Finite Element Analysis Of GFRP Tube Confined Steel Reinforced Recycled Concrete Composite Columns Under Compression

With the development of urbanization,it is of green social value to make recycled aggregate from waste concrete blocks.However,recycled aggregate concrete has large internal pores and low strength.In order to make up for the shortcomings of recycled aggregate concrete,recycled aggregate concrete,glass fiber reinforced polymer(GFRP)and recycled aggregate concrete(RAC)were combined.A new type of GFRP tube confined steel reinforced recycled concrete composite columns is formed by the combination of section steel and other materials.Due to the good corrosion resistance and high tensile strength of GFRP tube,it can not only effectively protect the core concrete and steel,but also provide constraints for the recycled concrete in the core,so that the recycled concrete can improve its performance due to threedimensional stress and make up for the shortcomings of recycled concrete.In addition,the buckling of the built-in section steel is restrained by the outside,which effectively gives play to the working function of the section steel,so as to further improve the mechanical performance of the composite column.GFRP tube confined steel reinforced recycled concrete composite columns is a relatively new component.At present,the research on all aspects of the composite column is still less.In order to further explore the compression performance of GFRP tube confined steel reinforced recycled concrete composite column,the parametric analysis is carried out on the basis of the existing compression test of the research group,so the numerical simulation will be carried out by ABAQUS finite element software.On the premise of verifying the correctness of the finite element model,the full stress process of the composite column is analyzed,and the influence of different parameters on the compression performance of the composite column is studied through parameter analysis.The main contents of this paper are as follows:(1)Based on ABAQUS general finite element software,the finite element models of GFRP tube confined steel reinforced recycled concrete composite columns under axial and eccentric compression are established respectively,and the correctness and reliability of the finite element model are verified by comparing with the existing compression test results of the research group.(2)Based on the results of finite element analysis,the mechanical performance of GFRP tube confined steel reinforced recycled concrete composite columns under axial and eccentric compression is analyzed.The whole process of stress of composite columns is explored,and the stress development and deformation of GFRP tube,built-in steel and core concrete at different stages are studied.(3)Taking the steel ratio,steel strength,recycled aggregate replacement rate,GFRP tube layers and concrete strength as variables,the axial compression performance of GFRP tube confined steel reinforced recycled concrete composite columns was analyzed.The results show that increasing the steel content and steel strength has little effect on the axial bearing capacity and deformation capacity of composite columns;increasing the replacement rate of recycled aggregate will reduce the stiffness and axial bearing capacity of composite columns;increasing the number of GFRP tube layers and concrete strength can greatly improve the bearing capacity and deformation capacity of composite columns,with better ductility.(4)Taking eccentricity,concrete strength,steel strength and the number of GFRP tube layers as variables,the eccentrically loaded behavior of GFRP tube confined steel reinforced recycled concrete composite columns is analyzed.The results show that the stiffness and eccentric bearing capacity of composite columns will decrease with the increase of eccentricity,and the flexural deformation will increase;increasing the steel strength is helpful to improve the eccentric bearing capacity of composite columns,but the increase is limited;increasing the concrete strength and the number of GFRP tube layers is helpful to improve the eccentric bearing capacity and deformation capacity of composite columns.