seismic design question

huangyhg

seismic design question
hi and thank you all for your tips,
i am working on two storey industrial (steel framing, concrete floors)) building 50 ft high, 100ftx300ft with partial basement (75 percent of the building).  1st floor is 4 ft above grade but on one side the grade goes down almost 8 ft bellow finish floor.  i am trying to figure out how to approach seismic analysis and if i can assume this is a three storey building with basement floor elevation being my grade what would make the base shear gigantic.
there is also heavy equipment on the first floor and some on the mezz.
any help is appreciated.
the cs=0.087.
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why do you want to assume the basement floor level as grade.  sounds like 8 ft below the 1st floor level can conservatively be used as grade.
bagman2524,
on one side of the building there is a ramp that actually goes down 4 ft below basement floor.