The Section 8 of the A89 expressway crosses the valley of the Sioule River with a 991m long viaduct, 150m above the river.
- The” La Sioule” viaduct has 8 spans: 49m, 98m, 157.50m, 192.5m, 192.5m, 150.50m, 98m and 52.5m.
- The deck is a single box section construction with two 19.50m wide webs, built by the successive corbelling method on a form traveller.
- Three balanced cantilevers of 2×25 segments are 190m long and of variable height (10m on piers and 5.5m at mid-span). They are housed in three large double-shafted piers P3 – P4 – P5, which are respectively 82m, 120m and 135m high.
- The four balanced cantilevers making up the side spans 1 – 2 and 7 – 8 are of constant height, 5.50m, and have a maximum length of 120m (P2).
- The single-shafted lateral piers bear the deck by sliding bearing systems and have transversal seismic stops.
- The viaduct is founded on shafts of large diameter: four 5m shafts for the large piers and a single 7m shaft for piers 2 and 6. The smallest piers, 1 and 7, are on shallow strip foundations. The piers are in B50 concrete and the deck is in B70 G silica fume concrete.
- The 31T15 cables of external prestressing were injected with petroleum wax to allow them to be removed.
- Throughout construction, the environment and the preservation of the Sioule valley were the main concerns of the Contractor and Project Manager.
setec tpi carried out the design and construction management, which included:
- Producing the tender documents
- Supervising the construction work
The pierhead segments of the large balanced cantilevers, 10m high and 18.60m long with a volume of 800 m3, are concreted in five stages: firstly, the lower slab, then the webs and angle braces in half-lengths, from a bottom work platform anchored in the tops of the piers.
Then the upper slab is concreted in half-lengths, forming the two last stages, from the top platform, which is suspended from the upper part of the webs.
Client: Motorways of South France
Design JV: MIKAELIAN Architect, setec tpi (Design and Construction Manager), SECOA (Designer)