The Effects of Soil-Structure Interaction on the Seismic Behavior of Geometrically Irregular Steel Structures in Base-Isolated Plan with Lead Rubber Bearing Isolators

The present paper aimed to evaluate the effects of soil-structure interaction (SSI) on the seismic behavior of base-isolated geometrically irregular steel sliding structures equipped with lead rubber bearing (LRB) isolators.To this aim, the behavior of the irregular system under nonlinear time-history dynamic analysis was assessed using numerical modeling based on the finite element method in ABAQUS. The study considered various factors including irregularity, number of structure floors, soil properties, isolation, and foundation stiffness to analyze their impact on the response of the structures. 3-, 5-, and 7-story structures with 20% and 40% irregularity were modeled to investigate the effects of irregularity and the number of floors. Additionally, models of five-story structures were used to study the impacts of soil-structure interaction (SSI) on three different types of soil: soft, medium, and hard. The results of the study demonstrated that the number of floors and the structure's irregularity have a significant impact on the seismic response of the structure in terms of displacement and acceleration. As the number of floors and irregularity increase, the maximum displacement response of the structure's floors decreases. The study also highlighted the substantial influence of soil type on the seismic response of isolated structures when considering the effects of SSI. Furthermore, the findings indicated that the presence of isolators on rigid foundations had a negligible effect on the dynamic response of the structures, compared to structures without isolators.