Numerical Study On The Bonding Performance Of Full Coral Aggregate Seawater Concrete With FRP Bars

The South China Sea Islands are mostly coral islands and reefs,which contain a lot of marine resources,which is of great significance to protect our legal rights and interests.In recent years,FRP reinforced full coral aggregate seawater concrete has been applied to the construction of islands and reefs with its excellent performance.The good bonding performance of both is the key to the collaborative work of FRP reinforced and all coral aggregate marine concrete members.Many bond slip models of FRP bars and ordinary concrete have been put forward by domestic and foreign scholars through drawing test and beam type test.However,it is still to be verified whether these models can be directly applied because of the difference of mechanical properties between coral concrete and ordinary concrete.In addition,due to the limitation of theoretical and experimental studies,the average bond strength can not fully describe the distribution of interfacial stress and strain.This paper first considers the influence of different factors to carry out the bond performance experiment of FRP reinforced coral concrete,then,based on the finite element model,the failure process of bond slip between FRP bars and all coral aggregate marine concrete is simulated by using the bonding element.After verifying the test value of the interface bond strength,the simplified coral concrete FRP bond slip model is used as the boundary condition to solve the problem The differential equations of slip and bond stress are given,and the stress-strain diagram of the interface from the loading end to the displacement end is drawn.The main contents and conclusions are as follows:(1)The results of drawing test of FRP reinforced full coral aggregate seawater concrete show that the longer the bond length is,the higher the bond force will be;with the strength of the whole coral aggregate seawater concrete,the average ultimate bond stress of the tensile specimens is raised,but the degree of improvement is small;the ultimate bond strength of CFRP bars is smaller than that of BFRP and GFRP,while the BFRP bars and GFRP Bars are less than those of BFRP and GFRP The maximum bond strength of the reinforced specimens is almost the same,and the bond force of CFRP is about 1/3 of the latter.(2)Based on the plastic damage model of ordinary concrete,the real stress-plastic strain relationship of coral concrete is derived,and the bond element is established to simulate the process of interface failure and slip,and the failure modes and rules of FRP reinforced coral concrete members are summarized.(3)The results of finite element simulation are analyzed,and the fracture energy and maximum bond strength of interface bond parameters are analyzed,and the accuracy of simulation is verified.The influence of bond length,reinforcement diameter and coral concrete strength on the interface bond strength was investigated.The results are in good agreement with the experimental results.(4)Based on the analysis of elastic theory,the differential equations of interface slip and bond stress are obtained,and a simplified bilinear bond slip model is established as boundary condition.The expressions of bond stress τ(x)and relative slip s(x)of reinforced concrete with FRP are derived.By origin graphics,the distribution of the relative slip and the bond stress of the interface are spread respectively.The theoretical solution is accord with FRP reinforced coral aggregate concrete.The results are close to the experimental values of the interfacial bond stress and relative slip.