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?