Page 320 - Handbook of Structural Steel Connection Design and Details

Partially Restrained Connections

Partially Restrained Connections 305

Check bearing strength:

R u 5 s2.4ddtF u 5 0.75s2.4ds1dstds58d $ 104.4t
Shear will govern if the thickness of the plate is greater than:

t 28.3/104.4 0.27 in
This is small so bearing probably will not govern; this thickness will be
checked again later.
Thus:

148.4 kips
M $ $ 5.2 use 6 bolts
28.3 kips
4. Determine thickness (t ) required to transmit tension on the stem of the tee
w
(AISC 306-05):
a. Assume plate width at critical section is approximately 9 in (total column
flange width is 10.13 in). Then the required tee stem thickness for capacity
controlled by gross area yielding is
148.4
T u
A g $ $ $ 4.58 in 2 so t 4.58/9.00 0.51 in
0.90F y 0.9 ? 36 w
b. Assume that the net area is given by the total width (9.00 in) minus two
bolt holes (2 1.125 2.25) or 6.75 in. Then the required required tee
stem thickness for capacity governed by net area fracture is

148.4
T u
A n 5 $ $ 3.41 in 2 so t 3.41/6.75 0.51 in
w
0.75 3 F u 0.75 3 58
Both of them are close enough to say that t should be just over 0.5 in.
w
5. Determine the flange thickness (t ) for the tee section. This needs to take
f
prying action into account. A simplified mechanism for computing the addi-
tional forces due to prying action is shown in Fig. 4.16. The prying forces Q
arise from the additional forces developed at the end of the T flanges as the
T stub is pulled. Assuming that each side of the flange can be modeled as a
two-span beam with one end fixed (at the web) and one end free to rotate
(edge of T stub), the maximum forces can be calculated based on the forma-
tion of plastic hinges at both the web and the edge of the bolt. For details
see Salmon and Johnson (1996, pp. 905–909).
From this type of model, an equation for the required plate thickness can
be derived. On such equation is that proposed by (Thornton, 1998):

4Tb
t t $ b $ 0.9
B b wF y s1 1 d
where T force in the bolt, kips
b distance from the web centerline to the inside edge of the
bolt, in
a distance from inside edge of the bolt to edge of T-stub, in

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