modal mass participating ratio

[monchie]

To all,

I'm just new in ETABS doing the dynamic analysis. I've modelled a 30 story bldg and ETABS generated 12 mode shapes(please see attached pdf file and my question is written there).

I'm not sure how to interpret the modal mass participating mass ratio table(whether the 90% mass participation ratio were attained in all mode shapes) in ETABS. What's the meaning of UX,UY,UZ,RX,RY & RZ in the said table. Any comment/reply would be greatly appreciated. Thank you very much.

 

[JoshPlumSE]

First off, I am not an ETABs user. I do not have any in-depth knowledge of their program. So, the following is just speculation.... But, since no one else has responded.

My guess is that UX, UY, and UZ represent the mass participation of the translational mass.

If so, then RX, RY and RZ would likely represent the mass particiaption of the rotational mass moment of inertia. If modes 3, 6, 8 and 10 look like torsional modes, then this would probably confirm my assumption.