Analytical Study of Multistorey Building With or Without Softy Storey

Multistorey buildings are becoming popular from the last few years due to their compact and space utilization concept due to increase in population and industrialization. This enables the accommodation of more people and offices in the vertical structure by using limited land area. The stability of structure is an important aspect against all the forces. The damage and collapse of any structure against the seismic forces may be due to structural irregularities i.e., horizontal or vertical irregularities. The discontinuity or drastic change in the lateral strength and stiffness of any storey in structure due to any reason become the main cause of failure against the seismic forces. The soft storey is one in which lateral stiffness is less than 70% of that in storey immediately above or less than 80% of the combined stiffness of three stories above. The effect of soft storey should be analyzed and structure should be designed to minimize their effects. The main purpose of this study is to compare the two cases of structure i.e., with and without soft story, under identical Indian standard loading conditions. Staad Pro is used for modelling and analysis of two almost identical models of 10 storey building (with soft or without soft story). The storey at middle of the building i.e. 5th storey of structure was considered as soft storey because it is not always possible for all terrains such as hilly terrains or corporate canteens to be at ground floor. From the analysis, it was found that one soft storey at middle height of structure causes structure to experience almost 50% increase of stresses.