Prestressed stayed beam-columns: Sensitivity to prestressing levels, pre-cambering and imperfections (original) (raw)

Buckling behaviour of prestressed steel stayed columns with imperfections and stress limitation

Engineering Structures, 2009

A steel column that is reinforced by prestressed stays, generally has an increased strength in axial compression. In the past, greater emphasis was placed on obtaining a higher critical buckling load. However, detailed knowledge of the post-buckling behaviour is important to ensure the safety and efficiency of the structure. The current work examines the buckling behaviour of a stayed column with geometrical imperfections, and stress limitation relating to possible material failure. A geometrically nonlinear model accounting for imperfect buckling behaviour of a stayed column was formulated using the Rayleigh–Ritz method, and then validated, using the finite element method. It is shown from these studies that the system tends to be most sensitive to imperfections at a prestress level that yields the highest critical load, and that the real maximum load capacity seems to increase as the prestress increases with a given configuration. The findings suggest that the optimal prestress should be greater than that found from using the previous convention that was based on linear analysis.

Post-buckling behaviour of prestressed steel stayed columns

Engineering Structures, 2008

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.

Design of prestressed stayed columns

2013

General design procedures for prestressed stayed columns with a single cross-arm system are presented. The accuracy of the proposed design expressions is confirmed by comparison with the results of physical experiments and validated finite element simulations. Reliability is assessed by following the approach set out in Annex D of EN 1990. The presented resistance expressions for prestressed stayed columns are a function of the system geometry, the level of initial prestress in the cables and the global imperfection level. Worked examples are also presented to illustrate the application of the developed design approach.

Optimal prestressing and configuration of stayed columns

Proceedings of the Institution of Civil Engineers - Structures and Buildings, 2010

A steel column that is reinforced by prestressed stays generally has an increased strength in axial compression. In the past, greater emphasis was placed on obtaining its higher critical buckling load. However, detailed knowledge of the post-buckling behaviour is important to ensure the safety and the efficiency of the structure. Although previous work revealed that the optimal design should be determined with the post-buckling response, the actual values of the optimal prestress had not been previously evaluated. The present work examines the issue of the true optimal prestress for stayed columns through proposed structural optimisation indicators involving both instability and material quantity measures. Non-linear finite-element analysis was performed to investigate the non-linear buckling behaviour, which gives values for these indicators. Through a comparison of these values, suggestions for the configurations for improving the structural efficiency are presented.