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medo
2010-06-15, 08:31 AM
What for 'Combination sign' option is used? (Analysis>Analysis Type>Combination sign)

pascal.bogdan
2010-06-15, 08:48 AM
What for 'Combination sign' option is used? (Analysis>Analysis Type>Combination sign)

When you use SRSS combination type for seismic analysis, you can say to program which mode of vibration will give the maximum mass for that seismic direction (if you have 90% of mass in mode 1 on x direction, you can set that the Seismic Action on X direction will be computed according to that mode).
Hope I was clear enough so that you understood. Actually you can check on help some infos about this option.

Regards

medo
2010-06-15, 08:59 AM
But, how do I know which mode will have maximum mass? I have to perform first modal analysis and learn from table of results.
Why do I need this to tell the program which mode has maximum mass since it can find it by itself from calculation results?

pascal.bogdan
2010-06-15, 10:14 AM
But, how do I know which mode will have maximum mass? I have to perform first modal analysis and learn from table of results.
Why do I need this to tell the program which mode has maximum mass since it can find it by itself from calculation results?


Yes, you will look at modal analysis table. It is very useful when you have X braces (or V ones) and you want to see how much tension/compression you have on them (because the compressed one aren't taken into account due to buckling).
For me is a very good setting.

Regards