Finite Element Analysis Of Axial Compression Behavior Of Steel Tubular Recycled Concrete Composite Columns

In the process of building industrialization and housing industrialization,a large amount of concrete is used in our country.Recycled concrete technology can significantly solve these problems,but recycled concrete has low strength and elastic modulus,which affects its use to a certain extent.Some scholars refer to the technology of concrete-filled steel tube column to form recycled concrete-filled steel tube column.However,under the action of fire,the steel tube outside is easy to lose its bearing capacity,and the exposed steel tube outside is also easy to corrode.Therefore,this paper USES the form of ordinary concrete composite column for reference and adds recycled concrete outside the steel tube to improve its performance and form recycled concrete composite column of steel tube,so as to provide reference for engineering application.The main work and conclusions of this paper are as follows:1.The research status of recycled concrete-filled steel tubular composite columns is introduced in detail.The finite element modeling process is analyzed,and the correctness of the modeling is verified based on the test curve.2.A finite element model was established for 39 composite column specimens of recycled concrete filled steel tubes(35 specimens of external and internal circular dimensions and 4 specimens of external and internal dimensions).The main parameters studied were replacement rate of recycled concrete,wall thickness of steel tubes,diameter of steel tubes,diameter of longitudinal bars,spacing of stirrups,length-fineness ratio,concrete strength and different sectional forms.Through the finite element analysis,the failure form and stress distribution of the specimens were obtained,and the load-displacement curves of the specimens were obtained.Based on the load-displacement curves,the axial compression performance indexes of the specimens,such as ductility,energy consumption and stiffness degradation,were analyzed.The results show that the replacement ratio of recycled concrete,steel tube wall thickness,steel tube diameter,length-to-width ratio,concrete strength and different cross-section forms have great influence on the mechanical performance of recycled concrete filled steel tube composite columns,while the longitudinal diameter and stirrup spacing have little influence on themechanical performance.The aspect ratio is an important parameter affecting the bearing capacity of the specimen.3.On the basis of parameter analysis,the specimen of recycled concrete is obtained by nonlinear fitting reduction factor and slenderness ratio and stable coefficient of recycled concrete filled steel tube is deduced from the formula of axial compression bearing capacity of composite column,and then set up considering and slenderness ratio dual recycled concrete axial compression bearing capacity calculation formula of reduction factor.