Effect of Elastomeric Snubber Properties on Seismic Response of Vibration‐Isolated Mechanical Equipment: An Experimental Study

Earthquake‐simulator experiments were conducted on a liquid centrifugal chiller supported by four isolation/restraint systems with built‐in elastomeric snubbers. The test plan incorporated variations of input motion amplitudes and snubber properties to investigate their effect on three response quantities: peak dynamic forces induced into the snubbers, peak acceleration, and peak relative displacement response of the equipment. The elastomeric snubbers limited the displacement responses of the vibration‐isolated equipment at the expense of excessive dynamic forces and amplification of the equipment acceleration response. The snubber gap size was the most influential property on the response quantities. For high‐amplitude input motions, all the response quantities increased with an increase of the gap size. Due to the compressibility of the snubber elastomeric contact‐surface, the actual gap size was always larger than the nominal gap size. Even with a nominal gap size less than 0.25 in. , the seismic response of the equipment was substantially different from the seismic response of rigidly mounted equipment. Compared to snubbers with constant contact‐surface, snubbers with expanding contact‐surface resulted in lower dynamic forces. The thicker and softer contact‐surface could lower the dynamic forces induced into the snubbers but resulted in larger relative displacement response of the equipment.