Stability and bracing of thin-walled columns

A three-dimensional second-order analysis is used to study the effects of lateral and torsional brace stiffness on the elastic stability of doubly and singly symmetric thin-walled columns. The finite element formulation uses an iterative updated Lagrangian scheme to include the second-order geometric-nonlinear effects in the space frame element as well as the connection element, which is used to model the lateral and torsional braces of a column. A parametric study has been performed to investigate the effects of various lateral and torsional brace stiffness on the buckling strength of columns with singly and doubly symmetric sections. Results on interaction among initial imperfections, the lateral and torsional brace stiffness and the corresponding buckling strength of columns are presented. It has been found that columns with singly symmetric sections are very sensitive to the magnitude and direction of initial imperfections and brace stiffness.