Please show your mesh, support face, load face, remote point and your Modal analysis results.

 Proper resolution of a 30 Hz frequency in a Transient analysis requires 20 time steps per cycle. That means the maximum time step should be 1/600 or 1.667e-3 seconds, and you say that is what you intended, but why does the result graph below only shows only 8 points between 0 and 0.125 s which implies a delta T of 1.7e-2?  The actual time step is 10 times too large.

Read this on alpha and beta damping.