HUT50913A - Lattice girder for producing partly prefabricated reinforced concrete floors - Google Patents

Abstract

A lattice girder for the fabrication of partially precast reinforced concrete floors possesses at least one top boom (1) and bottom booms which are to be embedded in the precast concrete part (5) and are connected to the top boom (1) by welded-on diagonal members (3, 7). In order that the number of supports when mounting the floor and applying the in-situ concrete can be reduced, the lattice girder possesses, in the region of the mounting support (6), its own reinforcement or a reinforcement which increases the flexural strength and buckling resistance of the precast floor element in this region relative to the regions adjoining it on both sides, which reinforcement can be obtained by using thicker diagonal members (7), additional members (8, 9) to the boom members (1, 2) and/or a lattice girder mounted on top. <IMAGE>

Description

FIELD OF THE INVENTION The present invention relates to a lattice support for the production of prefabricated reinforced concrete slabs having at least one upper belt and a lower belt embedded in the prefabricated concrete section connected to inclined lattice bars welded to the upper belt.

Partially prefabricated slab structures are generally made by embedding the lower belt with a surface reinforcement at the prefabricated plant, in the case of a slab for slabs, and in a thin concrete slab for large slabs, surrounded by concrete, while the inclined bars are and the upper belt protrudes completely from the precast concrete element. After the concrete has been set, the elements are transported to the construction site and, after placement, in the case of ribbed slabs, they are provided with lining bodies or slabs and filled with on-site concrete to form the final slab structure while the protruding parts are embedded in the concrete. The slab joints and thus the trusses are distributed according to the span and the designed load capacity. Because strength can only be achieved after partial hardening of the on-site concrete, the relatively low bending stiffness and crack-susceptible prefabricated elements are provided with their own rigidity and at least the on-site strength according to the reinforcement of the reinforced concrete structure ··· ··· ···· ··

- Leave indoors until partial curing of 3 concrete. Until now, their usual distance was 1 and 2 inches.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fastener, in addition to the design referred to in the introduction, which, without unnecessarily and costly reinforcing the entire reinforcement, results in prefabricated elements of strength requiring less temporary support for a given span. For a m span, a single center support is sufficient.

This object is achieved by the invention by increasing the flexural and stability strength of the lattice supports in the region of the temporary support by advantageous additional reinforcement compared to the joining regions.

According to the invention, reinforcement of the grid support is achieved in places where the need for slab reinforcement is otherwise low in the final state. For a span of 6.5 m and a ribbed slab, a support at the center of the rail is sufficient. Until now, such a span had to have several, at least three, supports, not only with the support costs, but also with the fact that the space just under the concrete slab was not added until the guardianship was removed. . ··. , ··.

,; ··· ·. · ... ···· ...., · ,, ·, _φ ·

- Ζ <available. In the above example, the cost of guardianship is reduced to one third compared to the previous version. The costs of additional reinforcement are only a fraction of the cost of guardianship, so considerable savings can be made in the cost of guardianship.

An additional advantage of the embodiment of the present invention is that during transport and assembly, hitherto highly crack-sensitive elements in the middle regions will be less sensitive.

According to the basic idea of the invention, the carrier can be designed in various ways according to its expected advantages. In the case of trusses having a continuous upper belt bar, a lower horizontal bar arranged with two horizontal gaps, and two inclined grid bars welded to theirs, at least one additional iron bar may be placed under the upper belt and inclined grid bars. Pót the replacement iron is advantageously implemented by placing a larger diameter under the upper belt to fill the oblique wedge opening, thereby minimizing the deformation resulting from the welding compression during welding to the oblique rod.

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- 5 It is also possible to place at least one of the lower belts in addition to the spare iron under the upper belt and weld it to the inclined grid on that side. Attaching auxiliary irons to the lower and upper belts and welding them to the inclined rods also increases the stability strength as the inclined rods bend! its length decreases. As you know, the critical force of the rod is the bend! varies with the reciprocal of the square of the length. With this additional ironing, partial clamping of the oblique rods is also accomplished, and so far the auxiliary stresses resulting from the deviation of the intersection of their oblique rods from the theoretical node provided by the theoretical axes are reduced.

In a further reinforcement process, either alone or with replacement reinforcement of the lower or upper belts, thicker reinforcing bars are incorporated in the reinforcing region, and accordingly provide greater stability, unlike the manufacture of general brackets.

A similar type of reinforcement can be applied in the vicinity of the truss support.

An additional option is to reinforce the bracket by installing an additional lattice support used in the area of the temporary support, which

- 6 · · · · ··· in its ancestors is at least occasionally connected to the main post by welding. Such a lattice holder serving as a fastening support may also be used.

The above solutions are advantageous if the welding machine used in the manufacture of the fastener supports does not allow the thickness of the oblique bars to be varied and the reinforcing bars to be positioned as described above, or when the truss supports are made infinitely from the same elements and are cut to length.

The invention is illustrated by way of example in the drawings. The

Fig. 1 is a lattice support for a slab element in the support environment, the prefabricated concrete part is removed for better clarity,

Figure 2 is a cross-sectional view of the support armrest away from the temporary support, and

Figure 3 is a sectional view of the support and a

Figure 4 is a side elevational view of a portion of the bracket of Figure 1.

The bracket shown has a continuous upper bar 1 with two horizontal gaps 2

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the lower waistband and the 3 oblique lattice bars, which in the exemplary embodiment, Zj. consist of rods. The oblique rods 3 are arranged parallel to each other in a slanting direction, while the oblique rods 3 opposite to each other at the vertex 4 are welded to the upper belt 1, while the lower belts 2 are welded at the ends of the oblique rods 3. When using the truss support with a ribbed ceiling, the lower ends of the lower belts 2 and the inclined bars 3 are placed in a concrete base 5, as shown in Figures 2 and 3. As illustrated in Figure 5a ··, the bracket can be embedded in a semi-finished prefabricated large slab, panel with parallel grid brackets and a surface reinforcement at the bottom.

In order to increase the strength of the truss support, the oblique truss bars 3 are replaced by thicker attachment bars 7 in the vicinity of the support 6. Further, the lower belt bars 2 are provided with additional bars 8 and are welded to their respective inclined bars 3. An additional auxiliary bar 9 is placed under the upper belt bar 1 and welded to the inclined bars 7. The additional auxiliary rod is larger in diameter than the upper belt 1, so the wedge opening between the 7 inclined rods ··· ···

- 8 fills. The welding points 10 between the oblique rods 7 and the rods 2, 8, 9 are indicated in FIG. Since the two welding locations 10 are formed one after the other in the reinforced region on the inclined rod 7, the clamping of the inclined rod 7 and the effective deflection thereof! a shortening of its length can be achieved.

Claims (6)

PATENT CLAIMS A lattice support for the production of partially prefabricated reinforced concrete slabs comprising at least one upper belt and lower belts embedded in the precast concrete part connected to the upper belt (1) by inclined lattice bars (3,7), characterized in that auxiliary reinforcements (7,8,9) for increasing bending stiffness and bending strength are provided in the temporary support environment (6). Lattice support according to Claim 1, characterized in that the auxiliary reinforcement (7,8,9) is welded with at least one auxiliary iron insert (9) placed under the upper belt (1) and inclined iron inserts (3,7). Lattice support according to claim 2, characterized in that a replacement iron insert (9) with a diameter greater than its diameter is disposed under the upper belt (1). Lt. The lattice support according to claims 2 and 3, characterized in that a reinforcing iron insert (8) is placed over one of the lower belts (2) and is welded therewith with inclined iron inserts (3, 7). 5. Lattice support according to claims 1 to 3, characterized in that the reinforcing section has inclined iron inserts (7) which have a diameter larger than the diameter of the reinforcement section (8). ·· ♦ · • ··· ... ... ··· ·· .. · .. · 6. Lattice support according to claim 1, characterized in that the support is reinforced by attaching an additional lattice support (6) in the vicinity of the germinal support. í