Page 141 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch03.qxd 9/29/05 5:05 PM Page 3.73

CONNECTIONS

CONNECTIONS 3.73

and the thickness required is 4.80/10.5 = 0.46 in. Try a plate 0.50 × 10.5 in

A gt = 0.5 × 10.5 = 5.25 in 2
A nt = (10.5 – 2 × 1) × 0.5 = 4.25 in 2
0.85A gt = 0.85 × 5.25 = 4.46 in 2
2
Since 0.85A gt > A nt , use A nt = 4.25 in as the effective net tension area:
φR nt = 0.75 × 58 × 4.25 =185 kips > 311/2 = 156 kips OK

Use a plate 0.50 × 10.5 in for the outer flange splice plate for the following limit state checks.
Outer Plate: Block Shear Rupture

A gv = 7.5 × 0.5 × 2 = 7.5 in 2
A gt = 1.5 × 0.5 × 2 = 1.5 in 2
A nv = (7.5 − 2.5 × 1)0.5 × 2 = 5.0 in 2
A nt = (1.5 − 0.5 × 1)0.5 × 2 = 1.0 in 2
F u A nt = 58 × 1.0 = 58.0 kips
0.6F y A gy = 0.6 × 36 × 7.5 = 162 kips
0.6F u A nv = 0.6 × 58 × 5.0 = 174 kips
φR bs = 0.75[58 + min(162, 174)] = 165 kips > 156 kips OK

Outer Plate: Bearing
φR p = 0.75 × 2.4 × 58 × 0.50 × 0.875 × 6 = 274 kips > 156 kips OK
Note that bearing/tear-out still needs to be checked.
Inner Plate: Gross and Net Area. The load to each plate is 156/2 = 78 kips. The gross area in ten-
sion required is
A = 78 = 241 in 2
.
gt
09 . × 36
If the plate is 4 in wide, the required thickness will be 2.41/4 = 0.60 in. Try a plate 0.75 × 4 in (A36):

A gt = 0.75 × 4 = 3 in 2
A nt = (4 − 1.0)0.75 = 2.25 in 2
0.85A gt = 0.85 × 3 = 2.55 in 2
φR nt = 0.75 × 58 × 2.25 = 97.9 kips > 78 kips OK

Inner Plate: Block Shear Rupture. Since there is only one line of bolts, this limit state is not possi-
ble. The plate limit state would be tension rupture on the net section instead. Note that bearing/tear-
out still needs to be checked.
Bearing/Tear-out of Flange Plates and W14 × 90. Now that the bolts, the outer plate, and the inner
plates have been tentatively selected, bearing/tear-out can be checked for the connection as a whole:
Bolt shear: φr v = 54.2 kips (double shear): φr v = 27.1 kips (single shear)
Bearing on W14 × 99 flange: φr p = 0.75 × 2.4 × 0.875 × 0.710 × 65 = 72.7 kips

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