Question:
There are two different add-on modules for a response spectrum analysis in RF‑/DYNAM Pro. What can be the reasons for the different results of both add-on modules?
Answer:
The differences between the two modules are explained in this FAQ.
When the settings are the same, the same results should also be calculated in both add-on modules. However, this does not apply to existing nonlinearities. The reason is that no nonlinearities are considered in the RF‑/DYNAM Pro add-on module. When displaying the results in the Forced Vibrations add-on module, all nonlinearities are thus ignored. In contrast, the equivalent loads are calculated on a linear structural system, but the exported load cases are then calculated on a real structure in RFEM and RSTAB; that is, with all nonlinearities. This may lead to inconsistent results.
If you deactivate the nonlinearities for the exported load cases, you should obtain the same results.
The method of considering nonlinearities in the response spectrum analysis is described on the basis of tension members in this FAQ.