The situation is this: I need to put in some pads to change the vertical stiffness of a machine base. But for the analysis, that would give it a different compressive stiffness than its uplift stiffness. So, for modeling purposes, it has me wondering: do I do 2 models (one with the pad vertical stiffness and the other with the bolt hold down stiffness)? How do I know which was is applicable to which situation? Possibly by looking at the mode shapes? (something I am leery of)
Before anyone asks: there is a net uplift at some bolt anchors.
Thanks in advance.