GB849814A - Improvements in or relating to pre-stressed concrete elements - Google Patents

Abstract

849,814. Prestressed concrete elements. CONCRETE Ltd., and OYLER, G. Feb. 6, 1957 [Feb. 6, 1956], No. 3615/56. Class 20(4) Wires 20 are tensioned in a straight line in a mould and then are disposed so that parts of the wires are angularly displaced and concrete is cast about the wires. In constructing a truss, the wires 20 are tensioned between end plates 12, 13 and have centrally two plates 14, 15 which have holes through which the reinforcement is passed. The central plates 14, 15, Fig. 1, are raised to the position shown by the chain dotted lines by a jack operating on a cross girder 16 to which the plates are attached. Shuttering is then arranged round the wires, Fig. 2, and the concrete cast to form a truss. The mould may have hollow cores 24 but the end and centre parts are cast solid. When the concrete has set the member 16 is removed from the plates 14, 15 which are left within the concrete and the shuttering removed. The plates 14, 15 have apertures centrally, Fig. 3, (not shown) so as to allow continuous concrete mass between the hollow cores. The holes in the plates may be countersunk or bell-mouthed to prevent wires coming into contact with sharp edges. Larger holes may receive reinforcement bars.