Research On Axially Compressed Behavior Of Closed Cross-section Built-up Section Cold-formed Steel Columns

The cold-formed thin-walled steel closed cross-section split column is composed of 2C-shaped basic components and 2 hat-shaped basic components through self-tapping and self-drilling screws.In this paper,the axial load performance and failure mode are studied through axial compression test and finite element simulation,and on the basis of existing code calculation methods and related theories,a suggested design method for the axial compression bearing capacity of the studied split column is proposed,the specific work is as follows:(1)The axial compression test of 18 closed cross-section split columns with different parameters is carried out,the test specimens,test devices,test methods,and the failure process and failure mode of the test specimens are introduced in detail,and the test data obtained are summarized and analyzed.Preliminary understanding of the axial compression performance of the cross-section split column.(2)The ABAQUS finite element software is used to refine the modeling of the test specimen,and the mutual contact and boundary conditions of the models are set according to the real test conditions,and the finite element results are output and compared with the test results to verify the modeling method adopted.Feasibility,to provide a reference for follow-up research.(3)Reasonable simplifications of proven finite element modeling methods and verification of their accuracy.The simplified model was used to study the influence of specimen slenderness ratio,web width-thickness ratio and screw connection spacing on the axial compressive bearing capacity of cross-section composite columns.And collate and analyze relevant data to provide support for follow-up theoretical research.(4)The effective width method of my country’s "Technical Code for Cold-Formed Thin-walled Steel Structures" and the effective width method and direct strength method of the North American AISI code were used to calculate the axial compressive bearing capacity of the test specimen and the slenderness variable parameter specimen,and the results of the code were compared and analyzed.Test results and finite element results.On this basis,the design method of the axial compression bearing capacity of the cross-section composite column is discussed,and finally,based on the effective width method of the North American Code,a suggested design method for the axial compression bearing capacity of the cross-section composite column is proposed.and verify its accuracy.