Patent GB-556572-A (GB)
Title: An improved manufacture of structures from reinforced materials
IPC: E04C3/22
Filed: 1942-03-03
Abstract: 556,572. Reinforced structural members. ABELES, P. W. March 3, 1942, Nos. 2768 and 7531. [Class 20 (iv)] [Also in Groups XXIII and XXXIII] A composite structural member consists of three components, (a) a moulded component formed from a plastic non-metallic substance which may be steel-reinforced, (b) pre-stressed ties, the tension of which is above 20,000 lb. per sq. in., (c) a filler of the same or different composition embedding the ties in external grooves in the moulded component. The moulded component may be a reinforced concrete beam or a number of preferably hollow moulded blocks which may have interlocking joints. The joints may be dry, with or without a felt layer, or adhesive mortar may be provided. The moulded component may be formed from suitable aggregates with a binder such as cement, lime, glue, or synthetic resin, or may be composed of bricks, glass blocks, or thermo-setting or thermo-plastic products. The ties are fully pre-stressed to ensure permanent compressive stress in the concrete, or partly prestressed as described in Specifications 541,835 and 554,693. A composite beam, Fig. 2, consists of a reinforced concrete element a having grooves along two lower corners, ties b lying in the grooves, and a filling c enclosing the ties b. Anchor plates may be provided at the ends of the beam for the ties b. The grooves may be formed in the lower surface of the beam, or in the sides, and a groove containing a tie may also be provided in the upper surface. The reinforcement of the element 1 may be linked with the ties b. A composite beam of T-section may be similarly formed. In manufacture, the component a, Fig. 8, is laid horizontally with the grooves upward, and the ties b are wound around it and through the anchor plates 6, forming a loop 10 through which a bar 11 is passed to twist the loop until the required tension is obtained. The grooves and recesses 7 are then filled with cement mortar. When rods are used as ties, they may be tensioned by nuts threaded on the ends. In another modification, the ties b are tensioned between anchor blocks before placing in the grooves, the pre-stressing being transmitted to the concrete by the adhesive filler. In Fig. 19 (not shown), tension is applied to the ties b by winding the ends around a spool which is rotated by a key and then rocked. Instead of an adhesive filler, a cohesive plastic filler may be used, in which case no additional bond due to this component occurs, but alteration of the tension may subsequently be effected. In a modification, Fig. 21, the component a comprises a series of preformed blocks which may be hollow with inclined or stepped abutting surfaces, the ties b being placed in grooves at the corners. Floor beams a, Fig. 28, with wire ties b may enclose concrete members 37 with or without untensioned reinforcement 38, and the concrete may extend over the upper surface. The blocks may be of synthetic resin, or light structural members for aircraft construction may be of synthetic resin. Specifications 338,864 and 338,934, [both in Class 20 (iv)], also are referred to.