Are there any reports that provide a detailed calculation of the Cs factor when using the equivelant lateral force procedure to calculate seismic forces? I have looked at the Loads and Applied Forces report and i don't agree with the Cs being used. My Sds is 0.163, Sd1 is 0.065 with an importance factor of 1.25, TL = 6 and a response of 3. I've tried everything with respect to the period, including using my calculated Ta=0.207 in the loads tab. However, in the loads and applied forces it does not indicate the numerical value for T, just whether it was user defined or calculated. r
This all being said, because it appears that the program is using Cs=0.01 even though Cs= Sds/(R/I)= (0.163/(3/1.25))=0.068 and Cs<= Sd1/(T*(R/I)=0.065/(0.207*3/1.25) = 0.131
Can anyone shed light?
The Loads and Applied forces report is the most detailed one we have. Based on your values above, it looks like you might be in Seismic Design Category A, where the simplified method kicks in and CS is just 0.01.