EP1471192B1 - Connecting device for concrete components - Google Patents

Description

Technical area

The present invention relates to a concrete component connecting device with at least one cable section, which is at least partially einbetonierbar for connecting the concrete components in this.

State of the art

In the field of reinforced concrete construction, in particular of prefabricated construction, it is known to connect prefabricated reinforced concrete by means of cast-in fasteners on the site together. For this purpose, fasteners are often used, which consist of a storage box and a connecting loop and are embedded in the precast concrete plant in an abutting surface of the finished part.

For example, the WO 03/008737 a device for bonding precast concrete parts with at least one arranged at one end cable loop, which is anchored at one end in the precast concrete and the other, loop-like end protrudes from a used in the precast concrete part or arranged on the precast concrete storage box. Similar connection devices are further, for example EP 0914531 B1 . EP 0819203 B2 or EP 0534475 B1 known.

These fasteners have been found to be suitable to achieve a sufficient maximum load capacity of a concrete component connection, as it has to be demonstrated for the design on the basis of common steel concrete standards such as DIN 1045-1 or Eurocode 2 in the so-called ultimate limit state. In contrast, it has not been possible with the known fasteners to meet the proof in the so-called limit state of serviceability. This is primarily due to the fact that in the known fasteners early cracks in the concrete of the compound set, the crack width is excessively large. Such cracks are not only undesirable for optical reasons, but significantly affect the durability and tightness of the reinforced concrete structure. In particular, occurs in wide cracks in the concrete, the problem that the reinforcement is no longer sufficiently protected against corrosion.

Some attempts to overcome these problems, such as increasing the loop strength, have not led to the desired result. Because of these difficulties, the known fasteners, despite their constructive advantages could not prevail generally.

As a further prior art is the WO 03/008737 A1 known, which discloses a device for bonding precast concrete parts according to the preamble of claim 1, consisting of at least one cable loop, which is anchored at one end in the precast concrete part, and the other loop-like end with an inserted into the precast concrete or arranged on the precast concrete holding device cooperates to bend the rope loop approximately elastically at right angles during the production of the precast concrete part and release it for the composite. Such a device comprises at least one fixing means which holds the cable loop in the upright position of the composite.

Furthermore, the EP 0 896 087 A1 known.

Presentation of the invention

It is therefore an object of the present invention to provide a concrete component connecting device of the type mentioned, which allows a sufficient usability of the concrete component connection and in particular a limited crack width in the concrete component connection.

This object is achieved by a concrete component connecting device with the features of claim 1. Advantageous developments of the concrete component connecting device according to the invention are specified in the dependent claims.

The inventors have found that for the limit state of serviceability and the limitation of cracks in concrete completely different criteria are decisive than for the ultimate limit state (failure state). Against this background, the inventors have recognized that, with regard to improved load-bearing behavior in the limit state of serviceability measures taken so far, such as increased rope strength are not expedient, but rather the rope stiffness and the anchoring rigidity of the cable section in the concrete is decisive for the load-bearing behavior.

Accordingly, the at least one cable section of the concrete component connecting device according to the present invention comprises means for increasing the rope stiffness of the at least one cable section in concrete. As a result, a concrete component connecting device is provided for the first time, with which the requirements of common reinforced concrete standards such as DIN 1045-1, Eurocode 2 or the like not only in the limit state of carrying capacity but also in the limit state of serviceability. In particular, thanks to the inventive means for increasing the rope stiffness of the at least one cable section in concrete, a significant reduction of the crack widths in the concrete of the concrete component connection can be carried out. This results in addition to an improved appearance increased durability and tightness of the connection. In particular, corrosion problems can be significantly reduced.

According to the present invention, the concrete component connecting device further comprises at least one storage element, wherein the at least one storage element has at least one opening through which the at least one cable section is passed.

The rigidity of the at least one cable section can be increased particularly efficiently in accordance with the present invention if means are provided for reducing the geometric extension of the at least one cable section. Under geometric stretching is understood the appearance that in a rope, which is usually formed of several wires and / or strands, when applying a tensile stress initially a transverse contraction of the rope takes place at which the individual wires or strands abut each other, which a comparatively low initial stiffness of the cable section leads. Correspondingly, means for reducing the geometric stretching ensure that the "installation" of the wires or strands is reduced when a load is applied and thus the initial rigidity of the cable section is increased. This results in a significantly improved response of the cable section, so that it is activated early in the occurrence of possible cracks in the concrete and thus the further opening of these cracks can be effectively prevented in contrast to the prior art.

According to the present invention, the at least one cable section has a ratio between rope diameter and Strike length of at most 0.1. This ratio value is also referred to as impact angle, wherein the lay length indicates the length on which a strand or a wire of the cable section once the outer circumference of the cable section circumnavigated. It has been shown that, with a ratio between rope diameter and lay length of at most 0.1, a significantly reduced geometric draft is already achieved.

According to a development of the present invention, the at least one cable section has a modulus of elasticity of at least 110,000 MPa, preferably at least 130,000 MPa. The term "modulus of elasticity of the cable section" here does not mean the modulus of elasticity of the material used as such, but rather the modulus of elasticity which results when a tensile force is applied to the at least one cable section, which may, for example, have a plurality of serpentine wires or strands. Suitable measures for increasing the modulus of elasticity of a cable section according to the present invention will be explained below. By these measures, the rigidity of the at least one cable section can be significantly increased without having to use, for example, a higher quality material or a higher material strength.

According to a further aspect of the present invention, there is provided a means for increasing anchoring rigidity comprising means for improving the bond between the surface of the at least one cable section and the concrete. By this measure according to the invention, which can be very well combined with the means described above for reducing the geometric draft, the response of the at least one cable section can be further improved in the event of a crack in the concrete. It should again be emphasized that the inventors have found that this response is decisive for the prevention of wide cracks in the concrete. Only if, after the formation of a crack in the concrete, a sufficient tension builds up quickly in the at least one cable section, can a further opening of the crack be prevented. this will According to the invention achieved by the improved response of the at least one cable section, which results from the means for increasing the Seehnehnsteifigkeit and / or the anchoring rigidity of the at least one cable section in the concrete.

The means for reducing the geometric extension of the at least one cable section or for improving the bond between the surface of the at least one cable section and concrete may comprise a variety of measures. Preferred embodiments of these compositions are particularly apparent from the following described developments of the present invention.

Although the at least one cable section according to the present invention may be formed by any arrangement or combination of wires or strands, according to one embodiment of the present invention it is preferred that the at least one cable section is formed by a spiral cable. On the one hand, due to their winding structure, such spiral cables have a comparatively small geometric stretch, and on the other hand, because of their helical surface, permit a good bond between the cable surface and the surrounding concrete. In addition, spiral ropes are economical to produce.

In order to achieve a tightly packed rope structure already in the unloaded rope, it is provided according to a development of the present invention that the at least one cable section has a plurality of strands, wherein at least one strand has a diameter which deviates from that of the remaining strands. Due to the different diameters result in the interior of the cable section lower closed cavities, so that when applying a tensile load on the at least one cable section a smaller transverse contraction and thus a lesser geometrical horizontal bar is to be observed. In addition, the different diameters lead to a more rugged surface of the cable section, which further improves the bonding behavior of the cable section.

According to a further aspect of the present invention, the at least one cable section has at least one cavity which is accessible in such a way that the penetration of concrete, mortar, cement paste or the like into the at least one cavity is possible. As a result, in turn, two effects are achieved simultaneously, namely on the one hand that the transverse contraction capability of the cable section is considerably reduced by the penetration of concrete, etc. in the at least one cavity and the occurrence of a geometric step is largely eliminated when applying a tensile force on the cable section. As a result, the Seildehnsteifigkeit is increased significantly in a simple but highly effective manner. On the other hand, the penetration of concrete etc. into the at least one cavity of the cable section also enables improved bonding between the surface of the cable section and the surrounding concrete, which increases the anchoring rigidity of the cable section. Overall, this results in a significantly improved response of the cable section with the advantages described above.

According to one embodiment of the present invention, it is further provided that the at least one cable section has a plurality of strands, wherein at least one strand is spaced from an adjacent strand, in particular in the circumferential direction of the cable section. As a result, voids are generated in a simple manner, in the concrete, mortar, cement paste or the like can penetrate from the outside, which as described above leads to improved rope stiffness and anchoring rigidity.

With regard to the bonding behavior, according to a development of the present invention, it is further provided that the at least one cable section is formed by at least one wire or at least one strand, which is looped around by at least one wire and / or at least one strand. The provision of an additional wire or an additional strand on the outer circumference of the cable section gives the cable section to a certain extent a thread-like surface, the liquid forms einkrallt in the surrounding concrete, so that in a simple way an excellent bond between the cable surface and concrete and thus a much improved Anchoring behavior with correspondingly improved response results.

According to a development of the present invention, the at least one cable section has at least one anchoring element, preferably at least two anchoring elements. The anchoring elements according to the invention preferably bring about a positive connection between the cable surface and the surrounding concrete, which drastically reduces the slip between the cable surface and the concrete and correspondingly drastically increases the anchoring rigidity of the at least one cable section in the concrete. This makes it possible that with the formation of a crack in the concrete lying in the crack rope section is activated directly, so that possible cracks held together securely and the crack widths are kept low.

It is particularly preferred that the at least one anchoring element is formed in a terminal shape, plate-shaped and / or jagged. These forms are easy to manufacture and allow a secure fit between the anchoring element and concrete.

According to a development of this concept, two cable sections each are arranged together, whose adjacent end areas are connected to each other by means of an anchoring element. This results in an advantageous combination of two cable sections by means of at least one anchoring element in a simple manner to form a loop and thereby achieve improved anchoring properties simultaneously.

According to a further aspect of the present invention, the at least one cable section is opposite the at least one Verwahrelement elastically deflectable in different angular positions. Such a concrete component connecting device allows safe carrying behavior both in terms of maximum load capacity and in terms of usability with a simple design and easy installation on site.

It is particularly preferred that the concrete component connecting device as described above has at least one anchoring element which is located adjacent to the at least one Verwahrelement and preferably at most three times the rope diameter of this is removed. The inventors have found that the most damaging cracks in the concrete often occur near the storage element, so that limiting these cracks is of crucial importance, which is achieved by the above inventive measure. In this context, it is also preferred according to the invention that the at least one cable section can be fixed or anchored in the storage element in order to further increase the anchoring rigidity of the cable section. Overall, the concrete component connecting device according to the invention allows for the first time a connection of concrete components, which has low crack widths in use. Accordingly, according to a further aspect, the present invention provides a connection of concrete components of at least one concrete component connecting device, wherein the crack width of a single crack in the region of the compound at a mean tensile stress in the at least one cable section in the crack of at most 33% of the minimum breaking force of the cable section at most 0 , 4 mm, preferably at most 0.25 mm.

Brief description of the drawings

Fig. 1

schematically shows a perspective view of an embodiment of the concrete component connecting device according to the present invention;

Fig. 2

schematically shows a sectional view of a first embodiment of the cable section according to the present invention;

Fig. 3

schematically shows a side view of in Fig. 2 shown first embodiment of the cable section according to the present invention;

Fig. 4

schematically shows a sectional view of a second embodiment of the cable section according to the present invention;

Fig. 5

shows schematically a partially sectioned perspective view of a third embodiment of the cable section according to the present invention;

Fig. 6

schematically shows a partially sectioned perspective view of a fourth embodiment of the cable section according to the present invention;

Fig. 7

schematically shows a side view of a fifth embodiment of the cable section according to the present invention;

Fig. 8

schematically shows plan views of a sixth ( Fig. 8a ), seventh ( Fig. 8b ) and pay attention ( Fig. 8c Embodiment of the cable section according to the present invention, each as part of a concrete component connecting device;

Fig. 9

schematically shows a connection of two concrete components using a novel invention Concrete component connecting device in a sectional plan view ( Fig. 9a )) and a sectional side view ( Fig. 9b )).

Detailed description of preferred embodiments

Preferred embodiments of the present invention will be described below in detail with reference to FIG Fig. 1 to 8 described.

Fig. 1 schematically shows a perspective view of an embodiment of the concrete component connecting device according to the present invention. The concrete component connecting device 1 comprises a storage box 10 with an opening 12, through which a cable loop 2, which in Fig. 1 is shown purely schematically, is passed. In the Fig. 1 shown concrete component connecting device 1 is intended to be embedded in concrete in each case in the end face of adjacent reinforced concrete components or precast elements, wherein adjacent loops in the region of the joint form a lap joint, which is cast with concrete or mortar.

In the Fig. 1 shown concrete component connecting device 1 may instead of the cable loop 2 have one or more cable sections, the preferred embodiments are described below. A first preferred embodiment of a cable section 2 according to the present invention is shown schematically in FIG Fig. 2 shown in a sectional view. The cable section 2 comprises a plurality of strands 2 a, 2 b, 2 c, which are spirally or helically wound. As in Fig. 2 can be seen, the cable sections 2a, 2b, 2c each have different diameters. In this case, the cable sections are arranged such that each cable section adjoins another cable section with different diameters. In this way, the dimensions of the cavities formed within the cable section 2 in Compared to cable sections with strands of the same diameter significantly reduced, so that the geometric extension of the cable section 2 is reduced compared to a conventional cable section. At the same time this results in an improved bonding behavior of the surface of the cable section with concrete.

The modulus of elasticity of the cable section 2 in the cable longitudinal direction (perpendicular to the plane in Fig. 2 ) can be increased to values above 110,000 MPa, preferably over 130,000 MPa, thanks to the low geometric draft.

A side view of in Fig. 2 shown first embodiment of the cable section 2 is in Fig. 3 shown schematically. It can be seen that due to the different diameters of the strands 2a, 2b results in a more corrugated compared to conventional strands outer contour, which improves the composite properties of the cable section in concrete. In addition, in Fig. 3 the so-called impact angle α indicated, which depends on the ratio between rope diameter d and lay length w. In the present embodiment, w / d is about 0.1, which corresponds to an impact angle α of about 5.7 °. Although low impact angles are preferred in the present invention in terms of reduced geometric stretch, it is to be understood that the present invention is not limited thereto.

Fig. 4 schematically shows a sectional view of a second preferred embodiment of the cable section 2 according to the present invention. At the in Fig. 4 Shown stranded 2d, 2e with different diameters are used again, although this embodiment can also be performed with strands of the same diameter. In contrast to the first embodiment, the in Fig. 4 shown rope section 2 cavities 4, from the outer surface of the Cable section 2 are accessible, so that concrete, mortar, cement paste or the like can each penetrate into the cavities 4. For this purpose, the outer strands 2e are circumferentially spaced from each other. The penetration of concrete or the like into the cavities 4 allows, as explained above, a reduction of the geometric stretching, as well as an increase in the anchoring rigidity of the cable section 2 shown.

A third preferred embodiment of the cable section 2 according to the present invention is shown schematically in FIG Fig. 5 shown in a partially sectioned perspective view. In the Fig. 5 The embodiment shown differs from that in FIG Fig. 4 embodiment shown mainly in that the strands 2d, 2e have substantially the same diameter and the cavities 4 are made larger between the outer strands 2e. In addition, lets Fig. 5 recognize how the tortuous structure of the cable section 2 according to the invention allows an excellent fit of the cable section in concrete or the like, in particular in conjunction with the cavities 4 between the outer strands 2e. It should be noted that it is not necessary in the context of the present invention that the outer strands 2e as shown abut the inner strand 2d. Rather, it may also be advantageous to provide a spacing here, at least in sections, in order to allow even more far-reaching penetration of concrete or the like and to further improve the positive connection in this way.

Fig. 6 schematically shows a partially sectioned perspective view of a fourth preferred embodiment of the cable section 2 according to the present invention. The cable section 2 comprises a central cable section 3, which in the present embodiment is formed by a plurality of serpentine strands 2f. It should be noted that the central cable section 3 by any other Embodiment of the present invention or may be formed by a conventional cable section. The central cable section 3 is looped by a strand 6, which propagates helically along the outer circumference of the central cable section 3. It goes without saying that, instead of a single stranded wire 6, a plurality of strands and / or wires can also be provided on the outer circumference of the central cable section 3. As a result, the positive connection between the rope surface and the surrounding concrete is significantly improved.

Fig. 7 schematically shows a side view of a fifth preferred embodiment of the cable section 2 according to the present invention. The in Fig. 7 Cable section 2 shown is equipped with an anchoring element 8, which in the present embodiment, a jagged, similar to a barbed wire or the like, is formed. It should be noted, however, that the anchoring element 8 may also have another suitable shape which allows an improved positive connection between the cable surface and the surrounding concrete.

Further preferred embodiments of the cable section according to the invention are shown in FIG Fig. 8 in each case as part of a concrete component connecting device 1 according to the invention are shown in each case two concrete component connecting devices 1, which together form a concrete component connection. The three in Fig. 8 embodiments shown include a lap joint of cable sections 2, 2 ', but differ in the design of the cable sections.

So shows Fig. 8 a) a sixth preferred embodiment of the concrete component connecting device having two cable sections 2, 2 ', each at its free, the other concrete component connecting device 1 facing the end with an anchoring element 8 in the form of a compression sleeve or the like. A major advantage of in Fig. 8 a) In addition to a good anchoring behavior, the embodiment shown therein has a high variability because the cable sections 2, 2 'are not connected to a loop, which facilitates the handling of the concrete component connecting device in some applications.

At the in Fig. 8b) embodiment shown, two cable sections 2, 2 'are also provided per concrete component connecting device, wherein the free, the other concrete component connecting device 1 facing ends of the cable sections 2, 2' are provided with a common anchoring element 8, which is formed for example by a crimp or the like. This can be compared to Fig. 8 a) Save components and work steps without complicating the use.

Finally shows Fig. 8c) an eighth preferred embodiment having only a single cable section 2, which is looped in a known manner, but additionally provided with two anchoring elements 8, which lie in the present embodiment, near the transition region straight cable sections to the curved loop end portion. The optimum position of the anchoring elements 8 may vary from application to application. Thus, it is often advantageous to place the anchoring elements 8 relatively close to the area of expected cracks, for example close to the associated storage box 10. It will be understood that the number and arrangement of the anchoring elements 8 in the context of the present invention will be varied and adjusted according to the constraints and requirements can. It should also be noted that the in Fig. 2 to 8 shown embodiments in an advantageous manner with each other can be combined. So it makes sense, for example, in Fig. 8 shown rope sections 2 with one of in Fig. 2 to 6 execute executed rope structures.

An example of the use of the concrete component connecting device 1 according to the invention is shown in FIG Fig. 9 illustrated. Fig. 9 1 schematically shows a connection of two wall components 22, 24 made of concrete using the concrete component connecting device 1 according to the invention in a sectional plan view (FIG. Fig. 9a ) and a sectional side view ( Fig. 9b ). The wall components 22, 24 are each provided in their mutually facing end faces with a concrete component connecting device 1, which is shown schematically and preferably corresponds to one of the embodiments described above. In the connected state, the cable sections 2 of the adjacent concrete component connecting devices 1 overlap, and in addition, a reinforcing bar 3 is inserted between the cable sections 2. Finally, between the wall members 22, 24 existing cavity in which the cable sections 2 and the reinforcing bar 3 are, shed with a suitable mortar or the like.

After the mortar has hardened, the concrete component connecting devices 1 enable a force transmission between the adjacent concrete components 22, 24. Cracking may occur in the joint area between the adjacent concrete components 22, 24 as a result of static loads, constraining forces, concrete shrinkage or the like. A frequently occurring crack in practice is in Fig. 9 schematically drawn. After that, a first crack 26 and then a second crack 28 often appear first. However, the concrete component connecting device 1 according to the invention makes it possible, due to the good rigidity of the cable or anchoring rigidity of the at least one cable section, to prevent the formation of excessive crack widths and this way to reliably ensure the serviceability of the concrete component connection 20. In particular, it has been shown that, thanks to the concrete component connecting device according to the invention, the width of the individual cracks 26, 28 in the connection 20 in the state of use can be limited to values of the highest 0.25 mm. As a state of use while a condition was considered in which in the cable section 2, an average tensile stress in each crack of 33% of the minimum breaking force of the cable section was present.

Claims (14)

1. Connecting device (1) for concrete components, having:

   at least one cable section (2) which can be embedded in concrete components in at least one section for the connection thereof, and

   at least one preserving element (10), wherein the at least one preserving element (10) has at least one aperture (12) through which is passed the at least one cable section (2),

   characterised in that
   the at least one cable section (2) has means for increasing the axial rigidity of the at least one cable section (2) in concrete, wherein the means for increasing the axial rigidity of the cable include means for reducing the geometrical stretch of the at least one cable section (2), wherein the at least one cable section (2) has a ratio between cable diameter (d) and length of lay (w) of not more than 0.1.
2. Connecting device for concrete components according to claim 1, characterised in that the at least one cable section (2) has a modulus of elasticity of at least 110,000 MPa, preferably at least 130,000 MPa.
3. Connecting device for concrete components according to either of the preceding claims, characterised in that the at least one cable section (2) is formed by a spiral cable, a round strand cable or a strand construction.
4. Connecting device for concrete components according to any of the preceding claims, characterised in that the at least one cable section (2) has a plurality of strands (2a, 2b, 2c), wherein at least one strand (2a) has a diameter which differs from that of the other strands (2b, 2c).
5. Connecting device for concrete components according to any of the preceding claims, characterised in that the at least one cable section (2) has at least one cavity (4) which is accessible in such a way that the entry of concrete, mortar, cement paste or the like into the at least one cavity (4) is possible.
6. Connecting device for concrete components according to any of the preceding claims, characterised in that the at least one cable section (2) has a plurality (2d, 2e) of strands, wherein at least one strand is spaced apart from an adjacent strand, in particular in the circumferential direction of the cable section.
7. Connecting device for concrete components according to any of the preceding claims, characterised in that there is provided a means for increasing the anchoring rigidity which has means for improving the bond between the surface of the at least one cable section (2) and concrete.
8. Connecting device for concrete components according to any of the preceding claims, characterised in that the at least one cable section (2) is formed by at least one wire or at least one strand (2f) round which is wound at least one wire and/or at least one strand (6).
9. Connecting device for concrete components according to any of the preceding claims, characterised in that the at least one cable section (2) has at least one anchor element (8), preferably at least two anchor elements.
10. Connecting device for concrete components according to any of the preceding claims, characterised in that in each case two cable sections (2, 2') are arranged together, of which the adjacent end regions are joined by means of an anchor element (8).
11. Connecting device for concrete components according to claim 9 or 10, characterised in that the at least one anchor element (8) has a clamp-like, plate-like and/or pronglike form.
12. Connecting device for concrete components according to any of the preceding claims, characterised in that the at least one cable section can be elastically deflected relative to the at least one preserving element (10) into different angular positions.
13. Connecting device for concrete components according to claim 12, characterised in that the at least one anchor element (8) of the at least one cable section (2) is located adjacent to the at least one preserving element (10) and is preferably not more than three times the cable diameter (d) away from it.
14. Connection (20) of concrete components (22, 24) with at least one connecting device (1) for concrete components according to any of the preceding claims, characterised in that the width of an individual crack (26, 28) in the region of the connection is not more than 0.4 mm, preferably not more than 0.25 mm under an average tensile stress in the at least one cable section (2) in the crack of not more than 33% of the minimum breaking force of the cable section.

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