Response Spectrum Analysis - Etabs - Multiple Towers

[bookowski]

Question regarding response spectrum analysis.

I have the following: Very large plan area at the lower levels, the building eventually breaks away into multiple towers, each independent from the others. I am using Etabs for the lateral analysis. Each of the towers is assigned a unique diaphragm. Is there any issue with letting Etabs run a response spectrum analysis for this situation?

 

[ishvaaag]

I see mainly 2 issues,

1 That the diaphragms let each tower move independently (structural design programs use to define the same diaphragm per level, so maybe you need to establish diaphragms at slightly different levels even when coincident)

2 Pounding. Joints need be of such width as to serve for seismic pounding control; the other way is the structure be continuous all over the level of nascent discontinuity, but for true large built area in plan it will be rare not setting some joints.

 

[bookowski]

In Etabs there is no problem with the diaphragms moving independently. Also, pounding does not occur in analysis programs (at least ones I've ever heard of).

I was just wondering if anyone had experience with this and if all of the response spectrum analysis works out ok internally with etabs. Do the forces and modal mass participations stay assigned to the proper diaphragm at each level and then get properly applied there et.