Experimental and Theoretical Study on the Flexural Performance of GFRP-Concrete-Steel Composite Beams

A novel GFRP (glass fiber-reinforced polymer)-concrete-steel composite beam bridge was proposed to prolong the service life of bridges. In order to investigate the flexural behavior of the composite beams, four-point bending tests and push-out tests were conducted. First, GFRP-concrete-steel composite beams with different interface types were fabricated and tested. Experimental results indicated the concrete ultimate strain and the ultimate deflection were increased because of the confining effect provided by GFRP plates. The GFRP-concrete interface had no obvious effect on flexural stiffness and flexural capacity. The slip effect of GFRP-concrete-steel beams was similar to that of steel-concrete beams. The failure process of GFRP-concrete-steel beams was different from that of steel-concrete beams due to the effect of the GFRP plate. Then, push-out specimens were tested to investigate the slip effect between GFRP-concrete decks and steel beams. The effect of GFRP plates on the studs was insignificant because of the large stud hole, and a regression formula of load-slip relationship was presented based on the experimental results. Finally, finite element model and theoretical model were employed to analyze the deflection calculation method and the flexural capacity calculation method, respectively.