Flexural behavior investigation of steel-GFRP hybrid-reinforced concrete beams based on experimental and numerical methods

摘要

Due to their superior corrosion resistance and strength-to-weight ratio, GFRP (glass fiber reinforced polymer) rebar are widely used as reinforcement for concrete structures, but the brittleness of GFRP and their inferior bonding performance with concrete needs to be addressed. Hybrid reinforcement is a strategy to address the brittleness of GFRP rebar, but the inferior bonding performance may cause inaccuracy in the performance prediction. To determine the effects of bonding performance on the flexural behavior of GFRP- and hybrid-reinforced concrete beams and compare their flexural behaviors, both types of beams were prepared and subjected to four-point bending tests in this research. Their flexural capacities from the experimental results were then compared with the theoretical results. Additionally, the bond-slip relation between the GFRP rebars and concrete was obtained by means of pull-out tests, and an FE model based of the bond-slip results was developed to simulate the flexural behavior of the beams. From the experimental results, the hybrid reinforcement was shown to be able to control the beginning of cracking and reduce the maximum crack width by over 50% in concrete compared that of to GFRP reinforcement at the same load level. The flexural behavior of the hybri-dreinforced beam can be accurately predicted by the theoretical and FE methods. For the GFRP-reinforced beams, the theoretical method overestimates the flexural capacity by 9%; according to the results from the FE simulation, inclusion of the nonlinear bond-slip constitutive relation between the GFRP rebar and concrete helps to mitigate the underestimation of the mid-span deflection from 14.4% to 2.1%.