Experimental Study of Section Enlargement with Reinforced Concrete to Increase Shear Capacity for Damaged Reinforced Concrete Beams

This paper presents the results of reinforced concrete (RC) beams strengthened in shear by external reinforcement with RC or epoxy resin mortar. The test specimen was 2000mm long with a cross section of 150mmx200mm and after section enlargement the cross section was increased to 250mmx300mm, in addition, shear span to beam depth ratio of a/h(0) was 2.35. All specimens had the same geometry and were distinguished by the configurations of stirrup which was the primary test variable. No shear reinforcement was provided in the first phase of test, while in the second phase external RC or epoxy resin mortar was provided to enable failure due to shear. Experiments are undertaken to investigate the influence of preexisting damage, configurations of stirrup and different methods on the strengthened behavior and mode of failure. A group unstrengthened control beams were tested and failed in shear. In contrast to the control beam, all of the strengthened beams showed a significant improvement in their ultimate load capacity when they were failing in shear. The enlarged section with reinforced concrete can significantly increase the ductility and ultimate shear strength of a concrete beam. The method of section enlargement with RC is a high effective technique to enhance shear ability. An analysis for shear strengthening of beams using external reinforcement with RC has also been carried out as well.