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Due to physical aging, chemical corrosion and social needs change, improve design standards and a variety of natural disasters, the impact of structural damage reduces the life of the building, civil engineering research in this area is one of the main problems faced. Reinforcement strength and durability to meet the requirements of the building extend the service life. Carbon fiber (CFRP) composite material used as a reinforcing material instead of the traditional, and there is outstanding advantages, so its reinforced concrete technology has a wide range of applications, and increasingly mature. This paper focuses on the initial load is large, concrete Beams force the situation, on the flexural CFRP reinforced concrete beams, beam capacity to improve the magnitude of deflection and crack. Experimental design of four identical sectional dimensions and the same reinforcement ratio rectangular concrete beams, which is not a reinforcement beam, the other three with different initial load and load in just pasted layer of the CFRP conditions tested. During the test, a record of each one loads the beam span deflection and steel, carbon fiber, concrete strain and cracks in the beam sides depict the development of CFRP rear spar observed failure modes, integrated analysis of the beams cracking load, yield and ultimate loads. The results showed that: Carbon fiber reinforced beam section better meet the plane assumption; compared with non-reinforced concrete beams, carbon fiber reinforced concrete beam, flexural capacity has greatly improved, crack spacing and width becomes smaller, indicating that the reinforcement Liang there is a certain rigidity to improve; in larger initial load, strain hysteresis larger deformation of the beam is large, the strength of carbon fiber and is not fully exploited. In the theoretical analysis: According to the ordinary reinforced concrete beam flexural basic theory and reference to existing research results, considering the initial strain on the reinforcement effect, focusing summarizes several existing CFRP strain hysteresis algorithm, and proposed method of calculation, and verify that this method is feasible. Capacity theoretical results agree well with the experimental results verify the capacity calculation method is feasible. Finally, using the finite element program ANSYS, CFRP flexural beams and reinforced concrete beams were unstrengthened nonlinear finite element numerical simulation, the calculated yield and ultimate loads basically consistent with the experimental results.
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