Experimental study on flexural behaviors of FRP and steel bars hybrid reinforced concrete beams

Abstract

To investigate the flexural behaviors of Fiber-reinforced polymer (FRP) and steel bars hybrid reinforced concrete (Hybrid-RC) beams, twelve beams were designed and manufactured, including one steel bars reinforced concrete (Steel-RC) beam, one GFRP reinforced concrete (GFRP-RC) beam, and ten Hybrid-RC beams. The effects of FRP bars type, concrete strength, and effective reinforcement ratio on the flexural behaviors of Hybrid-RC beams were studied through experiments and compared with the predicted results of theoretical models. The research results indicated that when the reinforcement area and service load were the same, the crack width, deflection, ultimate bearing capacity, and ductility of Hybrid-RC beams were between Steel-RC and GFRP-RC beam. The flexural bearing capacity of Hybrid-RC beams might also be increased by using FRP bars with a higher elastic modulus or by increasing the effective reinforcement ratio; however, it would reduce the ductility of the beams. In contrast, increasing the concrete strength could simultaneously increase the Hybrid-RC beams’ flexural bearing capacity and ductility. The equation for calculating the stress of FRP bars in the ultimate state of Hybrid-RC beams was obtained by fitting regression based on the test results, and the equation’s predicted results and test results showed good agreement. In addition, the predicted results of the flexural behaviors of Hybrid-RC beams using the theoretical model agreed with the experimental results.

Keywords

• Concrete beam
• FRP bars
• Hybrid reinforced
• Flexural behaviors
• Ductility
• Theoretical model