GB694596A - Method and apparatus for post-tensioning and anchoring reinforcements of concrete - Google Patents

Abstract

694,596. Reinforced concrete. BIR KENMAIER, M., BRANDESTINI, A., ROS, M. R., and VOGT, K. March 9, 1951 [March 10, 1950], No. 5813/51. Class 20(iv). A reinforcement, or reinforcements, is, or are, post-tensioned in a concrete structure, the ends of the reinforcements being upset at 14 so that they are held in an anchor member 7 which is drawn outwardly to tension the wire and is then located by means abutting on the end of the concrete structure. The reinforcements are housed in a metal envelope 12 embedded in the concrete, and, in Fig. 4, the anchor 7 is threaded internally to receive the screwed end of the draw bar 6 of an hydraulic jack 1, and externally to receive a nut 16 which bears on the end of the structure and holds the wires in tension. Cement mortar may be forced into the space between the reinforcements 13 and the envelope 12, the envelope having a radial feed pipe (not shown) for this purpose. In a modification, the nut 16 is dispensed with, the anchor 7 being held by the draw bar 6 until mortar in the envelope has set. The compressive force on the mortar inside the metal envelope 12 is transmitted, by bond, through the envelope to the main body of concrete. The surfaces of the envelope may be roughened to increase the bond. An. anchor 7, Fig. 11, for one or more reinforcements 13, is screwed externally for connection to the draw bar 6, the anchor being held in its tensioning position by horse-shoe distance pieces 20, or a nut previously placed on the threads may be screwed against the plate 10 to hold the reinforcements in tension. In a further modification, the anchor 7, which is located within the envelope 12, is internally threaded to receive a screwed rod which projects outside the envelope so as to be engageable by the draw bar 6 which enters a screwed recess in the end of the rod. The tensioning force is held by a nut on the rod bearing on the plate 10. Tensioning may be effected at both ends of the concrete structure. Specification 612,324 is referred to.