Study On Axial Compression Performance Of Concrete Filled Steel Tubular Columns With Inner Casing Connections

The concrete filled steel tube column has good mechanical properties and is widely used in engineering practice.However,because of the restriction of transportation and construction conditions,the construction of concrete filled steel tube column must be piecewise.It is not conducive to the efficient development of the project.In order to reduce the field welding work of the concrete filled steel tube column,this paper puts forward two kinds of joint construction method of concrete filled steel tube columns with inner casing connection.Study.(1)Based on the axial compression test data of the concrete filled steel tube column,the damage morphology and stress characteristics are analyzed,and the casing is set as the test parameters in different lengths.The test results show that after the component reaches the limit load,the failure begins first from the end of the concrete filled steel tube column,and gradually extends to the middle of the column to reach the splice.The structure area stops,the two kinds of joint structure nodes effectively resist the damage,and meet the requirements of the concrete filled steel tube column-column connection,and the node area is not damaged under the limit load condition.The length of the inner casing has significant influence on the joint.With the increase of the length of the inner casing,the better the safety and stability of the joint.The connection of the inner casing strengthens the hoop action of the joint,and improves the ultimate bearing capacity of the component.(2)Adoption includes specification AISC,BS5400,Eurocode,ACI,AIJ and some calculation methods proposed in the literature.The axial compression bearing capacity of the inner casing pipe concrete column is calculated.The ultimate bearing capacity of the test is compared with the calculated value.The reliability of the structure is analyzed by three different calculation methods of bearing capacity,and some suggestions are given for the value of the casing in the construction practice.The comparison results show that in engineering,the inner casing length of the inner sleeve connecting the concrete filled steel tubular column can meet the needs of 10% of the length of the column.(3)A simplified finite element model of the bolt connection form is established,and the finite element software ABAQUS is used to simulate the work performance of the inner casing joint.The effect of the change of the inner casing length on the bearing capacity of the member is studied,so that the axial pressure of the tubular column-column splicing node in the concrete filled steel tube column is subjected to the axial compression.Force mechanism analysis to create conditions.