EP2241700B1 - Dowel for connecting concrete panels - Google Patents

Description

The invention relates to a concrete plug for connecting concrete shells according to the preamble of claim 1.

Concrete trays are used in prefabrication to produce a so-called precast slab. It is known to first produce an upper concrete shell and then leave a lower concrete shell and between the two concrete shells a corresponding cavity to fill this cavity with an insulating material.

There is a need that one connects the upper and lower concrete shell in places firmly together, including special concrete dowels are used. It is known to use the so-called concrete dowels with headed bolts for the connection of the upper and the lower concrete shell for the purpose of producing a prefabricated slab. Such a concrete bolt has on both sides arranged head bolts, which emanate from an intermediate part and are secured thereto. The upper head bolts are each cast in the upper concrete shell, and the intermediate part extends through the cavity between the upper and lower concrete shell. In the same way, the lower head bolts are cast in the lower concrete shell.

The use of a concrete plug with headed bolts has proven itself. However, it has been found that the installation of such a concrete dowel is extremely complex, and there are high costs for installation and pouring in the upper and lower concrete shell.

The closest prior art discloses WO 2004/099520 A1 a concrete plug for connecting two concrete shells of a precast slab, which is anchored positively in the casting both in the one and in the other concrete shell, wherein the concrete dowel consists of a metal plate which extends across the cavity between the one and the other concrete shell, and that arranged in the metal plate recesses are forming in the metal plate facing each other and aligned with each other aligned teeth. The teeth are formed as tabs which engage in associated slots of arranged in the concrete shells corner flanges.

The US 2 334 369 A discloses an elongated concrete plug surrounded by a pressure distribution body in the form of a helix.
The CH 683933 A1 discloses a spacer bar for concrete reinforcing material having recesses, recesses and teeth.
The DE 296 13 627 U1 describes a spacer for concrete construction, which has recesses and teeth.

The invention has the object of providing a concrete plug of the type mentioned in such a way that it can be made particularly inexpensive and that it can be brought particularly favorable in a composite with the upper and lower concrete shell, without the risk that the Concrete in the area of the composite is attacked or even destroyed.

To achieve the object, the invention is characterized by a concrete plug with the features of claim 1.

With the given technical teaching, there is the significant advantage that it is now planned not to anchor the bare teeth of the concrete anchor in the concrete material of one and possibly the other concrete shell, but that these teeth are reinforced with a pressure distribution body.

This has the significant advantage that now by the arrangement of a pressure distribution body, it is no longer possible that with a corresponding movement load of the teeth sober it into the concrete and destroy the concrete in the engagement area in which they reach into, or "nibble".

By using a pressure distribution body, the pressure peaks, which are registered by the teeth of the concrete anchor in the concrete, removed, distributed and transferred over a large area on the surrounding concrete, which therefore no longer "nibbling" the teeth in the concrete material of the concrete shell ,

Such a pressure distribution body is formed in a first preferred embodiment is metal or plastic helix.

It is therefore a helical coil, wherein the one turn is positively seated on the one tooth, so that the tooth engages in the helical interior of this helix, and in the same way engages the opposite tooth of the concrete anchor in the interior of the helix.

Thus, the tooth attack surfaces, which would otherwise reach into the concrete, "defused" and they rather engage in the interior of the helix. This results in a pressure distribution when the two teeth move against each other due to acting compressive stresses, because they move into the interior of the coil inside and there poured concrete material is under compressive stress, so that the concrete material spreads radially and evades without it a local destruction of concrete material in this area comes.

This is a significant advantage over the prior art, where it was not yet known to place a pressure distribution body between the teeth of a concrete plug.

In a second preferred embodiment of the invention, a slotted tube or sleeve and the like body is used as the pressure distribution body.

It is only important that the force application point, which unfolds the respective tooth directly into the concrete, is now defused by the fact that in the region of this force application point a pressure distribution body is arranged, which in turn is filled with the concrete material.

The teeth get a "muzzle", so to speak, so that they no longer reach directly into the concrete, but accomplish this with the interposition of a pressure distribution body.

It is therefore necessary to defuse the local area with which the tooth intervenes in the concrete.

For the formation of the helix, it is not necessary for the solution that the helix is formed continuously cylindrical over the entire axial length. It can also be used other helical shapes, such. B. conical coils or biconical coils, the z. B. cone-shaped or pyramid-shaped.

It is advantageous if the helix is formed in the middle longitudinal symmetry, that is, on its left side as well as the same geometric conditions as on the right side.

The middle region can in this case have either larger spiral turns or even smaller spiral turns than the two end faces.

It is important here that the helix is provided only to provide a certain degree of compression for the purpose of mounting the helix on the opposite and mutually facing teeth. For this purpose (for the purpose of assembly), therefore, the coil must be compressed in the axial direction, to the extent that it fits in the recess between the two teeth and then spread apart resiliently, so that the one tooth in the one end of the helical winding engages and the other tooth in the other end.

If you want to do without a resilient coil, there are other opportunities for training as a pressure distribution body. It can be provided that a tubular body is slotted in such a way that it has in each case radially end having slots on the front side, which are attached directly to the teeth. Even with such a non-axially compressible tubular body (pressure distribution body), it is possible to defuse the engagement of the teeth in the concrete material. It is therefore not necessarily necessary solution to the resilient compressibility of the coil, although this embodiment is preferred, because this is a simple assembly is given.

In another embodiment, it may be provided that only a few turns of a coil are present on each side of the tooth and that these turns are connected to each other by a rod bendable articulated.

Here, also easy assembly is possible, because it is sufficient to bend the central connecting rod for mounting and put the two turns on the teeth, then to spread the rod and bring in a stretched clamping position, which ensures that the two turns from one and the other tooth are fixed correctly.

Instead of such articulated kinkable connecting rod and other connecting means can be used, such. B. a connection damper or a connecting spring.

The subject of the present invention results not only from the subject matter of the individual claims, but also from the combination of the individual claims with each other.

All information and features disclosed in the documents, including the abstract, in particular the spatial design shown in the drawings, are claimed to be essential to the invention insofar as they are novel individually or in combination with respect to the prior art.

In the following, the invention will be explained in more detail with reference to drawings illustrating several execution paths. Here are from the drawings and their description further features essential to the invention and advantages of the invention.

Figur 1:

schematisiert im Teilschnitt eine erste Ausführungsform eines teilweise in die Betonschalen eingebauten Betondübels

Figur 2:

die Abhängigkeit der Druckfestigkeit des Betons in Abhängigkeit von dem Wendeldurchmesser bezogen auf verschiedene Ganghöhen der Wendelbewehrung

Figur 3:

der Dehnungszuwachs im umschnürten Beton, der mit einer Wendel bewehrt ist

Figur 4:

schematisiert die Druckverhältnisse eines wendelbewehrten Zahnes

Figur 5:

eine zweite Ausführungsform eines Betondübels

Figur 6:

eine dritte Ausführungsform eines Betondübels

Figur 7:

eine vierte Ausführungsform eines Betondübels

Figuren 8 bis 10:

eine fünfte Ausführungsform eines Betondübels mit einem Druckverteilungskörper als geschlitztes Rohr

Show it:

FIG. 1:

schematized in the partial section of a first embodiment of a partially built into the concrete shells concrete dowel

FIG. 2:

the dependence of the compressive strength of the concrete as a function of the helical diameter relative to different pitches of the helical reinforcement

FIG. 3:

the increase in expansion in the constricted concrete, which is reinforced with a helix

FIG. 4:

schematizes the pressure conditions of a spiral-reinforced tooth

FIG. 5:

a second embodiment of a concrete plug

FIG. 6:

a third embodiment of a concrete plug

FIG. 7:

a fourth embodiment of a concrete plug

FIGS. 8 to 10:

a fifth embodiment of a concrete plug with a pressure distribution body as a slotted tube

In FIG. 1 is generally shown that in a concrete upper shell 1 and a lower concrete shell 2, a concrete plug 3 is at least partially cast, the pouring process in the lower concrete shell 2 already completed, while the pouring process is completed only partially in the upper concrete shell to to show the engagement of the concrete plug 3 in the upper concrete shell 1.

The concrete plug 3 consists of a metal plate 4, the lateral webs 6, 7, between which a central recess 5 is present, which is profiled approximately rectangular.

This recess is used to pass lines and pipes when the two concrete shells 1, 2 are connected to each other and in the cavity specific lines and pipes to be performed.

It is important now that in the run-off of the upper and lower concrete shell 1, 2 of the concrete plug 3 has a number of spaced approximately C-shaped recesses 8, so that in the region of the recess two opposing and mutually opposing teeth 9, 10th form.

It is important that in order to achieve a better bond of such a metal dowel according to the invention now a pressure distribution body 11 is provided in the region between the teeth 9, 10, which consists of a coil 12 in the embodiment shown.

Each recess 8 with the teeth 9, 10 carries such a coil 12, and there are shown only by way of example two such coils.

The length of such a concrete plug 3 corresponds to the connection width between the concrete shells 1, 2 and has z. B. a length of 6 to 15 m.

At intervals of about 40 cm, the recesses 8 indicated there are arranged with the teeth 9, 10.

In FIG. 2 the influence of the helixes with different helical diameters and different pitches compressive strength of the concrete is shown, if - as shown - the helix 12 each covers a tooth 9, 10.

• Durchmesser der Umschnürung d_c
• Durchmesser der Wendelbewehrung Ø_w
• Ganghöhe der Wendelbewehrung s_w
• Fließspannung der Wendelbewehrung f_y

The influence of a lashing with a helical reinforcement on the compressive strength and the elasticity can be computationally recorded. The following influencing parameters determine the increase in strength and associated elongation:

• Diameter of the strap d _c
• Diameter of spiral reinforcement Ø _w
• Pitch of helical reinforcement s _w
• Yield stress of helical reinforcement f _y

The following influence is noticeable. As the yield stress of the helical reinforcement increases, the increase in strength and elongation for the concrete increases. The smaller the dimensions of the strapped area, the more prominent the increase in material properties. With decreasing pitch increases the compressive strength and associated elasticity. With the diameter of the helical reinforcement also increase the material properties.

• Betondruckfestigkeit Ausgangsbeton fc = 30.0 N/mm2
• Dehnung bei Erreichen dieser Druckfestigkeit eo = 2.0 0/00
• Stahlfestigkeit fy = 500 N/mm2
• Durchmesser des umschnürten Bereichs Ø = 60 mm

In the diagram of FIG. 2 the following input values were processed:

• Concrete compressive strength starting concrete fc = 30.0 N / mm2
• Elongation on reaching this compressive strength eo = 2.0 0/00
• Steel strength fy = 500 N / mm2
• Diameter of the strapped area Ø = 60 mm

The results are shown in the increase of the concrete compressive strength for different spiral diameters Øw = 0, 2, 4, 6 mm (o - as reference without helix). The pitch was varied at intervals of 25 mm, starting at 25, 50, 75, 100 mm. It is found that the concrete compressive strength increased from an initial value of f _co = 30 N / mm 2 at a coil diameter of OW = 6 mm and a pitch of sw = 25 mm to the value of f _c1 = 105 N / mm2 (factor 3.5) can be. The values for helix diameter and helical pitch can be implemented in the practical version.

Furthermore, the shows FIG. 3 the expansion increase of the constricted concrete, if according to the invention a coil 12 between teeth 9, 10 is installed.

The associated strains in the strapped concrete are also massively increased, but to a degree which is even greater than the strength. For the aforementioned parameters, in the diagram below in FIG. 3 given the respective elongation the associated elongation.

Analogous to the increase in concrete compressive strength is for a helix diameter of Øw = 6 mm and an associated pitch of 25 mm an increase of the elongation of 2.0 ○ / ○○ for the starting concrete to 27.0 ○ / ○○ (factor 13.5) is to be expected.

This increase helps, in particular with the high concrete strength, also to ensure a similar elongation and thus to enable a ductile behavior. Thus, this technique differs from the use of high strength concrete in conjunction with concrete dowels with the use of helical reinforcement.

Based on the previous determination of the concrete compressive strengths, the resistance of the concrete can now be predicted when using concrete anchors. The results of the tests also show that a further increase in concrete resistance through the use of S500 steel coils and a helix diameter of 6 mm is still possible compared to the present results. This will probably be the steel of the failure mechanism in the future.

The possible large strains in the case of reinforced concrete can also be found in the experiments, as documented by the permanent large deformations from the steel teeth.

In FIG. 4 is shown schematically how a coil 12 according to the invention contributes to the distribution of pressure on the tooth 10.

The tooth 10 deforms due to corresponding deformation stresses in the direction of arrow 13 and thus assumes its position 10 '(dashed line). The contact point 16, which engages in the concrete material 14, thus shifts to the position 16 '. This results in significant shear stresses that extend in the direction of arrow 17 in the concrete material 14 and try to destroy this concrete material.

For this purpose, the coil according to the invention, which surrounds the tooth 10 at least partially with its turn 15, so that the shear stresses carried into the interior of the coil 12 in the arrow directions 17 in the Concrete material 14 of the helix are received and will not be carried to the outside. Thus, this is a reinforcement of the tooth 10 by the coil 12, and harmful shear stresses are not carried into the surrounding material, as was the case in the prior art.

The FIG. 5 shows as a further embodiment that it is sufficient only to pour a concrete plug 23 in an upper concrete shell 1 with the coil 12 according to the invention, the lower portion then remains free. Such a structure is z. B. used when the upper concrete shell is directly on the concrete dowel 3 on a corresponding bearing surface.

The FIG. 6 shows another embodiment of a dowel 23, which is designed as a double-T-carrier, wherein the upper plate 18 of the concrete plug 23 has the recesses 8 and in turn the teeth 9, 10 are formed, which are inventively covered by a respective coil 12 ,

The FIG. 6 shows that such a double-T-beam with its lower plate 19 can also be placed on a mounting plane, without it being necessary to pour the lower part in a lower concrete shell 2.

Of course, this particular form of the anchor 23 as a double-T-carrier also on the lower plate 19, the recesses 8 shown on the upper plate 18 with the teeth 9, 10 and the coils 12 show.

The FIG. 7 shows as a further embodiment that a double-T-carrier according to the FIG. 6 is poured directly into an upper and lower concrete shell 1, 2 and in this case the coils 12 are provided both in the upper region and in the lower region.

The FIGS. 8 to 10 show as a pressure distribution body a slotted tube 22, which has distributed around the circumference arranged slots 20.

There are frontal slots 20 so that they reach over the teeth to be reinforced 9, 10 and thus protect the teeth.

In the interior of the slot tube 22 in this case again the concrete material 14 is filled, so that therefore again the compressive stress, which is registered by the teeth 9, 10 in the interior of the slot tube 22, from the local concrete material 14 FIG. 10 recorded and distributed.

drawing Legend

1

upper concrete shell

2

lower concrete shell

3

concrete anchors

4

metal plate

5

recess

6

web

7

web

8th

recess

9

tooth

10

Tooth 10 '

11

Pressure distribution body

12

spiral

13

arrow

14

concrete material

15

convolution

16

Touch point 16 '

17

arrow

18

Plate above

19

Plate below

20

slot

21

22

slotted tube

23

dowel

Claims (7)

1. Dowel (3) for connecting two concrete shells (1, 2) of a prefabricated slab, which is anchored in form-locking manner in both the first and the second concrete shell (1, 2) during the casting process, wherein the dowel (3) consists of a metal plate (4) or a double T member (23) which extends transversely through the hollow space between the upper concrete shell (1) and the lower concrete shell (2), and arranged in the dowel (3) there are recesses (5) which form teeth (9, 10) which face one another in the dowel (3) and point towards one another in alignment, wherein at least one pressure distributing element (11) is arranged in the region between the teeth (9, 10) of the dowel (3), characterised in that
   the pressure distributing element (11) is either embodied in the form of a spiral (12) and at least one turn (15) of the spiral (12) is seated in form-locking manner on one tooth (9, 10), and the tooth (9, 10) engages in the interior of the spiral (12), and in that the opposing tooth (9, 10) of the dowel (3) engages in the interior of the spiral (12) in the same way,
   or it is embodied in the form of a slit tube (22) or sleeve, wherein the slits (20) engage over the teeth (9, 10) to be sheathed and protect the teeth (9, 10).
2. Dowel (3) according to claim 1, characterised in that the recesses (8) are profiled with a C-shape.
3. Dowel (3) according to claims 1 or 2, characterised in that the pressure distributing element (11) is embodied such that the concrete material is distributed radially and escapes.
4. Dowel (3) according to claims 1 to 3, characterised in that the spiral (12) is embodied in the form of a conical spiral or a double-conical spiral.
5. Dowel (3) according to claims 1 to 4, characterised in that a few turns (15) of the spiral (12) are present on each side of the tooth and in that these turns (15) are connected with one another by a connecting rod which can be bent like a hinge.
6. Dowel (3) according to claim 5, characterised in that instead of a connecting rod which can be bent like a hinge use is made of a connecting damper or a connecting spring.
7. Dowel (3) according to claims 1 to 6, characterised in that when the dowel (3) is embodied in the form of a double T member (23) at least one plate (18) of the dowel (3) has the recesses (8) and again in this case teeth (9, 10) are formed which are respectively covered by a spiral (12).

Images