The main bridge, which crosses the Lavapesson valley, is divided in three parts by two half-joints. These two joints were in the same span and caused security problems.
Between the months of April and July, the half-joints were demolished in 4 stages, using high-pressure waterjets. Prior to this work, the supported central span, between the two half-joints, was jacked on a centering hanging underneath the structure. This central span was then completely supported by the centering.
Meanwhile, this central span was equipped with 8 straight external prestressing cables each made of 19 strands. This prestressing insures the continuity of the span after the concreting of the half-joints. The cables are continuous along the whole span and are anchored beyond the piers. Before concreting the joints, rebars were also added to ensure the continuity of the steel rebars in the deck.
Because of the flexibility of the centering and the vibrations, the concreting and prestressing of the joints was done over one weekend, with the bridge closed to traffic. The joints were concreted with a flash setting concrete which reaches a compression strength over 30 N/mm2 after 24h. Post-tensioning of the cables was thus carried out a day after the concreting. Finally, the waterproofing layer and the bituminous overlays were placed over the newly concreted joints. Over the same weekend, the connections between the temporary bridges and the main bridges were also done.Share