Procedure of Earthquake analysis by Response Spectrum Method

1. STAAD v8i
EARTHQUAKE ANALYSIS BY RESPONSE SPECTRUM
1. Generate primary load case EQx
a. Go to load item page- response spectrum load
b. Select code IS 1893:2002
c. Chose SRSS combination
d. Enter value of input spectrum –X (
𝑍
2
) X (
𝐼
𝑅
) (work out manually)
e. Values of Z, I and R to be referred from code spectrum – acceleration
and scale intensity EQ1
2. Generate primary load case EQz
a. (repeat same steps from a to e but here values of input spectrum to be
entered is in Z direction)
3. Dead Load:
a. Create all dead loads on the structure under consideration
4. Live Load:
a. Create live load on the structure under consideration (i.e. Floor load)
5. Create the combination of Load Case of (DL + 0.25LL)
a. First freeze lines related to EQ
6. Now assign pin support to all the nodes of beams and column joints. Get the
supportreaction from postprocessor for combination of (DL + 0.25 LL) and
copy the same from STAAD Pro. to Excel sheet.
7. Now the page will show the table like
Node FX FY FZ MX MY MZ
1
2
3
Delete all the columns except Node No. and FY reactions.
8. The format of tables in Excel would be now
Table No. 1
Node FX Value
1 FX
2 FX
3 FX
4 FX

2. And so on..........
9. Table No. 2
Node FZ Value
1 FZ
2 FZ
3 FZ
4 FZ
And so on..........
10. Defreeze the earthquake items from input file
a. Copy above two tables from excel sheet to STAAD Pro. Input file
b. The format of input file should be
c. Load 1 EQX
d. Soil type I
e. Joint load (we have to type this string)
f. Table 1
g. Table 2
h. Spectrum load
11.Delete all the pin supports and provide the fixed supports
a. Analyze the structure