Effects of isolator modeling on the predicted responses of an HDR base-isolated building

Abstract

This manuscript presents the assessment of numerical responses from a High Damping Rubber base-isolated building using six hysteretic models to capture the nonlinear behavior of the isolation system. The experimental data used to evaluate the numerical predictions includes responses from earthquake simulations of a full-scale base-isolated building. The analysis of experimental responses of the isolation system revealed that the onset of strain rate dependency effects increases the loading-path stiffness of the bearings, and a threshold of minimum strain rates to develop strain rate dependency effects in the reference isolation system was identified. The prediction of structural responses shows that the agreement with the experimental responses does not depend on the model’s ability to capture the nonlinear stiffening at large deformations. Instead, a better agreement of predictions with experimental shear forces and strains of the isolation system and peak inter-story accelerations are observed after implementing stiffer properties to indirectly incorporate the strain rate dependency effects. This study shows that implementing properties only from the softened state may lead to underestimating shear forces at the isolation level and inter-story structural responses. The assessment of numerical and experimental responses of the isolation system demonstrated the need to include the potential stiffness variation due to strain rate dependency in the isolators’ modeling.