Anindya

"I would not necessarily expect the equivalent (horizontal) static loads to match the lateral loads from a dynamic aanalysis. There certainly seems to be no obvious reason why this should be the case, but there is a lot of supporting material that I haven't (and don't plan to) read that may explain how all the math"

To the extent I know, the concept of Pseudo Acceleration as is used in Time History/Response Spectrum is related to the way static push over load is represented in the Building codes.

Now the elastic resisting force = KX=MW^2X=MA where A=Pseudo Acceleration. Now M=W/g so resisting force= (W/g) A which is similar to the way equivalent base shear is expressed in the Building codes. Now the Dynamic analysis resisting load is a paricular direction should not fall short of this value as this has a sound basis , hence the two should match.

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We had an in-house seismic analysis seminar yesterday led by the chair of the ASCE 7 Code Committee. His description of this is that the pseudo-acceleration value is used to scale the results of a time history analysis so that the sum of the foundation shear loads match. So you are right, the intent of analysis is to make the two sets of loads match.

Son of a gun, you learn something new every day!

:-)