Page 308 - Handbook of Structural Steel Connection Design and Details

Partially Restrained Connections

Partially Restrained Connections 293

2. Check net area fracture versus gross section yielding of the girder flange by
AISC (2005) Section F13. (Note: Y (F /F ) 50/65 0.76 < 0.8 so Y
t y u t
1.0; for the W 21 62, b 8.24 in, t 0.615 in, d 20.99 in, and S 127
f f x
in ; holes for 7/8-in bolts assumed as 1 in in diameter):
3
F u A fn 5 s65ds8.24 2 2ds0.615d 5 249.4 kips
Y t F y A fg 5 s1.0ds50ds8.24ds0.615d 5 253.4 kips

Since the net section governs (F A < Y F A ), the moment capacity is
u fn t y fg
s65ds8.24 2 2ds0.615d
F u A fn
M n 5 S x 5 s127d 5 6251 kip-in
A fg s8.24ds0.615d
M n 5 s0.9ds6251d 5 5626 kip-in . M u 5 5100 kip-in ok
5100
F flange 5 F plate 5 0.9 kip-in 5 270.0 kips
20.99 in

3. Determine the size of the flange plate, assuming that the plate thickness (t )
p
will be 5/8 in and that the plate is 50 ksi. Balancing the plastic capacity of
the plate against that of the beam, gives a plate width (b ) of
p
s1.1ds270.0d
R y F beam
b p $ 5 5 9.50 in try b f 5 9.5 in
t p F yp s0.625ds50d
4. Check gross (A ) and net (A ) areas for the plate:
pg pn
Gross section:
A pg F y 5 s0.9ds9.50 3 0.625ds50d 5 267.2 kips

Net section:

A pn F u 5 s0.75dss9.50 2 2d 3 0.625ds65d
5 228.5 kips , F plate no good

Increase plate thickness to 0.75 in (net section capacity 274.2 kips > F , ok)
plate
5. Determine number of A325X 7/8-in bolts required for shear in the flanges:

267.3
N bolts 5 5 98 S 10 bolts
27.1
Assuming a gage of 5.0 in, this means the edge distance for a 9.5-in-wide
plate are approximately equal to the minimum required. Assuming (a) a bolt
spacing of 3d, (b) a distance between the last bolt and the weld at the col-
umn flange of equal to 4 in, and (c) a distance of 2 in between the centerline
of the last bolt and the end of the plate, the length is 16.5 in:

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