The Curved Cable-Stayed Bridge Directrices Design Method for Maximizing Structural Efficiency, and its Application to Footbridges.

This paper describes the principles, analysis and capacities of the axial-deck method developed in research on the optimization of the curved bridges directrices takin place at the UPM university in Madrid. The axial-deck method focuses on the two main structural challenges of curved cable-stayed bridges: the horizontal component of the load introduced by the stay cables on the deck; and the big torsion forces in the deck due to the unbalanced cable-stayed system. Hitherto, these problems have been addressed, either by optimizing the position of the tower and its geometric characteristics, or by modifying the morphology of the stay-cable system. Very little has been written about the possibilities of linking the structural behaviour to the deck directrix. This paper starts by describing the ideal solution equations, without considering the structure as statically indeterminate. Then, based on these equations, it follows the evolution of the method to a nonlinear iterative system. This evolution allows designs to be developed that consider the flexibility relation of all the structural systems involved in the problems. Finally, the method is validated with the redesign of two existing curved pedestrian bridges from prestigious engineering firms and the paper concludes with a structural behaviour analysis of all designs. [ABSTRACT FROM AUTHOR]