Research On Mechanical Performance Of GFRP-Concrete Beam Under The Influence Of Slip

In recent years,Fiber reinforced polymer(FRP)profiles have been gradually promoted and applied in the field of civil engineering due to its advantages of light weight,high strength,strong designability and corrosion resistance.Among them,glass fiber reinforced polymer(GFRP)profiles concrete composite beams are one of the economical and effective bridge forms.However,due to the large interface shear force,the deformation of FRP material and concrete material is not consistent,resulting in large slip.In order to study the influence of interface slip on the mechanical properties of gfrp-concrete composite beams.this thesis selected the FRP I-shear connector and combined with Abaqus to study the mechanical properties of gfrp-concrete composite beams under the influence of slip.The research results are as follows:(1)The formulas for calculating the deflection and flexural bearing capacity of composite beams considering the slip effect are analyzed and derived.The results show that the deflection of composite beams under the influence of slip is composed of bending deformation of composite beams,the shear deformation of FRP profiles,and the interface slip.Interfacial slip will reduce the flexural capacity of composite beams.(2)Twelve gfrp-concrete composite beams were designed.The slip and deflection values of composite beams were calculated and analyzed with Abaqus by changing the concrete strength,shear bond spacing,shear bond size and adhesive properties.the results show that the Two factors,shear bond spacing and adhesive shear performance,have the largest influence on the mechanical properties of composite beams.The reduction of shear bond spacing can increase the ultimate bearing capacity of composite beams by about 26%.The higher the shear strength of adhesive is,the higher the bearing capacity of composite beams will be,and the degree of improvement can reach21%.(3)The interface slip,deflection and strain of each composite beam were measured through beam test,and the experimental results were compared with the finite element calculation results.The results show that the experimental results are in good agreement with the overall trend of load-slip curve and load-deflection curve calculated by finite element method.However,with the increase of load grade,there is a significant gap between them.(4)According to the finite element results and experimental data,the shear deflection coefficient k_v and slip stiffness coefficient k_s are revised based on the original deflection calculation formula considering the influence of slip,and the bending capacity reduction coefficient lambda is fitted.The design and analysis method of interface shear capacity of composite beams is presented.