Experimental study of flexural behavior and serviceability of hybrid concrete beams reinforced by steel and G/BFRP bars

Abstract

In this paper, the flexural behavior and serviceability performance of concrete beams reinforced with hybrid glass/basalt fiber-reinforced polymer (G/BFRP) bars and steel bars were investigated. From the viewpoint of reducing the risk of steel corrosion, two kinds of hybrid reinforced beams were designed, eleven concrete beams including 3 steel-reinforced beams and 8 hybrid-reinforced beams were tested. The effect of the hybrid reinforcement ratio on the flexural performance was analyzed and the applicability of replacing steel bars with GFRP or BFRP bars in concrete beams was discussed. The results show that the ultimate bending moment of hybrid-reinforced concrete beam was about 91-97% of that of steel-reinforced concrete beam with the same reinforcement ratio. Since the reduction of the bearing capacity of hybridreinforced beam was small, it can be proved that it is feasible to replace the corner steel bar of concrete members with G/BFRP bars. For the serviceability performance of beams hybridreinforced with G/BFRP bars and steel bars, however, their deflection and maximum crack width were 20%-60% higher than that of steel-reinforced beams under the same load levels within the limit state of serviceability. It showed that the stiffness and crack resistance of hybrid beams weakened greatly. Finally, it was found that the FRP-to-steel ratio of bar areas had great influence on the flexural behavior and serviceability performance of concrete beams hybridreinforced with FRP and steel bars.