GBT-Based Buckling Analysis of Cold formed Steel Built Up Section Columns

This paper presents the first results of a research plan concerning the use of Generalized Beam Theory (GBT) to assess the global-distortional-local buckling behavior of cold-formed steel builtup members. Each individual profile is modeled using a GBT-based finite element, to keep the advantages of the unique modal-based GBT kinematic description while, as a first approximation towards more realistic simulations, the discrete fasteners are modeled using constraint equations. To provide evidence of the potential and advantages of the proposed approach, namely concerning its ability to provide in-depth information on the mechanics of instability in built-up members, several illustrative examples are presented and discussed. For comparison and validation purposes, results obtained with refined shell finite element models are provided and a virtually perfect match is invariably found.