GB397981A - Improvements in or relating to ferro-concrete bridge and other floor construction - Google Patents

Abstract

397,981. Reinforced-concrete girders ; floors; bridges. MOUCHEL & PARTNERS, Ltd., L. G., BUNNY, M. H. J., and HILEY, B. A. E., 36, Victoria Street, London. May 24, 1932, No. 14732. [Classes 20 (i) and 20 (iv).] A pre-cast, reinforced concrete girder a of tubular or trough shape is provided with a number of reinforcing bars l of different lengths and having diagonally bent parts L<1>, the arrangement being such that the inclined parts l<1> of the longer bars take up shear stresses adjacent the supports when the maximum span is used, whilst the inclined parts of the shorter bars take up these stresses when the girder is shortened to suit a shorter span. If desired, two bars l may be disposed at each side in the lower part of each girder, as shown in Fig. 2, and the inclined ends l<1> may terminate in hooks k, Fig. 1. The hooks k of the longer bars project beyond the ends of the girder. In addition to the bars l, the girder may be reinforced by a longitudinal bar d disposed in each corner of the girder with or without an additional longitudinal bar in each of the upper corners. The lower bars d may be provided with hook-shaped ends k<1>projecting from the girder, and the upper bars may have bent ends k<2>, as shown in Fig. 1. The bars d, l are interconnected at intervals by an open rectangular framework comprising vertical and horizontal wires e, f. U-shaped bars m may also be disposed transversely of the girder at intervals, as shown in Fig. 2. In constructing a bridge, the girders are placed side by side with the ribs b on the side faces in contact so as to leave spaces o for the reception of concrete, as shown in Fig. 5. The projecting ends of the bars l are embedded in a cast-in-situ concrete enclosure x disposed along the ends of the girders, rods w being threaded through the hooked or bent ends k<1>, k<2> of the bars, as shown in Fig. 6. The end girders q are provided with transverse channels, each adapted to receive an "extension s of a rail pillar t. A curb u of concrete is cast over each end girder q. In a modification, the upper side of the girder is omitted to provide a troughshaped girder which may be employed for carrying mains, pipes, &c. When the girder is shortened for use with a shorter span, the ends of the inclined parts l<1> of the shorter bars l may project beyond the ends of the girders.