Influence of masonry strength and rectangular spiral shear reinforcement on infilled RC frames under cyclic loading

Abstract

The effect of two types of shear reinforcement of the concrete members and two types of masonry infills on the seismic performance of reinforced concrete (RC) frames was experimentally investigated. Six single-story, one-bay, 1/3-scale frame specimens were tested under cyclic horizontal loading, up to a drift level of 40. Bare frames and infilled frames with weak and strong infills were sorted into two groups: Specimens of group A had stirrups while specimens of group B had spirals respectively, as shear reinforcement. The frames were designed in accordance with modern codes provisions. The types of masonry infills had different compressive strength but almost identical shear strength. Infills were designed so that the infill lateral cracking load is less than the available column shear resistance. The results from the specimens of group A were compared with the results from specimens of group B, in terms of hysteretic response, ductility and energy absorption. From the observed responses of the tested specimens it can be deduced that the use of rectangular spiral reinforcement in the beam and columns, even in the case of strong infills, improved the seismic capacity of the examined infilled RC frames.