INVESTIGATION OF DISTORTIONAL AND GLOBAL BUCKLING INTERACTION ON COLD FORMED STEEL LIPPED CHANNEL COLUMNS

The paper presents the investigation on cold formed steel lipped channel columns experiencing distortional and global buckling interaction under axial compression. Five cross sections are chosen based upon the limitations given in the draft IS 801 code. The cross section dimensions and length ensures equal distortional/global critical buckling loads, thus maximizing the distortional/global mode interaction effects through elastic buckling analysis using CUFSM software. The plate slenderness ratio (b/t) is within the limit to avoid local buckling. The ends of the columns are considered as Pinned-Pinned. The Numerical analysis are carried out by the finite element package ANSYS. Finite element model include the geometric and material non-linearities. Geometric imperfections are incorporated in the model by extracting distortional and global modes obtained from buckling analysis. Parametric studies are carried out by varying the yield stress as 250,350 and 550 N/mm2.Theoretical Analysis are carried out by Direct Strength Method DSM-AISI 100-2007 and Australian Standard AS/NZS:4600-2005.The results are compared and the effect of distortional and global interaction on ultimate strength is discussed.