AU2012372530A1

AU2012372530A1 - Turnbuckle for connecting structural elements

Info

Publication number: AU2012372530A1
Application number: AU2012372530A
Authority: AU
Inventors: Klaus Jaeschke
Original assignee: BT Innovation GmbH
Current assignee: BT Innovation GmbH
Priority date: 2012-03-08
Filing date: 2012-03-08
Publication date: 2014-09-25
Also published as: NI201400103A; MX2014010725A; EA201491502A1; IN2014DN07779A; WO2013131530A1; EP2823110A1; JP2015510062A; CN104271852A

Abstract

The invention relates to a turnbuckle (1) for connecting structural elements, particularly precast concrete parts (10), which is formed substantially in a shell shape, and a receiving chamber (2) accessible at least from the outside by means of an access opening (9) and also has passage sections (3, 4), preferably facing each other, opening into the receiving chamber, said passage sections being preferably designed as passage openings for the insertion of fastening means (13). The present invention also relates to a construction kit for connecting structural elements, a method for connecting structural elements, an arrangement for connecting structural elements and a method for preparing structural elements.

Description

Turnbuckle for joining structural elements The present invention refers to a turnbuckle for joining structural elements, to a kit for joining structural elements comprising a turnbuckle according to the invention, to a method of joining structural elements comprising a turnbuckle according to the invention, to an arrangement for joining structural elements and to a method of preparing structural elements into which the turnbuckle according to the invention is inserted. When constructing new buildings, prefabricated concrete parts are frequently used which are joined to one another on the construction side. High demands are made on the connection. The connection shall be creatable quickly and at a low price and shall also be capable of withstanding high loads. To date boxes with reinforcement elements were arranged in casting grooves of the structural elements. These reinforcement elements can for instance be made of concrete steel. When assembling the structural elements the reinforcement elements overlap. These overlapping reinforcement elements are cast in the casting joint by using joint mortar. However, this method is time-consuming, since some time passes until the joint mortar has cured and the connection is loadable. In order to be able to quickly erect new buildings it is required that the structural elements can quickly and safely be joined on the construction site. When erecting temporary buildings, additionally the economical dismantling is important. With respect to flood protection it is not sensible for cost reasons to set up the protective measures all year round, whereby a cost-effective alternative is required. Additional framework conditions result from the safety requirements made on the building to be erected. In coast-near regions resistance against salt water is a criterion. Salt water can chemically attack and thereby weaken the buildings over the period of their existence. For the use in tectonically active regions, buildings must be adapted to earthquakes. In this case vibrations of the earth surface must be safely taken up and compensated.

2 When erecting permanent buildings the maintenance and repair has a significant meaning. The connections must, if necessary, be inspected in regular intervals. Critical joints shall always have a simple access to ensure a cost-effective verifiability. The object of the invention is to simplify the joining of structural elements. A further object is to enable the use of buildings in tectonically active areas, which requires a fatigue strength. An additional object is to allow a simple and time-saving dismantling. At the same time the expenses shall be lowered. A further object of the invention is to enable a simple inspection of the quality and safety of the joint of the prefabricated concrete parts. The object is solved according to the invention by a turnbuckle for joining structural elements, particularly prefabricated concrete parts, which is substantially formed in the shape of a shell and with a housing chamber accessible from the outside via an access opening, and additionally passage sections preferably arranged opposite one another opening into the housing chamber, said passage sections preferably being formed as passage openings in the planar side walls, for fixing means to be pushed through, and that the turnbuckle preferably has a tensile strength of 400 N/mm 2 to 800 N/mm 2 , preferably 450 N/mm 2 to 780 N/mm 2 , especially preferably 500 n/mm 2 to 750 N/mm 2 . This solution has the advantage that structural elements, particularly prefabricated concrete parts, can quickly, rationally and safely be connected to one another. The joint can be loaded immediately after tensioning the turnbuckle. A curing time is not required. Thus, the turnbuckle according to the invention facilitates the assembly of concrete elements and leads to a significant saving of time on the construction site. Furthermore, the turnbuckle according to the invention can be rationally manufactured at high precision and in series. By using a material having a high strength and toughness, the joint can take up and transfer high forces. Particularly when being used in buildings in earthquake regions with the vibration requirements connected therewith it is required to absorb and compensate these occurring vibrations. By the use of a highly tough material, preferably a special steel, safety of the building is ensured so that the steel bears a high deformation before structure element failure occurs. By the use of preferably stainless steel or preferably acid-resistant steel the corrosion resistance of the turnbuckle can be increased so that a use in a salt water environment is possible. The use of composite materials can also enable an increased corrosion resistance. Thus, the turnbuckle can be used for flood protection buildings or offshore buildings. It is 3 advantageous in this context that a filling of the assembly opening for corrosion protection of the turnbuckle is not required, thus saving costs and assembly effort. It can be advantageous if the turnbuckle comprises at least two tapering, preferably conically tapering side walls. This has the advantage that the required free space for the rotational movement of a clamping tool when creating screw-type connections is given and a higher mechanical load-bearing capacity is achieved by the special geometric shape of the turnbuckle. If at least two side walls are substantially planar and oppose one another preferably in parallel, a straight load transfer in the tensile direction is given. It can also be advantageous if the passage sections are formed in the planar side walls, since in this manner assembly can even further be simplified. Furthermore, it can be advantageous if the tapering side walls are connected to one another so that the cross-section is V-shaped or U-shaped. In this manner the insertion of a clamping tool when creating the screw-type connection with the structural elements can even further be simplified. In an advantageous further development of the invention the passage sections can preferably be offset by 900 and can be formed as a slot and/or oblong hole, and preferably one of the passage sections can be formed as a slot and another one of the passage sections can be formed as a oblong hole. This constructions enables yet an easier and quicker assembly of the turnbuckle and compensates for tolerances of the fixing points generated during the assembly process when manufacturing the structural elements. If the slot is open at least on one side and preferably opens into the access opening, assembly can even further be simplified. It can also prove to be advantageous if the turnbuckle at least section-wise consists of an annealed cast iron or a spheroidal grahite cast iron. When designed with annealed cast iron the strength and hardness of the turnbuckle can advantageously be adapted to the assembly situation. The annealed cast iron enables, particularly in thin-walled elements, a favourable adaptability of tensile ductility and hardness during the manufacturing process. Hereby the material can preferably be adapted to the vibrational requirements. By the design according to the invention comprising nodular cast iron a high strength of the turnbuckle can be achieved 4 without using an additional tempering method. By the use of spheroidal grahite cast iron a cost effective realisation is possible. In a further preferred embodiment the turnbuckle can at least section-wise be composed of composite materials with carbon fibre and/or glass fibre and/or aramid fibre. By the use of composite materials the turnbuckle can specifically be adapted to the corrosion requirements. It is advantageously possible to enable a higher strength, which is particularly advantageous for the use near coasts or offshore regions. Due to the resistance against salt water and salt mist safety is ensured. In a further preferred embodiment the turnbuckle can at least section-wise be composed of steel, preferably stainless steel, and may have an elongation at break of preferred 35 per cent, preferably 40 per cent, especially preferred 45 per cent. This ensures a high tensile ductility and the steel can run through a high strain before the turnbuckle fails to work and the joint of the structural elements is no longer guaranteed. Thereby it is particularly advantageous for the erection in earthquake regions that before the failure a sufficient strain of the turnbuckle can take place. By this vibrations of the construction underground can efficiently be absorbed and damped so that a building is not destroyed or at least remains intact for a safety period. It can be advantageous if the turnbuckle is deep-drawn, wherein due to the cold working during deep drawing of the material the strength and tensile ductility can further be increased. Caused by the deep drawing the ability of taking up and transferring forces and tensions in the turnbuckle is positively improved. In a further advantageous embodiment the turnbuckle can be welded. The turnbuckle is then welded from the single parts. It can be advantageous if the side walls strained by bending and torsion have a greater wall thickness than the conically extending side walls, which predominantly are loaded by tensile stress. Hereby an optimisation of the turnbuckle to the forces applying can be implemented. It can be advantageous if the width and the height of the turnbuckle have the same length, or if the width is preferably at least 15 per cent smaller than the height. Due to the compact design the tensile forces in the turnbuckle can directly be dissipated and a high rigidity is achieved. It can be advantageous if the depth of the turnbuckle is preferably at least 10 per cent, preferably at least 25 per cent smaller than the width B. Caused by these relations the 5 turnbuckle is adapted to the occurring shear stresses and the safety of the turnbuckle against failure can be improved. The object is also solved by a kit for joining structural elements, particularly prefabricated concrete parts, with at least one turnbuckle according to the invention and at least one anchorage, preferably a pigtail anchor. This solution has the advantage that a significant saving of time on the construction site can be achieved, since curing time is not required and the joint of the structural elements after assembly of the turnbuckle can be loaded immediately. It can be favourable if the kit further comprises at least one recessed body, which is preferably provided for being attached at a formwork element for generating a structural element and which is further provided to hold at least one anchor, preferably a pigtail anchor, which is provided to be inserted into the structural element. This has the advantage that the structural elements can be provided in the factory for the accommodation of the turnbuckle according to the invention. It can be advantageous if the recessed body is composed at least section-wise of metal and/or plastic material and is preferably at least section-wise magnetic. The recessed body can in this manner even more easily be mounted to the formwork element and can also be removed therefrom. Furthermore, yet an even safer placement of the recessed body is possible. In an advantageous development of the invention the kit can further comprise a sealing means, preferably a sealing strip, which is provided to be inserted between the structural elements before joining them and it can comprise a sealing means which in the assembled state of the turnbuckle seals it against environmental influences from the outside and which can repeatedly be removed. By the use of such a sealing means, an even higher water and gas impermeability of the grooves between the structural elements is achieved. The sealing means is form instance formed as a folding or snap-on lid. By this the recess does not have to be closed after assembly by a filling material so that even after assembly the access to the turnbuckle is possible. Due to the accessibility the turnbuckle can be inspected any time for maintenance and repair purposes without having to remove filling mortar. The above object is also solved by a method of joining structural elements, particularly prefabricated concrete parts comprising the following steps: 6 Assembling structural elements provided with at least one recess and one anchor, preferably a pigtail anchor, so that the recesses oppose the structural elements to be joined, inserting the turnbuckle according to the invention into the recesses of the structural elements, inserting the fixing means through the access opening into the housing space and through a passage section of the turnbuckle into one anchor each, preferably a pigtail anchor, fixing the fixing means, attaching the sealing means. This solution has the advantage that the assembly of the structural elements is significantly facilitated and a high precision in manufacture is achieved. Furthermore a significant saving of time on the construction side is possible. The structural elements can therefore be rationally and quickly joined. The straining of the structural elements is possible without additional materials and special appliances. A disassembly of the structural elements can be carried out in reverse order. This has the advantage that temporary buildings can be dismantled at a low time and cost effort. Furthermore, it can prove to be advantageous if the thickness of the structural elements is larger than the depth of the recess. This enables an even better sealing of the structural elements. It can also be advantageous if the recess is at least 40 per cent or preferably at least 50 per cent of the thickness of the structural elements. Thereby the joining position of the structural elements can further be shifted in the direction of the axis of symmetry of the structural elements so that a symmetric load transmission from the turnbuckle into the structural elements is ensured. Thus, a straight-line arrangement of the structural elements is possible and the generation of shear forces by an asymmetric assembly of the structural elements can be prevented. If a sealing means, preferably a sealing strip is inserted between the sides of the structural elements before joining, the water and gas impermeability of a joint between the structural elements can be increased. Furthermore, it can prove to be advantageous if in the joined condition of the structural elements the sealing means proceeds behind the turnbuckle since thereby the sealing can be increased even further. Due to the positioning of the sealing means a free design of the sealing groove is ensured. Thus, structural elements designed as free surfaces can also sealingly be connected by the turnbuckle. The recesses can advantageously be arranged on the front and back side of the structural element. Thereby the structural elements can preferably be connected to two turnbuckles in a 7 manner that one turnbuckle is arranged on the front side and one turnbuckle is arranged on the back side. Due to the arrangement a favourable distribution of the shear forces is possible and the structural elements are loaded symmetrically. Furthermore, the above object is solved by the arrangement for joining structural elements, particularly prefabricated concrete parts, with at least one turnbuckle according to the invention, at least two structural elements which comprise at least one recess into which the turnbuckle can be inserted and an anchorage, preferably a pigtail anchor, which is accessible via the recess, and fixing means, wherein the recess is finally closed by a reversibly removable sealing means. This solution has the advantage that a rational and quick joining of structural elements is possible, which is also safe. In this manner cost and time can be saved. The sealing means additionally serves for the easy accessibility of the structural element connection for later maintenance work or for the purpose of the quick disassembly of the structural elements. In this manner a removal of filling mortar is not required, which is otherwise used to seal grooves. It can be advantageous if the arrangement additionally comprises a sealing element, preferably a sealing strip, which is provided to be inserted between the sides of the structural elements to be connected prior to joining same. In this manner the water and gas impermeability of a groove between the joined structural elements can be improved. Furthermore, the above-mentioned object is solved by a method of preparing structural elements, preferably prefabricated concrete parts, into which the turnbuckle according to the invention is to be inserted, comprising the following steps: Attaching an preferably at least section-wise magnetic recess body, which holds at least one anchorage, preferably a pigtail anchor at a formwork element, filling the formwork element by a filler material, preferably with concrete, curing the filler material, removing the formwork element and the recess body. This solution has the advantage that the structural elements can be pre-fabricated with a high precision and can be quickly and safely connected on the construction site by the turnbuckle according to the invention without any additional material. The invention will now be described in detail by the aid of an embodiment and associated drawings.

8 These drawings show: Fig. 1 a schematic view of the turnbuckle according to the invention with access openings, Fig. 2 a top plan view onto the turnbuckle according to the invention, Fig. 3 a sectional view of Fig. 2 along line E-E, Fig. 4 a sectional view of Fig. 2 along line D-D, Fig. 5 a sectional view of Fig. 2 along line C-C, Fig. 6 a schematic view of two structural element with a sealing band and an inserted turnbuckle, Fig. 7 a sectional view of Fig. 6 along line A-A, Fig. 8 a formwork element with a recess body and a pigtail anchor, Fig. 9 a schematic view of the turnbuckle according to the invention without access openings, Fig. 10 a sectional view according to Figure 7 of a further embodiment, Fig. 11 a sectional view according to Figure 7 of a further embodiment, Fig. 12 a view of the turnbuckle of a welded design, Fig. 13 a schematic view of the turnbuckle according to the invention to illustrate the dimensions. Fig. 1 shows a schematic view of the turnbuckle 1 according to the invention for joining structural elements 10, particularly prefabricated concrete parts 10 (cf. Fig. 6). As can be seen from Fig. 1, the turnbuckle 1 is substantially formed in a shell-like manner and comprises a housing chamber 2 that is accessible from the outside via an access opening 9. Furthermore, 9 the turnbuckle 1 comprises two opposing passage openings 3, 4 (offset by 900) opening into the housing chamber 2 for passing through fixing means, such as screws 13 (cf. Fig. 6). In the present embodiment a passage opening 3 is formed as a slot 3 that is open on one side and which opens into the access opening 9. The other passage opening 4 is in the present embodiment formed as a oblong hole 4. The slot 3 and the oblong hole 4 are formed in the planar and opposing side walls 7, 8. The number, design and arrangement of the passage openings 3, 4 shown in the embodiment is only to be seen as an example. For the more effective assembly and a better compensation possibility of the joining points provided with the tolerances caused by manufacture, the planar side walls 7, 8 of the turnbuckle 1 can for instance be provided with a slot 3 or slot hole and/or a oblong hole or with two oblong holes offset by 900. The side walls 5, 6 are formed in a tapered manner, i.e. in a conical and curved manner. The conical side walls 5, 6 are in the present embodiment formed integrally and have a U shaped cross-section. The integral design of the conical side walls 5, 6 is, however, only an example. As an alternative, the conical side walls 5 6 can also be formed as individual side walls that are connected to one another. A V-shaped cross-section is also conceivable. To save weight, access openings 20, which in this case are formed as recesses 20, are provided in the conical side walls 5, 6 and in the bottom 21 of the turnbuckle 1 (cf. Fig. 2). The arrangement and the number of access openings 20 depend on the respective conditions. In order to achieve an especially high stability of the turnbuckle 1, it is also conceivable not to provide access openings 20 (cf. Fig. 9). If required, access openings can also be arranged only or additionally in the planar side walls 7, 8. Due to the conical design of the side walls 5, 6 the required free space for the rotary motion of a tensioning tool that is not shown is given when creating a screw-type connection. The turnbuckle 1 is composed at least section-wise of plastics and/or metal and/or preferably of a cast steel and/or steel. The steel preferably has a tensile strength of at least 400 N/mm 2 to 800 N/mm 2 , preferably 450 N/mm 2 to 780 N/mm 2 , especially preferred 500 N/mm 2 to 750 N/mm 2 and is preferably made of stainless steel. A highly loadable cast steel ensures the dissipation of the tensile and shear forces and furthermore ensures a rational and cost-effective manufacture of the turnbuckle 1. Due to the geometric shape and arrangement of the passage openings 3, 4, which can also be regarded as recesses 3, 4, for the screw-type connections, the turnbuckle 1 10 according to the invention takes up the occurring tensile and shear forces for the connection to be created with the respective structural elements 10 (cf. Fig. 6). Instead of screw-type connections, other suitable connections are also possible. A top plan view onto the turnbuckle 1 can be seen from Fig. 2. Fig. 2 particularly shows the access openings 20. Fig. 3 also shows especially clearly an access opening 20. Fig. 4 shows the planar side wall 8 with the oblong hole 4 and Fig. 5 shows the planar side wall 7 with the slot 3. Furthermore, the angle of aperture of the side wall 7 is defined by 38.80 This angle is only to be regarded as an example and can be adapted to the circumstances. Fig. 6 shows two structural elements 10 with one recess 11 each into which the turnbuckle 1 according to the invention is inserted. The turnbuckle 1 is fixed with a screw 13 and a washer 12 at a structural element 10. A sealing strip 14 is arranged between the sides 18, 19 of the structural element 10 to be connected. As can be seen from Fig. 6, the sealing strip 14 is running behind the turnbuckle 1. In connection with an elastic, preferably swellable sealing strip 14 made of natural or synthetic rubber and/or on the basis of bitumen, as it is for instance known by the trade name RubberElast@, the turnbuckle 1 according to the invention can also be used for various constructive solutions with prefabricated concrete parts in water-proof applications. As can be seen from Fig. 6, the sealing strip 14 is attached in the joint area of the structural elements 10 to be joined and compressed by the introduced tensioning procedure by means of the turnbuckle 1. The assembly and sealing are reduced to one working step. Ideally, the sealing strip 14 is self-adhesive and due to the compression it adheres permanently elastic with the concrete part 10. Directly after assembly, the joint 22 between the concrete elements 10 is water pressure tight. Other embodiments of the sealing strip 14 that are not self-adhesive are also conceivable. Thanks to the extremely high water and gas impermeability of the material as well as its mechanical and chemical resistance a sealing strip 14, such as RubberElast@, is an ideal solution for the joint sealing of water-proof pre-fabricated parts. Troughs, shafts, channels but also water-proof basements in domestic architecture are thereby not only safely sealed but are also assembled in an especially quick and time-saving manner. Besides RubberElast@ other sealing strips or sealing means are also conceivable. The sealing strip 14 used ideally has, besides and extremely high water and gas impermeability, a very good adhesion, a quick processing, wherein a tool is not required, and is water-proof immediately after assembly. Depending on the use, the sealing strip 14 shall also be flexible, 11 acid-resistant, alkali-proof, salt-proof and slurry-proof also at low temperatures. Furthermore, the sealing strip 14 should be weatherproof and generally certified by building authorities. Depending on the application area the sealing strip 14 does not have to comprise all listed properties. The screw 12 of Fig. 6 is connected to a pigtail anchor 16 (cf. Fig. 8), which is located in the structural element 10. Fig. 7 shows a sectional view of Fig. 6 along line A-A. In this Figure it can particularly clearly be seen that a thickness D of the structural element 10 is larger than a depth T of the recess 11. It is also shown that the sealing strip 14 is passed behind the turnbuckle 1. Furthermore, the oblong hole 4, the washer 12 and the screw 13 are shown. Fig. 8 shows a formwork element 17 with a recess body 15 and the pigtail anchor. Usually, a formwork is composed of two formwork elements 17 between which the filler material, e.g. concrete, is filled. In Fig. 8 only one formwork element 17 is shown. The pigtail anchor 16 has proven to be particularly advantageous and has a certification from the building authorities for long-term stress. However, other suitable anchorages are also conceivable. The recess body 15 has conical side walls in order to be easier removed from the prefabricated concrete part. The specific design of the recess body can be adapted to the circumstances. The recess body 15 is advantageously magnetically attached to the formwork element 17. This enables an easy attachment of the recess body 15 to the formwork element 17. It is also conceivable to clamp the recess body 15 between two formwork elements 17 or to attach it with screws or nails. Other suitable attachment methods are also conceivable. As can be seen from Fig. 8, the pigtail anchor 16 is partially inserted into the recess body 15. Thus, the pigtail anchor 16 is fixed at the formwork element 17 when filling-in the concrete. The kit for joining structural elements 10, that can also be designated as tensioning system, comprises the turnbuckle 1 according to the invention and at least one anchorage 16. Furthermore, the kit can comprise at least one recess body 15 as described above and at least one anchorage 16 such as the above described pigtail anchor 16, which is provided to be inserted into the structural element 10. Additionally, the kit can comprise a sealing means 14 as the above-mentioned sealing strip if an especially tight connected between the structural element is required.

12 This sealing strip 14 is inserted before joining the structural elements 10 between the sides 18, 19 of the structural elements 10 to be joined. According to the method according to the invention for joining structural elements 10, such as prefabricated concrete parts 10, the structural elements 10, each comprising a recess 11, are first of all assembled in a manner that the recesses 11 of the structural elements 10 to be joined oppose each other. Ideally, an anchorage 16 e.g. the above-mentioned pigtail anchor 16 is embedded into the structural element such as the prefabricated concrete part 10. Then, the turnbuckle according to the invention is inserted into the recesses 11 of the structural elements 10. Thereupon the screws 13 are inserted through the access opening 9 into the housing chamber 2 and through a passage section 3, 4, such as the slot 3 or the oblong hole 4 of the turnbuckle into the anchorage. Due to the design of the slot 3 and the oblong hole 4 an effective assembly and improved compensation possibility of the joining points provided with tolerances caused by manufacture is possible. The turnbuckle 1 is then fixed by the screws 13 and the washers 12. Then, the screws 13 are fastened for instance by a long box-end ratchet or by a torque wrench. This order must only be regarded to be an example and can also be changed. It is for instance also conceivable that the anchorages are not pre-installed into the structural elements in the factory but are inserted on the construction site. If a water and/or gas impermeable connection is desired, it is required to insert a sealing means 14 between the sides 18, 19 of the structural elements 10 to be joined. The use of a sealing strip 14, such as RubberElast@ is particularly advantageous. If this sealing strip 14 in the joined state of the structural elements 10 runs behind the turnbuckle, an especially improved sealing is possible. The arrangement for joining structural elements 10 according to the invention comprises at least one turnbuckle 1 according to the invention, two structural elements 10 each comprises at least one recess 11 into which the turnbuckle 1 can be inserted, and an anchorage 16 preferably a pigtail anchor 16 which is accessible via the recess 11 and fixing means 13. Furthermore, the arrangement can comprise the above-mentioned sealing strip 14 if a tight connection is desired.

13 In the method of preparing structural elements 10 according to the invention, for instance prefabricated concrete parts 10, into which the turnbuckle 1 according to the invention shall be inserted, at least one recess body 15 is first of all attached to the formwork element 17. An easy assembly and disassembly of the recess body 15 is possible if this body is magnetically attached to the formwork element 17. However, other fixing possibilities such as screws or clamps are also conceivable. This recess body 15 at least holds one anchorage 16 such as a pigtail anchor 16. After attaching the recess body 15 to the anchorage 16 the formwork element 17 is filled by a filler material, e.g. concrete. In Figure 8 only one formwork element 17 is shown. However, for filling two formwork elements 17 are required. After curing the filler material, the formwork elements 17 and the recess body 15 are removed. The anchorage 16, which is removably attached to the recess body 15, remains in the structural element. The present invention refers to a turnbuckle 1, which can also be designated as tensioning device, for assembling a permanent connection of prefabricated concrete parts 10 or similar constructive elements made of other suitable materials. This turnbuckle 1 enables due to its specific shape and the fixing means attached such as screw-type connections, particularly screws, a tensioning as well as the quick rational assembly and permanent constructive joining of prefabricated concrete pats 10, e.g. prefabricated concrete parts made of steel 10 or structural elements 10 made of other suitable materials. The special geometric shape of the turnbuckle 1 enables via screw-type connections and pigtail anchors 16 of anchor sleeves embedded into the concrete elements 10 the assembly and permanent connection of the concrete elements 10 or prefabricated concrete parts 10. The turnbuckle 1 according to the invention therefore significantly facilitates the assembly of prefabricated concrete parts 10, it promises a high precision in manufacture and a significant saving of time on the construction site. Possible fields of application are amongst others fixed and permanent connections of bottom plates and ceiling panels, sandwich elements, double walls as well as angle supports. Besides the use as constructive joining element the turnbuckle 1 is provided for the regular and permanent transmission of tensile and shear forces in predominantly static loads. The tensioning system is composed of a turnbuckle 1 according to the invention and anchorages 16 such as pigtail anchors 16, which are provided to be embedded into the prefabricated concrete parts 10. Two versions are conceivable that can be loaded by tensile forces of up to 50 kN and 100 kN. These statements are only to be regarded as examples.

14 Depending on the circumstances, versions with lower or higher tensile forces are also conceivable. As described above in detail, pigtail anchors 16 and anchor sleeves and recess bodies that can magnetically be fixed on the formwork element 17 or a palette, which at least partially consist of plastic material exist for the preparation of the tensioning point in the factory. These recess bodies 15 can be positioned in only few working steps. At the construction site the concrete elements 10 are joined, the turnbuckle 1 is inserted, tensioned by the associated screws 13 to thereby be constructively joined. Particularly, the pre-fabrication can be carried out in an accurately-fitting manner in the precasting plant. The exact positioning of the pigtail anchors or anchor sleeves and the design of the recess is carried out by means of the magnetic recess bodies in one step only. A sealing strip 14, such as RubberElast@, is simply pressed during assembly in the area of the straight joint onto the concrete. In the ideal case this sealing strip 14 is self-adhesive. A protective strip of the sealing strip 14 is removed and the next concrete element is pressed against the sealing strip 14. The turnbuckle is inserted and fixed by means of the screws and flat washers or plain washers. Finally, the screws are tightened by a long box-end ratchet or torque wrench. The tensioning system offers many universal fields of application, e.g. in the assembly of angle supports which are used in road building, in underground engineering, in gardening and landscaping as well as in coast protection, and in the joining of bottom plates, shaft panels, ceiling and wall elements and many further constructive prefabricated concrete parts. The advantages of the turnbuckle according to the invention are seen in the rational and quick joining of structural elements 10, the tensioning of structural elements 10 without filler materials and special auxiliary means. Furthermore, the turnbuckle can be combined with all certified anchor systems and has a low dead weight. Extensive individual solutions can be dispensed with by the turnbuckle according to the invention. Due to magnetic technology (recess body 15 magnetically attachable to formwork element 17) a precise positioning in the manufacturing process is possible. Furthermore, the use of the turnbuckle offers the option to accessibly inspect the structural element connection for maintenance purposes at low effort. Thereby a 15 functioning connection of the connected structural elements can be ensured also over long periods of time. The use of a sealing strip 14, such as e.g. RubberElast@ ensures an extremely high water and gas impermeability, a very good grip by adhesion, a quick processing which does not require a tool. The connection is waterproof immediately after assembly. Furthermore, the sealing strip is also flexible at low temperatures, it is acid resistant, alkaline resistance, salt resistant and weatherproof. Figure 10 shows a further embodiment. The recess 11 has a higher depth T. Thereby the turnbuckle can together with the pigtail anchor be positioned closer to the central axis of the structural element 10. Due to this structure the force introduction is closer to the neutral fibre of the structural element 10 and the edges of the structural elements to be fastened by means of screws are evenly loaded. The path of the sealing means 14 is adapted to the position of the recess 11 and deviates in the area of the recess 11 from the straight path. An angled path of the sealing means 14 is shown, however, a curve-like course is also conceivable in which the direction can be continuously changed. Figure 11 shows a further embodiment. The turnbuckles 1 cannot only be installed on one side of the structural element 1. It is possible to attach the turnbuckles 1 on a different height level at opposing sides of the structural element 1. Due to this setup a favourable force path can be achieved, since the tensile forces are distributed evenly by screwing together the structural elements 1. The path of the sealing means 14 is adapted to the position of the recesses 11 and is shown in this example with an angled S-shaped path, however, continuous changes of direction can also be made. Figure 12 shows the turnbuckle 1 in an embodiment for a welded design. Due to the structural element forces acting onto the turnbuckle and the tensions resulting therefrom the design is adapted by a change of the wall thicknesses of the individual structural elements. Both conical side walls (5, 6) are connected to build a trough shape. During the manufacturing process the turnbuckle can easily be manufactured by inserting the side walls (7, 8) and by welding the turnbuckle. The side walls (7, 8) have a larger wall thickness than the conical side walls (5, 6). Due to the joining with the structural elements (10) the side walls (7, 8) are stressed by bending so that within the side walls (7, 8) shear stress is generated. This area can be specifically reinforced by a thickening. Furthermore, the thickening has the effect of preventing deformations that are generated by the generation of structural element tensions caused by welding.

16 In summary the possibility results by the turnbuckle according to the invention to join prefabricated structural elements in a cost and time saving manner. The turnbuckle can be manufactured in different designs, wherein advantageously a welded construction, a design using deep drawing or a design as composite material, possibly using adhesion technology is used. The materials that may be used may also be steel cast materials, but also annealed cast iron, spheroidal graphite cast iron or steel, wherein particularly high-grade steels, preferably stainless steels can be used. By these designs a higher mechanical strength of the turnbuckle can be achieved as well as an improved corrosion resistance. By the designs a use of the turnbuckle according to the invention is also possible in regions endangered by earthquakes. By the method of manufacturing the structural elements the use of different, variable modifiable recess bodies is possible.

Claims

1. Turnbuckle (1) for joining prefabricated concrete parts (10), which is substantially formed in the shape of a shell with at least two side walls (7, 8) which are essentially flat and are located opposite one another in parallel, and at least two contracting, preferably tapering side walls (5, 6), and which has a housing chamber (2) accessible at least from outside via an access opening (9) and, in addition, passage sections (3, 4) which are preferably located opposite one another and open into the housing chamber (2), and which are preferably configured as passage openings (3, 4) for fixing means (13) to be pushed through, wherein the passage sections (3, 4) are embodied in the flat side walls (7, 8), and that the turnbuckle (1) preferably has a tensile strength of 400 N/mm 2 to 800 N/mm 2 preferably 450 N/mm 2 to 780 N/mm 2 , particularly preferred 500 N/mm 2 to 750 N/mm 2 .

2. Turnbuckle (1) according to claim 1, characterized in that the contracting side walls (5, 6) are connected to one other, so that the cross-section is V- or U-shaped, and that the passage sections (3, 4) are preferably offset by 900 and are configured as slot (3) and/or oblong hole (4), and that preferably one of the passage sections is configured as slot (3) and another one of the passage sections is configured as an oblong hole (4), and/or that the slot (3) is open at least on one side and preferably opens into the access opening (9).

3. Turnbuckle (1) at least according to one of the preceding claims, characterized in that the turnbuckle (1) consists, at least in sections, of annealed cast iron or of spheroidal graphite cast iron.

4. Turnbuckle (1) at least according to one of the preceding claims, characterized in that the turnbuckle (1) consists, at least in sections, of a composite material with carbon fibre and/or glass fibre and/or aramid fibre.

5. Turnbuckle (1) at least according to one of the preceding claims, characterized in that the turnbuckle (1) consists, at least in sections, of steel, preferably of stainless steel, and that the per cent elongation at break of the steel is preferably 35%, preferably 40 %, particularly preferred 45 %. 18

6. Turnbuckle (1) at least according to one of the preceding claims, characterized in that the turnbuckle (1) is deep-drawn.

7. Turnbuckle (1) at least according to one of the preceding claims, characterized in that the turnbuckle (1) is welded, wherein preferably the side walls (7, 8) have a greater wall thickness than the conical side walls (5, 6).

8. Turnbuckle (1) at least according to one of the preceding claims, characterized in that the width (B) and the height (A) of the turnbuckle (1) are of the same lengths, or that the width (B) is preferably smaller than the height (A) by at least 15 %.

9. Turnbuckle (1) at least according to one of the preceding claims, characterized in that the depth (C) of the turnbuckle (1) is preferably smaller than the width (B) by at least 10 %, preferably by 25 %.

10. Kit for joining prefabricated concrete parts (10), with at least one turnbuckle (1) according to claim 1 to 10 and at least one anchorage (16), preferably a pigtail anchor (16).

11. Kit according to at least one of the preceding claims, characterized in that the kit furthermore comprises a sealing means (14), preferably a sealing strip (14), which is provided for being inserted between the structural elements (10) before these are joined, and a sealing means which locks the turnbuckle (1) in the mounted state in a sealing manner and can repeatedly be removed.

12. Method of joining prefabricated concrete parts (10), comprising the following steps: assembling structural elements (10) each provided with at least one recess (11) and one anchorage (16), preferably a pigtail anchor (16), so that the recesses (11) of the structural elements (10) to be joined are opposite one another, inserting the turnbuckle (1) according to claims 1 to 4 into the recesses (11) of the structural elements (10), that the thickness (D) of the structural elements (10) is larger than the depth (T) of the recess (11), wherein the depth (T) of the recess is preferably at least 40 %, particularly preferred at least 50% of the thickness (D) of the structural elements, inserting the fixing means (13) through the access opening (9) into the housing chamber (2) and through one of the passage openings (3, 4) of the turnbuckle (1) into one of the anchorages (16), preferably a pigtail anchor (16), 19 fixing the fixing means (13).

13. Method according to claim 12, characterized in that a sealing means (14), preferably a sealing strip (14), is inserted between the sides (18, 19) of the structural elements (10) to be joined before they are joined, and that preferably in the joined state of the structural elements (10), the sealing means (14) preferably runs behind the turnbuckle (1), and that preferably the recesses (11) are embodied on the front and back sides of the structural element (10).

14. Arrangement for joining prefabricated concrete parts (10), with at least one turnbuckle (1) according to claims 1 to 4, at least two structural elements (10), which comprise at least one recess (11) each into which the turnbuckle (1) can be inserted, and one anchorage, preferably a pigtail anchor (16) which is accessible via the recess (11), and fixing means (13), whereby the recess (11) is finally closed by a reversibly removable covering device.