For all structural damping (MAT1 GE, PARAM,G CBUSH GE field) used in transient response, you must convert it to viscous damping at a user-specified frequency... if using GE, it is converted by PARAM,W4 while PARAM,G is converted with PARAM,W3.
ALL damping specified in a run will be ADDED together, so if you define PARAM,G (affects the whole model) and use GE on the MAT1 entry (affects only the elements referencing this material), then the effects are added together for the overlapping portion.
The units for W3 and W4 are radians/sec.
Selecting the appropriate W3/W4 can be difficult, and the conversion is only truely accurate at those frequencies... elsewhere, the effect will be to over or under damp the response.
