|V = CsWt
is the seismic design coefficient and Wt
is the total seismic weight. A procedure for evaluating each of these
quantities is given in the sections that follow.
The seismic design coefficient
shall be determined from the following formula:
Z = seismic zoning factor
I = importance factor
S = structural system type factor
M = material factor
R = risk factor
Q = construction quality factor
Cs = shall not be taken as greater than 4.8×ZIMQ,
nor less than 0.02 for sites with seismic zone factors greater than zero.
The seismic zoning factor Z is given by
Z = ACF
A = standard value for horizontal acceleration ratio (expressed as fraction
of the acceleration of gravity g) to be determined from Table 1 and the
seismic zoning map shown in Fig. 1
F = foundation soil factor to be determined from Fig.
Importance Factor I
for the importance factor I are given in Table 14.3, as functions of
system-type factor S
Values for the structural
system-type factor S must be determined separately for each direction of
the building. Unless more precise values are determined, the recommended
values for this factor that are given in Table
2 may be used.