Abstract: A thread cutting apparatus and method are disclosed for the formation of tapered threads on the end of an elongated reinforcing bar of the type used in concrete structures. The apparatus includes a cutting head assembly having tool holder arms that are cantilevered outwardly from a face or barrier surface to effect cutting of the threads outwardly of the barrier so as to protect the guideways and cutting displacement structure control structure from chips and debris. The apparatus includes positive lead control for the thread cutting chasers, a rigid clamping structure for the bar and a fluid control assembly. The fluid control assembly is capable of positioning the cutting head and housing for one or a multiple number of frusto-conical cuts of predetermined depth to permit the simultaneous formation of threads and removal of material from the reinforcing bar end.

Abstract: A method and apparatus for tensioning concrete reinforcing tendons or the like are disclosed which are particularly well suited for use in the construction of prestressed concrete tanks. The method includes mounting a wedge assembly on the tendon and mounting a wedge assembly housing around the wedge assembly, with the improvement being comprised of the steps of forming a spiral groove of relatively shallow depth in the tendon prior to mounting the wedge assembly thereon, and rotating the housing in a manner similar to a turnbuckle to simultaneously and proportionally induce radial tendon gripping forces in the wedge assembly and substantial axial tension forces in the tendon. The method has the additional advantage of preventing relative slippage between the wedge assembly and tendon even when conventional tendon jacking techniques are employed to tension the tendon.

Abstract: A method for coupling together two generally axially aligned structures, preferably concrete tunnel sections, is disclosed. The method includes mounting coupling apparatus including coupling means having an outwardly facing socket with a tapered thread therein to a first structure, mounting a coupling tendon having a tapered threaded end dimensioned to mate with the socket to a second structure, coupling the tendon to the coupling means and applying an axial tension force to the tendon and coupling means. The method and apparatus enables coupling together of substantially misalignment structures which could not be accomplished if conventional cylindrical threads were employed.

Abstract: A method of forming an anchor member for use in a concrete prestressing anchorage is disclosed. The method includes the provision of plate means formed with a bore therethrough, positioning of a tubular conduit means in the bore, and urging of the conduit against the side walls of the bore to radially deform the conduit and bore into a tapered bore suitable for mounting of tendon gripping wedges therein. The urging step not only forms the taper in the bore, but also effects securement of the conduit to the plate. The conduit may be positioned to extend from either or both of the front or rear sides of the plate to provide or enable securement of auxiliary structures to the anchor member, e.g., means for mounting of the anchor member to a form board. The method employing the conduit may be used to effect securement of a plurality of plate-like elements together to form a unitized anchor plate. Anchor members including tubular conduit means press-fit into the tapered bore are also disclosed.