determined from Equations 8-23 and 8-24 using $eff-m
eff -m = m +
for the m-th mode.
If the maximum base shear force
where $m is the m-th mode damping in the building
calculated by dynamic analysis is less than 80 percent
frame, Wmj is work done by device j in one complete
of the modified equivalent base shear of Paragraph 8-
cycle corresponding to modal floor displacements
*mi, and Wmk is the maximum strain energy in the
deformations shall be proportionally increased to
frame in the m-th mode, determined using Equation
correspond to 80 percent of the modified equivalent
Nonlinear Elastic Static Procedure.
= ∑ Fmi dmi
Paragraph 5-4, should be followed unless explicitly
where Fmi is the m-th mode horizontal inertia force at
modified by the following paragraphs.
floor level i and *mi is the m-th mode horizontal
displacement at floor level i.
The work done by
(1) The nonlinear mathematical model of the
linear viscous device j in one complete cycle of
building should explicitly include the nonlinear
loading in the m-th mode may be calculated as:
force-velocity-displacement characteristics of the
C j dmrj
characteristics of the components supporting the
devices. Stiffness characteristics should be consistent
with the deformations corresponding to the target
where Tm is the m-th mode period of the rehabilitated
displacement and frequency equal to the inverse of
building, including the stiffness of the velocity-
period Te, as defined in Paragraph 5-4(e)(4).
dependent devices, Cj is the damping constant for
device j, and *mrj is the m-th mode relative
(2) The nonlinear mathematical model of the
displacement between the ends of device j along the
building shall include the nonlinear force-velocity-
axis of device j.
displacement characteristics of the energy-dissipation
Direct application of the Response
components supporting the devices.
Spectrum Method will result in member actions at
Member actions at maximum
characteristics that are dependent on excitation
frequency and/or temperature shall be modeled with
significant mode should be determined using the
characteristics consistent with (1) the deformations
procedure described in Paragraph 8-4e(2)(b).
combination factors CF1 and CF2 should be
8 - 36