Soil-Structure Interaction Effects on the Seismic Response of Steel Structures

Abstract

Significant earthquakes are one of the most damaging events for structures. Much research has been done to mitigate the effect of earthquakes on structures. Soil-structure interaction can have a significant impact on the seismic response and gives more realistic results for the structures’ seismic response. Previous work has shown that soil-structure interaction could have beneficial or detrimental effects on the seismic response of the structures. In this study, the seismic response of the three buildings (4-, 8-, and 16-story buildings) with two different lateral force resisting systems (SMF and BRBF) was investigated with the inclusion of the soil-structure interaction using OpenSeesPy. The foundation was modeled using idealized conditions (pin and fixed support) and using the Beam-on-Nonlinear-Winkler-Foundation (BNWF) concept. The soil-structure interaction was considered through modeling springs to represent the soil flexibility. Three types of foundations were considered (isolated, combined, and pile foundation). The same clay soil was utilized for all buildings in this study. Nonlinear Response history analysis (NRHA) was conducted for a suite of scaled earthquake records. The response was evaluated based on the maximum displacement, residual displacement, maximum drift, residual drift, maximum acceleration, maximum base shear, and the energy dissipation in the BRB element and RBS and columns’ springs. The results indicate that the soil-structure interaction has more pronounced effects on the SMF than BRBF and on 4-story than 8-story and 16-story buildings. In general, the amount of change is not very high to the degree that cause concern. So, it can be concluded that neglecting the soil-structure interaction is acceptable in the BRBF and SMF, especially in raft foundation case. But in the SMF of the 4-story building it is recommended to include the SSI because it leads to reduction in the floor shear.