STAAD Commands and Input Instructions
Section 5
5-182
5.31.2.1 UBC 1997 Load Definition
Purpose
This feature enables one to generate horizontal seismic loads per
the UBC 97 specifications using a static equivalent approach.
Depending on this definition, equivalent lateral loads will be
generated in horizontal direction(s).
Description
The seismic load generator can be used to generate lateral loads in
the X & Z directions for Y up or X & Y for Z up. Y up or Z up is
the vertical axis and the direction of gravity loads (See the SET Z
UP command). All vertical coordinates of the floors above the
base must be positive and the vertical axis must be perpendicular
to the floors.
Methodology
See Sections
1.17.2, 5.32.12
and
xample
manual
roblem no. 14
The design base shear is computed in accordance with Section
1630.2.1 of the UBC 1997 code. The primary equation, namely,
30-4, as shown below, is checked.
W
TR
IC
V
v
=
…………………. Eqn 30-4 of UBC 1997
In addition, the following equations are checked :
Equation 30-5 – The total design base shear shall not exceed
W
R
IC
V
a
5.2
=
Equation 30-6 - The total design base shear shall not be less than
IWCV
a
11.0
