Fragility Analysis of Masonry Infilled Reinforced Concrete Building by Coefficient Based Method

Abstract

Masonry infill Reinforced concrete frames are the most common type of structures used for multi storey constructions in the developing countries. Masonry infills, are the non-structural element, but provides resistance to the earthquake and prevent collapse of relatively flexible and weak RC structures. Seismic vulnerability of this type of structure has been studied in the earthquake ground motion. Present study focuses on the seismic fragility analysis of masonry in-filled (MI) reinforced concrete (RC) buildings using coefficient based method. The coefficient-based method, is a simplified procedure without finite element analysis, for assessing spectral acceleration demand (or capacity) of buildings subjected to earthquakes. This paper begins with validation study of the proposed coefficient-based method for masonry infilled (MI) reinforced concrete (RC) buildings. Two, four and six storey masonry infilled (MI) reinforced concrete (RC) buildings are designed considering a bare frame analysis, to estimates the inter-storey drift demand and periodic shift factor in response to the peak ground for different set of ground motions. Using coefficient based method both spectral acceleration and spectral displacement-based fragility curves under various damage states (in terms of IDR) were then constructed. Fragility curves obtained from the coefficient based method is compared with the SAC FEMA method at the collapse state and are correspondence well. The fragility curves obtained using both the method can provide a satisfactory vulnerability assessment for masonry infilled reinforced concrete (RC) buildings under different prescribed damage states (or performance level).