Effect steel reinforcement ratio on the behavior of RC beam without concrete at tension zone using truss-system reinforcement

Abstract

Massive exploration of the natural materials for producing concretes affect to the environment condition and global warming that may cause natural disasters. Therefore the using of the concrete materials should be as efficient as possible. According to its natural behavior of the concrete material, it is strong in compression and weak in tension. Therefore the contribution of the tensile stresses of the concrete to the flexural capacity of the beams is neglected. However, removing concrete on the tension zone affects to the decreasing of flexural capacity. Based on the previous studies, beam without concrete at the tension zone using truss-system reinforcement causes the tension crack near the supports. This crack might because decreasing the flexural capacity of the beam. One of the solutions to solve this problem is by strengthening the beams using steel reinforcements. Therefore, this study aims to investigate the effect of steel reinforcement near the supports on the behavior of beam without concrete at the tension zone using truss-system reinforcement. The parameter of this study was the length of the additional reinforcement near the support. It was varied into 40D, 60D and 80D, where D is the diameter of longitudinal reinforcement. The results indicated that the tensile cracks near the support could be avoided by adding the longitudinal reinforcement. Finally, the flexural capacity of RC beams without concrete at the tension zone can be increased.