PERFORMANCE EVALUATION OF RC BUILDINGS WITH AND WITHOUT INFILL WALLS

Abstract

Reinforced Concrete frames with infill walls as partitions are a common practice in India and many part of world. The infills are generally considered as a non structural element and the buildings are designed as bare frame, without considering the strength and stiffness contribution of the infills. However, field evidence has shown that, during earthquake these infill wall affect the response of the structure and the behaviour of infilled frame is different from that predicted from bare frame structure. In this respect, a comparative study between the bare frame buildings and infilled frames has been carried out with respect to dynamic characteristics, capacity curves, performance point, yield pattern, member forces and drift at performance levels, with the help of pushover analysis. The diagonal strut approach is adopted for modelling masonry infill walls. It has been observed that the addition of infills increase the stiffness and strength of structure under lateral loads, while deformation capacity reduces substantially as compared to that of the bare frame. The yield pattern shows that, in infilled frame yielding of masonry strut takes place before frame elements. It also has been observed that high axial forces are exerted in columns due to trussed action of infills as a result of which bending moment gets reduced in the columns.