Arganzuela Helix Footbridge

ABSTRACT The Arganzuela Footbridge is a helicoconical spatial truss consisting of two single-span bodies spanning 117 and 96 m over the Manzanares River and the Arganzuela Park in Madrid, Spain. It connects two residential neighborhoods and provides access to the park for both pedestrians and cyclists. The innovative main structure of both the bodies is a conical spatial steel truss of circular section, with curved diagonals and straight longitudinal chords, all of them inscribed in two tronco-conical surfaces. The diagonals run along four helixes, which may be grouped into two families of contrary directions. The geometrical arrangement thus generated responds to the architect's aesthetic purpose. This configuration determines the structure of the footbridge bodies that—although have an adequate overall depth in relation to the span and, being a truss, a favorable structural type for a longitudinal structure, lose part of this favorable disposition due to the curving of the diagonals, which introduce undesirable bending stresses in the diagonals. In addition to the unusual shape and dimensions, the foundation is very complex and is greatly conditioned by the existence of underground motorway tunnels and sewers.