V = C_{s}W_{t
}where C_{s}
is the seismic design coefficient and W_{t}
is the total seismic weight. A procedure for evaluating each of these
quantities is given in the sections that follow.
Seismic design
coefficient C_{s}
The seismic design coefficient
C_{s}
shall be determined from the following formula:
C_{s }=
ZISMRQ
Z = seismic zoning factor
I = importance factor
S = structural system type factor
M = material factor
R = risk factor
Q = construction quality factor
C_{s }= shall not be taken as greater than 4.8×ZIMQ,
nor less than 0.02 for sites with seismic zone factors greater than zero.
Seismic zoning
factor Z
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.
2
Importance Factor I
Values
for the importance factor I are given in Table 14.3, as functions of
buildings use.
Structural
systemtype factor S
Values for the structural
systemtype 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.
