Bridges prestressing

Four bridges on Calais Port 2015 site will be prestressed: OA4, OA5a, OA6a and OA6b.
For information, prestressing consists in exerting tension on steel cables going on either side of the bridge deck (up to a maximum of 542 bars at the cable anchorages for Calais Port 2015 construction site), and therefore compressing it at rest. Thus, when the structure is stressed, these cables stretch and the concrete tends to decompress without however putting itself in traction, since it was already partially compressed.

Aerial view of OA6 prestressing operations

Calais Port 2015 prestressing represents 112 tons of steel and 4,800 meters of cables. These figures are of course in line with the size of the construction site: nearly thirty cables from 26 up to 86 meters, each having 19 strands that will be installed on each deck. Worth to be noted that Bouygues Construction Group specialized teams are in charge of these highly technical operations.