Experimental and numerical investigation of elastomeric seismic isolators coupled with S-shaped steel dampers

This study investigates the seismic performance of a novel hybrid isolation system that integrates a steel-reinforced elastomeric isolator (SREI) with a pair of S-shaped steel dampers (SSSDs). The SSSD design features an innovative configuration, formed by assembling two U-shaped steel dampers using bolted connections instead of welding. This construction enhances the energy dissipation capacity of the system and ensures a more symmetric response under cyclic loading. This SREI+SSSD configuration represents a viable alternative to traditional high-damping rubber and lead plug isolators, addressing challenges such as durability, environmental concerns, and limited deformation capacity. Experimental testing was conducted to evaluate the lateral response of the hybrid system under varying vertical pressures, shape factors of the elastomeric bearings, and rubber compounds with different shear moduli. The investigation begins with cyclic shear tests of the elastomeric isolators alone, followed by tests of the complete SREI+SSSD assembly under identical conditions. A simplified numerical model is then developed and validated, capturing the combined mechanical behavior using a modular representation of non-linear springs and dashpots. The study provides critical insights into the interaction between isolators and dampers, underscoring the influence of the SSSDs on overall system performance with respect to stiffness and energy dissipation. The findings offer valuable guidelines for efficiently designing these seismic isolation systems and optimizing material and configuration choices for enhanced performance.