Research On Model Test Of Rectangular Beam Reinforced By CFRP Plate And Steel Plate

Prestressed CFRP plate reinforcement and repair of concrete structures has gradually matured in the application of increasingly extensive reinforcement projects.Although the reinforcement of prestressed CFRP plates has increased the bearing capacity of old bridges,the rigidity of CFRP plates to the main beams has been limited,resulting in reinforced bridges.The deformation of the structure under the action of the load is still large,especially for the bridge with the span over 20 m,the prestressed CFRP plate contributes less to the stiffness of the component.In order to solve the shortcomings of prestressed CFRP-reinforced bridges,the prestressed CFRP plates and the bonded steel plates are combined to reinforce the method.The stiffness of the steel plates is used to reduce the structural deformation of the bridge structures under load.This paper focuses on the test data of the cracking load,yield load,ultimate load,mid-span deflection,failure mode,ductility,etc.of reinforced concrete structures reinforced with prestressed CFRP plates reinforced concrete beams,prestressed CFRP plates and bonded steel plates.Compared with the theoretical analysis,the feasibility and rationality of the method for reinforcing the combination are demonstrated.The specific research work and achievements are as follows:1.Review the research results and research status of CFRP plate and steel plate reinforcement technology both at home and abroad,and demonstrate the necessity of the feasibility of combined reinforcement technology of prestressed CFRP plates and steel plates.The basic principles,reinforcement characteristics,service conditions,construction requirements,and research status at home and abroad of prestressed CFRP plate reinforcement technology,bonded steel plate reinforcement technology,and combination reinforcement technology are respectively introduced.2.Design three groups of test beams,namely the unreinforced reference beam,the CFRP plate with bonded prestressed reinforcement and the combined reinforcement of bonded prestressed CFRP plates and steel plates.Analyze the bearing capacity and cross The mid-deflection,co-stress,and whether it satisfies the flat-section assumption are also verified and the reliability of the wedge-clamping anchor is also verified.The main findings are as follows:(1)When the reinforced concrete beam is subjected to high external loads and the deformation is large,the CFRP plate and the beam body are normally subjected to load after being peeled off,and the CFRP plate has neither mechanical damage nor relative slipping with the anchorage device.The reliability of the wedge-shaped clip-type anchor with anchorage is proved.(2)Reinforced concrete flexural members strengthened with prestressed CFRP plates increased the cracking load,yield load,and ultimate load of the structure,and the increase rates were 47.37%,65.63%,and 57.50%,respectively.The combination of pre-stressed CFRP plates and steel plates increases the efficiency of the above three indicators by 110.53%,90.63%,and 78.75%,respectively.It is proved that the application of steel plates on the basis of prestressed CFRP plate reinforced concrete beams can greatly increase its cracking load,yield load and ultimate load.(3)Plot the load-deflection curve from the measured data to show that the prestressed CFRP reinforced concrete beam can improve the bending stiffness of the concrete beam and reduce the deflection under the same load level.On this basis,the steel plate is attached to the concrete structure to greatly improve the concrete structure.The overall bending stiffness and deflection at the same level of load are reduced.The structural rigidity improvement efficiency is related to the amount of reinforcement of CFRP plates and steel plates.(4)According to the strain study results of tensile reinforcement,CFRP plate,steel plate,and concrete under each loading condition,it shows that before tensile steel yield,whether it is prestressed CFRP plate reinforcement or prestressed CFRP plate and steel plate When the reinforced concrete beams are subjected to external loads,the tensioned steel bars,CFRP plates,and steel plates all meet the cooperative force.The height of the concrete beams meets the flat section assumption along the web,and the prestressed CFRP plates and the prestressed CFRP plates and steel plates are combined.After the reinforcement,the ductility of the concrete beam is reduced,and the mid-span deformation is reduced when the ultimate failure state occurs.(5)Based on the theoretical basis of ordinary reinforced concrete,the formulas for calculation of cracking load of prestressed CFRP plate reinforcement,prestressed CFRP plate and steel plate group and reinforcement are deduced,the formula of yield load and the ultimate load calculation formula(wherein the limit is derived The calculation formula for the load includes the calculation formulas for the three types of conditions: the ideal failure mode of the reinforced concrete beam,the failure mode of the lesser beam,and the failure mode of the super-reinforced beam.The theoretically calculated values are in good agreement with the experimental test data,which proves that it can be used to calculate the carrying capacity of actual reinforcement projects.(6)The theoretical calculation formulas for the flexural rigidity of concrete flexural members reinforced with prestressed CFRP plates and steel plates are deduced.The calculated values of the stiffness theories are in good agreement with the experimental test data and can be used to calculate the stiffness of actual reinforcement projects.