EP0355776B1 - Method for reinforcing of concrete slabs, device for carrying out the method as well as lattice girders - Google Patents

Abstract

The invention relates to a method for reinforcing concrete slabs, a device for carrying out the method as well as lattice girders (1) which can be manufactured by this means. The reinforcing structure made from lattice girders, which is designed in conventional manner to meet static requirements, is composed of individual wire rods of suitable diameter and suitable length. In particular, the diagonal rods (5, 6), which are firmly connected, in particular welded, via bases (7, 8) to the bottom booms (3, 4) and via vertices (9) to the top boom (2), can be produced individually in this way, varying over the length of the lattice girder (1). In particular, they can be produced in accordance with static requirements with a different base distance (a3) and/or different shape and/or different bending radius and/or different diameter. Furthermore, the neighbouring bases of neighbouring diagonal rods (5, 6) may be at different distances (a2) from one another. In this way, a cutting-free production of lattice girders (1), which meets static requirements in each case without fail, is possible. It is ensured that the terminal bases (7) of the terminal diagonal rods (5) are firmly connected to the respective bottom boom (4) and, if appropriate, are at a safe distance (a1) from the end of the bottom boom. In order to produce the diagonal rods (5, 6) and the booms (2 to 4), appropriate wire rods can be taken from a stock of wire coil, straightened and cut into suitable lengths. Positioning and/or sorting is expedient. The method makes possible considerable rationalisation in the manufacture of concrete slabs. Furthermore, a considerably saving of steel can be achieved. <IMAGE>

Description

The invention relates to a method for reinforcing concrete slabs, lattice girders and a device for carrying out the method or for producing such lattice girders.

The production of concrete slabs as prefabricated parts has become increasingly important. Methods and devices with which concrete slabs of different dimensions and at high cycle speeds can be produced have already become known.

Concrete slabs or other prefabricated concrete parts of this type are generally provided with reinforcements. These reinforcements are first calculated and manufactured according to static requirements and are then introduced into the device, which is then poured into the liquid concrete and compacted. In addition to reinforcement with mesh, reinforcement with lattice girders is also common. Lattice girders consist of an upper chord and two spaced lower chords and diagonals, usually parabolic or hyperbolic bent wire pieces, the base of which is firmly connected, in particular welded, to one of the lower chords and the apex of the upper chord. Such lattice girders are manufactured by special companies using appropriate devices (see EP-A-0 023 898 which represents the closest prior art) in standard lengths of usually 14 m and are supplied to a concrete plant that manufactures the precast concrete parts. In the concrete plant, the lengths required for the respective precast element are then cut from the required type of support in the lengths supplied. As a result, considerable waste is inevitably produced. In addition, lattice girders of different statics must be kept in stock, which results in considerable financing and storage costs. It also has the inevitable consequence that only certain types of lattice girders are available and therefore compromises have to be made in the manufacture of the precast concrete parts. Usually the actually used lattice girders are chosen "on the safe side", ie it is oversized. Only in very rare cases will they be longer Delivery times for special carriers, i.e. accepted for special productions. This is obviously expensive.

In addition, the regulations require that a base point of a diagonal must be provided at the end of a lattice girder. The consequence of this is that either overdimensioning in the length direction of the lattice girder is also required, or that when a plurality of lattice girders are arranged next to one another, overlaps are carried out in order to ensure the statics. As a result, more iron is used than is absolutely necessary, which increases the costs considerably. In particular, the arrangement with an overlap also results in additional waste.

It is therefore an object of the invention to develop a method and a device for the reinforcement of concrete slabs so that an inexpensive, in particular low-waste, production of concrete slabs is possible. A suitable lattice girder should also be specified.

The object is achieved in the method according to the preamble of claim 1 by the characterizing features of claim 1.

The invention is developed by the features of subclaims 2 to 9.

The object is further achieved by lattice girders according to claim 10.

The device for performing the method or for producing the lattice girder is characterized by the features of claim 13. Advantageous further developments result from the subclaims.

The invention is based on the knowledge that the problem can be achieved by automated manufacture of lattice girders on site. The invention is also based on the knowledge that in such an automated Manufacturing the diagonals can have different shapes in the course of a lattice girder, so that with the optimal length of the lattice girder it can always be ensured that a diagonal base point is present at the end of the lattice girder. In addition, this procedure, which can be largely automated, enables a high production speed to be achieved. This can be made extremely high, in particular in the event that the wire rods are withdrawn from a wire spool bearing. If only a selection of wire diameters is used, storage is also very simple, space-saving and therefore inexpensive. It is not necessary to over-dimension the lattice girders, since the base point distance of the diagonals or the distance between adjacent diagonals can be optimized according to the specifications. In addition, automation in the manufacture of the reinforcement enables the use of workers who do not require high qualifications. A further advantage is that the lattice girder can be placed on a pallet or can be manufactured on this pallet itself and can be placed in an intermediate storage with this and other lattice girders in a predetermined arrangement. This intermediate storage means that the manufacture of the reinforcements is comparatively independent of the cycle time of the precast concrete part manufacturing device that is required. Furthermore, such an intermediate store can serve as a buffer between several devices for the production of reinforcements and / or several production devices for concrete slabs.

Fig. 1

schematisch ein Fließbild zur Erläuterung des erfindungsgemäßen Verfahrens,

Fig. 2

schematisch und perspektivisch den Aufbau eines Gitterträger gemäß der Erfindung.

The invention is explained in more detail with reference to the exemplary embodiment shown in the drawing. Show it:

Fig. 1

schematically a flow diagram to explain the method according to the invention,

Fig. 2

schematically and in perspective the structure of a lattice girder according to the invention.

Wires of different diameters, in the exemplary embodiment four different diameters ⌀ 1 to ⌀ 4, are stored in a wire store. In a first step, wire of a selected diameter is drawn from the wire store and straightened. In a second step, the directional wire rod is cut to length. If the wire rod is provided for a lower flange 3, 4 (FIG. 2), it is cut to length l. A somewhat shorter length can be provided for an upper flange 2 (FIG. 2), but the same length can also be specified. For diagonals (5, 6), the length to be cut results from the distance h between the top flange 2 and the bottom flange 3, 4, the distance b of the bottom flange 3, 4 and the base point distance a3 of a diagonal. If necessary. also from the shape of the diagonal 5, 6 ultimately used, such as the bending radius, the relationship to symmetry and the like. In a third step, the wire rods cut to length for the different belts 2 to 4 are positioned and stored in a buffer. If applicable, i.e. depending on the structure of a downstream welding station, positioning can be dispensed with here. In a third step, the diagonals 5, 6 are bent in accordance with the specifications, taking into account the height h, the base point distance a3 and the predetermined shape (symmetrical shape, type of bending according to parabola, hyperbole or the like, asymmetry, etc.). The curved diagonals are then sorted in the order in which they will be needed later and temporarily stored.

Depending on the number of diagonals 5, 6 to be manufactured, the belts 2 to 4 and the diagonals 5, 6 have to be buffered for different lengths. If the belts 1 to 3 and diagonals 5, 6 are made, they are fed to a welding station. First of all, the upper chords 2 and the lower chords 3 and 4 which have reached the welding station are arranged in a position corresponding to the respective lattice girder 1 according to height h and lower chord distance b. The welding station has a corresponding one for this height adjustment device not explained in detail. Then the diagonals 5, 6 are arranged in succession on both sides of the upper chord 2 and the two lower chords 3 and 4 in the intended order and with the predetermined distances. First of all with the intended distance a1 from the end point 7 of the end diagonal 5 to the end of the lower chord 4 and then the remaining lower chords 6 with the corresponding distance a2 to the end point 8 of the end diagonal 5 facing away from the end or the one closest to the end already attached diagonal. After the respective diagonals 5, 6 have been placed on the respective lower flange 3, 4, welding is carried out immediately, not only at the base point 7, 8, but also at the respective apex point 9. If symmetrical diagonals 5, 6 are used, it can also be expedient to to take into account the apex distance a4 in the welding station. In particular, a cycle feed device is then expedient, which has adjustable feed length per cycle, so that the individual base points 7, 8 or vertices 9 are always reliably opposite the individual welding devices of the welding station required for welding. In this way, a diagonal pair in the statically and structurally necessary position (distance a3, distances a1, a2) is attached in every cycle by means of the clock feed device. It follows that the last diagonal of a lattice girder 1 to be manufactured can be welded to the upper and lower chord 2 and 3 or 2 and 4 in a corresponding predetermined position, such that there is always a diagonal base at the end of a lattice girder, which is static Principles is required.

It should be noted here that during the production of the individual diagonals 5, 6 these may also have different diameters in the course of a lattice girder.

It should also be noted that the introduction of the upper and lower belts 2 to 4 into the welding station has already begun can be made before all diagonals 5, 6 for the respective lattice girder 1 are made and stored in the buffer.

The respective lattice girder 1 is then either brought into an intermediate storage, for example placed on a pallet, or fed directly to the production device. The storage on a pallet has the advantage that several lattice girders 1, which together form a reinforcement for a concrete slab, are successively manufactured and can be fixed in a predetermined position on the pallet. The fixation can be done mechanically, electromechanically or electromagnetic. If necessary, the reinforcement thus formed can be supplemented by other reinforcement parts such as mats or the like. Furthermore, the pallet on which the lattice girders 1 are placed can be part of the production device.

It follows from the foregoing that the lattice girders can be produced without waste, all static requirements being taken into account and an overlap that was previously necessary being reliably avoided. Furthermore, oversizing is also avoided, on the other hand an optimal design of the lattice girder is achieved and thus also an optimal reinforcement of the concrete elements, which is also useful for the construction site, since the costs for the necessary support of the element ceilings can be greatly reduced at the construction sites. By optimizing the production of the concrete elements due to the optimization of the lattice girder production, so-called thrust beams are no longer required, which also leads to considerable savings.

Furthermore, the entire production of the lattice girders can be automated as far as possible, in particular if the statics are created by means of a program control, the control for the procedure according to the invention can also be triggered on the basis of this.

FIG. 2 is briefly explained again in connection. This shows the basic structure of a lattice girder 1 according to the invention with two lower chords 3 and 4 arranged at a distance b from one another and an upper chord 2 at a distance h from the two lower chords 3, 4, the upper chord 2 generally being symmetrical to the two lower chords 3, 4 is arranged. The lower chords 3, 4 have a length l and are arranged essentially parallel to one another and to the upper chord 2. The top chord 2 can be slightly shorter. There are diagonals 5, 6 between the upper chord 2 and the lower chords 3, 4. These are firmly connected at base points 7, 8 to the respective lower chord 3 or 4 and at apexes 9 to the upper chord 2, generally welded. The diagonals 5 and 6 consist of bent wire pieces. Depending on the bending radius and bending shape (for example according to parabolic or hyperbolic shape), the base points 7, 8 of the diagonals 5, 6 have different base point spacings a3. The end point 7 of the end diagonal 5 has a distance a1 from the end of the lower chord 4 (or 3), while there is a distance a2 between the adjacent base points of adjacent diagonals 5, 6. The distance a2 and the base point distance a3 can vary over the length of the lattice girder 1 depending on the required statics. In the case of symmetrical diagonals 5, 6, the vertex distance a4 can also be taken into account for design purposes. This can also vary over the length of the top chord 2. Furthermore, the diameter of the wire pieces used for the different diagonals 5, 6 can each be different. The diameter of the piece of wire used for the upper chord 2 can also differ from the diameter of the piece of wire used for the lower chords 3, 4.

The procedure according to the invention achieves a considerable rationalization effect in concrete plants. Substantial steel savings are also possible, since waste can be practically completely avoided.

Claims (15)

1. A method of reinforcing a concrete panel or the like,
      in which there is designed a reinforcement comprising a lattice girder corresponding to the statical requirements of the concrete panel concerned,
      in which an actual lattice girder is manufactured on the basis of the design data of the lattice girder concerned and in which the reinforcement manufactured on this basis is supplied to an apparatus for fabricating concrete panels or the like,
      the lattice girder (1) comprising an upper bar (2), a pair of lower bars (3, 4) and a plurality of diagonals (5, 6) and each diagonal being formed with a U-shape and being fixedly attached, in particular welded, by two base points to a lower bar and by an apex point to an upper bar,
      characterised in that,
      for forming the upper bar (2) and the lower bars (3, 4) wire rods of suitable cross-sections and of respective lengths corresponding to the designed reinforcement are prepared and arranged,
      in that for forming the diagonals (5, 6) wire pieces of suitable diameters with respective lengths corresponding to the designed reinforcement are prepared, bent and associated with the arrangement of upper bar (2) and lower bars (3, 4),
      in that the diagonals (5, 6) are fixedly attached to the upper bar (2) and lower bars (3, 4), the diagonals (5, 6) having at least in part differing base point spacings (a3) and that in each case a base point (7) is arranged at the end of a lower bar (3, 4) and
      in that the thus formed lattice girder (1) is delivered to the fabrication apparatus.
2. A method according to claim 1,
      characterised in that,
      in particular for the end regions of the lattice girder (1) there are prepared diagonals (5) having different wire diameters and/or different bending radii and thus different base points spacings (a3).
3. A method according to claim 1 or 2,
      characterised in that,
      in correspondence to the designed reinforcement, the spacings (a2) of neighbouring base points (7, 8) of neighbouring diagonals (5, 6) are so selected that the outermost base point (7) of the outermost diagonal (5) can be reliably attached to the lower bar (5) concerned.
4. A method according to any of claims 1 to 3,
      characterised in that,
      at least individual ones of the diagonals (5, 6) are asymmetrically bent.
5. A method according to any of claims 1 to 4,
      characterised in that,
      for forming the lower bars (3, 4), the upper bar (2) and/or the diagonals (5, 6) wires are drawn from a coiled-wire store, straightened and cut to length on site.
6. A method according to any of claims 1 to 5,
      characterised in that,
      the fabricated lattice girder is stored temporarily before supply to a fabrication apparatus and, if a appropriate together with other lattice girders, is called on demand.
7. A method according to claim 6,
      characterised in that,
      at least one lattice girder is placed on a pallet.
8. A method according to claim 7,
      characterised in that,
      to provide an immoveable arrangement of several, in particular all, lattice girders of the reinforcement, these lattice girders are, corresponding to the designed reinforcement, fixed in position on the pallet mechanically, electro-mechanically, magnetically or in another manner.
9. A method according to any of claims 1 to 8,
      characterised in that,
      only wire rods of a predetermined number of diameters are employed, i.e. 3 to 4 diameters for upper bars, lower bars, and diagonals.
10. A lattice girder (1) comprising two lower bars (3, 4) and an upper bar (2) and a plurality of diagonals (5, 6) formed in U-shape each between one of the lower bars (3, 4) and the upper bar (2) which are fixedly attached, in particular welded, each by two base points (7, 8) to the lower bar (3, 4) and each by an apex point (9) to the upper bar (2),
       characterised in that,
       diagonals (5, 6) of differing base point spacings (a3) are arranged in the longitudinal direction of the lattice girder (1).
11. Lattice girder according to claim 10,
       characterised in that,
       diagonals (5, 6) of differing diameters are arranged in the longitudinal direction of the lattice girder (1).
12. Lattice girder according to claim 10 or 11,
       characterised in that,
       in the longitudinal direction of the lattice girder (1), neighbouring base points of neighbouring diagonals (5, 6) have differing spacings (a2) from one another
13. Apparatus for fabricating lattice girders according to claim 10 or for carrying out the method according to claim 1,
       the lattice girders (1) comprising each an upper bar (2), a pair of lower bars (3, 4) and a plurality of diagonals (5, 6), each diagonal being formed with a U-shape and being fixedly attached, namely welded, by two base points to a lower bar and by an apex point to the upper bar,
       having a supply arrangement for supplying wire rods of suitable diameters and suitable lengths, for the purpose of forming the upper bar (2) and the lower bars (3, 4), to a welding station, and for supplying wire pieces of suitable diameters and respective lengths to a bending device for forming diagonals (5, 6) and then to the welding station, the diagonals (5, 6) being associated with the upper bar (2) and the lower bars (3, 4) in the welding station and with the aid of a feed device being fixedly attached thereto step by step, the welding station having a height adjustment device for variably fixing the height spacing (h) between the lower bars (3, 4) and the upper bar (2),
       characterised in that,
       the supply device and the bending device is equipped for forming diagonals (5, 6) of differing base point spacings (a3) for a lattice girder (1) and
       in that the feed lengths of the feed device of the welding station can be selected in the fabrication of a lattice girder (1) in order to reliably weld the diagonals (5, 6) of differing base points spacings (a3) for a lattice girder (1) to the lower bars (3, 4) and to the upper bar (2).
14. Apparatus according to claim 13,
       characterised in that,
       the feed device is a cyclic feed device with a feed length which can be set for each cycle.
15. Apparatus according to claim 13 or 14,
       characterised by a temporary store for diagonals, in which the prepared diagonals (5, 6) are temporarily stored for supply to the welding station in the sequence in which they are then needed for attachment to the upper bar (2) and the lower bars (3, 4).

Images