topic Mass participation is unsatisfactory warning in Robot Structural Analysis Forum

Mass participation is unsatisfactory warning

Anonymous — Thu, 02 Nov 2017 03:26:38 GMT

Hi, i am analyzing an industrial building, 40m tall with large 300mm thick concrete walls all around the envelope. These walls are shear walls and make up SFRS with couple of other internal walls. All columns and beams are simply supported. Modal analysis with dead weight alone gives warning that mass participation is not satisfatory(about 60%) and time period is 0.21 which is very less. When i add machinery load that is roughly about 10 to 15 % of dead weight modal analysis gives me a very high fundamental period (88 sec) with 95% mass participation. Any clues what is going on?

Re: Mass participation is unsatisfactory warning

Anonymous — Thu, 02 Nov 2017 09:53:25 GMT

Can you share the model?

Re: Mass participation is unsatisfactory warning

Anonymous — Thu, 02 Nov 2017 16:05:15 GMT

It is a large file but i will try. I have switched on filter for 90% mass participation but It seems that local modes are governing the fundamental period.

Re: Mass participation is unsatisfactory warning

Anonymous — Fri, 03 Nov 2017 15:18:18 GMT

Hi Suleyman,

I have uploaded the model. Please download it from:

https://www.dropbox.com/s/t24g64u8dvn0oqy/2%20Nov%202017%20Building%20103b%20Equivalent%20Static.rtd?dl=0

Thanks.