Post-buckling behaviour of prestressed steel stayed columns ∗ Daisuke Saito and M. Ahmer Wadee Department of Civil and Environmental Engineering, Imperial College of Science, Technology & Medicine, London SW7 2AZ, UK Abstract A steel column that is reinforced by prestressed stays generally has an increased strength in axial compression. A geometrically nonlinear model accounting for the post-buckling behaviour of the stayed column is formulated using the Rayleigh–Ritz method and then validated using the finite element method. It is found that the post-buckling behaviour is strongly linked to the level of the initial prestress. As the prestress is increased, the following different levels of the responses can be observed in sequence: initial Euler buckling that subsequently restabilizes strongly, the critical load increasing with a post-buckling path that is either stable or unstable, an upper limit for the critical load where the post-buckling is unstable after an initially rather flat response. These findings are important for designers aiming to achieve safer and more efficient designs for this structural component. Keywords Cable-supported structure; Nonlinear buckling; Rayleigh–Ritz method; Analytical mod- elling. 1 Introduction A prestressed steel stayed column (Figure 1) is a structural component that is reinforced by either cable stays or rods such that its strength is increased in axial compression. Ordinary columns have a propensity to buckle under axial compression primarily due to their char- acteristic of being slender. To counter this, the prestressed steel stayed column is equipped with pre-tensioned stay systems; these restrain the column buckling displacement through * Published in Engineering Structures : 30(5), pp. 1224–1239, 2008. 1