Load transfer under (pre)tension
In order to simultaneously transfer the load from the 120 existing structural columns, the Freyssinet teams implemented an exceptional system. This consisted in transferring the loads, previously taken up by the foundation sole plates of each column, to a falsework structure. To achieve this, each column was “waled” (i.e. “tightened”) by two reinforced concrete corsets flanged with Freyssibar + 1,200 prestressing bars. These prestressed structures were supported on four sets of micropiles by means of steel frames. Once this temporary structure was assembled, the stresses could be shifted to it and the columns sawed off.