Research Of Shear Behavior Of Recycled Concrete Beams Reinforced By Carbon Fiber

The emergence of recycled concrete not only solves the problem of construction waste pollution,but also reduces the development and utilization of land resources in our country.A large number of scholars have studied the mechanical properties and durability of recycled concrete and the recycled concrete mixed with other materials,such as steel fiber recycled concrete,steel recycled aggregate concrete.With the increasing application of recycled concrete in engineering structures,when recycled concrete structure has been used for a number of years,both the evaluation and reinforcement of recycled concrete structure will become a more prominent issue.Based on the above understanding,this paper will study the shear behavior of recycled concrete beams strengthened by carbon fiber cloth.The load deflection curve,crack development and failure modes of the shear performance of recycled concrete beams on different carbon fiber cloth paste and paste layers have been studied by 5 scale model.At the same time,The numerical analysis of the shear performance of 8 recycled concrete beams in different carbon fiber cloth paste form,different paste spacing has been carried out.While the test results and the numerical analysis results has been compared.There are some main conclusions:1)The shear capacity of recycled concrete has been improved by the carbon fiber cloth.3.15 ~ 10.35% of the shear bearing capacity has been improved by single U type reinforcement method.11.58% ~ 27.90% of the shear bearing capacity has been improved by single U type +layering reinforcement method and 28.24% by double U-shaped reinforcement method.Under the same carbon fiber bonding method,the shear capacity of recycled concrete is larger,and the shear capacity of recycled concrete is larger.The shear bearing capacity of the concrete beams strengthened with the damage is not large.2)The shear deformation behavior of recycled concrete beams has been improved by carbon fiber sheet.The shear stiffness of the shear zone and the deformation in the middle span have been increased by the carbon fiber cloth,so that the shear strength of recycled concrete beams is improved.3)The development degree of the diagonal cracks in the shear zone of the recycled concrete beam has been decreased by the carbon fiber cloth.The corresponding load value of the first crack in the shear zone is increased by about 3% ~ 7.2%.The cracks distribute symmetrically,and develop to the middle and upper part of the bridge.Crack development between the shear zone and the middle span is more rapid,and the recycled concrete beam destroyed rapidly.So it should not be used in the project.4)The stress distribution of recycled concrete beam has been changed by the carbon fiber cloth.The more uniform t of carbon fiber cloth,the more uniform the stress distribution of the beams in the recycled concrete beams.the recycled concrete beam on type U + layering reinforcement method has the larger tensile region on the bottom and the mechanical properties of the material can be more fully play to the recycled concrete beam on type U reinforcement method.5)The shear bearing capacity of recycled concrete beams pasting carbon fiber cloth after prior damage is roughly same to not damage before.But the beams pasting carbon fiber cloth after prior damage will occur larger deformation and mainly rely on CFRP shear in the late failure stage.6)The shear capacity of recycled concrete beams strengthened with carbon fiber sheets is calculated.