Effects of using high-strength concrete on flexural ductility of reinforced concrete beams

Abstract

The complete moment-curvature behavior and flexural ductility of reinforced concrete beams made of normal- or high-strength concrete have been analyzed by a newly developed theoretical method that uses the actual stress-strain curves of the materials and takes into account the strain reversal of the tension reinforcement in the analysis. It was found that as expected the flexural ductility decreases with the tension steel ratio and increases with the compression steel ratio. However, the variation of the flexural ductility with the concrete grade is quite complicated; at fixed tension and compression steel ratios, the flexural ductility increases as the concrete grade increases but at a given degree of being under- or over-reinforced, the flexural ductility decreases as the concrete grade increases. In order to better reveal the combined effects of the steel ratios and the concrete grade, the flexural ductility has been plotted against the flexural strength for different steel ratios and concrete grades. From the graphs plotted, it can be clearly seen that the use of a higher grade concrete could increase flexural ductility at same flexural strength, increase flexural strength at same flexural ductility, or increase both flexural strength and flexural ductility.