ASCE 7-10 Two Stage Procedure

[sgs114]

Hello,

I am working on a building that is a 6-story office building with buckling restrained braced frames on levels 2-6 and CMU shear walls at the first level. My building is torsionally irregular, so I am forced to do a response spectrum analysis. Looking at the two-stage procedure requirements, I am not sure if I meet item E of 12.2.3.2:

The upper portion is analyzed with the equivalent lateral force or modal response spectrum procedure............OK

AND

the lower portions is analyzed with the equivalent lateral force procedure.

Given my irregularites force me to use a response spectrum analysis, am I correct in interrupting I cannot use the two stage procedure to do my design? I am kicked to 12.2.3.1 correct?

Or since doing a two-stage procedure basically separates the building, I can say my lower portion (the first floor) meets the requirements to use the ELF procedure, and use the two stage analysis procedure? Anybody ran into something like this?

Thanks.

 

[sandman21]

You are kicked out of two stage, the lower portion irregularities will not allow ELF so you can not "separate" the building.