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

摘要

Nine reinforced high-strength concrete beams were tested to investiate the effect of concrete compressive strength and fluxural 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 reinfrocement ratios of 1.18, 1.77, and 2.37/100 were used. The results shwo that flexural rigidity increases as concrete compressive strengh increases. Also, the transition of effective moment of inertia from uncracked to fully cracked section depends on flexural tensil reinforcement ratio. A previously proposed formual 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 ducility index of 3, the ratio ρ/ρ_b should not exceed 0.25 and 0.50 for concrete beams with concrete compressive strenth of 102 and 48 MPa, respectivley.