GB468706A - Method and apparatus for the construction of reinforced concrete monolithic structures - Google Patents

Abstract

468,706. Moulding reinforced concrete. FREYSSINET, E. Jan. 9, 1936, No. 778. - Convention date, Jan. 11, 1935. [Class 87 (ii)] [Also in Group X] A method of making a monolithic reinforced concrete structure comprises casting said structure section by section successively in moulds of relatively small size, the reinforcements common to a plurality of sections being placed in position prior to casting said sections, and, during the casting of a section, but after the hardening of the previously-cast section, being placed in a state of tension along the part thereof that extends through the section being cast so that the mutual reactions of adjacent sections along their intersurfaces are in the nature of compressions. The concrete may be vibrated, compressed and heated. Prior to casting the first section, the reinforcement adapted to extend therethrough is placed in tension by means such as described in Specifications 338,864 and 338,934, [both in Class 87 (ii)], 364,621, 393,576, 393,606 ; and 422,741, [Group X], after casting of this section the reinforcement of the next section is placed in position. The reinforcement of the second section which is independent of the first section is then tensioned, and the tension of that reinforcement which is common to the two sections is suitably modified. A reinforcedconcrete roof beam, which is cast in situ in sections, is of I-cross-section and is reinforced by steel rods c, c<1> .. arranged in the lower flange and horizontal rods u and vertical rods j, j<1> arranged in the web. As shown in Figs. 1 and 2. The rods c, c<1> ... extend substantially the full length of the beam and are of different lengths, being anchored at their ends in concrete sections 11, 11a, 11b, Fig. 4a, which are cast prior to casting the main sections of the beam. The lower ends of the adjacent rods j, j<1> are also anchored in the sections 11, 11a, 11b. Other elements which are cast prior to the casting of the main sections of the beam are members 59 adapted to enclose the upper ends of the rods j, j<1> and elements adapted to enclose the lower ends of those rods j, j<1> which are not anchored in the elements 11, 11a, 11b. The elements on the ends of the rods j, j<1> may be cast around the same prior to positioning of the rods in the structure. The beam is then cast to the desired I-shape in sections commencing at one end of the beam. The beam is cast on two girders a, a<1>, Fig. 4, carried by vertical frames 50 which are mounted on movable carriages 51. The two girders are adjustable vertically by jacks 52, and, since the frames 50 are mounted on rollers 53, the girders are adapted to be moved apart by a jack b. The separate elements at the ends of the rods c, c<1>, j, j<1> are then cast or positioned, the elements 11 11a, 11b, being temporarily anchored to the upper faces of the girders a, a<1> by means of ridges, 12 on the latter and by screws 13 which pass through the girders into the elements. Alternative abutments to prevent movement of the elements 11, lla, 11b relatively to the girders a, a<1> are inserted through the base of the latter members. The two girders are then moved apart by the jack b so as to tension the reinforcement c. The various sections of the beam are then cast, commencing at one end, by means of moulds which are formed of sheet-metal elements l and section members m, as shown in Fig. 1, such members being assembled together by welding so as to provide tubular mould walls. The moulds are built up to the desired I-section of the beam and are supported on opposite sides thereof by section irons o, the moulds on opposite sides being connected together by rods p extending through rubber tubes p<1> passing across the web of the beam. The moulds are shown in Fig. 3 as arranged for moulding a section N against a section previously cast, being connected thereto by members 61 bolted to the previouslycast section which is ridged at 61a to engage the members 61. The joints between the previously-cast section and the moulds are closed by a metal gutter 65 provided with rubber packing. The opposite end of the mould is closed by a movable wall 54, and the longitudinal reinforcement u passes through such wall and is fixed thereto. The upper wall of the mould consists of metal cover sheets 57, on which are welded transverse irons 56 of inverted U-shape adapted to support longitudinal U - irons 58. A jack 60 mounted on the irons 58 is connected by bars 59b with rods 59a screwed into the elements 59. The mould is filled with concrete through apertures in the upper wall so as to enclose the elements previously formed and the reinforcement. The concrete is vibrated by means of unbalanced masses mounted on shafts 62 which rotate at high speed in bearings on the lateral mould walls. The concrete is compressed by means of the jack 60 acting upon the upper wall, and, if desired, by nuts acting upon the rods p so as to compress the lateral mould walls. This compression serves to tension the reinforcement j, j<1> and the horizontal reinforcement u, the wall 54 of the mould being connected to the reinforcement m by wedges 3 ... 6 which are fixed to the reinforcement so that at the desired degree of tension of the reinforcement u the wall 54 is maintained in position. After the compression of the concrete steam may be passed through the channels of the section irons m, 56 and, if desired, through channels provided between the upper faces of the girder a, a<1> and a metal sheet h on which the beam is cast. The mould is adapted to be displaced by carriages on track carried by the girder a, a<1>. The hardening of the separate elements at the ends of the rods e, j, j may be accelerated by vibrating the concrete, with or without compression and heating, as for instance, by steam passed through the ridges 12 of the girders a, a<1> and through the screws 13.