Request for Assistance – Low Dynamic Mass Participation in Seismic Model

[sohjiangwen]

Dear Engineers,

I am currently working on the seismic design of a hotel development with two transfer floors. However, despite multiple attempts, I have been unable to achieve sufficient dynamic mass participation in the analysis model.

Would anyone be able to kindly assist by reviewing the model and suggesting possible improvements?

Thank you in advance for your help.

 

[sohjiangwen]

Download model link: https://we.tl/t-1KLISJ0CIt

 

[JoshPlumSE]

Okay, just looking at your model, the lowest level probably has a pretty good amount of mass associated with it, right? But, it's also probably pretty rigid....

My guess is that you'll have more luck switching from a standard Modal solution to a Ritz Vector solution. Some explanation on this subject:

https://web.wiki.csiamerica.com/wiki/spaces/kb/pages/2005633/Ritz+vs.+Eigen+vectors

I just tested out your model and I'm seeing 99 % mass participation in both horizontal directions for your structure. That seems pretty good to me. Is the purpose of your modal solution something other than lateral loading / response spectra?