This traction actuator is of the take-up type for prestressing concrete. In order to exert tractive effort on a greater number of wire-rope strands, a fixed retaining block and a movable traction block acting on the wire-rope have longitudinal bores formed therein, each bore receiving four or five strands being disposed on a common circumference of the blocks and being each provided on its end faces with bearing plates acting as movable abutment members to keys clamping said strands.

In the assembly of a tension tie member between spaced anchors when the tie member is made up of a number of individual tension elements, such as steel wires, steel strands or the like, enclosed within a tubular sheathing, the tension elements are inserted individually and successively between the anchors and it is necessary to insert the annular wedges which anchor each element before the tension elements are released from a threading device. To prevent the annular wedges from prematurely entering into the boreholes in the anchor plate, an auxiliary plate is positioned spaced from the anchor plate. The auxiliary plate has at least one through borehole axially alignable with the boreholes in the anchor plate. A tubular section is secured to the auxiliary plate and forms an extension of the borehole therein. An annular wedge to be inserted into one of the boreholes and the anchor plate can be held on the tubular section by resiliently expanding the wedge about the outer surface of the tubular section. An individual tension element can be inserted through the auxiliary plate and then through the anchor plate and the tubular sheathing and finally through the other anchor plate without any interference from the annular wedge. After the tension element is completely inserted, the wedge can be slipped off the tubular section and inserted into the borehole in the anchor plate by means of a simple handle.

A method and apparatus for securing a foundation anchor to a foundation wall. Tension members comprising the foundation anchor are individually fixed to a plurality of stacked anchor plates positioned over an access hole in a foundation wall by use of threaded fasteners. The method comprises inserting each tension member through an anchor plate hole and separately fixing each tension member to at least one anchor plate. A plurality of tension members are permitted to be threaded with threaded fasteners in a manner calculated to reduce the bearing load exerted on the threaded fasteners. Further, by selectively staggering the threaded fasteners over a plurality of stacked anchor plates, the surface area of the anchor plates can be reduced to a minimum, thereby permitting a proportionate reduction in the size of the foundation wall access hole.

A bridge cable fixing structure, including a fixing plate having multiple cylindrical insertion holes and cylindrical fixing grips corresponding to the insertion holes, each fixing grip being attached to an end of a twisted steel wire. The fixing grips are positioned in the insertion holes on a compression side of the fixing structure, such that the twisted steel wires extend from a tensile side of the fixing structure. When a load is applied to the twisted steel wires attached to the fixing grips, the fixing plate deforms toward the tensile side, compressing the insertion holes against the fixing grips.

A reinforcement comprises a group of generally parallel, longitudinally extending, and transversely spaced multifilament cables extending in a concrete mass and each having a pair of longitudinally opposite ends. A respective longitudinally extending resin sheath surrounds each cable between its ends and a plurality of spacers spaced longitudinally along the cables and their sheaths hold same transversely apart with the concrete mass extending between the sheaths. An anticorrosion and antifriction agent inside each sheath surrounds each cable inside the respective sheath between the respective cable ends and a respective anchor braces each cable end against the concrete mass.