NUMERICAL ANALYSIS OF THE EFFECTS OF DIFFERENT BEHAVIOR MODELS OF ISOLATORS ON THE SEISMIC RESPONSES OF MULTI-STORY BUILDINGS

Abstract

Seismic base isolation (SBI) is widely recognized as a highly effective solution for earthquake-resistant design, extensively implemented in high-seismicity regions, and increasingly adopted in areas with moderate seismic activity. While structural analysis software provides various behavior models to simulate SBI elements, the suitability of these models for specific analytical applications remains unclear. This study conducts a numerical analysis to assess the impact of different isolator behavior models - including equivalent linear, plastic Wen, bilinear, and rubber isolators - on the seismic response of isolated buildings. Nonlinear time-history analyses are performed on a typical seismically isolated building using the 1994 Northridge earthquake record, scaled to match the target spectrum. The seismic isolators are modeled using link elements with constitutive parameters corresponding to the selected models. Key response parameters, such as isolator behavior, lateral displacements, and base shear forces, are analyzed to compare the structural performance across different isolator models. The results indicate that nonlinear models (plastic Wen, bilinear, and rubber) yield comparable and realistic seismic responses, whereas the linear model significantly overestimates displacements and forces. These findings highlight the limitations of linear assumptions in seismic analysis and underscore the necessity of employing nonlinear models for a more accurate evaluation of structural behavior during earthquakes.