Effect of Masonry Infills on Seismic Response of RC Framed Buildings

While performing structural design of multi-storeyed RC framed buildings with masonry infills, it is a common practice to exclude the increase in stiffness of the structure caused by the presence of masonry infills. This practice can lead to incorrect estimation of various seismic responses and hence, the seismic design results obtained for the structure shall be unreliable. In the present study, the effect of variation of structural size and stiffness on base shear and fundamental period has been investigated. Response spectrum analysis has been performed on all the frames under investigation and analysis has been carried out on ETABS 2015 software. Masonry infills are modelled as equivalent diagonal compressive struts to simulate the compressive behaviour of masonry walls under lateral seismic forces. Results have been compared for base shear and fundamental period in lateral direction of earthquake vibration. Building models were prepared with variation in infill panel stiffness and infill opening percentages were varied as 20, 40 and 60%. The incorporation of the stiffness of the infills shows an increase in the base shear but decreases the fundamental period of the building. However, an increase in infill openings decreases the base shear but increases the fundamental period of the building.