Shake table tests on a rigid block isolated with high-damping unbonded fiber-reinforced elastomeric isolators

Fiber-reinforced elastomeric isolators (FREIs) represent a relatively recent type of elastomeric device. In contrast to traditional steel-reinforced elastomeric isolators (SREIs), FREIs are constructed with multiple layers of rubber pads and fiber layers instead of steel laminas. This choice is aimed at cost reduction during the manufacturing and installation process. To enhance cost-efficiency, FREIs can also be used in unbonded applications (UFREIs), where the device is placed between the foundation and the superstructure without bonding or fastening. This approach helps to further minimize installation expenses. Furthermore, the lateral rollover deformation, a characteristic feature of this configuration, improves energy dissipation. This study investigates the seismic isolation capabilities of high-damping unbonded FREIs for low-rise masonry buildings. Specifically, unidirectional cyclic and shake table tests of a rigid block isolated with two UFREIs are discussed. The primary goals of this experimental study include evaluating the effectiveness of UFREIs in reducing seismic demands, analyzing the response of UFREIs under unidirectional ground-motion excitation, confirming the ability of UFREIs to withstand major unidirectional excitation without sustaining damage, and exploring the limitations of this isolation system under a range of seismic inputs and low axial loads.