GB1489579A - Prestressing concrete - Google Patents

Abstract

1489579 Prestressing concrete R L CREEDON and W A CALDWELL 7 Jan 1975 [11 Oct 1973] 47506/73 Heading EIW A prestressing unit comprises an elongate core member 2 surrounded by helically arranged elongate outer members 1, each of smaller cross-section than the core, and separated therefrom by a release layer of lubricant or of a plastics material, the core and outer members being stressed by, e.g. a jack to place the core member 2 in compression and the outer member 1 in tension, after swaging the members together at one end, the stressed members then being swaged together at the other end. The core member 2 may be a solid rod, which may be formed from four steel wires drawn through a die (Fig. 3, not shown). One end of the unit may be unlocked after the unit has been embedded in concrete, to stress the concrete via the outer members, or alternatively both ends may be unlocked, and a further compressive force applied by then post-tensioning the core member and anchoring the ends thereof in conventional anchorages.