Effect of stirrup, longitudinal reinforcement and steel fibers ratios on the torsional behavior of high strength concrete beams

Abstract

Many factors affect the torsional behavior of reinforced concrete beams, such as concrete strength, section dimensions, aspect ratio and concrete cover. Improvements in the torsional behavior of RC members had led researchers to investigate the effect of additional factors such as steel fibers, torsional reinforcement ratio and reinforcement arrangement. Based on the above, there is a gap in previous studies in taking effect of the distribution of stirrups with longitudinal reinforcement steel with steel fibers. Twenty-six reinforced concrete beams 250 mm wide, 250 mm high and 1150 mm long are investigated under pure torsion. Consider the effect of the steel fiber ratio, stirrup ratio and the longitudinal reinforcement ratio of high strength concrete. The results show the behavior of the concrete changing from brittle to ductile when increasing the ratio of the steel fiber registering the maximum torsional ductility index (3.98). The increase in the percentage of steel fiber to 6% caused a 105% increase in torque, but it was a slight increase in torque with respect to the percentage of steel fibers 2%. The optimum ratio of the steel fiber is 2% in terms of increased torque and workability, as it gave an increase in torque which reached 98.8%. Increasing the percentage of the stirrups to 2.5%, while the percentage of longitudinal reinforcement and the percentage of steel fiber was fixed, which led to an increase in torque which reached 130.4%. Increasing the percentage of the longitudinal reinforcement to 50%, while the percentage of stirrups and the percentage of steel fiber was fixed, which led to an increase in torque which reached 66.9%.