Finite element analyses of failure of fiber reinforced polymer-concrete interface considering the concrete tension–compression softening effect

•Concrete tension–compression softening has been applied in interface failure.•The model replicated the generation of discontinuous interfacial micro-cracks.•The model reflected the phenomenon of interfacial shear stress reversal.•The model effectively predicts the shear failure behavior of the interface. The concrete near the shear failure surface of the FRP (fiber reinforced polymer)-concrete interface is subjected to both tensile and compressive biaxial stress. However, existing finite element methods of the interfacial failure behavior of FRP-concrete interface to describe the tension–compression softening effect of concrete failure are not sufficiently accurate, and some detailed results may not be reflected. To address these issues, a finite element analysis method is proposed that accurately considers the tension–compression softening effect on concrete failure. The effectiveness of the method is demonstrated through analysis of literature data from experiments on plain concrete failure, FRP-concrete interface shear, and three-point bending. The method accurately reflects the generation of interfacial discontinuous micro-cracks, the oscillation singularity of stress field near the interfacial crack tip, the phenomenon of interface mismatch, the dispersion observed in the bond-slip curves, and the phenomenon of interfacial shear stress reversal. Moreover, this finite element analysis method is applied to the double shear experiments of the fully-bonded FRP-concrete interface under different boundary conditions, and the reasons for the different failure modes observed in the specimens are explained. The results indicate that considering the biaxial effect on concrete failure strength in numerical analysis can more accurately and comprehensively describe the shear failure behavior of the FRP-concrete interface.