Stress Analysis Of FRP-concrete Interface

With the wide application of FRP materials in the field of Engineeringreinforcement. In recent decades, the domestic and foreign scholars have conducted a lotof research about the stress analysis of FRP-concrete interface. Many studies have shownthat the FRP-concrete interface often occurs debonding failures. Therefore, theFRP-concrete interface debonding is becoming the focus of the study.There are threeforms of debonding failures for FRP strengthening structure:the plate enddebonding(debonding failures of modeⅠ)、shear cracks induced debonding(debondingfailures of modeⅡ)、shear-flexure cracks induced debonding(debonding failures ofcomplexity of modeⅠand modeⅡ).This paper describes debonding definition、common failure types、affecting factorsand test equipment of different modes about the FRP-concrete interface debonding.Focus on the debonding mechanism of different modes on FRP-concrete interface. At thesame time, summarizes the debonding test results of complexity of modeⅠand modeⅡon FRP-concrete interface caused by shear-flexure cracks.Then the theoretical analysis are conducted on beam segment between two adjacentcracks for FRP reinforced beams. Based on the solutions conducted by the domestic andforeign scholars,this pater considered the shear forces and couple moments, thedebonding process of the FRP–concrete interface is discussed in detail, and closed-formsolutions of bond slip, interface shear stress, and axial force of FRP in different stagesare obtained. Experimental study confirmed the result of theoretical analyses.This paperreally disclosed the bond failure process of the FRP-concrete interface in the multiple ICdebonding beams as the externally applied load increases.Because most of the FRP-concrete interface are in the stress state of failures ofcomplexity of modeⅠand modeⅡ in practical engineering. In order to better study thedebonding failures of complexity of modeⅠand modeⅡ on FRP-concrete interface. Asimplified mechanical model of beam segment between two adjacent cracks is proposed.Saint-Venant theory and numerical simulation method verified the correctness of thissimplified mechanical model. The simplified mechanical model of beam segment wassimulated through the Finite element analysis technique of ANSYS. Parametric studiesare further carried out to investigate the effect of the stress levels of FRP、the thickness ofFRP sheet、the thickness of adhesive layer、FRP-concrete constitutive laws and the lengthof beam segment. Combined with the results of the existing experimental studies,three-dimensional finite element analysis model are conducted used the geometry parameters and material parameters of the beam specimen. Compared the results of finiteelement analysis with the test results, proved the correctness of this simplifiedmechanical model and the feasibility of this finite element analysis method. In order tomake a better research, The author proposed some improvement measures.Finally,the author propose the model for single crack and the model for multiplecracks, an equation for the prediction of the ultimate force per unit width in the FRP toprevent FRP debonding is proposed. The model is of very easy application and very fewcalculations.The equation has been experimentally checked with beams of small andlarge size, representative of real structures.