Analysis Of Flexural Stability Of Cold - Formed Thin - Walled Steel Strip With Stiff

With the section of cold-formed thin-walled become more and more complex, they become more prone to distortional buckling, also the bearing capacity and the critical buckling stress become more uncertain, so the traditional effective width method can not meet the design requirements, component-based whole section of cold-formed thin-walled, and distortional buckling, direct strength method has showed its huge superiority, this method only needs solving the buckling mode of failure and the elastic buckling of load, then the calculation results into the buckling mode of the direct strength method formula, can get the ultimate bearing capacity of cold-formed thin-walled.Through the finite element analysis of section parameters, and the research of channel on the flange stiffened by linear distortional buckling of flexural members. Found that when the panel thickness is1.5mm, all the flange unstiffened cold-formed thin-walled local distortional buckling, only some of the flange stiffened cold-formed thin-walled local distortional buckling, the buckling mode makes the bearing capacity of cold-formed thin-walled has fallen sharply; The other panel thickness, all the flange cold-formed thin-walled distortional buckling, when the web/flange(H/B=2), some of the flange unstiffened cold-formed thin-walled local distortional buckling. Increased stiffener. height and the thickness of sheet metal can substantially improve the bearing capacity of cold-formed thin-walled, but with the increase of flange width, the stiffener height and thickness increase weakened on the flange support. Based on the above, based on the original direct strength method of distortional buckling of the DSM formula, fitting the cold-formed thin-walled component suitable for flange of the modified DSM formula. Select a certain amount of the flange stiffener, calculate by DSM formula and the formula of the original, then analysis results with finite element method, found that t the modified formula is more accurate.Through the finite strip method of cold-formed thin-walled channel on the flange bending member elastic buckling stress of parametric analysis shows that the stiffeners, the local buckling component elastic stress increased by4.5%～52%, the elastic distortional buckling stress range is-1.22%～14%, and the flange stiffener can lead to failure modes of components changes, making it easier to send the distortional buckling. By sheet elastic buckling stress formula of flange distortional buckling coefficient KBD and the local buckling coefficient KBL, through the analysis of the effect of parameters on the thickness, found that high KBD and edge width to thickness ratio, web depth and width of the flange and stiffen er is linear relation. KBL and web curling and flange was basically linear, high thickness and stiffening rib is two times than the function relation. On this basis, the elastic distortional buckling of cold-formed thin-walled channel are established for flange under pure bending stress simplified formula for calculating stress and local buckling force and elastic. And select a certain number of flange cold-formed thin-walled channel components were calculated, through the analysis and finite strip program results found, two simplified formula calculation error is very small, can meet the accuracy requirements.