Shear Strengthening Effect And Analytical Model Of RC Beams Reinforced By FRP Grid-FRCC

Reinforced concrete structure in the long-term natural environment and the use of the dual role of the environment,its function will gradually weaken,resulting in the structure of safety,applicability and durability will be reduced to varying degrees,thus affecting the safety of the structure or affect its normal use of functional requirements.At the same time,if the demolition and reconstruction will inevitably cause economic waste,so it is necessary to strengthen the structure.In view of the defects of CFRP strengthening method,such as easy aging,poor high temperature resistance and durability,and easy to reduce its bonding performance or even failure in low temperature and humid environment,it is not suitable for underwater structures and other humid environment.The FRP grid FRCC composite reinforcement method can greatly improve the durability,fire resistance,impact resistance and UV resistance of FRP grid,significantly improve the peel resistance,and avoid the obvious decline of bonding performance.In view of this,this paper will carry out the shear strengthening test and corresponding finite element analysis of RC Beams Strengthened with CFRP grid and ECC,further study the strengthening performance of RC Beams Strengthened with FRP grid and FRCC,discuss the influence of specific parameters of FRP grid,original beam conditions and FRCC materials on this kind of strengthening method,analyze the shear mechanism of RC Beams Strengthened with FRP grid and FRCC,and the influence on f The calculation formula of shear capacity of RC Beams Strengthened with RP grid and FRCC is improved to guide the reinforcement design of structures in the future.The main works have been taken as follows:1)Experimental study on shear behavior of RC Beams Strengthened with CFRP grid and ECC.A total of 7 reinforced concrete specimens were designed,including 1 original reinforced concrete beam,1 reinforced concrete beam strengthened by ECC only,and 5reinforced concrete beams strengthened by CFRP grid ECC composite.Based on the four point static bending test of RC Beams Strengthened with CFRP grid and ECC,the effects of grid section area,grid spacing,shear span ratio and FRCC material on the strengthening performance are discussed,so as to reveal the mechanical mechanism of RC Beams Strengthened with FRP grid and FRCC.2)Numerical analysis of shear behavior of RC Beams Strengthened with CFRP grid and ECC.The finite element analysis software ABAQUS / standard is used to simulate the specimen.The bond slip cohesion model is used to simulate the bond slip cohesion between the FRP grid ECC composite reinforcement layer and the concrete.The crack angle of the specimen is simulated according to the stress nephogram of the FRP grid.The accuracy of the finite element model is verified by comparing the finite element results with the experimental results.3)The calculation method of shear capacity of reinforced concrete beams strengthened with FRP grid and FRCC is presented.Based on the traditional truss model,the characteristics of the shear capacity calculation methods of FRP mesh and FRCC material in the existing research are analyzed and discussed.At the same time,according to the angle of main inclined crack,based on the test and finite element parametric analysis,the improved calculation formula of shear capacity of reinforced concrete beams strengthened with FRP grid and FRCC is proposed,and the relevant test data of reinforced concrete beams strengthened with FRP grid and FRCC are collected for comparison and verification.The results show that the improved calculation model can effectively predict the shear capacity of the specimens.