AISC Design Guide 13..

connected beams coincide, a pair of double concentrated
Pu
Fr o P u 04 . Py, R v 09 . 06 . Fydct w 14 .
forces results as illustrated in Figures 2-4b (the gravity
Py
load case) and 2-4c (the lateral load case).
The design strength of the panel-zone in shear must be
(2.2-2)
checked for all columns with moment connected beams.
In the second assumption, it is recognized that signif-
For a tensile flange force, the design strength of the flange
icant post-yield panel-zone strength is ignored by limitin
local flange bending and the design strength of the web
ing the calculated panel-zone shear strength to
that in the
in local yielding must also be checked. For a compres-
nominally elastic range. At the same time, it must be realsive
flange force, the design strength of the web in lo-
ized that inelastic deformations of the panel-zone can sigcal
yielding, crippling, and compression buckling must be
nificantly impact the strength and stability of the frame.
checked. Note that the compression buckling limit state
Accordingly, a higher strength can generally be utilized
is applicable only when the compressive components of a
as long as the effect of inelastic panel-zone deformation
pair of double concentrated forces coincide as illustrated in
on frame stability is considered in the analysis. When this
Figure 2-4b (i.e., at the bottom flanges). If the magnitudes
option is selected, the resulting design strength given in
of these opposing flange forces are not equal, the compres-
Equations 2.2-3 and 2.2-4 is determined from LRFD Specsion
buckling limit state is checked for the smaller flange
ification Equations K1-11 and K1-12 with consideration of
force, since only this portion of the larger flange force must
the magnitude of the axial load
Pu
in the column:
be resisted. Each of these limit states is discussed below.
Fr o P u 075 . Py,
2.2.1 Panel-Zone Shear Strength
3b t2
f f
In wind and low-seismic applications and high-seismic R v 0. 9 0. 6Fydctw
1
ddt
applications involving Ordinary Moment Frames (OMF),
b cw
(2.2-3)
(P uf ) 1 (P uf ) 1
the design shear strength of the panel-zone Rv
is determined
with the provisions of LRFD Specification Section
Fr o P u 075 . Py,
K1.7, which allows two alternative assumptions.
b t
2
The first assumption is that, for calculation purposes,
3 f f 12 . Pu
R v 09 . 06 . Fydct w 1
19 .
the behavior
of the panel-zone remains nominally within
ddt b cw Py
the elastic range. The resulting design strength given in
Equations 2.2-1 and 2.2-2 is then determined from LRFD (2.2-4)
Specification Equations K1-9 or K1-10 with consideration
of the magnitude of the axial load
Pu
in the column:
For Fy
equal to or less than 50 ksi, all W-shapes listed
in ASTM A6 except a W30 90 and a W16 31 have
For P u 0. 4 Py, R v 0. 9 0. 6 Fydctw
(2.2-1) a web thickness that is adequate to
prevent buckling
(M u ) 2 (M u ) 1
V us
(P uf ) 1
(P uf ) 1
V u
V us
Note: shear forces in beams and moments and axial forces in column omitted for clarity.
Figure 2-3 Panel-zone web shear at an interior column (with
moment-connected beams bending in reverse curvature).
6
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