Curved Bridges

Abstract

In contrast to road and rail bridges subject to high-speed traffic, the footbridge designer is literally allowed to design some pretty crooked structures. The low speed of the user opens up a spatial dimension and a multiplicity of forms. The deck can elegantly flow into the existing pathways and closely follow the adjacent elevations. The structure may also contain multiple approaches or decks in order to connect a network of pathways. If approach ramps are parallel to the central obstacle being bridged, a curved deck with a seamless transition from one approach to the other seems a natural solution. In some instances, the curvature of the deck and the resulting increase in length may be exploited to minimize the steepness of the bridge gradient, similarly to a spiral staircase. This opens a completely new level of design freedom, as the deck is not simply curved, but pylons become inclined, arches become tilted, and suspension cables create spatial silhouettes. The complex structural behaviour of these three dimensional structures is discussed here.