Vibration Modes on SAP2000 (Frames + Slabs)

[pmvr80]

Hi there,

I´m having some issues with a building in SAP2000, which combines frames and slabs. Modal analysis results provide frame and slab modes, but i would like to discard the latter.
My current solution is a slab with zero density and lumped masses at the nodes (assign, joint masses). However I presume that there must be a more practical solution to this problem.
A major disadvantage with this current practice arises when combining static and dynamic analysis results, since dead loads vanish. Nodal mass computation is also time consuming.

Are there any alternatives to:

- Model frames and slabs (without zero density) and filter only frame mode shapes, neglecting additional stiffness provided by the slabs
- A complete model that is suitable for static and dynamic analyses.

Thanks
Best regards

Paulo M. V. Ribeiro

 

[LQQD]

Hi,

I don´t know if im getting your problem right, but try defining mass source form a load pattern in Define>Mass Source. Using Ritz mehotds could also solve your problem.
Also check the following post

http://www.eng-tips.com/viewthread.cfm?qid=349916

Good luck