Modelling lead-rubber seismic isolation bearings using the unified mechanics theory

Lead-rubber seismic isolation bearings (LRB) have been installed in a number of essential and critical structures, like hospitals, universities bridges, located earthquake-prone areas. The purpose using LRB is providing the structure with period lengthening capacity dissipating considerable amount earthquake energy to mitigate effects strong ground motions. Therefore, studying damage mechanics this kind devices fundamental understand accurately describe their thermomechanical behavior, so that seismically isolated structures can be designed more safely. Traditionally, up point, hysteretic behavior LBR has modeled 1) Newtonian empirical curve fitting degradation functions, or 2) heat conduction theories idealized bilinear curves which include effects. reason for models are essentially phenomenological contain some adjusted parameters fact universal laws motion by Newton lack term account loss system. In paper, Unified Mechanics Theory, integrates Thermodynamics at ab-initio level, used model force-displacement response LRB. When Theory used, there no need techniques material. Damage every point calculated entropy generation physics based equations material along State Index (TSI) axis. A finite element lead-rubber bearing was constructed ABAQUS, where user subroutine UMAT implemented define viscoplastic constitutive lead. Finite analysis results were compared experimental test data.