Flexural and Serviceability Behavior of Steel, GFRP, and Steel-GFRP Hybrid Reinforced Beams

Concrete beams reinforced with a combination of steel rebars and glass fiber-reinforced polymer (GFRP) rebars can offer enhanced ductility, serviceability, and durability compared to those reinforced with the same total number of steel or GFRP rebars. This paper presents the flexural and serviceability behavior of steel-GFRP hybrid reinforced concrete (RC) beams. A total of four reinforced concrete beams, including two control beams, one reinforced with steel rebars and one with GFRP bars, and two steel-GFRP hybrid beams were tested under a four-point bending setup. All the beams were reinforced with four 20 mm (No. 6) rebars placed in one layer. The ratio of GFRP to steel reinforcement was the main parameter investigated. The experimental results of the beams were analyzed and compared in terms of flexural capacity, yielding load, and deflection. Based on the experimental results, steel-GFRP hybrid RC beams exhibited a higher ultimate strength than the steel RC beam but a lower ultimate strength than the GFRP RC beam. Moreover, the deflection at the same load level increased by increasing the GFRP to steel reinforcement ratio in the cross section. In addition, the results showed that the GFRP to steel reinforcement ratio significantly affects the flexural behavior of hybrid RC beams. Finally, the moment capacity of the beams was calculated using the fundamentals of section analysis, which showed very good agreement with the experimental results.