Lateral torsional instability of I-beams considers the relative displacement of the unstable compression flange to the stable tension flange. It is commonly assumed that little or no distortion takes place between the two flanges. In this paper, an approach is proposed whereby the section properties that control lateral torsional buckling are adjusted to allow for the influence of cross-section distortion, by the use of simple spring models representing the relative stiffness of the flanges and the web. The model is developed for elastic, inelastic, and plastic cases and compared with the results obtained from finite element models developed by other researchers. A method of quantifying the lateral distortional buckling resistance of I-beams is of particular importance in the hogging moment region of continuous composite beams; the ability of the proposed model to deal with this complex problem has been previously demonstrated by the authors. In this paper, the proposed model is used to illustrate the influence of distortional buckling on doubly symmetrical I-sections.Key words: lateral, distortional, I-beams, elastic, inelastic.
DISTORTIONAL BUCKLING RESISTANCE OF THIN-WALLED PROFILES MADE OF STAINLESS STEEL
