TRIPS,

thanks for ur reply..

whether this statement is true or false????

1. for user defined spectrum , before cutoff freqency we know accleration value from our user defined spectrum so no problem . but after cutoff frequency i.e usally 33 HZ what ever ZPA value we entered is used as acceleration value

F=ma , we know mass value and after 33 hz this ZPA acts as accleration.. so force is calculted and applied at that node.

if it is used for predefined spectrum, then how force is calculted after 33 hz