| 摘要 |
1,250,976. Post-tensioned concrete. PHILIPP HOLZMANN A.G. 6 May, 1969 [7 May, 1968], No. 23145/69. Heading E1W. [Also in Division H5] A tube 3 extending through a concrete structure 1 to define a duct for post-tensioned reinforcement 2 is, upon the introduction and during curing of the grout 7, heated by passing current through one or more insulated electrical conductors 5 in direct contact with the tube. The conductor or conductors may be wound helically around the exterior or interior of the tube and may be housed in a helically extended corrugation formed around the tube, Figs. 3 and 5 not shown or within a folded seam forming part of a known per se tube construction. Fig. 7 (not shown). The conductor or conductors may extend parallel to the axis, internally or externally of a tube which may be of corrugated profile or smooth. The heating may be effected prior to the introduction of grout and preferably with the tube filled with water, before the tensioning and anchoring of the reinforcement so that the reinforcement is subjected to thermal extension whereby an increase in prestressing force is effected when subsequent cooling is allowed to take place. |
