FR2883591A1 - Comb-like split formwork for reinforced concrete beam end, has teeth with pivoting bars revealing slits, and front sides having crenated contour forming orifices between them for passage and positioning of beam`s longitudinal reinforcements - Google Patents

Abstract

The formwork has a rectangular mechanical unit whose central part has teeth constituted of bars (2) pivoting at 90 degrees and revealing slits (9) opening on the base of the formwork. The teeth have front sides with a crenated contour (5) forming orifices between them permitting the passage and the positioning of projecting longitudinal reinforcements (4, 8) of beams made of reinforced concrete.

Description

The present invention relates to a slotted formwork device of abutments of

  reinforced concrete beam. It makes it possible to form the concrete and to keep the active reinforcements stretched in the molds in the shape of a chute. The longitudinal reinforcements are arranged in vertical and horizontal layers. The device also makes it possible to maintain reinforcements

  can be misaligned vertically.

  The prestressed reinforced concrete beams are manufactured in open molds in the form of trough of generally rectangular section, their length up to 100 m or more. In these molds are arranged active longitudinal reinforcements stretched between two anchor heads located at the ends of the mold. The reinforcements are arranged in a bundle whose arrangement is defined by calculation of resistance of the materials. They consist of high tensile steel cables with a diameter ranging from 5 to 15 mm or more. Passive longitudinal reinforcement and transversal reinforcement complete the reinforcement of the beams.

  The abutment forms are placed at each end of the beams inside the trough mold perpendicular to the reinforcement beam in order to produce beams of desired length.

  The existing beam end forms are made with rectangular metal plates pierced with holes in which are introduced one by one cables and rebar outside the mold. The dimensions of a formwork of abouts are function of the section of the mold, they can reach widths of 500 mm and more for 800 mm and more height.

  The transverse reinforcements are placed on the bundle of reinforcements outside the mold. The number of cables in a bundle can reach up to thirty units and more than a diameter of 13 mm for routine production. The number of abutment forms can be up to thirty units or more. The assembly consisting of reinforcements and formwork abouts, a weight and a large footprint, is then introduced into the chute mold. The operation is carried out manually by the operators assisted by handling cranes. This daily operation is tedious, painful and dangerous.

  On the other hand, if the protruding reinforcements are cross-shaped or in the form of a loop, the drilled metal end forms can not be used because they are prisoners of the reinforcements and can not be removed. They are then made of wood and are destroyed during stripping.

  If the cables are vertically aligned, vertically split abutment forms with flexible lip-shaped sealing devices may be used. A complementary device for vertical wedging of the reinforcements is associated with the split formwork.

  The slotted formwork allows their placement on the bundle of tensile reinforcement in the chute mold. However, the shape of the transverse reinforcement requires a horizontal shift of the longitudinal active reinforcement. If this vertical misalignment of the active reinforcement is not compatible with the deformation of the sealing lips, the slotted formings with the lips are not usable in this case.

  The formwork of abouts of reinforced concrete beams according to the invention makes it possible to accept a vertical misalignment of the longitudinal reinforcements. Indeed, the form of beam end caps, in the form of a comb, comprises according to a first characteristic vertical teeth separated by sufficiently wide slots to overlap the vertical plies of reinforcements. The second feature allows to close these slots on the frames which are found housed and held in orifices arranged on the contour of the teeth.

  After placing the transverse and longitudinal reinforcement in the chute mold, after having tensioned the active frames; the slots of the abutment forms make it possible to install the abutment forms by overlapping the reinforcements directly in the trough mold. These different operations being done one after the other, simple and light handling means can be implemented because of the reduced weight and limited dimensions of each element. Then, the operation of setting up the entire device loses its tedious side, painful and dangerous; which improves the working conditions and the safety of the operators.

  The accompanying drawings illustrate the invention: - Figure 1 shows the formwork seen from the front. Two bars being in open position and two bars being in closed position.

  - Figure 2 shows the formwork seen in profile.

  - Figure 3 shows a horizontal section of a bar.

  - Figure 4 shows the detail of the lateral locking mechanism of a misaligned frame.

  - Figure 5 shows the detail of the locking mechanism of formwork abutting in mold trunking.

  The formwork (1) consists of an inverted U-shaped sheet metal plate. Inside the U are arranged vertically pivoting metal bars (2) whose section (section AA) is part of a rectangle; one of the faces, flat and wide, ensures the formwork of the beam end. Projected forms are indentations (3), they are arranged on the formwork faces of the formwork of abouts and bars.

  When the width of the beam is less than or equal to 200 mm, it is generally not possible to accommodate bars between the reinforcing plies. The inverted U-shape of the formwork will be abandoned and the lower part of the formwork will consist entirely of pivoting bars (2) resting on pins (7).

  The external dimensions of the abutment formwork and its external shape depend on the section of the beam. The internal dimensions of the U-shape depend on the position of the vertical reinforcing plies (4) and the number of bars (2) depends on the number of vertical plies.

  The inner edges of the U-shape are generally straight.

  The pivot bars are used in two positions 90 to one another: 1) The bars being positioned from the front (figl closed) in the U-shape of the formwork, they have widths and heights to cover the entire of the inner surface of the U. The crenellated contour (5) of the front face of the bars forms between them and with the interior of the U orifices allowing the passage of the reinforcements (4). The front faces of the bars are aligned with the front face of the U-shaped casing. In the particular case where the vertical reinforcing plies are not spaced apart enough to accommodate a bar, deeper slots (6) will be made, they will overlap horizontally. two frames.

  Horizontal positioning of the reinforcements of two vertical sheets close together will be provided by pins (7) of appropriate section to the space between the layers. The pins will be fixed on the formwork U. The crenellated parts of the bars will be based on the pins and the assembly will be the housing holes of the frames.

  2) The bars being positioned in profile (Fig.1 open) and their thickness being less important than their width, they emit slots (9) to overlap the vertical sheets of tensioned frames.

  Metal pivots (11) secured to the bars, housed in bearings (10) arranged in the transverse part of the U-formwork, ensure the maintenance and positioning of the bars. Their shape is cylindrical and partially equipped with a flat (12). This flat aligns with the front face of the U-form to form a flat formwork surface. It is also used to promote the stripping of beam ends; it is then maneuvered in rotation in order to exert a force of separation of the formwork. At the ends of the pivots are machined two flats (17) opposite, they allow the operation of rotation of the bars with a key. A transverse pin (13) passing through each pivot makes it possible to immobilize the bars vertically.

  The misaligned armatures (8) are held laterally in the crenellations by two cam mechanisms (21) articulated on an axis (22) fixed at the rear and bottom of the inverted U-shaped (fig.2 and 4 BB section) . These cams release the slots (9) when the formwork of abouts is free. When the abutment formwork touches the bottom of the chute mold, the cams rest on the bottom of the mold and they pivot which brings their upper part into contact with the frames (8).

  The abutment forms are fixed inside the trough mold by a bolt mechanism (14) actuated by a cam (16) pressing, via two pins (20), on a device of elastic bars (19). ) housed in the bolt. The axis (18) maneuver pinned on the cam (16) rotates the cam and moves the bolt that pinches the triangular rail (15) welded to the chute mold.

Claims (6)

  1) Formwork (1) of reinforced concrete beam ends characterized by its comb-like shape now, in a chute mold, the active and passive longitudinal reinforcements (4) and (8) projecting beyond the ends of the beams.   2> formwork according to claim 1 characterized by teeth consisting of pivoting bars (2) having a flat and wide face with a crenellated contour and a narrow profile, the teeth having a pivot housed in bearings arranged in the. frame (1) of the comb.   3) Formwork according to claims 1 and 2 characterized by slots between the teeth allowing, in the open formwork position, to overlap the reinforcements, the flat and crenellated faces of the bars are then parallel to the longitudinal reinforcement.   4) Formwork according to claims 1 and 2 characterized by orifices between the teeth now in closed formwork position, the armatures (4) and (8) can be misaligned vertically, the flat faces and crenellated bars are then perpendicular to the longitudinal reinforcements (4) and (8).   5) Formwork according to claim 4 characterized by a cam mechanism (21) maintaining the misaligned frames (8) horizontally.   6) formwork according to claim 1 characterized by a latch bolt (14), housed in the frame (1), operated by cam (16) fixing on a triangular rail (15) the formwork of abouts of beams inside chute mold.