huangyhg

asce 7-05 possible typo
i've stumbled on something that i'd like to run past some seasoned earthquake structural engineers:
in asce 7-05, equations 15.4-2 and 15.4-4, the variable s1 is used. it seems to me an sm1 or sd1 should be there because s1 is not adjusted for soil type or spectral response. is this a typo or was it really intended to be this way?
my case is for soil class d and the s1 numbers on the map are based on soil class b. the fv and fa site coefficients are pretty substantial to make soil type changes (tables 11.4-1 and 11.4-2). if s1 is used and it is supposed to be sm1 or sd1, the result would be very unconservative.
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while i do not claim to be a seasoned eq engineer, i looked at this, and while it is hard to follow since asce 7-05 is in a new format, i believe that eq.15.4-4 is intended to replace the cs min equations 12.8-5 and 12.8-6, which also use s1. i believe that the r values from table 15.4-2 are to be used in the chapter 12.8 cs equations, where eqs.12.8-2, -3, and -4 use either sds or sd1.
in short, i don't think that this is a typo and it probably isn't unconservative because it defines the lower bound, and 15.4-1 and 15.4-2 is more severe than the minimums in 12.8.
that makes perfect sense, and after re-reading the associated sections, i think you're right.
if anyone has hard knowledge of this being the case, please weigh in.
thanks

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