Page 144 - Handbook of Structural Steel Connection Design and Details

Design of Connections for Axial, Moment, and Shear Forces

Design of Connections for Axial, Moment, and Shear Forces 129

Web yielding: P P t P 167 0.615 24.3 182 kips
wy wo b wi
229 kips, thus stiffeners are required at both flanges.
Web buckling: P 260 kips > 229 kips no stiffener required at
wb
compression flange.
Flange bending: P 171 kips 229 kips stiffener required at ten-
fb
sion flange.
From the preceding three checks (limit states), a stiffener is required
at both flanges. For the tension flange, the total stiffener force is 229
171 58 kips and for the compression flange, the stiffener force is 229
189 40 kips. But the loads may reverse, so use the larger of 58 and
40 as the stiffener force for both flanges. Then, the force in each stiff-
58
ener is / 29 kips, both top and bottom.
2
Determination of stiffener size. The minimum stiffener width w is
s
t 8.24 0.485
b fb wc
2 5 2 5 2.5 in
3 2 3 2
1
Use a stiffener 6 / 2 in wide to match column.
The minimum stiffener thickness t is
s
0.615
t fb
5 5 0.31 in
2 2
3
Use a stiffener at least / in thick.
8
The minimum stiffener length l is
s
14.2
d c
2 t 5 2 0.78 5 6.3 in
fc
2 2
The minimum length is for a “half depth” stiffener, which is not pos-
sible in this example because of the weak axis connections. Therefore,
1
use a full-depth stiffener of 12 / in length.
2
A final stiffener size check is a plate buckling check that requires
that
Ws 6.5
t $ 5 5 0.433 in
s
15 15
1
Therefore, the minimum stiffener thickness is / in. The final stiffener
2
1
1
1
size for the strong axis beam is / 6 / 12 / . The contact area of this
2 2 2
stiffener against the inside of the column flange is 6.5 0.75 5.75 due
to the snip to clear the column web to flange fillet. The stiffener design
strength is thus 0.9 36 5.75 0.5 93.2 kips > 29 kips, ok.
Welds of stiffeners to column flange and web. Putting aside for the moment
that the weak axis moment connections still need to be considered and
will affect both the strong axis connection stiffeners and welds, the

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