Effect of compressive strength and tensile reinforcement ratio on flexural behavior of high-strength concrete beams

Abstract

Nine reinforced high-strength concrete beams were tested to investigate the effect of concrete compressive strength and flexural tensile reinforcement ratio on load-deflection behavior and displacement ductility of cracked rectangular reinforced concrete beams. Concrete compressive strengths of 48, 78, and 102 MPa and tensile reinforcement ratios of 1.18, 1.77, and 2.37% were used. The results show that flexural rigidity increases as concrete compressive strength increases. Also, the transition of effective moment of inertia from uncracked to fully cracked section depends on flexural tensile reinforcement ratio. A previously proposed formula in the literature for the estimation of the effective moment of inertia is modified to consider the effect of reinforcement ratio and concrete compressive strength. Displacement ductility was investigated and it was found that, for a displacement ductility index of 3, the ratio ρ/ ρ b should not exceed 0.25 and 0.50 for concrete beams with concrete compressive strength of 102 and 48 MPa, respectively.