Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

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Connection Connection Design Design

Transcript of Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Page 1: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Connection DesignConnection Design

Page 2: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Bolted Steel Connections Bolted Steel Connections

Bolts in tension

Bolts in shear

6 x 200 =1200 kN

Page 3: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Failure modes of bolts in shearFailure modes of bolts in shear

Hole tearout

Bolt shear

Hole bearing

Page 4: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Bolts in Bolts in shearshear

Hole bearing

Br = 3 φ t d n Fu

e

d

d + 2 mm

t

φ = 0.67; n = number of bolts; m = number of shear planes

Bolt shear

Vr = 0.6 φ n m Ab Fu

A325M bolts: Fu = 830 MPaA490M bolts: Fu = 1040 MPa

Hole tearout

Br = φ t n e Fu

350W steel: Fu = 450 MPa

Page 5: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Bolts in tensionBolts in tension

d

Tensile strengthTr = 0.75 φ n Ab Fu

=0.75(0.67)(1)(314)(830) N = 131 kN

threads shank

A325M 20 mm dia

Page 6: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Bolts in tension and shearBolts in tension and shear

Page 7: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Bolts in combined shear and Bolts in combined shear and tensiontension

2222

2

56.0 ubbff FATm

V

Where β = an interaction factor derived from test results= 0.69 for A325 bolts, shear plane through shank= 0.41 for A325 bolts, shear plane through threads= 0.56 for A490 bolts, shear plane through shank= 0.30 for A490 bolts, shear plane through threads

Page 8: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Interaction FormulaInteraction Formula

• A simpler version:

0.1

56.0

2

22

2

75.0

2222

2

2

2

r

f

V

r

f

FA

ubbff

T

T

T

mV

FATm

V

r

ubb

Vf/Vr

Tf/Tr

1.0

1.0

Page 9: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

ExampleExample

Hole bearing

Br = 3 φ t d n Fu

= (3)(0.67)(12)(20)(3)(450)= 651 x 103 N = 651 kN

e = 45mm

d = 20mm

d + 2 mm = 22 mm

t = 12mm

Bolt shear

Vr = 0.6 φ n m Ab Fu = 0.6(0.67)(3)(2)(314)(830) N= 630 kN

A325M bolt: Fu = 830 MPa

Hole tear-out

Br = φ t n e Fu

= (0.67)(12)(3)(45)(450)= 487 x 103 N = 487 kN

350W steel: Fu = 450 MPa

Ab= πd2/4=314 mm2

To avoid hole tear-oute > 3d

Page 10: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Slip-critical connectionsSlip-critical connections

• When slippage of a connection during normal service conditions (under unfactored loads) is undesirable

• Bolts are pretensioned to at least 70% of their ultimate strength

Vs = c1 ks m n (0.7)(0.75) AbFu

where ks = slip coefficient and c1 = coefficient that relates the specific initial tension and mean slip to a 5% probability of slip for bolts installed by the turn-of-the-nut method

Page 11: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Values of cValues of c11 and k and kss

Contact surface of bolted parts

ks

c1

A325 and A325M bolts

A490 and A490M bolts

Clean mill scale, or blast-cleaned with class A coatings 0.33 0.82 0.78

Blast-cleaned or blast-cleaned with class B coatings 0.50 0.89 0.85

Hot-dipped galvanized with wire brushed surfaces 0.40 0.90 0.85

Page 12: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Slip-critical connections in Slip-critical connections in combined shear and tensioncombined shear and tension

0.19.1 ubs FnA

T

V

V

Page 13: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Welded connectionsWelded connections

4 Times Square, NYC

Page 14: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Welded connectionsWelded connections

Types of welds:

Page 15: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Welded truss connectionsWelded truss connections

Page 16: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Welded beam connectionsWelded beam connections

Bolted connection for web

Full penetration groove weld

Backing bar

Moment connectionSimple

connection

Page 17: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Strength of welded connectionStrength of welded connection

Shear

Base metal: Vr = 0.67 φw Am Fu

Weld metal: Vr = 0.67 φw Aw Xu

Tension

Base metal: Tr = φ Ag Fy

Weld metal: Tr = φw An Xu

φw = 0.67

Page 18: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Fillet weld Fillet weld strengthsstrengths

0.707b

b

Am = b LAw = 0.707 b L

Base metal: Vr = 0.67 φw Am Fu

Weld metal: Vr = 0.67 φw Aw Xu (1 + 0.5 sin1.5θ)

θ = 90o

θ = 0o

L

P

P

Page 19: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Electrode strengths, XElectrode strengths, Xuu

Matching electrode strength

Xu [MPa]

Steel grades (G40.21-M)

260 300 350 380 400 480 700

410 X X

480 X X X X

550 X

620 X

820 X

Page 20: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Fillet weld exampleFillet weld example

0.707b = 4.2 mm

b = 6 mm

Am = b LAw = 0.707 b L

Weld strength:

Base metal: Pr = 0.67 φw Am Fu

= 0.67(0.67)(6)L(450) N = 1.2 L = 1.2 (550) = 660 kN

Weld metal: Pr = 0.67 φw Aw Xu (1 + 0.5 sin1.5θ) = 0.67(0.67)(0.707)(6)L(480)(…..) N = 0.914 [400 + 1.5(150)] = 571 kN

6 mm fillet

6 mm fillet20

0 m

m

P

P

150 mm

Base metal: Vr = 0.67 φw Am Fu

Weld metal: Vr = 0.67 φw Aw Xu (1 + 0.5 sin1.5θ)

Page 21: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Example Example

150 mm

200 mm

C

Tr = 2 x571= 1142 kN

1000 kN

400 kN

1000 kN

400 kN1142 kN

800 kN

Lreq = [800 / 0.9] / 2 = 444 mm

6 mm fillet

Page 22: Connection Design. Bolted Steel Connections Bolts in tension Bolts in shear 6 x 200 =1200 kN.

Example Example

16 mm

150 mm

450

mm

Mr

= Tr (0.45) kNm= 756 (0.45)= 340 kNm

Tr = φ A Fy = 0.9 (16) (150) (350) N = 756 kN Vr = 210/2 x 10

= 1050 kN

Vr

A325 20 mm dia