EP0314927A2 - Anchoring device for a tensioning member and method of anchoring - Google Patents

Abstract

Fibre composite prestressing element, and method and device to tense and anchor such a prestressing element, in which the ends of the prestressing element are embedded using synthetic-resin mortar in a transversely corrugated anchoring or prestressing sleeve, which is deformed during the tensing and permits cracks caused by stretching the prestressing bars inside the sleeve, which cracks subdivide the anchoring member over part of its length into discs and consequently permit movement of the prestressing bars when subjected to vibratory stresses. After the tensing, the prestressing bars of the prestressing element can be anchored directly in sheath enlargements by means of anchoring mortar. <IMAGE>

Description

The invention relates to a tendon made of fiber composite materials, as well as a method and a device for tensioning and anchoring such a tendon for prestressed concrete components, ground anchors, rock anchors or the like, which has at least one tension rod or a tension wire bundle made of fiber composite materials with a surrounding tension at least at one end - Or anchoring sleeve, which is filled with a synthetic resin mortar affinity to the fiber composite materials, in which the tie rods or wires are embedded and which produces the adhesive-shear bond between them and the sleeve.

For prestressing prestressed concrete components, tendons with tendons or tendons made of fiber composite materials have been used in recent times, which have the advantage over tendons with high-strength steel rods or steel wires that they are corrosion-resistant and can also be used in components that are exposed to corrosive liquids or gases . For example, it is advisable to reinforce concrete tanks for chemical liquids with tendons made of fiber composite materials or for rock or earth anchors that are exposed to groundwater to insert tendons made of fiber composite materials put. With tendons made of fiber composite materials, however, their end anchoring in the concrete of the respective component is difficult, since the tendons or tension wire bundles made of organic or inorganic fiber materials embedded in synthetic resin matrix are sensitive to transverse pressure and are not readily clamped at their ends in the manner known for steel bars and steel wires and under tension can be placed. In addition, the modulus of elasticity of fiber composite materials is considerably smaller than the elastic modulus of high-strength steels, so that the tendons made of fiber composite materials must be subjected to a large longitudinal expansion in order to achieve a sufficiently high prestress.

An end anchorage for tendons made of fiber composite materials is known (EP-PS 0 025 856), in which the tension wires made of fiber composite materials are held between clamping plates, to which a transverse pressure dependent on the applied tensile force is exerted and at the same time means are provided that the clamping pressure does not rise too high to keep the transverse pressure exerted on the tension wires within permissible limits.

In order to gently grasp tension rods or tension wires made of fiber composite materials at their ends and to apply a tension force, it is also known to accommodate the ends of the tension rods in strong, cylindrical tension or anchor sleeves, where they are embedded in a synthetic resin mortar, which is an adhesive clipper -Connects between the tension rods and the tension or anchor sleeve. In order to transmit the clamping forces introduced into the clamping sleeve by the clamping press to the clamping rods or tensioning wires made of fiber composite materials embedded in the clamping sleeve, a large anchoring length is required so that the rigid clamping or anchor sleeves have a large length. This in turn makes it difficult to wind up the pre-fabricated tendons on the tendon drums used to transport the tendons to the construction site.

Above all, however, both known types of anchoring have the disadvantage that the fatigue strength of the tendons is insufficient at the points where the tendons or tendons made of fiber composite materials enter between the clamping plates or into the clamping sleeve of the anchoring.

The object of the invention is to avoid these disadvantages of the known end anchoring and to design a tendon made of fiber composite materials so that it can be tensioned and securely anchored with simple means and in particular has the required fatigue strength at the anchoring points and can easily be connected to devices for function monitoring .

This object is achieved according to the invention in that the tensioning or anchor sleeve consists of a thin-walled corrugated tube which can be gripped by a tensioning device at least over a length corresponding to the working load to be accommodated or can be concreted in the anchoring area of the respective component.

This configuration has the advantage that the tensioning or anchor sleeve can expand when the tension is applied by the tensioning device and follows the expansions that the tension rods or wires suffer when the tension is applied. The synthetic resin mortar adhering to the tie rods can therefore tear at certain longitudinal distances transversely to the direction of pull without losing cohesion, since the resulting synthetic resin discs adhere to the tendons inside and are held at their outer edge by the corrugated pipe, which holds the synthetic resin mortar filling surrounds. The resulting mortar discs allow mutual displacement in the direction of force, so that the fatigue strength of the anchor is improved. In addition, the adhesive-shear bond on the inside and outside of the corrugated pipe to the surrounding mortar is considerably higher than with a cylindrical adapter sleeve, and a thin-walled corrugated pipe is considerably less expensive than thick-walled threaded adapter sleeves or clamp anchoring devices. In addition, the corrugated tube can be easily gripped and clamped by a suitably adapted clamping device.

The clamping or anchor sleeve can be wound from thin-walled sheet metal strips which interlock with folds at their edges. When tensioning, the windings of the anchor sleeve can then yield in the folds.

The clamping or anchor sleeves can be made of sheet steel or aluminum and preferably have a sinusoidal corrugation. The wave crests and troughs of the corrugations expediently run in the circumferential direction of the tensioning or anchor sleeve according to a helical line. The clamping sleeve can then be screwed into a correspondingly shaped coupling member of a device for tensioning and temporarily anchoring the clamping member on an abutment part.

The device necessary for tensioning and temporarily anchoring a tendon to an abutment part has a support nut and a tensioning device, in which the support nut and the threaded sleeve of the tensioning device have corrugated pipe threaded sleeve pieces with which they can be screwed over the threaded screw tube of the tensioning sleeve of the tendon.

Such a device is easy to manufacture in that the corrugated pipe threaded sleeve pieces are fastened with a synthetic resin adhesive or mortar in the threaded opening of the support nut or the threaded sleeve of the clamping device. Corrugated pipe threaded sleeve pieces of this type, which can be screwed onto helically shaped corrugated pipes, are commercially available and can be easily procured and processed.

For the end anchoring of a tendon according to the invention, which is at least temporarily shifted longitudinally in a cladding tube, which has extensions at its ends for receiving the tensioning or anchor sleeves, an anchoring mortar is arranged in the extensions of the cladding tube, in which the tensioning or anchor sleeves and / or the tension rods or tension wire bundles inserted out of them and into the cladding tubes are embedded and which produces the adhesive-shear bond between them and the cladding tube extensions. At that end of the tendon that is firmly anchored in the concrete of the component before the prestressing is applied, the end of the tendon provided with an anchor sleeve is embedded in the concrete of the component in such a way that the necessary to transfer the working load from the tendon to the component Length of the anchor sleeve is in the concrete. The remaining part of the anchor sleeve protrudes into the extension of the cladding tube and, as described above, can follow the expansion of the tie rods which they suffer when the tendon is tensioned, so that in this area the synthetic resin mortar inside the anchor sleeve tears open in disks and that ensures the desired elasticity in the continuous vibration loading of the component.

Instead, however, it is also possible to fully concrete the anchor sleeve at the fixed anchor end of the tendon so that the tie rods or wires are exposed in the region of the cladding tube extension, where they are only after their Tensioning are embedded in the anchoring mortar, which after tensioning is injected at least into the cladding tube extensions at the ends of the tendon in order to produce the adhesive-shear bond between the tendon ends on the one hand and the building or the cladding tube extension embedded in it.

Since the tie rods are only embedded in the anchoring mortar after they have been tensioned to the working load and until then no relative movement has taken place between the tie rods and the anchoring mortar surrounding them, the bond at the beginning of the anchoring section is only stressed by the differential stresses resulting from permanent vibration stress and the Stresses result from the working load, so that sufficient fatigue strength is also achieved in this embodiment. In addition, there is the advantage that the anchor sleeve firmly concreted in concrete, which is required for fastening the tension rods during prestressing to the working load, can be kept much shorter, which facilitates the winding of the tendons prefabricated in the manufacturing plant onto transport drums.

A similar procedure can also be used when anchoring the tendon end, which is initially movable longitudinally, on which the prestressing press acts to tension the tendon. Here it is possible to stretch the tendon during tensioning to the working load so that the clamping sleeve with the tendon end fastened in it emerges completely from the cladding tube extension surrounding it, and of course it still has to be grasped by the support nut to keep the tendon end on the Stop abutment part until the final bond between this tendon end and the building part is established. After embedding the tie rod ends freely crossing the cladding tube extension in the anchoring mortar and after it has hardened NEN then the tie rods or tension wires between the rear end of the clamping sleeve and the end face of the component are cut. The tensioning force is then transferred directly from the tensioning bars or tensioning wires through the anchoring mortar to the prestressed part of the building or the cladding tube extension, which is embedded in this component.

In addition, after the clamping sleeve has been cut off, the tendon rod ends protruding from the prestressed component are free, to which the sensors of a monitoring device can then be immediately attached, which monitor the effectiveness of the tendons in use.

In order to increase the adhesive-shear bond between the anchoring mortar and the cladding tube extension, this cladding tube extension, like the anchor or adapter sleeves, can consist of a steel or aluminum corrugated tube.

In order to facilitate the transport of the tendons to the construction site, the tendons can also be cut to suitable lengths on the construction site, provided at their ends with the anchor or tensioning sleeves and connected to them with synthetic resin mortar, which can then be heated by heating the anchor or Adapter sleeves with infrared radiators, microwave devices or the like. is cured on the spot.

The anchoring described above can be used for pre-stresses with composite, in which the tendon is pressed in its cladding tube along the entire length with a cement mortar or plastic mortar. However, the anchorage can also be used for pre-stressing without a bond, such as for rock anchors or ground anchors. In all cases, it is necessary that the grout or anchoring mortar, which comes into direct contact with the tendons or tendons made of fiber composite material has a high affinity for them in order to transmit the forces from the tendons or tension wires to the surrounding anchoring parts through a good adhesive-shear bond. Of course, the individual tie rods or tension wires of each tendon must also have a sufficient distance from each other so that they can be completely covered by the mortar.

• Fig. 1 eine feste Endverankerung nach der Er­findung für ein Spannglied aus Faser­verbundwerkstoffen in einem Betonbauteil nach dem Verpressen der Verankerungs­strecke im Längsschnitt,
• Fig. 2 das bewegliche, zu spannende Ende eines Spanngliedes nach der Erfindung mit einer am Bauteil angesetzten Spannvorrichtung vor Beginn des Spannens in einem Teil­längsschnitt und
• Fig. 3 die Endverankerung des beweglichen Spann­gliedendes nach dem Spannen und Injizieren des Verankerungsbereiches im Längsschnitt.

Further features and advantages of the invention result from the following description and the drawings, in which preferred embodiments of the invention are explained in more detail by means of examples. It shows:

• 1 is a fixed end anchoring according to the invention for a tendon made of fiber composite materials in a concrete component after pressing the anchoring section in longitudinal section,
• Fig. 2 shows the movable, to be tensioned end of a tendon according to the invention with a clamping device attached to the component before the start of tensioning in a partial longitudinal section and
• Fig. 3 shows the end anchoring of the movable tendon end after tensioning and injecting the anchoring area in longitudinal section.

In the drawings, 10 denotes a tendon which is intended for prestressing a concrete component 11 and consists of a plurality of tendons 12 which are guided essentially parallel to one another. The tendon 10 is laid in a cladding tube 13, which is at its rear end 13a and nem front end 13b each has an extension 14 or 15. The cladding tube 13 can be made of plastic or sheet steel, but the cladding tube extensions 14 and 15 are expediently made of corrugated steel or aluminum tubes.

The tie rods 12 are accommodated at one, rear end 10a of the tendon 10 in an anchor sleeve 16 which surrounds the tie rods 12 at a distance and is connected to them by a synthetic resin mortar 17 which has a high affinity for the fiber composite material of the tie rods 12. In the exemplary embodiment shown here, the anchor sleeve 16 consists of a longitudinally welded corrugated tube made of sheet steel with a sinusoidal corrugation 18, and the outer diameter d of the anchor sleeve 16 is somewhat smaller than the inner diameter D of the cladding tube extension 14.

It can be seen from FIG. 1 that the anchor sleeve 16 protrudes a little way into the interior of the cladding tube extension 14, but is otherwise firmly concreted in the concrete component 11. As long as the tendon is not tensioned, the cladding tube 13 and the cladding tube extension 14 are empty, i.e. they form a free space in which the tie rods 12 of the tendon 10 can expand freely. The rear end 10a of the tendon 10, which is firmly connected to the anchor sleeve 16 by the mortar 17, is held in the concrete of the component 11.

The front end 10b of the tendon 10 is arranged similar to its rear end in a clamping sleeve 19, in which the tie rods 12 are embedded with a: synthetic resin mortar 17. The clamping sleeve 19 also consists of a corrugated tube with sinusoidal corrugation, the wave crests 20 and troughs 21 of which run along a helix. Like the anchor sleeve 16, the clamping sleeve can consist of a longitudinally welded corrugated steel tube. In the present Trap, however, the corrugated tube is wound from thin-walled sheet metal strips that interlock with folds at their edges.

The clamping sleeve 19 is surrounded by the cladding tube extension 15 at a distance and protrudes to the front a little way beyond the front end face 22 of the concrete component 11. A supporting nut 23 is screwed onto this protruding, front end 19a of the clamping sleeve 19 and is supported on an annular anchor plate serving as an abutment part 24. On this anchor plate there is also a tensioning device, which is designated in its entirety by 25 and serves to grasp the tensioning member 10 on the tensioning sleeve 19 connected to its front end 10b and to pull it out a little from the cladding tube 13 and thereby pre-tension it.

For this purpose, the clamping device is provided with a threaded sleeve 26 which is screwed onto the front end 19a of the clamping sleeve 19. Since support nuts and threaded sockets, which have a thread matching the corrugated pipe thread of the adapter sleeve 19, are not readily available, the support nut 23 and the threaded sleeve 26 are produced in that the threaded opening 28 of a commercially available nut and the threaded opening 29 of a commercially available threaded sleeve Corrugated pipe threaded sleeve pieces 27 are glued in with a synthetic resin adhesive or mortar. The support nut 23 and the threaded sleeve 26 can then be easily screwed onto the free front end 19a of the clamping sleeve 19, the length L ascertainable by the threaded sleeve 26 and the support nut 23 being as large as the anchoring area 1 of the anchor sleeve 16, which is the corresponds to the payload to be absorbed.

For tensioning the tendon 10, the tensioning sleeve 16 with the tension rod ends fastened in it is pulled out piece by piece from the cladding tube extension 15. Here, the Clamping sleeve 19 is supported by by adjusting the support nut 23 via an intermediate sliding layer 30, as is known per se when prestressing tendons. Here, the tensioning rods 12 are stretched, this stretching continuing into the inner end 16a of the anchor sleeve and into the inner end 19a of the tensioning sleeve 19. Since the synthetic resin mortar 17 adheres firmly to the tie rods 12, but cannot fully follow the expansion of the tie rods 12, cracks 31 run transversely to the longitudinal direction of the tendon in the synthetic resin mortar, which break the mortar plug at the inner end into more or less thin disks 17 a, but which are held together on their outer circumference by the anchor sleeve 16 or the clamping sleeve 19 (FIGS. 1 and 3). This disassembly of the synthetic resin mortar plug 17 in disks achieves a certain degree of mobility within the tensioning sleeve 17 or the anchor sleeve 16, which enables them to elastically absorb vibrations of the concrete component.

After tensioning the tendon 10, the cavities enclosed by the cladding tube extensions 14 and 15 are filled with an anchoring mortar 32, which can also be pressed into the cladding tube 13 if a full bond between the tendon and the concrete component is to be produced. Here, the anchoring mortar 32 indirectly creates an adhesive-shear bond to the corrugated pipe of the cladding tube extensions 14 and 15 over almost the entire length of the rear cladding tube extension 14 and in the rear region 33 of the front cladding tube extension 14. In this anchoring area, which is also to be referred to as the “pre-length” and is indicated in FIG. 3 by 33 and in FIG. 1 by 34, the tie rods 12 are only embedded in the anchoring mortar in the already prestressed state. Any dynamic stress that occurs is therefore only slight in this area.

It can be seen that an end anchoring of the front, initially movable end 10b of the tensioning member 10 is also possible in that the tensioning sleeve 19 is pulled completely out of the component 11 until the working load is applied and that the tensioning rods 12 still located in the cladding tube extension 15 are then located be embedded in the anchor mortar 32. When this anchoring mortar 32 is then completely hardened, the tie rods 12 can be cut through between the pulled-out clamping sleeve 19 and the front end face 22 or the abutment part. You then individually look a little bit beyond the front end face 22 of the concrete component 11 and can then be connected directly to the sensors of a monitoring device, not shown here. Such a sensor connection is of course also possible at the ends 12a of the tension rods 12 if they are embedded in the tensioning sleeve 19.

The invention is not limited to the exemplary embodiments described and illustrated, but several changes and additions are possible without leaving the scope of the invention. For example, the anchor sleeve 16 at the rear end 10a of the tendon 10, which is to be firmly concreted in, can also be so long that it almost completely fills the cladding tube extension 14. Cracks 31 then occur in the synthetic resin mortar 17 in that area of the anchor sleeve which is located in the interior of the cladding tube extension 14.

Claims (15)

1. tendon made of fiber composite materials for prestressed concrete components, ground anchors, rock anchors or the like, which has at least one tension rod or a tension wire bundle made of fiber composite materials at a distance from a surrounding tendon or anchor sleeve, which is filled with a synthetic resin mortar affinity to the fiber composite materials, in which the tension rods or wires are embedded and which produces the adhesive-shear bond between them and the sleeve, characterized in that the tension or anchor sleeve (19 or 16) consists of a thin-walled corrugated tube which is at least on one The length ( 1 ) corresponding to the working load to be picked up can be gripped by a tensioning device (25) or can be concreted in the anchoring area of the respective component (11). 2. Tensioning element according to claim 1, characterized in that the tensioning or anchor sleeve (19 or 16) is wound from thin-walled sheet metal strips which interlock with folds at their edges. 3. Tendon according to claim 1 or 2, characterized in that the clamping or anchor sleeves (19 or 16) consist of sheet steel, aluminum sheet or plastic. 4. tendon according to one of claims 1 to 3, characterized in that the clamping or anchor sleeves (19 or 16) have a sinusoidal corrugation (18). 5. Tendon according to one of claims 1 to 4, characterized in that the wave crests (20) and troughs (21) of the corrugation (18) in the circumferential direction of the clamping or anchor sleeve (19, 16) run along a helix. 6. Device for tensioning and temporarily anchoring a tendon to an abutment part according to one of claims 1 to 5, with a support nut supported on the abutment part and a clamping device which has a threaded sleeve which can be screwed onto the clamping sleeve and with which a tension is exerted on the tendon can, characterized in that the support nut (23) and the threaded sleeve (26) of the tensioning device (25) have corrugated pipe threaded sleeve pieces (27) with which they can be screwed over the screw threaded shaft of the tensioning sleeve (19) of the tensioning member (10). 7. Device according to claim 6, characterized in that the corrugated pipe threaded sleeve pieces (27) with a synthetic resin adhesive or mortar in the threaded opening (28) of the support nut (23) or the threaded sleeve (26) of the clamping device (25) are attached. 8. Device according to claim 6 or 7, characterized in that the support nut (23) on its abutment part (24) facing the contact surface is provided with a sliding layer (30). 9. Device for end anchoring of a tendon according to one of claims 1 to 5, which is at least temporarily shifted longitudinally in a cladding tube, which has extensions at its ends for receiving the clamping or anchor sleeves, characterized in that in the extensions (14, 15th ) of the cladding tube (13), an anchoring mortar (32) is arranged, in which the tensioning or anchor sleeves (19 or 16) and / or the tensioning rods or tensioning wire bundles (12) guided out of them and into the cladding tubes (13) are embedded and which produces the adhesive-shear bond between these and the cladding tube extensions (14, 15). 10. Device according to claim 9, characterized in that the anchoring mortar (32) is a cement mortar. 11. The device according to claim 9, characterized in that the anchoring mortar (32) is a synthetic resin mortar. 12. Device according to one of claims 9 to 11, characterized in that the cladding tube extensions (14, 15) are formed by steel, aluminum or plastic corrugated tubes, the inner diameter (D) of which is greater than the outer diameter ( d ) of the clamping or Anchor sleeves (19 or 16). 13. A method for tensioning and end anchoring of tendons laid in cladding tubes, in particular according to one of claims 1 to 5, characterized in that provided with an anchor sleeve (16) one end (10a) of the tendon (10) in the concrete of the component ( 11) is embedded in that for transferring the working load from the tendon (10) on the component (11) required length ( 1 ) of the anchor sleeve (16) in the concrete (8) and the clamping sleeve (19) with the other end (10b) of the tendon (10) fastened therein approximately at the in Cladding tube (13) passing over the root of the cladding tube extension (15), that the prestress is then applied to the tensioning element (10) by pulling on the tensioning sleeve (19) and this is temporarily supported on the abutment part (24) with the support nut (23), that then at least the extensions (14, 15) of the cladding tube (13) are filled with the anchoring mortar (32) and that after the hardening of the anchoring mortar (32) the support nut (23) and the abutment part (24) are removed and the protruding part is pulled out Part of the clamping sleeve (19) or the tendon (10) is cut off. 14. The method according to claim 13, characterized in that the tendon (10) is stretched so far during tensioning that the clamping sleeve (19) with the tendon end arranged in it (10b) completely emerges from the surrounding tubular extension (15) and that the tension rods or tension wires (12) are cut off after embedding in the anchoring mortar (32) and after it has hardened between the tensioning sleeve (19) and the component (11). 15. The method according to claim 13 or 14, characterized in that the tendons (10) cut on the construction site to suitable lengths, provided at their ends (10a, 10b) with the anchor or clamping sleeves (16 or 19) and with these are connected by synthetic resin mortar (17), which is then cured in place by heating the anchor or tensioning sleeves (16 or 19).

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