Bifurcation and large-deflection analyses of thin-walled beam-columns with non-symmetric open-sections

Non-symmetric thin-walled open-sections are used extensively in metal structures. The behaviour of such sections is usually complex because their shear centre and centroid do not coincide, and as a result, they are often susceptible to lateral-torsional and/or flexural-torsional buckling. This paper develops an efficient and robust computational framework for practical application, including a refined beam-column element for non-symmetric sections, a cross-section analysis algorithm for determining pertinent properties of open-sections, and an Updated-Lagrangian (UL) solution method for large deflection analysis. Details of the derivation of element stiffness matrices and the related numerical procedures are provided. Several examples are given that demonstrate accurate results from its implementation within the educational structural analysis software MASTAN2.