I would like to ask what is the difference between the elements nonlinearBeamColumn and ForceBeamColumn. The question arises from the fact that both elements are force-based and also that the ForceBeamColumn element is not included in the manual.
they are the same .. when you issue the command element nonlinearBeamColumn yoy actaully get the same as element forceBeamColumn .. both give you a ForceBeamColumn elemenet found in the SRC directry OpenSees/SRC/element/forceBeamColumn