Dear,
When I use Response spectrum seismic definition, there is no input for structure natural frequency. Does it mean that software will do it in background?
If yes, which method does it use (Eigen or Rayleigh)? What is a mass source used?
Regards,
Yes, the program will automatically calculate the frequency by using the Eigen method. Dynamic mass must be modeled either in the Mass Reference Load or in the same Load Case where the Response Spectrum load is applied. More details can be found in STAAD.Pro Help section Technical Reference of STAAD Commands > TR.31 Definition of Load Systems > TR.31.8 Mass Modeling.
Answer Verified By: Ivan Hadži Bošković