Page 123 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch03.qxd 9/29/05 5:05 PM Page 3.55

CONNECTIONS

CONNECTIONS 3.55

Design strength for web buckling with combined force (39 kips applied axially):
 V   33 × 4 50 
.
<
φR =  φF − S  A = 45 − 24 1 .  985 = 382 kips 39 kips OK
e
.

n
cr
Design tensile strength of bolt for shear/tension interaction:
Design strength is φF nt ′, where F nt ′= 1.3F nt − (F nt /φF nv )f v ≤ F nt
 90  33 
×
≤
×

φ ′ = .075 13 90 −  2   = 64.5 0.75 90 = 67.5 ksi
.
F
nt
(.

 36 6 0 75) ( π 4 /) 
φ ′ =F nt 64 5 . ksi
Design tensile strength of / 4-in-diameter A325N bolt reduced for shear is
3
φr n ′=φF nt ′A b = 64.5 × 0.442 = 28.5 kips/bolt
For 6 bolts = 28.5 × 6 = 171 kips ≥ 39 kips OK
Design strength for prying action of angles:
Follow procedure in AISC Manual. See Art. 3.5 for background.
a = distance from bolt centerline to edge of angle = 1.93 in
b = distance from bolt centerline to centerline of angle leg = 2.76 in
d b = bolt diameter = 0.75 in
d h = bolt diameter = 0.875 in
p = tributary length per bolt = 2.83 in
d′= width of hole along length of angle = 0.875 in
a′= a + d b /2 ≤ 1.25 × b + d b /2 = 1.93 + 0.75/2 ≤ 1.25 × 2.76 + 0.75/2
= 2.30 ≤ 2.98 Use a′= 2.30 in
b′= b − d b /2 = 2.76 − 0.75/2 = 2.38 in
ρ= b′/a′= 2.38/2.30 = 1.03
δ= 1 − d′/p = 1 − 0.875/2.83 = 0.691
t c = angle thickness required to develop strength of bolt with no prying action, in
4 44φ Rb′ 4 44 × 28 5 2 38
.
.
.
× .
t = n t = = 135 in
.
c
.
pF t c 283 × 58
 
.
α ′ = 1  t c 2 −  1  α ′ = 1    135  2 −  1  = 261

.
 
.
.
δ 1 ( + ρ)  t  0 691 1 ( +1 03)   0 625  
.
  2 .  2
t
α ′ >1; therefore T d = φr n ′   1 ( + δ) = 28 5 .  0 625  1 ( + 0 691) = 10 3 . kips bolt
.
/
 
t
 135
.
c
For 6 bolts = 10.3 × 6 = 61.8 kips ≥ 39 kips OK
3.4.3 Example: Extended Single-Plate Shear Connections
Single-plate shear connections as shown in Fig. 3.35 can be very economical connections. In-fill
beams can be drilled on the fabricator’s drill line with no further handling, since the beams will
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