BUCKLING OF COLD-FORMED SECTIONS UNDER PURE AXIAL LOADS USING cFSM.

Cold-formed sections usually failed in three basic modes, or classes: i) local, ii) distortional, and iii) global, in addition to other modes which, are formed from the interaction of these basic modes. In this work the different buckling modes of two frequently used sections such as simple lipped channel and sigma sections have been studied using the finite strip method. In addition a new developed method based on adding constrained matrix to the finite strip general stiffness matrix has been used to study the pure buckling modes alone, and also quantify the percentage of these pure modes in the general deformed shape. Results reflect that the critical distortional failure mode usually accompanied by small percentage of local and global modes. Also, sigma sections have buckling strength higher than that of simple lipped channel sections.