Question:
I am doing a dynamic analysis. Is there a way for me to find out the structural responses specific to a few modes ?
Answer:
By default STAAD.Pro considers contribution from ALL modes, specified as part of the CUT OFF MODE command, for computing the structural response. However it is possible to have the software calculate the response based on certain modes only. One needs to use the MODE SELECT command for that as indicated in the example below
...
CUT OFF MODE 40
MODE SELECT 3 TO 5
LOAD 1 ...
LOAD 2 ...
...
PERFORM ANALYSIS
...
The MODE SELECT command needs to be entered using the editor. In the above example, although the software would extract 40 modes during the analysis but will only consider the effect of modes 3 to 5 when computing the response. The technical reference manual section 5.30.2 has more details on this feature.