Flexural Performance and Design of Concrete Beams Reinforced with BFRP and Steel Bars

This study aims to investigate the flexural performance and design methods of flexural concrete beams reinforced with basalt fiber-reinforced polymer (BFRP) and steel bars. Eight concrete beams, which included six reinforced with a combination of BFRP and steel bars, one reinforced with only steel bars, and one reinforced with only BFRP bars, were constructed and then tested under four-point loading. For hybrid-reinforced concrete (RC) beams, two types of BFRP bars (ribbed and sand-coated) and different reinforcement ratios were considered. The test results are discussed in terms of the flexural capacity, reinforcement strain, deflection responses, and cracking behavior. Experimental results showed that the crack width of the hybrid-RC beam, obtained by adding BFRP bars in the concrete cover of the steel-RC beam, reduced by approximately 40% compared with that of the steel-RC beam, and the strength utilization of BFRP bars in hybrid-RC beams was higher than that in the BFRP-RC beam. Additionally, the cracking moment, nominal flexural strength, and midspan deflection of the hybrid-RC beams were predicted by using existing design models. The bond-dependent coefficients (kb) of the ribbed and sand-coated BFRP bars were assessed by using test data.