Scaling Effect on the Behaviour and Design of Prestressed Stayed Steel Columns

This study presents the results of a small-scale experimental campaign on prestressed stayed steel columns, subsequent numerical model validation and design guideline development. The majority of previous experimental studies have focused on large-scale systems, which are expensive and can be difficult to perform due to the required specialised experimental set-up, whereas small-scale experiments are less restrictive with both space and experimental set-up requirements. Also, existing design guidelines were developed from a single system scale, so have not been shown to be applicable to changes in geometric scale. Thus, the scaling effect on prestressed stayed steel columns was investigated to promote the use of small-scale experiments in the study of large-scale prestressed stayed steel column systems and update design guidelines for change in geometric scale. A total of 17 prestressed stayed steel columns and a control column with no cross-arms were tested. These tests investigated the symmetric and antisymmetric buckling behaviour as well as the interactive post-buckling phenomenon. These tests were designed to investigate the scaling effect on the behaviour of the system and to determine the optimal prestress level of prestressed stayed steel columns close to the transition point. A numerical model was also validated by the experimental results to perform a full geometric scaling comparison study and update existing design guidelines. It was found that small-scale structures are capable of representing the behaviour of large-scale prestressed stayed steel columns. Furthermore, it was shown that the highest efficiency in terms of the weight of materials is found close to the transition point between symmetric and antisymmetric buckling behaviour. Various scale systems were modelled numerically, and the results compared with existing guidelines, which resulted in low levels of accuracy. Therefore, existing design guidelines were updated using the validated numerical model and shown to yield more accurate results for the L/400 and L/200 imperfection levels.