Research On Axial Compression Performance Of Thin-walled Concrete-filled Steel Tube Short Columns Confined By Tie Bars

At present,many improvement measures have been proposed to improve the ultimate bearing capacity and ductility and stiffness of concrete-filled steel tube at home and abroad.The relevant research and test results clearly show that the built-in transverse reinforcement in the concrete-filled steel tube can enhance the bearing capacity and ductility of the short column.Mechanical properties,but the research is not perfect,there are some shortcomings such as relatively low strength of the specimen material and single connection mode of the brace and steel pipe.In this paper,the volumetric stirrup ratio of the tie bars,the compressive strength of the concrete and the connection mode of the tie bars and the steel tube wall are used as experimental variables to study their influence on the axial compression performance of the thin-walled concrete-filled steel tube short column,so as to enrich the domestic constraints on the tie bars.Research on the axial compressive properties of thin-walled high-strength steel high-strength concrete short columns.The corresponding Abaqus finite element software nonlinear finite element analysis was carried out for each test,which proved the reliability of the finite element analysis.The main research contents are as follows:(1)According to the concrete strength grade,the axial compression test of 10 specimens in 2 groups of C60 strength and C80 strength is set to analyze the concrete strength,the volumetric stirrup ratio of the reinforcement,and the connection method of the reinforcement and the steel pipe wall.The influence of ultimate bearing capacity,stiffness,ductility and failure mode of concrete short columns.The results show that the strength of concrete,the ratio of stirrups and the connection method of the brace and the pipe wall have a positive effect on the ultimate bearing capacity of the specimen,while the ratio of stirrup and the connection method of the brace and the pipe wall have an effect on the stiffness and ductility of the specimen.Smaller.(2)The Abaqus6.14 finite element software was used to establish a threedimensional solid model of the test piece,and the Standard module of the software was used to perform a nonlinear finite element analysis under a pseudo-static force state.The stress-strain data curve and load-The displacement data curve and ultimate bearing capacity are compared and analyzed with each data curve generated by the finite element simulation one by one,and the correctness of the model is verified and the parameter analysis is performed.Parameter analysis shows that increasing the reinforcement will obviously increase the stiffness of the low concrete strength grade specimens in the elastoplastic stage and the ultimate bearing capacity of the specimens.(3)Analyze the mechanical properties of specimens such as bearing capacity,ductility,stiffness,etc.,expound the mechanism of the reinforcement of the mechanical properties of the specimens,derive the calculation formula of the ultimate bearing capacity of the built-in reinforcement thin-walled steel concrete short column,and carry out the formula verification.