Research On Bearing Capacity Of Quadruple-C Built-up Section Cold-formed Steel Columns Under Axial Compression

Quadruple-C built-up section cold-formed steel column is a mainly structural member consisting of four single C-sections connected by self-drilling screws. This paper mainly describes the detailed study resulted on axial load carrying capacity of Quadruple-C built-up section cold-formed steel columns by tests and numerical analysis, and the corresponding proposed design method is proposed.At first, the single C-section and Quadruple-C built-up section experimental models were tested, which had different slenderness ratio. The trial device, test method and full test course as well as the analysis of test result are introduced in details. And the working and destruction mechanism of Quadruple-C built-up section column is concluded in this part. The results of study show that the load carrying capacity of Quadruple-C built-up section column is four times larger than single C-section.After that, nonlinear finite element analysis involving geometric large deformation, materials nonlinear and contact problem is used to simulate test models under axial load in this paper. From the comparison of computer analysis with experimental results, the finite element model is more accurate. Then simplified finite element models of Quadruple-C built-up section column were set up, and the parametric study analysis was carried out to mainly determine the effect of slenderness ratio, spacing of screw and the width to thickness ratio. The results of the study indicate that the axial load bearing capacity of the Quadruple-C built-up section column increases when the slenderness ratio and the width to thickness ratio decreased, but the spacing of screw is not a main factor.Finally, based on the test and the numerical analysis, the design rule and the simple corresponding design method are brought forward. Two modified methods are proposed. Compared with the ANSYS and the test results, the proposed methods indicate high degree of accuracy. Furthermore, the suggestion to the modifying of the current GB50018-2002 is put out in this paper.