The Influence of Imperfections on the Strength and Stability of Cold-Formed Sigma Channels with Corrugated Flanges

摘要

Cold-formed, thin walled beams are popular structural members. They are made of thin, cold-rolled steel sheets by using cold-rolling or edge bending machines. The dimensional accuracy of those beams is dependent on manufacturing machines, which can be manually or numerically controlled, and the experience of their operators. If the cross-section of beam is complicated, the actual beams may differ from their idealized counterparts. In this paper the influence of actual imperfections on the strength of sigma channels with corrugated flanges was evaluated. The actual beam was scanned using a high resolution camera and then the generated cloud of 3d points was converted into a surface model using OPTOCAD software. The strength and stability of actual and ideal beams subjected to pure bending were analysed using Finite Element Method. The presented numerical model included material and geometrical non-linearity that is typical for thin-walled structural members. The obtained results, i.e. critical moment, stresses and deflections, were compared with each other. The influence of the beam length on the results was also evaluated.