Hi,
I am doing a response spectrum analysis of a 10 storey building. I understood that all the codes have made a response spectrum graph out of the possible peak accelerations of single degree of freedom systems having a variety of natural frequencies when they are subjected to standard ground accelerations say El Centro. So we get the peak acceleration of a SDOF system for various natural frequencies.
But I dont understand, how Staad uses this data of a SDOF system for analyzing a Multiple degree of freedom system like a High rise building which has many modes?
Also, I have seen some where a building has 3 dof at each floor if a rigid diaphragm is assigned. But , I am able to extract a large number of modes. Why is that so? I am new to dynamics and most of my doubts may be very silly. Please suggest some resources to make these things clear.
