GB912170A - Improvements in or relating to pre-stressed concrete structures - Google Patents

Abstract

912,170. Reinforced concrete building structures. GILBERT-ASH Ltd. Feb. 24, 1959 [Feb. 28, 1958], No. 6595/58. Class 20 (4). A prestressed concrete grillage for a floor, roof or the like is constructed by first erecting precast prestressed concrete primary beams 6 in parallel relationship and thereafter assembling composite secondary beams in stages between the primary beams at right angles thereto by first placing in position precast, lower longitudinal portions 7 of the secondary beams, secondly prestressing said lower portions and thirdly completing the composite secondary beams by placing upon the lower portions precast or cast-in-situ concrete upper portions 21, which may form the concrete floor or roof slab. The lower portions 7 of the secondary beams may be formed as troughs into which the prestressing tendons 9 are installed and stressed before placing the upper portions of the secondary beams. In the exemplified embodiment the primary beams and the lower portions of certain secondary beams are supported by primary boundary beams 3 and secondary boundary beams 4, these boundary beams having ends seated and pin jointed within recesses formed in the columns 2. The columns are of pressed concrete and incorporate a cast in metal member 30 in the recesses. In an exemplified construction, Figs. 2 and 3 (not shown), the columns at the top of the recesses are divided into separate storey lengths and an upwardly projecting pin is mounted at the top of the metal member 30 so that it engages a hole in a metal member cast in the lower end face of the superadjacent storey length of the column. In the embodiment of Fig. 1 a concrete roof screed 17 is provided over wood-wool slabs 18 and supports a roof covering material 19. Specifications 744,756 and 808,835 are referred to.