Effect of the concrete compressive strength and tensile reinforcement ratio on the flexural behavior of fibrous concrete beams

Twenty seven reinforced concrete beams were tested to study the effects of steel fibers, longitudinal tensile reinforcement ratio and concrete compressive strength on the flexural behavior of reinforced concrete beams. Concrete compressive strengths of 49, 79 and 102 MPa and tensile reinforcement ratios of 1.18, 1.77 and 2.37% were used. The fiber contents were 0.0, 0.5 and 1.0% by volume. The results show that the additional moment strength provided by fibers was not affected by the amount of tensile reinforcement ratio. However, the concrete compressive strength influenced the fiber contribution significantly. The flexural rigidity increases as the concrete compressive strength and steel fiber content increases. The transition of effective moment of inertia from uncracked to fully cracked sections depends strongly on the considered variables. 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 as well as fiber content. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.