Here is the input to the Transient Dynamics model. I stopped the solution at 2.4 seconds to check the progress.
Here is the output at the top mass:
What we see here is a mistake in the model. I forgot to turn off Time Integration in Step 1 so we see the bouncing up and down for 2 seconds. It looks like the natural frequency is about 2 Hz. So at t=3 when the shaking starts, the mass is not at rest. I will rerun that with the proper setting for Step 1. I also forgot to enter some damping. In the attached model, I have entered 0.05 damping ratio at 2 Hz and turned off Time Integration in Step 1.
ANSYS 2021 R1 Archive.