GB741953A - An improved method of prestressing concrete articles - Google Patents

Abstract

741,953. Reinforced concrete. PRELOAD CO., Inc. June 23, 1954 [March 23, 1953], No. 7915/53. Class 20(4). [Also in Group XXVIII] In a method of applying longitudinal and circumferential prestress to concrete pipes and beams a number of circumferentially spaced rods or wires 6 of high-tensile steel are disposed longitudinal of the pipe 1 and the ends of the rods pass through slots or holes 4 in end plates 2, 3 bearing against the ends of the pipe, the rods being tensioned to the desired extent and gripping members 5 bearing against the outer surfaces of the plates 2, 3 being applied to the ends of the rods. A high-tensile steel wire 7 is circumferentially wound under tension and over the rods 6 to grip or bind the rods against the surface of the pipe to prevent any substantial loss of tension in the rods, the ends of the wire being anchored and the rods being severed adjacent the inner surfaces of the plates so that the plates and gripping members may be re-used. A final coating of concrete may be applied to the pipe. In a modification, the rods 6 are replaced by a continuous length of rod passed backwards and forwards along the length of the pipe and around anchorages provided at or near each end of the pipe.