The Experimental Study Of Stiffness Of Concrete Beams Reinforced With Carbon Fiber Under Service Load

In recent years, with the improvement of the theory of reinforcement and the material price reduction, the technology of CFRP (Carbon Fiber Reinforced Polymer/Plastic) reinforced concrete structure has been widely used in practical projects. As the light,high strength,corrosion,construction convenient, etc of carbon fiber materials, carbon fiber reinforced concrete structures in civil engineering field has become a hot issue. Many of the existing studies focus on the ultimate bearing capacity of the reinforced beams, and there are few researchers investigate the performence of strengthened beams in the normal use. For this reason, in this article, the author does some research to the stiffness of the CFRP strengthened beams in the normal use through experimental study and finite element simulation.In the actual reinforcement project, the original structure has already withstand a certain load, so reinforced structure is in the state of the secondary load. This paper does some experimental studis on20strengthened beams including direct reinforcing beams and reinforcing beams under secondary load.And on the basis of experiments, the author makes an analysis of CFRP strengthened beams about its failure mode, crack development and the changes of deflection. The experimental results reveal that the strain on the section of CFRP strengthened beams is also according with flat section assumption, and the flexural capacity has been significant improved.The carbon fiber can effectively suppress the crack development and improve the stiffness of strengthened beams in the normal use. The initial damage has certain effect on the stiffness of strengthened beams.Based on the experimental study and finite element simulation, the formula of CFRP strengthened beam’s stiffness is derivated, and the rationality and practicality of the formula are proved by experiment.