Architect:
Santiago Calatrava - Zurich.
Constructeur:
Santiago Calatrava - Zurich.
The Alamillo Bridge forms a dramatic landmark, pointing the way to the site of the 1992 Seville Exposition. A single inclined pylon removes the need for backstays in the asymmetrical cable-stayed solution. Traversing the Meandro de San Jeronimo of the Rio Guadalquivir in Seville, the 250 m long Alamillo Bridge is perhaps the most controversial and dramatic of Calatrava's bridges to date. Originally conceived as one of a symmetrical pair of bridges approximately 1.5 km apart, the 142 m high steel and concrete inclined pylon marks one of the main entrances to Cartuja Island, site of the Seville Expo 1992. The germ of the idea for the structural system of the bridge can be seen in Calatrava's sculptures, such as Toros (1985), which he uses to explore statical problems. Here the dead weight of the inclined pylon counter-balances the weight of the bridge deck to which it is attached by cable stays.
To support the bridge deck a torsionally rigid hexagonal box girder spine 200 m long runs along the centre. This carries the pedestrian footway, on its top flange, above the level of the two carriageways that are supported on steel ribs, 12.5 m long, cantilevered from the central spine. There are openings between the ribs to separate the carriageway decks and the main spine beam thus allowing the twin stay cables to be attached at low level to both sides of the box spine and light to penetrate through the deck. More transparency is achieved by cutting away a triangular section of each rib web adjacent to the box spine, thus separating completely the tension and compression zones of the cantilevers. A tie element within the box spine joins the tensile flanges of the ribs and the compressive flanges are connected by the lower flange of the box girder.
