Understanding Calatrava’s bridges: A conceptual approach to the ‘La Devesa-type’ footbridges

As a recent result of the modern structural mastery of developed societies, many designers concerned with aesthetics, most of them with low technical training, but with hardly any technical restriction to their creative freedom, have begun to collaborate with structural engineers. They play an increasingly important role in design teams, which are now interdisciplinary, mainly for short and medium-span bridges located in urban environments, where aesthetic quality may be a desired, or even the primary, objective. This paper is focused on understanding the complex structural behaviour of one of the most frequently built types of bridges born from this collaboration: the bridge composed of a straight deck supported by an eccentric inclined arch attached to its edge. This type of bridge was pioneered by the well-known Spanish engineer and architect Santiago Calatrava, who designed the ‘La Devesa’ footbridge. udy is carried out gradually. Firstly, the ‘classical’ arch bridge (with a vertical arch attached to the axis of the deck by means of a set of vertical hangers) is studied and taken as a reference. Then, the effect of moving laterally the vertical arch as far as the edge is described and analysed. After that, and keeping the arch attached to the edge of the deck, the effect of rotating the arch about a longitudinal axis is analysed. Finally, the effect of stiffening the hangers is discussed. The paper finishes by presenting some considerations about the structural response of these bridges and recommendations about their most suitable structural configuration.