GB639917A - Improvements in prefabricated concrete buildings and their method of erection - Google Patents

Abstract

639,917. Walls roofs ; floors ; beams ; building slabs. MARTIN, G. J. H. Feb. 28, 1948, No. 6254. [Classes 20 (iv) and 87 (i)] A concrete wall slab for a prefabricated concrete building is provided along its upper edge with an integral beam of which only the central length, which is shorter than the upper edge, is precast around the central length of an assembly of metal reinforcement, the reinforcement protruding from the ends of the precast length and exceeding in length the clear span of the beam. In the form shown, a storey high slab 1 has an outer skin 2, framing ribs 3 and inner horizontal ribs 4 between which are positioned lightweight concrete troughs 5. Above the slab proper, beam reinforcement 8 is integrally connected to the slab by concrete 9. In assembly, the slabs are positioned with the excess length of reinforcement 8 extending into reinforcement 18 placed between the slabs for the supporting columns. After shuttering, concrete is poured to form the columns and to complete the beam as an integral connection therebetween. Thus supported, the bending moment of the beam has two points of contraflexure and the length of the precast portion 9 is calculated so that its ends coincide with these points. The slab may include a window or door opening and the outer skin may be extended as flanges (Figs. 12 and 13, not shown) to form permanent external shuttering for the in situ concrete of the beam and columns. Flat roofs and floors are constructed as shown in Fig. 10, the beam 9 and interbeams 12 being formed with piles 34 and 33, which support slabs 30 which may be lined with lightweight concrete 32. With the above construction all load stresses are taken by the beams and columns rather than by the slabs.