Page 277 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch05.qxd 9/29/05 5:12 PM Page 5.57

CRITERIA FOR BUILDING DESIGN

CRITERIA FOR BUILDING DESIGN 5.57

6. Web Panel Zone Shear. This limit state applies to double-concentrated forces applied to one or
both flanges of a member at the same location. A typical case is the web of a column having a
moment connection to its flanges from intersecting beams. The available strength of the web panel
zone for the limit state of shear yielding is determined using φ = 0.90 (LRFD) and Ω = 1.67 (ASD)
for all cases. If the required strength of the web exceeds the available strength, provide a doubler
plate (on one side of the web or both) or a pair of diagonal stiffeners within the boundaries of the
rigid connection where the webs lie in a common plane.
When the effect of panel-zone deformation on frame stability is not considered in the analysis,
the nominal strength R v is as follows.
If P r ≤ 0.4P c ,
(5.171)
R v = 0.60F y d c t w
If P r > 0.4P c ,
 P 
r
R = 060. F d t   14 − P   (5.172)
.
v
y c w
c
When frame stability, including plastic panel-zone deformation, is considered in the analysis, the
nominal strength R v is as follows.
If P r ≤ 0.75P c ,
 3 bt 
2
y c w
.
R = 060 F d t 1 + cf cf  (5.173)
v
 dd t 
b cw
If P r > 0.75P c ,
 3 bt  12 . P 
2
y c w
.
R = 060 F d t 1 + cf cf  19 . − r  (5.174)
v
 dd t  P 
c
b cw
The following definitions apply in Eqs. (5.171) to (5.174):
P r = required strength
P c = P y , kips (N) (LRFD)
P c = 0.6P y , kips (N) (ASD)
P y = F y A = axial yield strength of the column, kips (N)
2
2
A = column cross-sectional area, in (mm )
t w = column web thickness, in (mm)
b cf = width of column flange, in (mm)
t cf = thickness of the column flange, in (mm)
d b = beam depth, in (mm)
d c = column depth, in (mm)
F y = specified minimum yield stress of the column web, ksi (MPa)

5.9.15 Additional Stiffener and Doubler Plate Requirements
The AISC Specification gives additional requirements that must be met for stiffeners and doubler plates.

1. Unframed Ends of Beams and Girders. At unframed ends of beams and girders not otherwise
restrained against rotation about their longitudinal axes, a pair of transverse stiffeners, extending the
full depth of the web, must be provided.

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