Study On Axially Compressed Behavior Of Built-Up Cold-Formed Thin-Walled Steel Multi-Limb-Section Columns

Cold-formed thin-walled steel structure has the advantages of reasonable section shape,good mechanical properties,high utilization rate of steel,reasonable economy and so on.With the continuous development of cold-formed thin-walled steel structures,the commonly used single-limb or double-limb built-up cold-formed thin-walled steel columns have been unable to meet the requirements of high bearing capacity due to their relatively poor stability.To improve the stability and bearing capacity of single-limb column and double-limb column,a new cross-shaped built-up cold-formed thin-walled steel multi-limb-section column is proposed.Specifically,through theoretical analysis and experimental research,the axial compressive properties of the built-up section column will be studied.The process is as follows:(1)Axial compression tests were conducted on single-limb c-section column and built-up cold-formed thin-walled steel multi-limb-section column of different lengths,and the rationality of the built-up section form was determined by the failure characteristics and test results.(2)Finite element analysis of ABAQUS was used to model and analyze the test specimens according to the actual measured size,and the test failure characteristics,test results and finite element analysis results were compared and analyzed,so as to verify the reliability of finite element analysis and the accuracy of the test.(3)Based on the finite element analysis and the test results,the finite element variable parameter analysis of the built-up cold-formed thin-walled steel multi-limb-section column will be carried out,including the ratio of slenderness,the ratio of web height to thickness and screw spacing.The results show that the ratio of slenderness and the ratio of web height to thickness have great influence on the axial bearing capacity of the built-up section column,while the change of screw spacing has little influence on the axial bearing capacity of the component.(4)The axial bearing capacity of built-up cold-formed thin-walled steel multi-limb-section column was calculated according to the relevant calculationmethods of the Chinese code and the American code AISI,and the calculated results of the code were compared with the test results or the finite element analysis results.Because the effect of actual imperfection cannot be considered by using the ideal nominal size,there is a certain error between the finite element analysis results of components with different the ratio of slenderness and the calculated results of the specification.Finally,in a certain range of application,a simple formula for calculating the axial bearing capacity of built-up cold-formed thin-walled steel multi-limb-section column with modified coefficient is presented.Through the research in this paper,it is also proved that the integrity of the new cross section column is good,the spacing of the screws is reasonable,the load bearing capacity combination multiple is much higher than the section combination multiple,So,the efficiency is higher,and the larger the ratio of slenderness,the more significant the effect is,and the higher the material utilization rate is.