Study On Compressive And Torsional Behavior Of Concrete-filled Steel Tubular Members With Hollow Sandwich Of Square Steel Tubes

The hollow sandwich steel tube concrete is a composite member formed by pouring concrete between two concentrically placed steel tubes.In this composite structure,the compressive performance of concrete and the tensile performance of steel pipe can be utilized,and the respective advantages of steel pipe and concrete can be fully utilized to form a composite structure with high bearing capacity,light weight,good ductility and fire resistance.In actual engineering,this combined structure can not only satisfy the building’s lighter weight,better bending and torsion resistance,but also withstand greater vertical bearing capacity.In order to explore the mechanical properties and failure mechanism of the hollow sandwich steel tube concrete under compression and torsion,this project designed 12 square-set square hollow sandwich steel tube concrete and 12 round-set square hollow sandwich steel tube concrete members.Among them,the square-set square hollow sandwich steel tube concrete is to study the mechanical properties and failure mechanism under compression and torsion,while the round-set square hollow sandwich steel tube concrete is to explore the mechanical properties and failure mechanism of components under compression and torsion in actual engineering.From the analysis of 24 sets of data,the ultimate bearing capacity and ductility of specimens with different section forms,different axial compression ratios and different steel ratios are obtained.The main research work of this paper includes the following parts:(1)Systemically to expound the characteristics of hollow sandwich steel tube concrete,to understand the research results of hollow sandwich steel tube concrete at home and abroad,and to find the theoretical analysis and test plan for hollow sandwich steel tube concrete.(2)Compression and torsion experiments were carried out on 12 square-set square hollow sandwich steel tube concrete and 12 round-set square hollow sandwich steel tube concrete.The main parameters of different section forms,external section dimensions,length,axial compression ratio and hollow ratio are tested and analyzed.(3)The experiment was modeled and analyzed by finite element software,and the torque-angle curve in the simulation and the torque-angle curve in the experiment were compared and analyzed.The results show that the two curves are in good agreement,thus verifying the accuracy of the finite element simulation.(4)Through the analysis of 24 sets of test data,the ductility performance under different axial compression ratio and hollow ratio under different cross sections is obtained,which provides reference for future scholars.