Commissioned by the Ajuntament de la Comtal Vila de Ripoll, north of Barcelona in the Pyrenees, Le Devesa Footbridge was designed in 1989 and realized between August 1990 and July 1991. This pedestrian bridge, accommodating a height difference of 5 meters (16.4 feet), spans the Ter near the center of Ripoll and connects the area of La Devesa with the railway station. A canted steel arch spanning 44 meters (144 feet) is employed to carry the loads of the walkway from the existing retaining wall across to a new concrete pylon — a total distance of 65 meters (213 feet).
As with the Gentil Bridge project for Paris, steel tension arms lying within the plane of the arch take the walkway loads. These arms are set at an angle of 65 degrees, so that their tensioning includes both horizontal and vertical components. While the vertical component stems from the dead and live loads, the horizontal component is developed by a cross truss, which lies directly beneath the walkway and prevents it from distorting laterally. Because the weight of the timber-surfaced deck is not centered beneath the arch, it will tend to rotate, together with the tension arms, into a position of equilibrium below the arch.
This rotation is prevented by the torque of the tubular steel spine of the bridge, which collects torsion at each strut and delivers it to the springing points: the pylon and the retaining wall. The tension arms brace the plane of the arch, preventing it from buckling. As gravity loads tend to deflect both walkway and tension arms, the arch is displaced to a more vertical position, slightly stiffening it and protecting it against buckling.
1989 - 1991