EFFECT OF SOFT STOREYS IN EARTHQUAKE RESISTANT ANALYSIS OF RC FRAMED STRUCTURES

Abstract

As per the codal provisions, a soft storey is defined as the storey in which the stiffness is less than 70% of the storey above or less than 80% of the combined stiffnesses of the three storeys above. It is the general practice in the multistoreyed buildings to accommodate parking facilities for the vehicles of the occupants of the building. As we know that the soft storey in a building structure causes stiffness irregularity in a structure, due to this the structure undergoes unequal storey drifts, formation of the plastic hinges and then finally resulting into the collapse of the structure.This research work purely interacts with the effect of the soft storeys in the analysis of RC framed structures as entitled above, and in this work the soft storeys positions has been provided at different levels as shown in the analytical modelling. All the models are analyzed by using the ETABS software. The seismic analysis performed consists of the Equivalent static analysis (ESA), response spectrum analysis (RSA), and the push over analysis (PA). The seismic base shear forces, storey drifts, and the displacements has been compared with the three analysis methods as listed above. With the aid of the push over analysis the values of the ductility and the response reduction factor have been obtained. Apart from these, the performance point parameters such as spectral acceleration(Sa) , spectral displacement (Sd), Base shear(V) and the roof displacement(D) has been also illustrated in this work and a detailed information of several stages of the hinge formation (A,B,IO,LS,CP,C,D,E) has also been illustrated..