| With the development of cold-formed steel, the composite member of cold-formed steel has been widely applied in the engineering projects during the last decades. The formed composite member still has the cold-formed and welding residual stresses which make great influence to the overall stability of the composite members subject to the axle center pressure force. Due to the complex working process of cold-formed composite member and complicated theory analysis, the research achievements are less on the influence of cold-formed and welding residual stresses to the member's overall stability, and even the results gained also have some shortages. So it leads to the lack of the design equation considering the impact of the cold-formed and welding residual stresses on the overall stabilityIn this paper, combining the study achievements on the cold-formed and welding residual stress, the distributions form of them are put forward. Applying the ANSYS and considering the impacts of the initial imperfection, the overall stability of 72 thick-walled double channels with welding composite section is analyzed, on the effect of the separate cold-formed residual stress and the combination of the cold-formed and welding residual stresses. The members are divided into three groups, each group with three different widths 8mm, 10mm and 12mm separately, meanwhile the members in same width have 8 different lengths.Supposing the residual stresses unchanged along the pole, the residual stresses transfer program by VB language solves the difficulty of initial stress programming in ANSYS when the elements are huge. This program is convenient to apply in every type ofmembers.Using the Oringin software to analyze the results, the φ value calculation equation is gained (relation equation between the λ and φ). Based on the dividing method ofthe curved line (parabola equation applied when slendemess ratio small while Euler hyperbola used when it large), the λ -φ curved lines fitted by Matlab software underdifferent conditions can be got.Analyzing and comparing the X-cp curved lines under different conditions, it is found that, with only cold-formed residual stress, the overall stability of thick-walled steel member subject to axial compression accords with the current specification. However, under the combined effects of the cold-formed and welding residual stresses, the result is a little lower than the specification. So for thick-walled double channels with welding composite section, the combined effects of the cold-formed and welding residual stresses shall be considered to assure the stability bearing capacity. A X - |
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