Investigation of the seismic behavior of base isolated steel frames considering the effects of soil-structure interaction

In this study, the effect of soil-structure interaction on the seismic behavior of base-insolated steel structures is investigated. A numerical model based on the Finite Element Method (FEM) has been developed using SAP2000 software for seismic analysis of structural models. In the seismic analysis, the effects of soil, seismic isolator, earthquake and superstructure characteristic on structural behavior are evaluated. The analysis are performed in two cases as free vibration analysis and forced vibration analysis. In the forced vibration analysis performed in the time domain using numerical integration analysis method, the behavior of the superstructure and seismic isolators are assumed to be nonlinear and the soil behavior is linear. According to the results obtained from the analysis, seismic behavior parameters such as natural free vibration period, relative displacement and base shear force are investigated. In addition, in order to obtain the performance of the seismic base isolation system, the isolator performance factor has been defined and the performance of the isolator for different soil types has been evaluated using this factor. Obtained results can be used as a basis for considering the effect of soil-structure interaction in the analysis and design of seismic base isolated buildings in design codes.