load combinations prescribed above to the
permit selection of a shallower, and more
moment-connected beam or beams in the plane
economical, beam section. However, the beam
of the frame at the column. Vu is not required to
depth and the length and depth of the haunch
must be carefully selected to assure that the
exceed the shear force determined from 0.8G Mp
plastic hinge will occur at the end of the haunch,
of the beams framing into the column flanges at
and not at the column face, for the combined
the connection.
seismic and factored gravity load moments. If
(5) Width-thickness ratios. Beams shall
the beam size is based on stiffness to control
8
comply
with
in
the
AISC
Design
drift, the haunches may not contribute adequate
p
Specifications Table B5-1. When the ratio in
stiffness to permit reduction in the size of the
Equation 7-3 is less than or equal to 1.25,
beam.
columns shall comply with 8 in Table I-9-1 of
p
Exception:
Connections
that
the
AISC
Seismic
Provisions;
otherwise,
accommodate the required rotations within the
columns shall comply with Table B5-1 of the
connection itself and maintain the minimum
AISC Design Specifications.
required strength of Paragraph 7-5b(2)(a) are
(6) Continuity plates. Continuity plates
permitted to be used provided that the additional
shall
be
provided
to
match
the
tested
drift due to the connection deformation can be
connections. When tested connections do not
accommodated by the structure as demonstrated
include continuity plates, neither columns with
by rational analysis. Such rational analysis shall
thinner flanges nor beams with thicker or wider
include consideration of overall frame stability,
flanges shall be considered to be qualified by the
including the P-delta effect.
test.
(3)
Connection shear strength.
The
(7) Column/beam moment ratio. At any
required shear strength, Vu, of a beam-to-column
beam-to-column
connection,
the
following
shall be determined using the load combination
strong column/weak beam relationship shall be
1.2D + 0.5L + 0.2S plus the shear resulting from
satisfied:
applying 1.1RyFyZ in the opposite sense on each
Alternately, Vu shall be
end of the beam.
∑M
∗
justified by rational analysis. The required shear
pc
f1.0
(7-3)
∑M
∗
strength is not required to exceed the shear
pb
resulting from the load combinations prescribed
by Equations 4-6 and 4-7.
Where:
(4)
Panel zone shear strength.
The
ΣM ∗c
=
the
moment
at
the
p
required shear strength, Vu, of the panel zone
intersection of the beam and column center-line
shall be the shear force determined by applying
determined by projecting the sum of the nominal
7-99
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