Seismic behaviour of plan irregular reinforced concrete buildings considering soil effects

In Nepal, like in other parts of the world, irregular buildings are regularly built due to the rapid rise of urbanization. Such irregularities make structure seismically weak during earthquake. The majority of seismic analyses of structures ignore the effect of soil in response of structure. In fact, when a structure experiences seismic excitation, it interferes with the soil, impacting structural response. Soil structure interaction plays an important role in evaluating the seismic performance of the structure. In this study, Winkler foundation linear model is adapted to create the soil model. The current research work focuses on the seismic behaviors of plan irregular reinforced concrete structures while taking the influence of soil type into consideration. In a finite element-based software SAP2000, five different models; regular, T-shaped, L-shaped, H-shaped, and Plus-shaped are modelled. Response spectrum analysis is carried out to study the seismic performance of the prototype building models. The seismic responses of these buildings resting on three different soil types namely hard, medium, and soft soil are examined. The results are interpreted and discussed in terms of seismic parameters. Based on the outcomes obtained from seismic analysis, it is found that the incorporation of soil-structure interaction (SSI) has a substantial impact on building performance. The storey displacement and drift increase when the effect of soil is considered. Similarly, the base shear is decreased due to soil flexibility whereas the time period is increased by considering SSI. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.