Hi,

I have a question regarding load cases for static seismic analysis for linear model (no gaps on restraints and no friction) vs non linear model (restraints with gaps, and friction).

I know that there is a cookbook approach given in CAESARII User's Guide (Section 8) which I normally follow for doing static seismic analysis. This approach is based on the segregated earthquake load cases which user has to add in the end to the sustained case for code compliance.

But if we have a linear model, can we add uniform loads(earthquake) directly to the sustained case, like:

W+P1+U1
W+P1-U1
W+P1+U2
W+P1-U2

and then check code compliance or we still need to do it in the way that is defined in section 8 of the user's guide.

Why do I ask this. Recently I've received stress report with load cases for static seismic defined in a way like the ones above. Two uniform loads were set in the model, U1 and U2 and for occasional stress code compliance they were added directly to the SUS case.

Is this way of calculating OCC stress correct or not?