GB989663A - Improvements in or relating to pre-stressed concrete vessels - Google Patents

Abstract

989,663. Prestressing concrete structures. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Feb. 19, 1964 [Feb. 28, 1963], No. 7985/63. Heading E1V. [Also in Division G6] A concrete pressure vessel is braced against bursting due to internal pressure by prestressing the vessel by forming at least one girdle from a multiplicity of continuous turns of wire or cable, providing the girdle(s) with a plurality of tensioning members spaced about the vessel periphery, applying an outward pull to each of the tensioners so as to tension the girdle(s), and then securing the girdle(s) in its/their tensioned position(s). The girdle(s) may be tensioned prior to subjecting the vessel to internal pressure, and further tensioned after pressurising. Girdle assembly. A number of carriages 2 are placed around the periphery of a concrete pressure vessel, and joined in a continuous train by the bars 3. A wire or chain 4 (not a prestressing member) is passed over a driven pulley 5 and around the train of carriages 2, being located in blocks 18 on each carriage. Troughs 16 are located on each carriage. By rotating the pulley 5 and attaching a wire 7 to one of the saddles, the train of carriage is rotated about the pressure vessel and a multi-turn girdle 9 laid around it in the saddles; two or more wires may be wound in parallel. No significant tension is applied to the wire 7. After a suitable binding has been applied to secure the turns of wire together and to the saddles, packing blocks 17 are removed and the assembled girdle transported on a second train of carriages 19 to the required position on the vessel. Tensioning (Fig. 2). Each saddle is provided with a pair of abutments 24 carrying pairs of hydraulic jacks 10 linked by tensioning loops 11. After tensioning, the space between each pair of abutments beneath the saddle is filled with cement through holes 26, and the jacks are removed. Instead of packing each saddle, the tensioning loops 11 may be anchored. Alternatively, removable packing may be inserted between the saddles and pressure vessels.