Restoration and enhancement of the fortified system and architectural promenade
As part of a larger plan of projects for a sustainable urban development, the Municipality of Pisa has given importance to the valorisation of the monumental fortification complex, with a series of projects aiming the conservation of the ancient walls and the public use of the walkaway. One of those projects was a steel footbridge to join two parts of the walkaway which were separated in the 20th century to let a street enter the town centre from via San Francesco, consisting of a reticular spatial structure with a double cross-shaped upper beam and a single T-shaped lower beam to form a triangular shape; the lower beam follows a circular curvature, thus forming a variable-height truss which gets larger towards the ends on a 15.5-m span. The constraint scheme is a fixed bearing to both sides; no sliding bearings were used in order to maintain the simplicity of the bearing, considering that the temperature does not provide significant hazards for the structure. All elements were welded at the smith workshop and bolted to an end plate on the building site.
The footbridge rests on the ramparts via a RC foundation plinth, which receives the efforts transmitted to the walls by the bridge and transmits them to two pairs of RC foundation piles whose upper head is buried inside the plinth.