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Section 5
5-299
5.32.10.1.1 Response Spectrum Specification in
Conjunction with the Indian IS: 1893 (Part
1)-2002 Code for Dynamic Analysis
Methodology
The design lateral shear force at each floor in each mode is
computed by STAAD in accordance with the Indian IS: 1893 (Part
1)-2002 equations 7.8.4.5c and 7.8.4.5d.
Q
ik
= A
k
*φ
ik
*P
k
*W
k
and V
ik
= Q
∑
+=
n
ii
1
ik
Note: All symbols and notations in the above equation are as per
IS: 1893(Part 1)-2002.
STAAD utilizes the following procedure to generate the lateral
seismic loads.
1. User provides the value for
R
IZ
*
2
as factors for input spectrum
2. Program calculates time periods for first six modes or as specified
by the user.
3. Program calculates S
a
/g for each mode utilizing time period and
damping for each mode.
4. The program calculates design horizontal acceleration spectrum
A
k
for different modes.
5. The program then calculates mode participation factor for different
modes.
6. The peak lateral seismic force at each floor in each mode is
calculated.
7. All response quantities for each mode are calculated.
8. The peak response quantities are then combined as per method
(CQC or SRSS or ABS or TEN or CSM) as defined by the user to
get the final results.