| Cold-formed steel(CFS)built-up I-section column was made by connecting the webs of two C-section basic members of a single limb with tapping screws.Because the structure of this kind of component is simple and widely used,which has attracted the attention of scholars at home and abroad.A large number of experiments and theoretical studies have been conducted on it,but there is still no clear universal design method,and the theoretical and application research on this kind of component is still in the preliminary stage.In view of this,on the basis of summarizing the real instability mechanism of the CFS split column,and considering the influences of "screw connection and cross-section plate group correlation",the research group extracted typical bearing capacity unit,and proposed a "superposition method based on bearing capacity unit".In this paper,CFS Built-up I-section column is taken as the research object to carry out experimental research,numerical simulation and theoretical analysis on the split-section column and the corresponding bearing capacity unit.Specific work contents are as follows:(1)The axial compression test was carried out on the CFS I-section split stub column and its corresponding bearing capacity unit,and the influences of section size and screw spacing on the mechanical properties,failure modes and deformation characteristics of the two specimens were studied.The relationship between bearing capacity element and CFS I-section split column is studied.(2)Finite element analysis of bearing capacity element members was carried out with the help of ABAQUS finite element analysis software.The finite element simulation results are compared with the experimental results to verify the reliability of the finite element modeling.On this basis,the variable parameters of the ratio of height to thickness,the ratio of width to height and the screw spacing were analyzed,and the influence of the three factors on the ultimate bearing capacity of local buckling of the specimen was revealed.(3)The effective width method and the direct strength method of the Chinese and American codes were used to calculate the ultimate axial bearing capacity of the split column studied in this paper,and the calculation results were compared with the bearing capacity of the experimental study and the finite element simulation results to analyze the applicability of the calculation method of the codes.(4)On the basis of experimental research and finite element analysis,the bearing capacity calculation formula of the bearing capacity unit and the split column was obtained by Origin software fitting regression,and then the proposed bearing capacity calculation formula was verified according to the test results.Finally,the calculation method proposed in this paper and the calculation method of Chinese and American codes are compared with the test results to verify its superiority and accuracy,which can be used as a reference for engineering practice. |
