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Section 5
5-183
Equation 30-7 – In addition, for Seismic Zone 4, the total base
shear shall also not be less than
W
R
IZN
V
v
8.0
=
For an explanation of the terms used in the above equations, please
refer to the UBC 1997 code.
There are 2 stages of command specification for generating lateral
loads. This is the first stage and is activated through the DEFINE
UBC LOAD command.
General Format
DEFINE UBC (ACCIDENTAL) LOAD
ZON
E f1 ubc-spec
SEL
FWEIGHT
JOI
NT WEIGHT
Joint-list WEI
GHT w
[See Section 5.31.2.2 for complete weight input definition]
ubc-spec = { I f2, RWX f3, RWZ f4, STYP f5, NA f6,
NV f7, (CT f8), (PX f9), (PZ f10)}
where,
f1 = Seismic zone coefficient. Instead of using an integer value
like 1, 2, 3 or 4, use the fractional value like 0.075, 0.15, 0.2,
0.3, 0.4, etc.
f2 = Importance factor
f3 = Numerical coefficient R for lateral load in X direction
f4 = Numerical coefficient R for lateral load in Z direction
f5 = Soil Profile type
f6 = Near source factor Na
f7 = Near source factor Nv
f8 = Optional CT value to calculate time period based on Method
A (see Note 7)
f9 = Optional Period of structure (in sec) in X-direction to be used
in Method B