Effects of soil small strain nonlinearity on the dynamic behavior of floating column structures considering soil-structure interaction

Past seismic events reveal that soil and structural responses are interdependent, not independent. The seismic behavior of irregular structures, considering soil-structure interaction (SSI) effects, significantly increases the structural vulnerability compared to traditional fixed-base structures. The study on the impact of SSI on irregular structures, especially those with floating columns, is currently limited. Hence, this study primarily examines the influence of nonlinear soil structure interactions on the dynamic response of mid-rise reinforced floating column structures resting on different soil mediums. A three-dimensional finite element programming tool is used to simulate the seismic response of structures with and without floating columns. This study explores the use of elastoplastic hinges to study the inelastic behavior of structural components. The isotropic hardening elastoplastic hysteretic soil model is used to account for the nonlinear behavior of the soil. The nonlinear time history analysis is used to perform and evaluate structural demand parameters subjected to selected ground motions. Moreover, the seismic structural response parameters, such as storey displacement, peak storey drift, peak horizontal acceleration, base shear, and member forces, are compared for both fixed and SSI bases. The analysis results show that the presence of floating columns in structures significantly alters the dynamic response of buildings compared to those without floating column structures. The incorporation of SSI effects increases the flexibility of the foundation and increases the seismic structural response of storey displacement and inter-storey drift ratio while reducing the base shear value.