Test Research And Theoretical Analysis Of RC Beams Strengthened With Various FRP

At present, domestic and overseas research on concrete structure strengthened with fiber reinforced polymer (FRP) focus on carbon fiber polymer (CFRP), glass fiber polymer (GFRP) and aramid fiber polymer (AFRP). Basalt fiber polymer (BFRP) is a new type of reinforcement material, which owns slightly lower strength and better ductility than CFRP, and larger strength than GFRP. Moreover, BFRP has higher high temperature resistance than other reinforcement materials. Further research is imperative since the restricting number of studies involving BFRP in the civil engineering, as well as the diversity compared with traditional fiber. Due to most of the existing calculation model based on the RC beams strengthened with CFRP and the limit test results, it is essential to verify the feasibility on RC beams bonded with BFRP and the experimental results of this dissertation. Test results and theoretical analysis of RC beams strengthened with various FRP are discussed and investigated in this dissertation. Concretely the main research work and conclusions are summarized as follow:1. Based on the test results, the performance diversity between RC beams strengthened with BFRP, CFRP and GFRP and unreinforced RC beams is discussed, which includes the effects of bearing capacity, ductility and failure type caused by various FRP, loading history and arrangement of U-stirrup. Research shows that strengthened RC beams anchored with U-stirrup at FRP ends offer better reinforcement than that along the beam, and the beams bonded with BFRP exhibit higher bearing capacity than beams bonded with GFRP and better ductility than beams bonded with CFRP. When the reinforcement failure is determined by delamination of epoxy-concrete interface, the strengthening effects on pre-damaged beams are more obvious than intact beam.2. Flexural behaviors of RC beams strengthened with various FRP are simulated via software Ansys. From the aspects of bearing capacity, stiffness and ductility, failure type and initial loading, etc. test results and numerical results are compared. The finite element model adopted in this paper can be used to determine cracking loads, yield loads, the tendency of relevant deflection, the effects of pre-damage on the FRP strain and the valid ductile factors. It is demonstrated that the finite element model proposed in this dissertation is acceptable for simulating strengthened beams. 3. According to three typical algorithmic methods, Chen&Teng formula, China regulation and ACI guide, comparative analysis between calculation and test value indicate that:in the case of peeling failure mode, the strengthening effects of CFRP are overestimated by the three formulas. Reckoning results of Chen&Teng’s formula are much closer to the test results than the other two methods. When interface delamination is considered, Chen&Teng’s formula gives better solution, and both the results of the three computing methods and test indicate that the effects of pre-damage on the RC beams are not obvious.