Numerical Simulation Study On Bond Behavior Of FRP-masonry Interface Under Single Shear Action

At present,the bond model of the interface between FRP and masonry structure is mainly based on the bond model of the interface between FRP and concrete.At present,with the improvement of computer level,many scholars have simulated the bond between FRP and masonry structures through finite element software,which can reduce a lot of complex test work and provide more convenient conditions for the further study of FRP strengthened masonry.In this paper,based on the test data of 28 groups of FRP(CFRP and BFRP)reinforced masonry specimens,the numerical simulation study of FRP and masonry was carried out.The main parameters of influence were fiber type,adhesive length and width,and the type of substrate(standard brick and masonry).Numerical simulation of the bond between FRP and masonry is mainly focused on the nonlinear research of interfacial bond layer.In this paper,the bond layer is simulated in the form of zero thickness,the mechanical behavior of the interface layer is defined by the bilinear constitutive curve,and the traction and separation constitutive model in ABAQUS software is used to realize the input of the bilinear constitutive curve of the bond layer.The bilinear constitutive curve mainly contains three key parameters: interface bond stiffness,maximum shear stress and limit slip value.Based on the experimental strain,the value range of the maximum shear stress and the limit slip value is calculated by the difference formula.According to the limit test force and strain value,the curve parameters of the constitutive relation of bonding interface layer(interface bonding stiffness,maximum shear stress and limit slip value)were calibrated.Then the optimal parameters of the bifilar relationship curves of different samples are obtained.Finally,the formulae of interface stiffness,maximum shear stress and limit slip of bilinear constitutive parameters of bond layer of single brick sample are obtained through analysis and fitting.By introducing the influence coefficient of mortar,the formulae for calculating the interface stiffness,maximum shear stress and limit slip of the parameters of bilinear constitutive relation of the bond layer of the masonry sample are obtained.Based on the values of the constitutive relationship parameters of the interface bond layer,the numerical simulation limit test force of each specimen is obtained by re-entering the numerical model.Through the comparison error analysis with the experimental results,the model results are in good agreement with the experimental results.At the same time,the numerical simulation results and experimental results of the load displacement response curve are compared and analyzed,and the stripping process of the fiber is explained.Finally,the bond interface stress transfer is analyzed to further understand the bond stress transfer law between FRP and substrate.In this paper,the parameters are further refined,the influence of fiber modulus,bonding length,width and base strength on the ultimate bearing capacity is analyzed,and the recommended calculation formulas of effective bonding length and ultimate bearing capacity are respectively fitted.