Research On Compressive Behavior Of Concrete Columns Confined By GFRP Tubes With Geometric Defects

Along with tremendous development of architectural technology,fiber reinforced composites are applied in the construction industry gradually due to the unique properties of lightweight,high-strength and excellent corrosion resistance.Composite structures with FRP(Fiberglass-Reinforced Plastics)confined concrete ameliorates the stabilization of the FRP material when used independently,meanwhile,the core concrete maintains the triaxial-stress state under the constraints of FRP,which can enhance the compressive strength of components and the ultimate bearing capacity of composite structures effectively.So far several research results about the whole progress performance of FRP confined concrete columns under axial compressive load have been achieved,however,the research on mechanical behavior of GFRP confined concrete composite columns with geometrical imperfection,which may be caused by some special circumstances in the practical engineering,still has not been developed by now.In order to study the mechanical behavior of GFRP confined concrete composite columns under axial compressive load,this paper has conducted a series of works,the main content are as followed:On the basis of a summary of the experimental results related to FRP confined concrete columns,this paper uses the ABAQUS software to establish the finite element model of the non destructive GFRP confined concrete composite column under the axial compression condition,the correctness of the finite element model is verified by comparing with the whole process curves of the ultimate bearing capacity and load strain of each specimen.The correctness of the finite element model is verified by comparing with the ultimate bearing capacity and load strain full process curves of each specimen;with the concrete strength grade,the thickness of the GFRP tube wall,the location of reinforcement and the filament winding angle as the main parameters,twenty-four non destructive GFRP tube confined concrete column specimens are designed,based on the simulation results,the stress distribution,the ultimate bearing capacity and the full process curve of the load-strain process under the control of different parameters are discussed and analyzed.Based on the lossless model,the finite element model of GFRP confined concrete composite columns with geometric imperfections is established,and with the opening size,opening position,concrete strength grade,GFRP tube wall thickness,steel bar configuration and filament winding angle as the research parameters,thirty-two GFRP tube restrained concrete column specimens with geometric defects were designed,based on the finite element model,the axial compression performance of composite columns with geometric imperfections is analyzed thoroughly,and the effect of different parameters on the axial compression performance of composite columns is discussed.From a large number of simulation test rules,the bearing capacity of specimens with nondestructive and geometric defects increases with the increase of the strength of concrete,the thickness of GFRP tube wall and the ratio of reinforcement,but with the increaseof filament winding angle,the bearing capacity gradually decreases;as the size of opening increases,the bearing capacity of specimens with geometric imperfections decreases,and the location of openings has a slight effect on the bearing capacity of specimens with geometric imperfections.Finally,based on the analysis results,the relevant design suggestions for the GFRP constrained concrete composite columns with geometric defects are given in order to provide some reference for the design of practical engineering.