Simulation of push and release tests on HDRBs-based isolation systems accounting for viscous effects

Push and release tests on full-scale base-isolated buildings serve as in situ verification of the actual performance of base-isolation systems. However, for systems using High Damping Rubber Bearings (HDRBs), the test response is highly sensitive to the velocity during the pushing phase. When this velocity is low—often due to hydraulic system limitations—the free vibration response may significantly deviate from expectations based on the nominal properties of HDRBs, due to their viscous behaviour. To accurately interpret test results, a model that captures the strain-rate-dependent viscous effects is essential. In this paper a simple linear viscoelastic model, calibrated on laboratory tests on HDRBs, is proposed and shown to effectively reproduce the experimental response, including final residual displacements. It also confirms that the nominal properties of HDRBs and LFSs align with design specifications, even when deviations occur.