800 กก./. 2 AB: = 20 2Ls 75x75x10 ก ก ก ก ก A π π = d F v = = ton ก ก = d 2t F p = 1.9 2(1.0) 4.8= ton ก ก ก = 20/11.91 = Control BC: = 28 2Ls 90x90x10 ก ก ก π π = d F v = = ton ก ก = d 2t F p = 1.9 2(1.0) 4.8= ton ก ก ก = 28/11.91 = Control

33 BD: = 8 1Ls 50x50x8 ก ก ก π π d F v = = = ton ก ก = d t F p = = 7.30 ton ก ก ก = 8/5.95 = Control BE: = 7 1Ls 50x50x8 ก ก ก π π d F v = = = ton ก ก = d t F p = = 7.30 ton ก ก ก = 7/5.95 = Control Detail Drawing A 2Ls 75x75x10 B 2Ls 90x90x10 C 1L 50x50x8 E 1L 50x50x8 D Bolt A mm Gusset plate 20 mm More ckeck for: - Effective area of tension members (0.5F u A e ) - Block shear failure of tension members