Improvement in the Ductility of Over-reinforced NSC and HSC Beams by Confining the Compression Zone

This paper investigates the behavior of over - reinforced concrete beams with confinement in the compression zone to increase the beam ductility. To avoid brittle failure, the amount of tensile reinforcement should not exceed a certain limit proposed in most design codes. However, sometimes a large amount of reinforcement are used to decrease the depth of the beam. In this study, two types of confinement are used, rectangular ties and helix (spiral). An experimental investigation was carried out involving ten beams. The variables included the spacing between the ties in the compression zone, pitch of spiral and concrete compressive strength. Normal and high strength concrete (NSC and HSC) were taken into consideration. The results conclude that the ductility of over reinforced NSC and HSC beams can be improved by confining the compression zone with helix as well as rectangular ties. However, using helical confinement was more effective than rectangular ties.