Theoretical And Experimental Study On Flexural Reinforcent Design Of FRP Based On Component Fuse Theory

The carbon fiber reinforced sheet has the advantages of light weight,high strength,corrosion resistance,etc.In the engineering,the prestressed CFRP reinforcement technology has been more and more widely used.The load-carrying capacity,material utilization rate,crack resistance and stiffness of the prestressed CFRP-reinforced components are significantly improved;however,the ductility of the strengthened components is significantly reduced,and the failure modes of the components are changed,and concrete crushing is likely to occur.Destruction,CFRP and bond slippage between components and CFRP are broken and broken.The above failure modes have no obvious signs before failure and the failure process is rapid.It is a form of brittle failure.The bearing capacity of the components is rapidly reduced and cracked.Insufficient development.In order to solve the problem that there is no obvious omen before the failure of the reinforcement member,this paper proposes a design method of bending reinforcement based on the component fuse theory:the reinforcement method can obviously emit the fracture through the fuse when the actual reliability index of the component is lower than the target value of the design.The early warning signal is convenient for the project maintenance personnel to find and take countermeasures in time.This method can relax the requirement of the reinforcement ratio of the component,and the influence of the fuse fracture on the bearing capacity of the component is negligible.Based on the design method of flexural reinforcement,four reinforced concrete beams strengthened with prestressed CFRP plates were tested for bending resistance,and finite element simulations of reinforced concrete beams strengthened with six prestressed CFRP plates were carried out on the basis of the test.Analysis,main research contents and research results are as follows:（1）Proposed a prestressed FRP bending reinforcement design method based on fuse theoryBy attaching a fuse to the reinforcing member of the prestressed FRP plate,the reinforcing member is issued with an early warning signal by breaking the fuse before the failure,thereby solving the problem that the FRP reinforcing member has no obvious omen before the destruction.Through the theory of flat section assumption and equilibrium equation,the design method of prestressed FRP plate bending reinforcement based on component fuse theory is deduced.The parameters such as reinforcement ratio,reinforcement amount and initial prestress are strengthened by experiment and ABAQUS simulation.The internal force redistribution,deformation,crack development and bearing capacity of the components under different conditions verify the correctness of the proposed theory.（2）Reasonable value of recommended safety reserve indicatorsCombined with China’s current norms,this paper analyzes the basic bearing capacity safety reserve index and equivalent safety reserve index selected in this paper,and gives the recommended range of values for strengthening elastoplastic components:basic safety reserve index of approximate ideal elastoplastic model The value is:K₀≈1.5;the basic safety reserve index of the ideal elastic model is:K₀≈2.0;the basic bearing capacity safety reserve index of the enhanced elastoplastic model is:1.5≤K₀≤2.0.The equivalent safety reserve index of the ideal elastoplastic model is:K_eq≈2;the equivalent safety reserve index of the traditional reinforced concrete members approximated by the ideal elastoplastic model is:K_eq≥2.5;ideal elastic model The equivalent safety reserve index value is:K_eq≈3.0;the equivalent safety reserve index of the enhanced elastoplastic model is 2.0≤K_eq≤3.0.（3）Determine the yield point of the component and give the recommended value of the design parameters of the reinforcement design methodThe combination of the farthest method and the mapping method is used to determine the early warning point of the reinforcing member as the yield point of the member,instead of simply yielding the material as the yield point of the member.Based on the experimental,theoretical and ABAQUS simulation analysis,the design parameters recommended for the reinforcement design method based on the component fuse theory are given:the basic bearing capacity safety reserve index is"1.5≤K₀≤2.0";the bearing capacity safety reserve index is"1.5≤K_F≤2.0";the value of the increase factor γ_r of the bearing capacity is:"1.0≤γ_r≤2.2".