Enhancing performance and energy dissipation in a multi-core rubber seismic isolator

Abstract

Base-isolation devices are widely used to reduce seismic demand by increasing structural flexibility and dissipating energy. This study numerically investigates the hysteretic response of high-damping rubber bearings (HDRBs) with alternative rubber core arrangements as a lead-free design concept. A reference HDRB-D700 × 296 bearing and three rubber core configurations (D700-200 × 1, D700-100 × 4, and D700-100 × 9) were simulated in ABAQUS under vertical compression and cyclic lateral displacement corresponding to 200% shear strain. The baseline HDRB model was calibrated against published manufacturer data for post-yield horizontal stiffness, vertical stiffness and equivalent damping ratio. The results show that the core arrangement substantially affects equivalent damping, horizontal stiffness, peak horizontal force, hysteretic strength, and stress distribution. Among the investigated rubber core models, D700-100 × 4 produced the highest equivalent damping ratio, 13.47%, compared with 8.62% for D700-200 × 1 and 12.48% for D700-100 × 9. At constant total core area, redistributing a single central core into four radial cores increased the equivalent damping ratio by 56.3% at essentially unchanged horizontal stiffness. Relative to the reference HDRB, however, D700-100 × 4 increased damping by only 9.3% while increasing the post-yield horizontal stiffness Kb by 48.7%. The four-core arrangement is therefore numerically favourable among the configurations investigated under the adopted geometry and loading conditions, subject to experimental verification.