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Re: Quick/Easy Question for Seismic List

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Story drift is relative displacement between each story level, not overall 
building height.  It shouldn't matter whether you're in feet or inches, as 
the factor should be dimensionless (i.e. a %age) so that the resultant drift 
would be in the same proportional units. (Unless BOCA has some other way of 
stating the factor, since .02 seems unusually high.  UBC seismic drift is on 
the order of .004 or .005 times the story height depending on the natural 
period.)  The value calculated using the total building height would not be 
story drift but total cumulative horizontal displacement at the roof.  By the 
way, a 3 story building 74 feet high?!

E. G. Hirsch, SE