STUDY OF INELASTIC RESPONSE OF OPEN-GROUND STOREY RCC BUILDINGS

Abstract

Reinforced Concrete (RC) frames with unreinforced masonry infills (URM) are the most commonly used construction practice in India and worldwide. The infills are generally treated as nonstructural elements and are not considered while designing because of the complexity attached to its interaction with the surrounding frame elements and lack of knowledge about its modelling. However, the presence of infills drastically increase the strength and stiffness thus affects the performance sufficiently. Increase in stiffness the infill frames attracts higher lateral forces for which the buildings are not designed generally. In addition to that the irregular placing of infills also adds to the vulnerability of the buildings. In this study seismic performance of RC building with open ground storey has been studied. The considered building is 6 storey with an open ground storey located in a zone V of IS-1893 (2016) on a medium soil. The bare frame was first designed using Response spectrum analysis. Three cases are considered, where in each case the ground storey columns were designed for higher forces. After designing, Infills are modelled as Equivalent Strut elements and performance have been assessed under pushover and nonlinear time history analysis. For the first case the hinges pattern and the inter storey drift ratio has shown that the ground storey column and beams are most vulnerable. And over all the structure was vulnerable to soft storey mechanism. But in the later stages for Case 2 and Case 3 the performance improved in pushover analysis and also in case of nonlinear time history analysis