The Method And Performance Of The Prestressed Cfrp Reinforcing Steel Research

Compared with the traditional strengthening technology using Carbon Fiber Reinforced Polymer (CFRP), the strengthening technology using Prestressed CFRP has a series of merits. Considering the difficult of prestressed strengthening, develop a prestressed CFRP exerting and anchor system that can be easily applied in practical projects. Put forward a new method in the prestressed CFRP flexural reinforcement. Through the tests of 7 steel beams, we validated the practicability of this new method, the main works and achievements are as follows:1. In the experimental research of this paper, the magnitude of the stress of the prestressed CFRP and end-anchor are taken into consideration. Experimental results indicate that the strengthening technology using prestressed CFRP can improve the load capacity of steel beams and enhance section stiffness.2. Test and analyze the stress losses after exerting pretension to CFRP sheet. Test results show that 90% of the prestress loss can be completed in the first 10 hours. After that the strain was stable.The rationality and correctness of the theoretical expressions were verified by comparison of the analytical results with the experimental ones about the effective strain and camber deflection.3. The steel beams strengthened by the prestressed CFRP are analyzed with the theory of plasticity. Thus, the formulas about the bend strength of the tested beams are derived. The effect of secondary loading on the normal section flexural load-bearing capacity is also analyzed. Furthermore, the formulas about the deflection of the tested beams are also proposed through the continuous double integral method and the virtual principle. The results of theoretical analysis are in good agreement with the experimental ones.4. In this paper, analyses and tests are performed to investigate the overall effect of releasing pretension in Prestressed FRP strip bonded on steel beam flexural members, including stresses on the FRP, stresses on the interface,and at the cross-section of a beam, effective prestresses and prestress loss, and camber of the beam as well.Such research would be essential for further research and development of the strengthening technique of bonding Prestressed strip and establishment of corresponding design theory.