Rolling devices for seismic isolation of lightweight structures and equipment. Design and realization of a prototype

The present paper shows the results of an experimental study on new rolling seismic isolators made with steel cylindrical elements arranged on two levels, interposed between flat rubber layers, and rolling in the same direction. It is a rather simplified version of an isolator designed to have the cylinders disposed on two levels, according to two directions perpendicular to one another in the horizontal plane, in order to uncouple any component of the seismic force. In the original basic idea, the rolling planes present a concave surface with a high radius of curvature for recentering capabilities of the device. The rolling of the cylinders allows the isolation of the structure uncoupling the motion of the structure by the ground motion, although the rubber layers have to activate a viscous dissipation process, thanks to the steel-rubber contact. A prototype of the simplified version of the device has been realized and tested to obtain the hysteresis behavior and the equivalent viscous damping under increasing values of the axial preload, either with glued or vulcanized rubber layers. The results have been finally discussed also to identify the possible future developments and improvements of the proposed device.