a sealing device 8 which seals around each sheathed strand 1 and at the inner face of the cylindrical tube 10 which delimits the chamber 7 the sealing device 8 may in particular be of the stuffing box type as described in application ep a 0 323 285 at a certain distance away from the anchoring device a deflector member 11 collects all of the strands 1 together into a more compact formation than in the anchor point so as to minimize the overall cross section of the stay in the running part there is therefore a slight amount of angular convergence of the strands 1 from the anchoring device toward the deflector member 11 the anchoring device depicted in fig1 comprises a guide member 12 housed inside the aforementioned tube 10 this tube 10 is connected to the bearing piece 4 it may for example be as a single piece with this piece 4 as depicted or with the pieces 4 and 3 or alternatively fixed to an anchor yoke in the example of fig1 the guide member 12 consists of a rigid cylindrical block for example made of hdpe inserted with practically no clearance into the tube 10 individual passages 13 are formed in this block 12 to allow each of the strands 1 to pass and to guide them on the side facing toward the anchor block 3 this side lies just behind the rear.