Hello,

I'm try to run nonlinear dynamic simulation to bellow show structure.

The result looks abnormal. I believe the reason was wrong input of alpha, beta.

I used alpha-0.11 beta -0.000289

please suggest propper alpha, beta value to use with this.

3D drawing attached here with.

Force-1 = force -2

Thank you.

Udaya.

If you have the modal damping for the modes of interest, and their frequency than there is a relation between that, and the alpha and beta coefficient.

Below is an extract from Strand7 Help, were the alpha and beta are given explicitly:

Further more if you assume that the two modes of interest have the same modal damping (different freq. of course), then these relations/equations become trivial and are as shown below:

This is all explained in the solidworks help (just search for Rayleigh damping).

Finally typical damping ratios values (Greek letter z in the above equations, is modal damping ratio) for steel welded frames can be between 0.5% - 2% (0.005-0.02).