Research Of Seismic Performance On Double-cell Concrete-filled Steel Tubular Columns

The double-cell concrete-filled steel tubular column is new type of reinforced concrete-filled steel tube,which can solve the problem that the steel tube of conventional cross section with large aspect ratio rectangular concrete-filled steel tubular column prone to local buckling in the popularization and application and the confinement of the concrete is weak and so on.It obtains the advantages of simple structure,convenient construction,economical and reasonable,flexible layout and so on.It has a broad prospect of engineering application.In this paper,the seismic performance of double-cell concrete-filled steel tubular column is studied deeply.The main contents of this paper are as follows:(1)Two full-scale double-cell concrete-filled steel tubular columns are subjected to horizontal cyclic loading under constant axial pressure,and the damage process and the horizontal load of each stage are recorded in detail.Through the deep analysis of the failure process and test results of the specimen,the failure modes,bearing capacity,energy absorption capacity and ductility of the double-cell concrete-filled steel tubular columns with different axial compression ratios under the horizontal cyclic load are obtained,and the influence of axial compression ratio on the aseismic behavior of the double-cell concrete-filled steel tubular column is obtained by comparison and analysis.(2)Finite element analysis software ABAQUS is used to simulate the behavior of double-cell concrete-filled steel tubular columns under constant axial load and horizontal cyclic loading.The finite element model takes full account of the stress-strain relationship of steel and concrete under low cyclic reciprocating loads,the boundary conditions of components and the contact relationship between different materials.The finite element simulation results are compared with the experimental results,and the model results are in good agreement with the experimental results.(3)Based on the analysis of finite element models,the failure mode,material stress distribution and load-displacement relationship of double-cell concrete-filled steel tubular column under low cyclic reciprocating load is analyzed theoretically.The working stage of the double-cell concrete-filled steel tubular column is divided into elastic section,elastic-plastic section and failure section.According to whether the short-side steel plate of the compression side is buckled,the elastic section is subdivided into complete elastic section and approximately elastic section.Furthermore,the main factors influencing the seismic performance of double-cell concrete-filled steel tubular columns are studied by changing the axial pressure ratio,steel content and material strength of the model.(4)Experimental study and finite element analysis of the seismic behavior of double-cell concrete-filled steel tubular columns shows that the axial compression ratio has a pronounced influence on the ductility and energy absorption capacity of the members.In this paper,four kinds of mainstream concrete-filled steel tube calculation theory are compared,and according to the previous research results,the calculation formula of axial bearing capacity and the calculation method of axial compression ratio for double-cell concrete-filled steel tubular columns are proposed,and then compare the results of calculated with the results of finite element models to verify the correctness.