Abstract: A long concrete unit, prestressed by tendons tensioned before concreting, at least one section of which, near the end of the said unit, is submitted to maximum loads, characterized by the fact that at least one improved-bond prestressing tendon is surrounded by spirals located on either side of the zone of maximum tensile stress.

Abstract: In the post-stressing of concrete structures, a tendon comprised of a plurality of elongated strands is formed by inserting elongated strands which will eventually form the tendon into a plurality of parking ducts and then withdrawing the plurality of strands simultaneously as a group from the parking ducts and into the duct of the structure to be post-stressed without fouling and jamming. Once in the ducts of the structure, the strands are anchored and post-tensioned as a tendon to develop the desired stress.

Abstract: A tie for connecting together parts of a structure, for example a stay for suspending the deck of a bridge from a tower, is constructed so that its length can be adjusted in a simple manner with the tie in service. The tie is made up from several stressed steel tendons, enclosed in a protective sheath filled with hardened material. At its ends the sheath incorporates anchoring devices for the transfer of the pull from the tie to the structure. The sheath forms a conduit whose ends are fixed securely to the anchoring devices. The conduit is isolated, throughout its length, from the structure so as to be capable of sliding longitudinally with respect thereto. At least one of the anchoring devices includes connection means for the active part of a tensioning apparatus and also includes means for bearing against the structure. This bearing means is adjustable on the anchoring device in the longitudinal direction of the tie.