Experimental study and numerical model of a new passive adaptive isolation bearing

Abstract

This study presents a novel assembled passive adaptive isolation bearing (PAIB) for structures against various seismic design levels, which offering variable stiffness functions change with the displacement, vertical stress and rate. The operational mechanism of the bearing is initially described, followed by experiments conducted on 6 specimens with NR (Natural rubber) drum dampers and 10 specimens with HDR (High damping rubber) drum dampers. The test results demonstrate a notable hardening segment in the horizontal shear force of HDR drum dampers compared to NR drum dampers when lateral displacement exceeds 200% total rubber thickness. Furthermore, the friction characteristics of sliding polyurethane elastomer bearing with different friction surfaces and the lateral mechanical properties of the whole device under different working conditions are examined. A numerical model, considering strong nonlinear reinforcement and frictional nonlinearity, is proposed based on the OpenSees platform, and its effectiveness is verified thorough experimental investigation. Additionally, parameter analyses are carried out to assess the contribution of each component of the new bearing to the lateral stiffness adaptive performance and the proportion of energy dissipation. The findings reveal that the hysteretic behavior of PAIB equipped with HDR drum dampers exhibits significant correlations between velocity, vertical pressure, and displacement. This highlights its excellent adaptability in both design and earthquake beyond the designed level, particularly when the frictional energy consumption remains relatively low.