Studies On FRP-Concrete Interface With Bond-Slip Law Which Contains An Exponential Softening

In the application of using fiber reinforced polymer (FRP) to strengthen reinforced concrete (RC) structures, the mechanic behavior and debonding process of FRP-concrete interface are the crucial basic problems. Based on the latest test results on bond-slip law of FRP-to-concrete interface, the mechanic behavior and debonding process of FRP-concrete interface are studied in this paper.Firstly, through the nonliner fracture mechanics, the analytical expressions of the interfacial shear stress, the axial normal stress in FRP and the load-displacement relationship at loaded end of FRP-to-concrete interface with single shear test model could be got. Thus the shear stress propagation and the debonding process of the whole interface for different bond lengths could be predicted.Secondly, a new interface bond-slip law after suitably simplifying the law would be acquired. Then the analytical solutions of the interfacial shear stress, the axial normal stress in FRP and the load-displacement relationship at loaded end of FRP-concrete interface with single shear test model were also got. And the shear stress propagation and the debonding process of the whole interface for different bond lengths under this simplified law could be predicted.Afterwards, through the analytical solutions of the two bond-slip laws, the influences of different FRP bond length and stiffness on the load-displacement curve, and the ultimate load were studied. The stress transfer mechanism, the interface crack propagation and the ductility behavior of the joint could be explained. And the similarities and differences between the two bond-slip laws were also studied.Finally, the single shear test model of the two bond-slip laws by the finite element software (ANSYS) were studied, and the load-displacement curve, the distribution of the shear and axial normal stress for different bond lengths were analyzed.On the basis of fully knowing FRP-concrete interfacial mechanical behavior which based on the two bond-slip laws, the full-range behavioral characteristic and the crucial factors of the FRP-concrete interfacial debonding problem can be further understanded, and it can provide a realiable theoretical basis for concrete strengthening technology by FRP.