Method and device for detensioning a tension element

Abstract

The invention relates to a method for releasing a tensioning element (106) that is clamped between two sections of a structure (100). The method comprises the steps of: providing a release device (130) with at least one force device (148) that has a holding device (140) for establishing a holding engagement with the tensioning element (106); attaching the release device (130) to the structure (100) at a location between the two anchoring arrangements (102, 103); and bringing the holding device (140) of the at least one force device (148) into holding engagement with the tensioning element (106) to be released. According to the invention, the at least one force device (148) is an active force device.Furthermore, the method comprises the following steps: actuating the at least one force device (148) in order to take over the clamping force of the clamping element (106); releasing the anchoring engagement between the anchoring arrangement (102) and the clamping element (106); and actuating the at least one force device (148) in order to relax the clamping element (106).

Description

[0001] The invention relates to a method for relaxing a clamping element according to the preamble of claim 1.

[0002] The invention relates to a method for relaxing a tensioning element, according to claim 1, which is tensioned by means of two anchoring arrangements between two sections of a structure with a given tensioning force, wherein the tensioning element is anchored in at least one of the anchoring arrangements by means of an anchoring device, the method comprising the steps: Providing a tension-releasing device with at least one force device which, on the one hand, is designed to be supported on the structure and, on the other hand, has a holding device for establishing a holding engagement with the tensioning element, attaching the tension-releasing device to the structure at a location located between the two anchoring arrangements, wherein the tension-releasing device is arranged on the side of a structure section facing another structure section, and bringing the holding device of the at least one force device of the tension-releasing device into holding engagement with the tensioning element to be relaxed.

[0003] It should be noted at this point that both the support of the power tool and the attachment of the tensioning device to the structure can be done directly and / or indirectly. The indirect support or attachment can preferably be done via one of the structure's anchoring devices.

[0004] In order to be able to reduce the force of a tensioned tendon element to a state of zero force for the purpose of removing the tendon element as part of a tendon, if necessary with the aim of removing all tendon elements of the tendon, the projection of the tendon element(s) behind the anchorage arrangement is usually selected to be so large that the tendon element still projects slightly behind the anchorage arrangement at the time of its complete relaxation.

[0005] The required overhang length depends primarily on the tensioning force and the elastic modulus of the tensioning element, as well as its length. Since this can exceed 100 m, this can lead to very large overhangs and thus to very long caps, which permanently protect the freely accessible part of the anchorage. Furthermore, the space required for the arrangement of these caps must be provided behind the anchorage arrangements. This can lead to uneconomical dimensions of the anchorage areas. Furthermore, the interior of the caps must be filled with corrosion protection, which also represents a significant cost factor.

[0006] For example, the anchoring device can extend through one of the two sections of the structure. The projection of the tensioning element and the cap enclosing it can be arranged on one side of the structural section, namely on the side of the structural section in question facing away from the other structural section, while the tension-releasing device is arranged on the other side of the structural section in question, namely on the side of the structural section in question facing the other structural section, i.e., between the two structural sections or, in other words, between the two anchoring arrangements.

[0007] It should be expressly pointed out that the previous explanations also apply to the relaxation device of a method according to the invention.

[0008] Document FR 2 745 829 A1, which is considered to be the closest prior art, discloses a method for relaxing a clamping element having the features of the preamble of claim 1. Furthermore, reference is made to documents JP S5754673 A, JP S63 312468 A, JP H06 330630 A and JP S59 88570 A.

[0009] A method and device similar to the present invention are known, for example, from US 2002 / 0113231 A1. However, US 2002 / 0113231 A1 proposes severing the tensioning element on the side of the anchorage facing away from the projection. To prevent the tensioning element from swinging around uncontrollably during spontaneous release as a result of the severing, a damping device is attached to it before the severing, which dampens the release movement of the tensioning element. However, even this procedure cannot ensure a truly controlled movement of the tensioning element.

[0010] It is the object of the present invention to remedy this situation.

[0011] This object is achieved according to the invention by a method according to claim 1.

[0012] For the purposes of the present invention, an "active power device" is understood to mean a power device that is adjustable by an electric motor through the supply of energy, for example in the form of a hydraulic medium, in particular hydraulic oil, hydraulically and / or in the form of a pneumatic medium, in particular compressed air, pneumatically and / or in the form of electric current, and is designed to actively exert a force on the tensioning element as a result of the energy supply. This means that the terms "active" and "passive" are used in the context of the present invention in the same way as in the chassis technology of motor vehicles, where a passive chassis is used when the chassis responds to external forces purely through damping, while an active chassis is used when the chassis is capable of counteracting external forces through the supply of energy.In this sense, the damper known from US 2002 / 0113231 A1 represents a passive force device.

[0013] In contrast to the damper known from US 2002 / 0113231 A1, the active force device used according to the invention can exert a force on the tensioning element that prevents the tensioning element from being released. Only when an operator actuates the force device accordingly is the part of the force device containing the holding device moved relative to the part of the force device connected to the base unit in such a way that the tensioning element is released. In this way, the tensioning element can be released in a completely controlled manner.

[0014] In a further development of the invention, it is proposed that the tensioning device comprise a base unit on which the power device is supported. The base unit can be formed, for example, by a frame and / or a housing. Furthermore, the base unit can be attached to one of the anchoring devices of the structure and / or directly to the structure.

[0015] The holding device of the at least one strength device can comprise at least one clamping wedge, preferably a plurality of clamping wedges, as are known per se from the anchoring of the tensioning element to the anchoring devices. In this case, the holding device can comprise a base bearing, which is arranged on the movable part of the at least one strength device and is designed to engage around the tensioning element. Thus, the base bearing can comprise a plurality of, for example two, elements, which receive the tensioning element between them and can then be connected to one another, for example by clamping or screwing. Furthermore, the base bearing can comprise a recess for the passage of the tensioning element and for receiving the at least one clamping wedge. In this case, the holding engagement of the holding device is a clamping engagement mediated by the at least one clamping wedge.

[0016] It should also be noted that the base bearing on the base unit can be guided in a direction essentially parallel to the longitudinal extension of the tensioning element. This can facilitate the movement of the base bearing by the associated power device.

[0017] The holding device of the at least one strength training device can, for example, be manually operable. In this case, the above-described actuation steps can be performed manually by one or more operators. Alternatively, however, it is also possible for the holding device of the at least one strength training device to be automatically operable. For example, additional strength training devices can be provided that perform the above-described actuation steps.

[0018] In the event that the stroke of the power device is not sufficient to completely release the tensioning element in one step, it is proposed according to the invention that the release device has at least one further holding device for establishing a holding engagement with the tensioning element, wherein the method comprises the further steps: Bringing the at least one further holding device into holding engagement with the tensioning element to be relaxed, actuating the at least one force device in the sense of transferring the tensioning force of the tensioning element to the at least one further holding device, releasing the holding engagement of the holding device of the at least one first force device, adjusting the at least one first force device, bringing the holding device of the at least one force device back into engagement with the tensioning element to be relaxed, releasing the holding engagement of the at least one further holding device, and actuating the at least one force device again in the sense of relaxing the tensioning element.

[0019] The additional holding device can also be a manually operable or automatically operable holding device. Regarding the structure of the additional holding device, reference is made to the above explanation of the structure of the holding device of the at least one strength device, although the base bearing of the additional holding device is preferably attached to the base unit of the relaxation device.

[0020] The interaction of the additional holding device with the at least one force device enables the use of cost-effective force devices, in particular force devices whose stroke is shorter than the relaxation path required for complete relaxation of the tensioning element. Furthermore, this limits the installation space required for the relaxation device. In particular, it is thus possible to keep the relaxation device shorter than the path length that is already required adjacent to the anchoring devices in order to expand the bundle of tensioning elements of the tensioning member, starting from their closely spaced course, in preparation for anchoring in the anchoring devices.

[0021] The further holding device can be arranged both on the side of the at least one power device facing the associated anchoring device and on the side of the at least one power device facing away from the associated anchoring device. In the latter case, the further holding device and the at least one power device can be supported on a common section of the base unit, preferably on a section of the base unit surrounding the tensioning element. According to an alternative method variant, however, it is also conceivable for the relaxation device to comprise, in addition to the at least one (first) active power device, at least one second active power device having a holding device for establishing a holding engagement with the tensioning element, wherein the method comprises the further steps: Bringing the holding device of the at least one second strength device into holding engagement with the tensioning element to be relaxed, actuating the at least one second strength device in the sense of taking over the tensioning force of the tensioning element from the at least one first strength device, releasing the holding engagement of the holding device of the at least one first strength device, adjusting the at least one first strength device, bringing the holding device of the at least one first strength device back into engagement with the tensioning element to be relaxed, specifically at a different engagement point, releasing the holding engagement of the holding device of the at least one second strength device, and actuating the at least one first strength device again in the sense of relaxing the tensioning element.

[0022] Through the interaction of the at least one first strength device with the at least one second strength device, the same advantages can be achieved as with the first method alternative.

[0023] In the following, a relaxation device is described which does not form part of the invention, but which is suitable for use in connection with the method according to the invention.

[0024] With regard to the advantages that can be achieved with this relaxation device, reference is made to the above explanation of the relaxation method according to the invention.

[0025] In order to be able to work with a (first) power device whose stroke is smaller than the unclamping path required for complete unclamping of the clamping element, it is provided, based on the method variants of the unclamping method according to the invention, that the unclamping device has at least one further holding device for establishing a holding engagement with the clamping element, while according to a second alternative development of the unclamping device, it is provided that, in addition to the at least one (first) active power device, it comprises at least one second active power device which has a holding device for establishing a holding engagement with the clamping element.

[0026] It should also be noted that the structure can, for example, be a bridge or a tower, where the tendons are arranged outside and / or inside the structure. Specific examples, which do not, however, limit the scope of protection, include cable-stayed bridges and wind towers, i.e., the towers of wind turbines.

[0027] The tensioning elements can be formed in a conventional manner from wires, strands, or rods. Tensioning elements comprising strands formed from seven steel wires are frequently used. Each of the steel wires can be galvanized to provide a primary corrosion protection. Furthermore, the strand can be coated with a corrosion protection compound, such as a corrosion protection wax or grease, as a secondary corrosion protection layer and, if desired, encased in a plastic sheath, such as a polyethylene sheath, as a third corrosion protection layer. Such tensioning elements can also be used according to the invention, although it may be necessary to remove the plastic sheath over part of the length of the tensioning element to enable the retaining engagement.

[0028] Furthermore, each tendon may comprise at least one such tensioning element.

[0029] The invention will be explained in more detail below with reference to exemplary embodiments in the accompanying drawings. It shows: Figure 1 shows a schematic representation of a part of a cable-stayed bridge as an example of a structure in which the tension-relieving method according to the invention can be used, Figure 2 shows a perspective view of a tension-relieving device; Figures 3a to 3f show perspective representations similar to Figure 2 to explain the individual steps of the relaxation process according to the invention; and Figures 4 and 5 are similar views Figure 2 an embodiment of the relaxation device.

[0030] In Figure 1 a part of a cable-stayed bridge 100 is shown as an example of a structure in which the invention can be used to advantage. In particular, Figure 1The lower anchoring arrangement 102 of the structure 100 is shown, which is located in the area of ​​the bridge deck 104. From the anchoring arrangement 102, a tendon 108 comprising several tensioning elements 106 extends to the upper (not shown) anchoring arrangement 103, which is located on the pylon of the cable-stayed bridge 100.

[0031] The anchoring arrangement 102 comprises an anchor block 110 having a plurality of passageways 112, each of which is designed for the passage of one of the tensioning elements 106. The tensioning elements 106 are anchored in the anchor block 110 by means of clamping wedges 114. On its outer peripheral surface, the anchor block 110 is threadedly engaged with an anchor nut 116, which in turn is supported on an anchor plate 118 integrated into the structure 100. On the rear side of the anchor plate 118, the anchoring arrangement 102 further comprises a receiving tube 120, which passes through a passage opening 122 of the structure 100 and exits the structure 100 on the side facing away from the anchor plate 118. The anchor block 110, the clamping wedges 114, the anchor nut 116, the anchor plate 118 and the receiving tube 120 together form the anchoring device 124 associated with the anchoring arrangement 102.

[0032] Furthermore, in Figure 1a relaxation device 130 is shown, which is attached to the end 120a of the receiving tube 120 protruding from the structure 100 for carrying out the relaxation method according to the invention. The exact structure of the relaxation device 130 and the exact sequence of the relaxation method are described below with reference to the Figure 2 and 3a to 3f be explained in more detail: In Figure 2 On the right you can see the end 120a of the receiving tube 120.

[0033] Furthermore, Figure 2 For the sake of clarity, only the clamping element 106 is shown which is to be relaxed by means of the relaxation device 130.

[0034] The tension release device 130 comprises a frame 132, which, in the illustrated embodiments, has four threaded rods 134 that run substantially parallel to the longitudinal direction L of the tensioning element 106 and are arranged to receive the tensioning element 106 between them. The ends 134a of the threaded rods 134 facing the anchoring device 124 are fastened to, in particular screwed to, mounting plates 136, which in turn are fastened to the end 120a of the receiving tube 120. In a similar manner, the ends 134b of the threaded rods 134 facing away from the anchoring device 124 are connected to one another in pairs by means of mounting plates 138. This design has the advantage that the frame 132 of the tension release device 130 can be easily arranged around the tensioning member 108 or the plurality of tensioning elements 106.

[0035] In principle, it is of course also conceivable to design the frame 132 in the form of two half-shells connected to one another by means of a hinge, which can be closed around the tensioning member 108, connected to one another and fastened to the receiving tube 120.

[0036] Furthermore, the unclamping device 130 comprises a first holding device 140 and a second holding device 142, both of which can be brought into holding engagement with the clamping element 106, for example by means of clamping wedges 144 and 146. The second holding device 142 is rigidly supported directly on the mounting plates 138, while the first holding device 140 is adjustable in the longitudinal direction L via two active force devices 148. In the illustrated embodiments, the two force devices 148 are supported on the mounting plates 138 via the second holding device 142. Furthermore, the two force devices 148 are designed as double-acting hydraulic units in all illustrated embodiments.

[0037] The two holding devices 140 and 142 each have a through-channel 140a or 142a for receiving the clamping element 106. In order to be able to insert the clamping element 106 easily into the respective through-channel 140a or 142a, the two holding devices 140 and 142 are each formed by two mounting strips 150 which are screwed together during operation of the unclamping device 130.

[0038] With reference to the Figures 3a to 3f The relaxation process according to the invention will be explained in more detail below: Figure 3ashows the initial situation, i.e. a situation in which the tensioning device 130 has just been arranged around the tensioning element 106 and fastened to the receiving tube 120. In this situation, the tensioning element 106 is still firmly anchored in the anchor block 110 via the clamping wedges 114 engaging in the passage channel 112 of the anchor block 110. In contrast, the tensioning element 106 is neither in holding engagement with the first holding device 140 nor with the second holding device 142, but can move freely through the passage channels 140a and 142a, respectively. This is shown in Figure 3a indicated by the fact that the clamping wedges 144 and 146 are shown at a certain distance from the associated holding devices 140 and 142.

[0039] It should also be added that in this initial situation the power devices 148 are in an almost completely extended state, ie the piston rods 148b which are displaceable relative to the base cylinder 148a of the power devices 148 are in a state in which they are almost completely extended from the base cylinders 148a.

[0040] It should also be added that the holding device 140 can be guided on the frame 132, as shown in Figure 2 is only indicated schematically by a dashed arc 154.

[0041] To activate the relaxation device 130, according to Figure 3b First, the holding engagement of the first holding device 140 is established. For this purpose, the clamping wedges 144 are inserted into the through-channel 140a so that they clamp against the outer peripheral surface of the clamping element 106.

[0042] In the next step, according to Figure 3cthe force devices 148 are moved into their fully extended state. As a result, the first holding device 140 essentially completely assumes the clamping force of the clamping element 106, so that the anchoring of the clamping element 106 in the anchor block 110 becomes forceless. Subsequently, the anchoring of the clamping element 106 in the anchor block 110 can be released by removing the clamping wedges 114 from the passage channel 112. Although the clamping wedges 114 can be removed from the clamping element 106 in practice, they are Figures 3c to 3f For the sake of clarity, it is shown at a certain distance from the through hole 112.

[0043] According to Figure 3d the force devices 148 are then shortened so that the first holding device 140 moves away from the anchoring device 124, whereby the tensioning element 106 is at least partially relaxed.

[0044] Typically, the stroke of the force devices 148 will not be sufficient to completely release the tensioning element 106 with a single stroke. Therefore, it is necessary for the holding device 140 to "follow up." For this purpose, Figure 3e First, the second holding device 142 is brought into engagement with the clamping element 106 by inserting the clamping wedges 146 into the through-channel 142a. The clamping force of the clamping element 106 is then transferred from the first holding device 140 to the second holding device 142 by moving the force devices 148 from the Figure 3d shown position to its fully shortened position according to Figure 3e In this position, the second holding device 142 holds the remaining clamping force of the clamping element 106. Finally, the holding engagement of the first holding device 140 can be released. This is in Figure 3erepresented by the fact that the retaining wedges 144 are shown at a certain distance from the first holding device 140.

[0045] Now the strength machines 148 can be used according to Figure 3f be returned to the almost fully extended position, as already shown in Figure 3b The condition according to Figure 3b and the state according to 3f differ only in that the holding force of the clamping element 106 according to Figure 3f is held by the second holding device 142 while it is in accordance with Figure 3b was held by the anchorage 124. Finally, the clamping wedges 144 can be reinserted into the through-channel 140a and the force devices 148 can be moved to their fully extended position, so that the first holding device 140 again takes over the clamping force of the clamping element 106 and the holding engagement of the second holding device 142 can be released. This corresponds to the already described in Figure 3c shown state.

[0046] If necessary, the Figures 3c to 3f The steps shown are repeated until the clamping element 106 has been completely relaxed.

[0047] In Figure 4 a second embodiment of the relaxation device is shown, which is essentially the same as the first embodiment according to Figure 2 Therefore, in Figure 4 analogous parts are provided with the same reference numerals as in Figure 2 , but increased by the number 100. In addition, the relaxation device 230 is Figure 4 are described below only insofar as they differ from the relaxation device 130 according to Figure 2 to whose description express reference is hereby made.

[0048] The relaxation device 230 according to Figure 4 differs from the relaxation device 130 according to Figure 2in that the second holding device 242 is arranged on the side of the first holding device 240 facing the receiving tube 220. As a result, the power devices 248 are supported directly on the mounting bars 238. Furthermore, the frame 232 has additional mounting bars 238' on which the second holding device 242 is supported.

[0049] Despite these design differences, with regard to the Figures 3a to 3f for the embodiment according to Figure 2 The relaxation process described in the same way also by means of the relaxation device 230 according to Figure 4 be performed.

[0050] In Figure 5 a third embodiment of a relaxation device is shown, which is essentially the second embodiment according to Figure 4 Therefore, in Figure 5 analogous parts are provided with the same reference numerals as in Figure 4, but increased by the number 100. In addition, the relaxation device 330 is Figure 5 are described below only insofar as they differ from the relaxation device 230 according to Figure 4 to whose description express reference is hereby made.

[0051] In the relaxation device 330 according to Figure 5 Both holding devices 340 and 342 are assigned force devices 348 and 352, respectively, which are each supported directly on the mounting bars 338 and 338' of the frame 332 of the unclamping device 330. By extending or shortening the force devices 348 and 352 in opposite directions, it is possible to have the holding devices 340 and 342 work alternately to relax the tension on the clamping element 306.

Claims

1. Method for relaxing a tension element (106) which is braced between two portions of a structure (100), with a given tensioning force, by means of two anchoring arrangements (102, 103), the tension element (106) being anchored in at least one of the anchoring arrangements (102, 103) by means of an anchoring device (124), the method comprising the steps of: • providing a relaxation device (130) having at least one (first) force device (148) that on the one hand is designed to be supported on the structure (100) and on the other hand comprises a holding device (140) for establishing holding engagement with the tension element (106), • attaching the relaxation device (130) to the structure (100) at a point located between the two anchoring arrangements (102, 103), the relaxation device being arranged on a side of the structure portion that faces the other structure portion, and • bringing the holding device (140) of the at least one (first) force device (148) of the relaxation device (130) into holding engagement with the tension element (106) to be relaxed, the at least one (first) force device (148) being an active force device, and the method comprises the following further steps: • actuating the at least one (first) force device (148) in the sense of transferring the tensioning force of the tension element (106) and thus unloading the anchoring device (124), • releasing the anchoring engagement between the anchoring device (124) and the tension element (106), and • actuating the at least one (first) force device (148) in the sense of relaxing the tension element (106), characterised in that the relaxation device (130) comprises at least one further holding device (142) for establishing holding engagement with the tension element (106), the method comprising the further steps of: • bringing the at least one further holding device (142) into holding engagement with the tension element (106) to be relaxed, • actuating the at least one force device (148) in the sense of transferring the tensioning force of the tension element (106) at the at least one further holding device (142), • releasing the holding engagement of the holding device (140) of the at least one first force device (148), • adjusting the at least one first force device (148), • bringing the holding device (140) of the at least one first force device (148) back into holding engagement with the tension element (106) to be relaxed, • releasing the holding engagement of the at least one further holding device (142), and • actuating the at least one force device (148) again, in the sense of relaxing the tension element (106).

2. Method according to claim 1, characterised in that the relaxation device (330) comprises at least one second active force device (352) in addition to the at least one first active force device (348), which second active force device comprises a holding device (342) for establishing holding engagement with the tension element (306), the method comprising the further steps of: • bringing the holding device (342) of the at least one second force device (352) into holding engagement with the tension element (306) to be relaxed, • actuating the at least one second force device (352) in the sense of transferring the tensioning force of the tension element (306) from the at least one first force device (348), • releasing the holding engagement of the holding device (340) of the at least one first force device (348), • adjusting the at least one first force device (348), • bringing the holding device (340) of the at least one first force device (348) back into holding engagement with the tension element (306) to be relaxed, • releasing the holding engagement of the holding device (352) of the at least one second force device (342), and • actuating the at least one first force device (348) again, in the sense of relaxing the tension element (306).

3. Method according to either claim 1 or claim 2, characterised in that the holding device (140; 340) of the at least one first force device (148, 348) and / or the holding device (342) of the at least one second force device (352) comprises at least one clamping wedge (144, 146).

4. Method according to any of claims 1 to 3, characterised in that the holding device (140; 340) of the at least one first force device (148; 348) and / or the holding device (342) of the at least one second force device (352) comprises a base bearing which is arranged on the movable part of the respective force device (148; 348, 352) and is designed to surround the tension element (106; 306).

5. Method according to claim 4, provided this is dependent on claim 3, characterised in that the base bearing comprises a recess (140a, 142a) for the tension element (106) to pass through and for receiving the at least one clamping wedge (144, 146).

6. Method according to any of claims 1 to 5, characterised in that the relaxation device comprises a base unit (132; 332), on which the at least one first force device (148; 348) and / or the at least one second force device (352) is supported.

7. Method according to claim 6, provided this is dependent on claim 4, characterised in that the base bearing is guided (154) on the base unit (132) in a direction extending substantially in parallel with the longitudinal extension direction (L) of the tension element (106).

8. Method according to any of claims 1 to 7, characterised in that the at least one first force device (148; 348) and / or the at least one second force device (352) is an electromotively and / or pneumatically and / or hydraulically actuatable force device.

9. Method according to any of claims 1 to 8, characterised in that the at least one first force device (148; 348) and / or the at least one second force device (352) is a force device that can be lengthened and shortened in a direction extending substantially in parallel with the longitudinal extension direction (L) of the tension element (106; 306).

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