Modeling the Multiaxial Behavior of High Damping Rubber Bearings (HDRBs)

ABSTRACT The dynamic behavior of seismically isolated structures is governed by the force‐deformation response of the isolation devices. Consequently, significant efforts have been made to accurately simulate the behavior of different types of devices. High damping rubber bearings (HDRBs) are among the most widely manufactured and used isolators in practice. Given the internal structure of these devices and the characteristic behavior of the rubber compound, HDRBs show highly nonlinear behavior with strong coupling between deformation directions, which is challenging to simulate numerically. Capturing these complex multiaxial interactions is essential for reliably predicting device behavior and ensuring the dynamic stability of the isolation system during seismic events, therefore, a holistic multiaxial modeling approach is critical. This study presents a robust and sufficiently accurate numerical model for simulating the multiaxial behavior of HDRBs under large deformations. This elaborate model includes: bidirectional shear response that accounts for stiffness degradation with load‐direction dependency, including scragging (long‐term degradation) and Mullins effect (short‐term degradation), and temporary hardening; coupling between axial and shear response, including axial stiffness softening due to lateral displacement and shear stiffness variability due to axial load variation; axial instability due to large compressive loads; and cavitation under tensile forces. The proposed model is validated using a wide range of load patterns applied to an HDRB, as well as experimental results from the literature. The proposed model demonstrates good agreement with experimental data, accurately simulating HDRB responses across diverse validation tests, including double bidirectional shear tests in rotated directions, cyclic shear response under different axial loads, tensile loads, bidirectional deformation history with an elliptical orbit, extremely large deformations (beyond the design limits), and dynamic analyses. The results show that the model provides reliable predictions of the static and dynamic behavior of HDRBs under different load patterns, including deformations until the onset of failure. The proposed model has been implemented in OpenSees and is openly available at the supplementary repository https://github.com/JAGallardo1992/HDRB_model .