Effects of soft storey level variation on the seismic response of masonry-infilled reinforced concrete buildings

Multi-storey reinforced concrete buildings are necessary to provide ever-increasing housing and office requirements. Most of these buildings generally include one or several storeys, which have storey heights larger than the rest of the storeys, known as soft storeys. These soft storeys become essential to accommodate parking for vehicles or to include large halls or open spaces at intermediate levels. Due to their slender nature, multi-storey buildings are prone to earthquakes. Further, the presence of soft storeys in tall buildings significantly affects the structural behaviour of these structures. This study aims to understand the seismic response of the building due to soft storeys located at various levels in different seismic zones as per IS: 1893 - 2016. Conventionally, infills within the frames of the buildings are ignored in the structural analysis due to the complexities in modelling. However, ignoring the contribution of infill may be unrealistic. Therefore, in this paper, the effect of infill modelling on the soft storey structure is also studied. For the study, equivalent static analysis is considered. Storey drifts and displacements are the response parameters used for this study. It was found that infill modelling has a considerable effect on the seismic behaviour of the structure. Further, it was observed that storey drifts and displacements reduce significantly when the soft storeys are located at higher levels.