Flexural response of hollow high strength concrete beams considering different size reductions

Abstract

In this work, 14 reinforced concrete solid and hollow beams were tested under four-point bending test to evaluate the flexural behavior of hollow concrete beams. The experimental program focused on two main variables which are the size reduction percentage and the inclusion of steel fiber. In addition, the longitudinal reinforcement ratio and the presence of lateral stirrups were also within the investigated parameters. Four solid beams in addition to 10 hollow beams with central square holes with side lengths of 60, 80, and 100 mm were fabricated to evaluate the test parameters. These beams were either reinforced with 1% steel fiber or contain no fiber. The flexural performance of the beams was evaluated using the load–deflection behavior, flexural ductility, stiffness and toughness. In addition to the experimental work, analytical formulas were introduced to evaluate the cracking and peak loads of the hollow beams. The test results showed that ductility of hollow beams with size reductions of 16% and 28.4% was higher than that of the reference solid beam, while the ductility of the hollow beam with 44.4% size reduction was quite comparable to that of the solid beam. Moreover, the toughness values of the hollow beams were higher by 19 to 37% than that of the reference solid beam. Based on the obtained results, it can be concluded that hollow reinforced concrete beams with 1.0% steel fiber and with size reduction up to 44.4% can replace solid beams without suffering significant reductions in strength, ductility and toughness.