Actions and Deformations.
deformations, 2 y.
compliance with the performance objective requires
compliance with the global displacement criteria for
i. For beams:
the structure as a whole, and the local deformation
criteria for individual structural elements.
ZFye l b
(a) Global displacement. The displacement
for the control node of the structure in the
ii. For columns:
force/displacement plot (i.e., pushover analysis) must
equal or exceed the target displacement, δ described
in Paragraph 5-4f. Story drifts shall not exceed the
values indicated in Table 6-1.
Primary and secondary components shall have
Z = Plastic section modulus, in3 (mm3).
expected deformation capacities not less than the
deformations derived from the pushover analysis
Fye = Expected yield strength, psi (kPa), as
when the target displacement, δ is attained.
defined in the AISC Seismic provisions.
Modeling parameters and numerical acceptance
criteria are provided for each performance objective
Moment of inertia of beams, in4
for the structural systems described in Chapters 7
through 10. The acceptance criteria are provided in
terms of rotations, 2 , in radians; rotation ratios, 2 /2 y;
Ic = Moment of inertia of columns, in4
or deformation ratios ) /) y, as depicted in Figure 6-2.
Steel moment and braced frames.
lb = Beam length, in (mm).
Acceptance criteria are provided in terms of either
plastic rotations of ratios or plastic rotations to yield
lc = Column length, in (mm).
Figure 6-3 illustrates the definition of
chord rotation for frame beams and columns. If it is
P = Axial force in the columns, kips (kN).
assumed that the total chord rotation, 2 , (elastic plus
plastic rotation) is defined by the interstory drift,
Pye = Expected axial yield strength, Ag Fye
) /h, then the interstory drift ratio becomes a
convenient parameter to monitor the inelastic
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