Extension of modal decomposition approach for buckling analysis of thin-walled lipped channel columns: Local, distortional, flexural and torsional modes

摘要

This paper presents a new version of the modal identification method previously proposed by the authors. The method is aimed at experimental tests of lipped channel columns but may also be applied to numerical columns. The first version of the method considered only three main deformation modes: local, symmetric distortional and minor axis flexural global modes. In this new version, anti-symmetric distortional and flexural-torsional modes are included in the formulation and original expressions for local mode are improved. The inclusion of new modes does not alter the procedure to perform the modal identification of the first version. In short, simple displacement functions are assumed for each buckling mode and through an error minimization process the participation of each mode in a generic deformed shape of the column is assessed. The new version of the method is validated against numerical results from Generalized Beam Theory (GBT) for columns undergoing D-G interaction and applied to experimental results of lipped channel columns.