Research On Mechanical Performance Of GFRP-concrete Composite Beam With Gratings

Fiber Reinforced Polymer(FRP),has been achieving much attention since it was introduced into civil engineering,as its light weight,high strength and good corrosion resistance.With the development of technology and craftsmanship,as well as the continuous efforts of international and national researchers,the applications of FRP are becoming more and more widespread.In the structures of marine and other severe environments,it is considered the most suitable alternative to steel material at this stage.During the present researches of GFRP(Glass Fiber Reinforced Polymer)and concrete composite beams,although GFRP can take the place of steel in the tensile zone,as the main strengthening component absolutely,the GFRP bars cannot replace the steel bars in the compressive zone,due to its low compressive strength,the corrosion problems still cannot be properly resolved.In view of this,in order to improve the bearing capacity of the compressive zone and the composite beam,this paper comes up with a new form of GFRP and concrete composite beam,by placing a certain number of GFRP grating into the compression area.When the external load is applied,GFRP grating can not only resist the compressive load with the internal concrete,but also provide constraint effects to the internal concrete,which can improve its compressive strength.In this paper,the flexural capacity theoretical formulas of GFRP and concrete composite beam were derived,and parameter analysis was done via MATLAB.Then,by the simulation of four-point bending experiments via ABAQUS,the effects of GFRP grating size,thickness,and concrete strength on the composite beams have been studied,as well as the failure process of these composite beams,and the tensile stress of the transverse grating.Besides,a GFRPreinforced concrete composite beam was studied as a reference.The results show that the flexural capacity of GFRP and concrete composite beam has positive correlation with GFRP grating size,thickness and concrete strength,and the grating can provide certain degree of constraint effects on internal concrete.The minimum grating size in the paper is100mm×100mm,and the ultimate capacity of GFRP and concrete composite beam with gratings is 1.8 times that of composite beam with plain concrete,and 0.85 times that of composite beam with reinforced concrete,when the GFRP grid thickness is 6mm,and the concrete is C50.The shearing performance of GFRP and concrete composite beam was also studied in this research,and based on the related theories and literatures,the calculation methods of the critical load of web fracture and buckling is given: when calculating the critical load of anisotropic web fracture,the ratio of the maximum shear stress to the average shear stress was further explored by setting different GFRP lay angles;when calculating the critical load of web buckling,Holmes and Just model was amended via ABAQUS and MATLAB.