Research On The Axial Pressure Properties Of CFRP-CFST Short Columns

Since the new century,in order to meet the needs of the contemporary heavy-load,ultrahigh and large-span building structures,making our country’s researchers and scholars for the study of new components increasingly rich.The building components needed for the construction of this structure must meet the requirements of large bearing capacity,light weight,and able to withstand the harsh environment.Based on the above conditions,a new composite structure—the composite structure of carbon fiber reinforced plastic(CFRP)and concrete filled steel tube(CFST)is proposed in this paper,which is based on FRP confined concrete,FRP sleeve concrete and CFST.CFRP-cfst is a composite structure formed by taking concrete as a filler and then wrapping and pasting CFRP on the surface of a steel tube in a specific way.The composite structure has the advantages of carbon fiber and concrete filled steel tube at the same time,namely,the plasticity of the CFRP is enhanced,and the corrosion resistance of the steel tube is improved.At the same time,the cost can be saved and the steel consumption can be reduced,so that the invention has a very wide development prospect.However,the three materials that constitute the CFRP steel tube concrete composite structure are not uniform and nonlinear,which means that the mechanical analysis of the composite structure has become a difficult problem.In this paper,based on the existing research results of CFRP-cfst composite short column axial compression behavior of the theoretical analysis and ANSYS finite element simulation analysis,the main research contents are as follows:The confinement effect of CFRP and steel pipe on the core concrete and the joint working mechanism and stress process of the three materials are analyzed.The concept of the confinement effect coefficient of CFRP and steel pipe on concrete,the concrete strength improvement coefficient k and the confinement hoop force p are introduced.concept;based on the limit equilibrium theory,the calculation formula of the ultimate bearing capacity of CFRPCFST composite short columns under the action of axial load is deduced.Under the premise of theoretical analysis,a constitutive model that satisfies CFRP,steel tube and core concrete is obtained,and ANSYS finite element software is used to carry out nonlinear analysis on the axial compression performance of CFRP-CFST composite short column,and the thickness,thickness and thickness of CFRP are discussed.The influence of steel tube thickness,concrete strength grade and FRP type on the ultimate bearing capacity of the member;the obtained numerical solution and analytical solution are compared and analyzed,which proves the correctness of the theoretical deduction and the applicability of ANSYS finite element software to analyze such problems.The results of ANSYS simulation analysis show that compared with CFST,the three materials of CFRP,steel pipe and concrete can work well together,and the stiffness and ultimate bearing capacity of CFRP-CFST composite short column are greatly improved;With the increase of the thickness of the steel pipe,the yield strength and ultimate bearing capacity of the components also increase;with the increase of the concrete strength grade,the ultimate bearing capacity of the composite column can also be appropriately increased;due to the different material properties and mechanical properties of different FRPs,which will have different effects on the failure process.The existence of fiber cloth will indeed improve the bearing capacity of the component,and the constraining effect of GFRP on the core concrete is greater than that of CFRP.