Page 143 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch03.qxd 9/29/05 5:05 PM Page 3.75

CONNECTIONS

CONNECTIONS 3.75

A gv = 7.75 × 0.440 × 2 = 6.82 in 2
A gt = 1.32 in 2
U bs = 1.0
F u A nt = 65 × 0.88 = 57.2 kips
0.6F u A nv = 0.60 × 65 × 5.50 = 214 kips
0.6F y A gv = 0.60 × 50 × 6.82 = 205 kips
φR bs = 0.75[57.2 + min(214, 205)] =197 kips > 178 kips OK
Figure 3.43 shows the web bolt pattern with four bolts in the web at 6-in pitch. Other checks must
be made as follows.
Web Plates. Try two A36 plates, one on each side of web, 0.50 × 6 in.
Gross area:

φR gt = 0.9 × 36 × 0.5 × 6 × 2 = 194 kips > 178 kips OK
Net area:

A nt = (6 − 2 × 1) × 0.50 × 2 = 4.0 in 2
0.85A gt = 0.85 × 0.50 × 6 × 2 = 5.1 in 2
φR nt = 0.75 × 58 × 4.0 = 174 kips < 178 kips No good

5
Increase web plates to / 8 in thick. Net area will be OK by inspection. Block shear rupture: Check
as shown in previous calculations; not critical here.
Bearing/Tear-out of Web Plates and W14 × 90. The bolt pattern and plates have been tentatively
selected, so this combined limit state can be checked.
Bolt shear: φr v = 54.2 kips double shear; φr v = 27.1 kips single shear
Bearing on W14 × 99 web: φr p = 0.75 × 2.4 × 0.875 × 0.440 × 65 = 45.0 kips
Bearing on splice plates: φr p = 0.75 × 2.4 × 0.875 × 0.625 × 2 × 58 = 114 kips
Tear-out on W14 × 99 web: L c = 1.75 – 0.5 × 0.9375 = 1.281 in
φr to = 0.75 × 1.2 × 1.281 × 0.440 × 65 = 33.0 kips

Tear-out on splice plates: φr to = 0.75 × 1.2 × 1.281 × 0.625 × 2 × 58 = 83.6 kips
Tear-out between bolts: Will not control in this case.
From the above, the shear/bearing/tear-out strength of the web splice is

φR vpt = 2 × 33.0 + 2 × 45.0 = 156 kips < 178 kips No good
Add two bolts in the web so that the 6-in pitch becomes 3-in pitch. The shear/bearing/tear-out capac-
ities per bolt given above do not change. Tear-out between bolts is still not critical. Thus
φR vpt = 2 × 33.0 + 4 × 45.0 = 246 kips > 178 kips OK

Note that, in this case, none of the bolts was able to achieve its double shear value.

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