In the presence of the project’s various players, heritage curator Stéphanie Quantin and Philippe Prost praised a shared capacity for innovation and thanked the Group’s different entities, from Eiffage Génie Civil to Via Pontis.
Our high-performance fibred concrete BFUP, prestressed by post-tensioning, was the obvious construction material for this 120 m pseudo-elliptical box-girder in 3 spans covering 60 metres and cantilevered over 10 m. It comprises 49 reinforced arch segments of 3.45 m x 2.52 m x 0.80 m, some of which weigh nearly 10 tonnes, and its walls are only 10 cm thick.
BSI's structural capacities include excellent resistance to compression, but the product also brings other essential qualities to the project. It is mass-dyed an intense anthracite grey, making the structure directly visible, and offers a perfectly smooth finish. Its tensile strength capacities make it particuarly suitable for slender elements like the overhang, whose cantilevered point was streamlined from 4 cm to just 2 cm. 
This outstanding engineering structure was built in under a year, benefitting fully from the prefabrication of its components during site preparation time. These were delivered and assembled like a Meccano kit, and the structure was then prestressed by Via Pontis’s dedicated teams.
Apart from the original prototype, some beautiful models of design and construction details were also built of BSI® for the occasion and are now accessible to the general public in the modern and contemporary architecture gallery on the 2^nd floor of the Cité de l’Architecture.
Cité de l’Architecture et du Patrimoine
Galerie d’architecture moderne et contemporaine
45 avenue du Président Wilson
Paris 16^e
M° Iéna ou Trocadéro