Bois Canal Footbridge, development of a monolithic UHPFRC structure for an "ordinary" crossing near the Saone River

<p>The Bois Canal footbridge is an Ultra High Performances Fiber Reinforced Concrete monolithic structure, that tries to get the most of this materials’ proprieties, that’s to say its long-lasting durability, high compressive strength, lightness and environmental performance. The location of the project is typical of the Saone River 20th century short span footbridges. Nowadays it only remains disjointed masonry supports and an 11 meters long gap after the dismantle of the old wooden deck. The proposal for new footbridge draws on the current know-how in the Saone Valley, especially the presence of numerous fine sand quarries and prefabrication factories. It takes shape as a monolithic lateral-beam bridge made of UHPFRC. The footbridge is fully built in a prefabrication factory, then delivered and craned into place. It can be realised using only a formwork table for precast panels and punch dies made of wooden planks, leading to a low-cost structure adapted to this "ordinary" crossing. The beams shape is the result of both an architectural and a technical design. The variation of thickness optimizes the structure’s efficiency by creating a Vierendeel beam. The form of the punch dies echoes the Art Deco architecture of the early 20th century, which earned Pont-de-Veyle its reputation. The approach developed in this project aims at finding the right shape adapted to its context by drastically limiting the technical means involved and the resources. The comparative life cycle assessment of the footbridge shows a reduction by 80% of CO2eq between an UHPRFC structure and an equivalent aluminium structure.</p>