Seismic Analysis of Vertical Geometric Irregular Building Considering Soil–Structure Interaction

Prevailing studies consider the design of reinforced concrete moment resisting frame having fixed base. When a structure is subjected to earthquake, foundation undergoes three modes of deformation, namely vertical, sliding and rocking. These deformations increase the force demand due to uncertainties in the characterization of soil. In the present study, a numerical modelling is carried out using the finite element software OpenSees to evaluate the seismic response of a typical eight-storey four-bay vertical geometric irregular building considering soil–structure interaction and the results are compared with a reference regular building. The numerical modelling is carried out considering the footings as beams on nonlinear Winkler foundation in which footing is modelled as elastic elements and the soil is modelled as discrete nonlinear springs in both vertical and horizontal directions. Fibre-based nonlinear element is used for modelling the reinforced concrete beams and columns. A suite of five earthquake ground motion records of different magnitudes is considered for the dynamic analyses. Four types of soil–structure interactions are considered: fixed regular, fixed VGI, flexible regular and flexible VGI. The effect of soil–structure interaction on the seismic response of framed building is demonstrated in terms of probabilistic seismic demand models and fragility curves.