GB743406A - Improvements in or relating to a pre-stressed beam, column or pile - Google Patents

Abstract

743,406. Concrete structural members; posts. FELDMAN, A. May 21, 1953 [Feb. 21, 1952; March 1, 1952; March 20, 1952; April 4, 1952], Nos. 4583/52, 5444/52, 7175/52 and 8638/52. Classes 20(1) and 20(4). A beam, column or pile consists of reinforced concrete elements 1, 2, 3 held together under compression by a number, preferably two, of high tensile wires 22. The elements are assembled face to face in two groups on two working benches 14 which run on guide rails 17 on rollers 15, 16. The ends 16 may be raised as in Fig. 25, to facilitate the positioning of the wires, by a jack which co-operates with extendible arms to transmit the longitudinal thrust from one group to the other. The jack then presses the ends 16 downwards to bring the groups. into alignment whereby the wires 22 are tensioned. The groups in the aligned position are spaced slightly, the space either being closed by the tension in the wires when the arms are removed, the residual tension being sufficient, or the space is filled with a buffer plate before releasing them. The benches are kept in the horizontal position, against the tendency of the tension in the wires to raise the ends 16, by spring pressed balls 19, which engage the underside of a slot between the rails 17. Alternatively, the wires may be tensioned by a jack acting horizontally on brackets attached to the adjacent ends of the horizontally aligned groups, the rollers 16 remaining on the rails. A buffer plate is inserted before the jack is removed. Preferably a mild steel rod, which may later be removed, is tensioned, in a groove 4 along the back of the beam to prevent it bellying out. The elements 1, 2, 3 are rebated and grooved at 4 and 6 and the end elements 2 have metal anchoring plates 9. The thrust transmitting elements 3 may be specially reinforced or fitted with apertured thrust plates 11 to take actuating pins of the jack. The rebates and grooves may be grouted with cement or other fireproof material to cover the wires and to give the cross section of the structure a regular outline.