how to model anti-vibration supports in CesarII to avoid vibration in dynamic modal analysis

i modeled support as a rest+holddown having 0.4 friction.

the problem is in dynamic analysis. That pipe has modal vibration <4Hz also if there is an antivibration support because dynamic doesn't know it is an antivibration support.

how can i solve the vibration "false" vibration in modal dynamic analysis?

have i to insert a virtual dampener in dynamic table to stop vibration?