Investigation of the ductility of RC beams : based on AS3600 design

Reinforced concrete beams are likely to experience high bending moment when subjected to ultimate loading. Curvature ductility is a well accepted index of expressing the ability of the structure to sustain high load intensities. The member ductility – rotational ductility in case of bending moment - arises from section ductility e.g. curvature ductility. Issuing of the new version of AS3600 and emergence of 500N rebar steel have introduced new possibilities in RC member design in Australia. Concerns on 500N rebar steel ductility due to its lower elongation strain compared to other ductile steel require a more careful focus on the design process. This study is an attempt to quantify the section ductility of RC beams designed based on the latest Australian code using 500N rebar steel. Different section dimensions as well as various concrete compressive strengths were used in the study. The nonlinear moment-curvature analysis carried out for designed cases. As expected heavily reinforced sections exhibit lower ductility comparing to those reinforced lightly. In addition increasing the section height and the concrete compressive strength have positive effects on curvature ductility. It is found that the curvature ductility for considered cases ranges between 2.0 and 12.0. It seems that for small sections, the curvature ductility is low and is less than predicted. Generally speaking, more research is necessary in order to verify the ability of 500N rebar steel in providing reasonable ductility required for load redistribution and other requirements in limit state design