Clamping device, de-tensioning system and methods for clamping and for de-tensioning an object

Abstract

The present invention relates to a clamping device (100, 100') for clamping an object (10), a de-tensioning system (1) and a method for clamping an object (10) and for de-tensioning the object (10). The clamping device (100, 100') comprises a body (110) comprising at least a first confining plate (140) and a second confining plate (140') defining between them a substantially elongated cavity (130) with a gradually declining width along a longitudinal axis (X) thereof by means of alignment means (160) and a gripping assembly (120) comprising one or more segments (121) and being at least partially receivable and movable within the cavity (130), wherein the gripping assembly (120) provides an inner bore to receive the object (10); and stressing means (200) either mounted directly on the clamping device (100, 100') or on a stressing chair (22) comprising at least one stressbar (210) and a stressing hydraulic cylinder (20) configured to exert a clamping force to the clamping device (100, 100') by inducing a movement of the gripping assembly (120) in order to come into contact with the object (10) and to clamp the object (10).

Description

[0001] Clamping device, de-tensioning system and methods for clamping and for de-tensioning an object

[0002] Technical Field

[0003] The invention relates to a clamping device, in particular to a clamping device for clamping tensioning elements or structural elements in civil engineering structures such as external post-tensioning tendons, stay cables, guy lines or bridge hangers for de-tensioning, demounting, or replacing. In addition, the clamping device according to the invention is suitable for tensioning elements formed by multiple individual tensile elements or wires such as those configured as locked coil cables or as parallel wire tendons. Furthermore the invention relates to method for clamping an object, to a de- tensioning system and a method thereof.

[0004] Background of the invention

[0005] Structural elements or tensioning elements of civil engineering structures such as bridges, buildings or towers need to be maintained or replaced from time to time in order to ensure safety of these civil engineering structures. Therefore, pre-tensioned elements such as guy lines acted as a whole need to be de-tensioned in a controlled manner by transferring the load from the tensioning element to post-tensioning tendons or bars by means of friction clamps before being demounted and replaced.

[0006] Such guy lines are frequently formed by a bundle of tensile elements, such as wires, strands, bars, or other types of load-bearing elements, which can be covered by a collective sheath within which the bundle of tensile elements is located and the interface between the strands, wires, or load-bearing elements. The sheath can be injected with cement grout or other material which acts as a filler element and protection against corrosion.

[0007] One type of guy lines used as hangers or main suspension cables on bridges are the so-called locked coil cables. The locked coil cable can be described as an assembly of a classic wire rope core consisting of multiple helically twisted wires, with one or more layers of profiled, z-shaped wires or t- shaped wires, that interlock with each other arranged around the core. These interlocking outer layers creates a dense rope assembly, with high strength and stiffness. Another type of cables are formed by multiple individual wires that may be arranged parallel or threaded.

[0008] For demounting such tensioning elements the load is transferred to a bridging device before manipulating the tensioning elements. Such bridging device comprises friction clamps, auxiliary tensile elements such as posttensioning bars and hydraulic jacks that allow de-tensioning in a controlled manner. The clamps must be solidly connected to the tensioning element, withstand force, and avoid any slippage of the tensile elements.

[0009] Known clamps consist of two or more collars that are tightened against the tensioning elements by means of bolts. The tightening force generates friction that must be higher than the remaining force of the tensioning elements in order to prevent any slippage.

[0010] One possible solution to clamp the tensile element consists of using solid steel grippers, usually made of heat-treated steel. These grippers may be similar to those commonly used for post-tensioning and are known to stress or de-tension a tensile element made of a single wire, or a threaded strand made out of a central wire and a plurality of smaller wires threaded onto the central wire. A stressing jack may be formed by two parallel hydraulic cylinders with an opening in the form of an inverted II, which is saddled over the strand to be detensioned. The lower part of the inverted U-shape remains open during the installation and operation of this stressing jack. This type of stressing jacks is known as twin ram jacks and has proven its effectiveness to transfer the load from a commonly 7-wire threaded strand to the post-tensioning jack. Hereby, the grippers actuate on the surface of the strand and prevent any slippage. However, the use of this device is not applicable on tensile elements made of multiple wires, such as locked coil cables or parallel wire tendons. While it is possible to clamp the outer wires, the open configuration of the inverted II- shape may not be solid enough to generate enough clamping force to hold the whole tensile element due to practical difficulties to generate the necessary friction on the internal wires.

[0011] In the state of art some systems related to demounting or replacing pre-tensioning cables such as those described in the following documents are known.

[0012] Document EP3808899 A1 discloses a method and a system for detensioning guy lines wherein in a certain area, a filler material of the guy lines is replaced by another one with improved features or the filler material is incorporated into the guy line if it initially lacked it. Specifically, the method consists of removing in one area the sheath and the cement grout covering the guy line and leaving it clean, placing a formwork around it wherein the improved filler material is injected. This enables, once set, having an area with improved strength and adhesion in order to be able to locate thereon clamps at the ends and starting from them yoke-shaped structures joined to each other by posttensioning bars or tendons.

[0013] However, this system is rather elaborate since the tensile element has to be carefully cleaned, protective layers have to be removed, and a framework has to be installed in order to contain the filler material, furthermore after the de-tensioning the filler material has to be demolished and the clamps have to be thoroughly cleaned before being reused. The load transfer from the tensile element to the auxiliary structure is only possible once the filler material has set and achieved the required strength. In summary, the method is timeconsuming.

[0014] Document WO2023046298 presents a de-tensioning system at least one clamping device with a substantially elongated annular cavity comprising gradually declining diameter sections and forming a multiple internal wedge shape that may be filled with mortar. The mechanism of a load transfer in this system relies on a wedge effect formed by the wedge shape and is not based on the friction and tightening force of clamps. This system might be more effective than other systems based solely on friction, but the cavity has to be filled with the mortar to achieve the required strength before the load transfer. Additionally, the clamps have to be cleaned thoroughly of all rests of debris before being usable on another cable.

[0015] However, it remains several limitations in the above-explained examples. For instance, the set-up of the device is required such that an extended time is needed in order to be prepared to carry out maintenance works. Furthermore, in the case of cables made of multiple wires these clamping devices may not exert a clamping force high enough to penetrate into the inner core.

[0016] Therefore, it remains a need to find an improved clamping device, de-tensioning system, and method thereof for a fully controlled de-tensioning and complete force release of an object such as multiple wire tendons, for example locked coil cables, to enable the replacement of guy lines that are being pre-tensioned or pre-stressed. The improved clamping device, de- tensioning system and method thereof are simple in structure, low in pre-stress loss, high in de-tensioning load holding rate and in particular show good mechanical performance und usability.

[0017] Summary of the invention

[0018] In the present invention, it is proposed that the tendon force of a guy line, hereinafter mentioned as object to be clamped or simple as object, is transferred to stressbars of a de-tensioning system, clamped to the object, which is pre-stressed, with the objective to reduce the tendon force in at least part thereof. The object to be tensioned can be a multiple wire tendon, in particular comprising at least seven wires. Examples of such an object are steel wire ropes, parallel wire tendons and locked coil cables. The locally detensioned object is then cut in said portion which is positioned between an activated clamping device and an anchored structure or between two activated clamping devices. Once the object has been cut, the restrained stressbars of the de-tensioning system can be released in a controlled manner by de- tensioning the stressbars for instance through hydraulic cylinders, which in turn will release the tendon force over the full object length. The de-tensioning system according to the invention comprises at least one clamping device, preferably two clamping devices provided on both sides of the portion of the object to be clamped for de-tensioning within the free length. The clamping device for clamping an object according to the invention comprises:

[0019] - a body comprising at least a first confining plate and a second confining plate defining between them a substantially elongated cavity with a gradually declining width along a longitudinal axis thereof, alignment means and a gripping assembly with one or more segments which gripping assembly is at least partially receivable and movable within the cavity wherein the gripping assembly provides an inner bore to receive the object; and

[0020] - stressing means either mounted directly on the clamping device or on a stressing chair comprising at least one stressbar and a stressing hydraulic cylinder configured to exert a clamping force to the clamping device by inducing a movement of the gripping assembly in order to come into contact with the object and to clamp the object.

[0021] The body comprising the at least two confining plates may comprise further plates such as side plates and front plates connectable to each other and linkable to the confining plates to form a casing in which the elongated cavity with a gradually declining width for accepting the gripping assembly and an opening for the object to be clamped are provided. This closed configuration allows to increase the clamping force in order to generate enough friction on inner elements of the multiple wire tendon. The body may be assembled by connecting means such as the connecting side and / or front plates and / or mechanical fixing means in order to resist the clamping force transmitted by the gripping assembly. Such assembled body allows a simpler attachment or removal to the object to be clamped. Furthermore, providing confining plates creates a closed configuration that allows to increase the clamping force in order to generate enough friction on the inner elements of multiple wire tendon.

[0022] According to some embodiments, the alignment means are provided as a tapered structure provided at inner surfaces of the first confining plate and second confining plate. The tapered structures have a gradually inclining width along the longitudinal axis and limits the cavity with the gradually declining width such that the gripping assembly is guided along its outer surface by this structure allowing a locking effect to be achieved by pushing or moving the gripping assembly towards the object to be clamped. Complementary to the tapered cavity formed by the alignment means the outer surface of the gripping assembly may be formed into a substantially tapered surface.

[0023] The gripping assembly may comprise one or more segments in form of a wedge, a trapezoid, or a conical segment, so as to increase the gripping force transferred between the object to be clamped and the clamping device. The one or more segments when mated to each other, conjointly assume the outer shape of the gripping assembly such as a trapezoid or truncated cone with the outer surface complementary to the cavity with the gradually declining width. In this case the object to be clamped received in the formed inner bore may be sandwiched from opposing sides by the wedge-like elements such that by pushing or moving at least one of the segments an increasing gripping force is exerted and therefore enhancing the clamping force initiated by the stressing means.

[0024] In one preferred embodiment the one or more segments of the gripping assembly are formed as wedge-like elements with an inclined outer surface forming a wedge angle with the longitudinal axis between 2° and 30°, preferably 5° and 15°, even more preferably between 7° and 12° to give the most optimum gripping force.

[0025] According to some embodiments, the inner bore of the gripping assembly at least partly formed by the at least one segment, preferably a wedge-like element, has an inner surface, preferably a curved inner surface transversely to the object to be clamped and forming part of the inner bore. In other words, in case the gripping assembly includes two segments each of the curved inner surfaces is formed as a semicylindrical surface defining the internal surface of the inner bore to receive the cable. Preferably, the internal surface of the inner bore has a profile, preferably a toothed profile. Other profiles may be formed by recesses or ribs in order to clamp the object with an increase gripping force.

[0026] Additionally or alternatively the inner surface transversely to the object may be provided with material for increasing gripping force to the object to be gripped and clamped.

[0027] Moreover, the elongated inner bore formed by the gripping assembly comprising at least one or more segments such as wedge-like elements may have a substantially cylindrical form with an outer periphery with edges or with a constant annular diameter or alternatively have a substantially conical form with a gradually declining annular diameter. The gripping assembly in combination with the two confining plates of the body allows a high gripping force and a smaller and more compact clamping device as well as a de-tensioning system, which is advantageous at limited spatial conditions and for an object configured as a multiple wire cable.

[0028] According to some embodiments, the clamping device may be configured to clamp the object configured as a multiple wire cable. Alternatively, the object to be clamped may be a composed cable such as a cable with parallel bars, parallel wires and / or parallel strands or etc. In case of a locked coil cable the clamping device according to the invention is configured to exert a gripping and clamping force that is higher compared to other composed cables. The applied force exerts until the core of the locked coil cable such that the clamping of the entire locked coil cable is secure enough to de-tension the object.

[0029] Another aspect of the invention is to provide a method for clamping the object, comprising the following steps: a) Positioning the clamping device such that the object to be detensioned is received in the inner bore of the gripping assembly comprising one or more segments; b) Moving or pushing at least one of the segments of the gripping assembly towards the object to be de-tensioned; c) Exerting a clamping force to the clamping device.

[0030] This method for clamping the object to be de-tensioned at a portion thereof allows cutting of the object without providing a filler material or a precast material in the cavity of the clamping device before exerting the clamping force.

[0031] Another aspect of the invention is to provide a de-tensioning system for de-tensioning a portion of an object, comprising:

[0032] - at least one clamping device arranged on at least one side of the portion of the object to be de-tensioned wherein the clamping device comprises a body defining an elongated cavity with a gradually declining width along the longitudinal axis thereof and a gripping assembly at least partly receivable and movable within the cavity which gripping assembly forms a substantially elongated inner bore to receive the object; and

[0033] - stressing means, comprising:

[0034] • two or more stressbars connectable between an anchored structure and the clamping device arranged on one side of the portion of the object to be de-tensioned or connectable between a first clamping device and a second clamping device arranged on both sides of the portion of the object to be de- tensioned; and

[0035] • two or more stressbar hydraulic cylinders, wherein each of the stressbar hydraulic cylinder is either mounted directly on one of the clamping devices, or on a stressing chair which in turn is bearing against the clamping devices located on at least one side of the portion of the object to be clamped for de- tensioning. To this end, it is disclosed that the stressbar can be replaced with other similar component or element having similar function. For instance, instead of stressbar, one or more strands or ropes can be used.

[0036] Preferably, the de-tensioning system comprises one or more clamping devices which are provided at each side of the portion of the object to be clamped for de-tensioning. Therefore, the de-tensioning system is configured to be used for de-tensioning a portion of the object to be clamped in the free length of the object such that it is not necessary to provide a filler material before exerting a clamping force.

[0037] A further aspect of the invention is to provide a de-tensioning method for de-tensioning a portion of the object to be clamped, comprising the following steps: a) Positioning at least one clamping device on at least one side of the portion of the object to be de-tensioned if another side of the portion is anchored to an anchored structure, or placing a first clamping device and a second clamping device on either side of the portion of the object to be detensioned, wherein the clamping device comprises a body defining an elongated cavity with a gradually declining width along the longitudinal axis and a gripping assembly at least partly receivable and movable within the cavity, which gripping assembly forms a substantially elongated inner bore to receive the object; b) Joining the clamping device arranged on at least one side of the portion of the object with at least two stressbars, bearing plates, washers, and / or nuts; c) Exerting a clamping force to the at least one clamping device until reaching approximately the same or slightly below an original load carried by the object; d) Cutting the portion of the object while the load and strain of the object is hold by the de-tensioning system. These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description, and claims.

[0038] Brief description of the drawings

[0039] For a more complete understanding of the invention and the advantages thereof, exemplary embodiments of the invention are explained in more detail in the following description with reference to the accompanying figures, in which like reference characters designate like parts and in which:

[0040] Fig. 1 is a schematic perspective view of a de-tensioning system according to one embodiment of the present invention;

[0041] Fig. 2 is a schematic perspective view of a detail of the de-tensioning system according to Fig. 1 ;

[0042] Fig. 3a is a schematic perspective view of a detail of an inside of the de-tensioning system according to Fig. 1 ; and

[0043] Fig. 3b is a schematic perspective top view of the detail of the inside of the de-tensioning system according to Fig. 1 .

[0044] Detailed description of a preferred embodiment

[0045] It is proposed a de-tensioning system for controlled de-tensioning an object to be replaced or repaired such as a tensioning element, e.g. tendon or guy line, which has been previously pre-tensioned, comprising one or more clamping devices. The clamping devices are mounted for example on both sides of a cutting location, wherein both clamping devices are stressed via stressbars against one another before cutting the object. By this even very high tension can be transferred so that the tension of the object can be de-tensioned to allow a safe cutting. After cutting the object at the cutting location by means of for instance a diamond wire cutting machine, the object, e.g. the tendon, can be de-tensioned in a controlled manner by de-tensioning the stressbars with stressbar hydraulic cylinders until the entire tendon force of the object is released.

[0046] Figure 1 shows in a schematic perspective view a de-tensioning system 1 comprising a first clamping device 100 and a second clamping device 100’, arranged on both sides of a portion 12 of an object 10 to be clamped, such as a multiple wire cable and stressing means 200. The stressing means 200 comprise stressbars 210 which are temporarily employed to connect the first clamping device 100 and the second clamping device 100’ and which may alternatively be connected to a bearing plate 220.

[0047] As shown in Figure 1 , the de-tensioning system 1 , wherein the first clamping device 100 and the second clamping device 100’ are arranged on each side of the portion 12 of the object 10 to be de-tensioned and to be cut is suitable for de-tensioning pre-tensioned forces. In this embodiment of the de- tensioning system 1 , two stressbar hydraulic cylinders 20 and two stressbars 210 are employed. By activating the stressbar hydraulic cylinder 20 each stressbar 210 is stressed so as to allow the reduction of the tendon force in the portion 12 between the two clamping devices 100, 100’ to a nominal force before being cut.

[0048] Figure 1 shows an embodiment of the de-tensioning system 1 in which each of the stressbar hydraulic cylinders 20 is mounted on its respective stressing chair 22. Alternatively, the stressbar hydraulic cylinder 20 may be arranged directly on the clamping devices 100, 100’.

[0049] Figure 2 shows one of the clamping devices 100, wherein the first clamping device 100 and the second clamping device 100’ can be configured similarly. The clamping device 100, 100’ comprises a body 110. The body 110 comprises at least a first confined plate 140 and a second confined plate 140’ (not visible in figure 2) which are arranged parallel to each other, wherein these confined plates 140, 140’ together with side plates 114 and / or front plates 112 and / or mechanical connection means form a closed configuration. Figure 3A shows in more detail an inside view of the body 110, whereby one confined plate 140 is removed. The body 110 may be formed by a front plate 112 and side plates 114, wherein the confined plates 140, 140’ be inserted in grooves provided on the side plates 114 and secured together by mechanical fixing means such as bolts or screws. Moreover, in this embodiment the front plate 112 has three openings, through which the stressbars 210 (not shown) and the object 10 to be clamped are conducted, respectively.

[0050] In the inner volume of the body 110 between the first confining plate 140 (not shown) and the second confining plate 140’ a substantially elongated cavity 130 with a gradually declined width is formed by alignment means 160, which may be configured as structures 162 formed on each of the surfaces 142 (not shown), 142’ of the confined plates 140, 140’ transversely to each other. Within the substantially elongated cavity 130 with gradually declining width along the longitudinal axis X the gripping assembly 120 is receivable, movable, and guidable.

[0051] According to some embodiments, the gripping assembly 120 comprises one or preferably more segments 121 which may be designed as wedge-like elements 122 having a tapered outer surface 124 and a groove 123. These wedge-like elements 122 conjointly define an inner bore 170 of a size to receive the object 10. The tapered outer surface 124 of the wedge-like elements 122 is formed substantially complementary to the tapered cavity 130 of the body 110 limited by the alignment means 160. In case of more than one segments 121 forming the gripping assembly 120 at least one segment 121 is movable independently from the other within the cavity 130. The alignment means 160 may have a wedge-like shape with an orientation opposite to the orientation of wedge-like elements 122 of the gripping assembly 120 to withstand the gripping and clamping force exerted by the cavity 130 with gradually declining width and for enhancing guiding of the wedge-like element 122 towards the object 10.

[0052] The segment 121 or the wedge-like element 122 provides on one side the longitudinal groove 123 for receiving part of the object 10 to be clamped. In the embodiment shown in Figure 3A two wedge-like elements 122 form the gripping assembly 120 and are arranged next to each other providing an internal surface profile of the inner bore 170 with cylindrical annular shape, in particular the longitudinal groove 123 in which the object 10 to be clamped is receivable. The inner surface of the bore 170 can be formed with a surfaced or a threaded profile in order to enhance the clamping effect on the object 10.

[0053] Figure 3B illustrates a schematical cross sectional top view of one embodiment of the body 110. As the gripping assembly 120 two wedge-like elements 122 are accommodated in the substantially elongated cavity 130, wherein an inclined outer surface 124 of each wedge-like element 122 bears on a surface of the alignment means 160. The wedge angle a of this outer surface 124 with the longitudinal axis X can be provided in between 2° and 30°, preferably 5° and 15°, even more preferably between 7° and 12° to give the most optimum gripping force.

[0054] It has been found that such clamping device 100, 100’ gives an optimum performance in terms of friction between clamping device100, 100’ and each wedge-like element 122, as well as between each wedge-like element 122 and the object 10 to be clamped.

[0055] While the invention has been described in detail with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modification may be made, and equivalents thereof employed, without departing from the scope of the claims.

Claims

Claims1. A clamping device (100, 100’) for clamping an object (10), wherein the clamping device (100, 100’) comprises- a body (110) comprising at least a first confining plate (140) and a second confining plate (140’) defining between them a substantially elongated cavity (130) with a gradually declining width along a longitudinal axis (X) thereof by means of alignment means (160) and a gripping assembly (120) comprising one or more segments (121 ) and being at least partially receivable and movable within the cavity (130), wherein the gripping assembly (120) provides an inner bore to receive the object (10); and- stressing means (200) either mounted directly on the clamping device (100, 100’) or on a stressing chair (22) comprising at least one stressbar (210) and a stressing hydraulic cylinder (20) configured to exert a clamping force to the clamping device (100, 100’) by inducing a movement of the gripping assembly (120) in order to come into contact with the object (10) and to clamp the object (10).

2. The clamping device (100, 100’) according to claim 1 , wherein the object (10) to be de-tensioned is a tendon formed by multiple wires, in particular formed by more than 7 wires.

3. The clamping device (100, 100’) according to claim 1 or 2, wherein the alignment means (160) are formed as a tapered structure (162) provided at inner surfaces (142, 142’) of the first confining plate (140) and the second confining plate (140’) respectively.

4. The clamping device (100, 100’) according to one or more of the preceding claims, wherein the one or more segments (121 ) are formed as a wedge, a trapezoid, or a conical segment wherein the gripping assembly (120) has an outer surface complementary to the cavity (130).

5. The clamping device (100, 100’) according to claim 4, wherein the one or more segments (121 ) are formed as wedge-like elements (122) with an inclined outer surface (124) forming a wedge angle (a) with the longitudinal axis (X) between 2° and 30°, preferably 5° and 15°, even more preferably between 7° and 12°.

6. The clamping device (100, 100’) according to one or more of the preceding claims, wherein the inner bore (170) formed by the gripping assembly (120) has an inner surface with a profile, preferably a toothed profile.

7. The clamping device (100, 100’) according to one or more of the preceding claims, wherein the inner bore (170) formed by the gripping assembly (120) has a substantially cylindrical form with a constant annular diameter or a substantially conical form with a gradually declining annular diameter.

8. The clamping device (100, 100’) according to one or more of the preceding claims, wherein the object (10) to be clamped is a locked coil cable.

9. A method for clamping an object (10) to be de-tensioned, comprising the following steps: a) Positioning a clamping device (100, 100’) according to one or more of the claims 1 to 7 such that the object (10) to be de-tensioned is received in the inner bore (170) of the gripping assembly (120) comprising one or more segments (121 ); b) Moving or pushing at least one of the segments (121 ) of the gripping assembly (120) towards the object (10) to be de-tensioned; c) Exerting a clamping force to the clamping device (100, 100’).

10. A de-tensioning system (1 ) for de-tensioning a portion (12) of an object (10), comprising:- at least one clamping device (100, 100’) arranged on at least one side of the portion (12) of the object (10) to be de-tensioned wherein the clamping device (100, 100’) comprises a body (110) defining an elongated cavity (130) with a gradually declining width along the longitudinal axis (X) and a gripping assembly (120) at least partly receivable and movable within the cavity (130) which gripping assembly (120) forms a substantially elongated inner bore (170) to receive the object; and- stressing means (200), comprising:• two or more stressbars (210) connectable between an anchored structure and the clamping device (100, 100’) arranged on one side of the portion (12) of the object (10) to be de-tensioned or connectable between a first clamping device (100) and a second clamping device (100’) arranged on both sides of the portion (12) of the object (10) to be de- tensioned; and• two or more stressbar hydraulic cylinders (20), wherein each of the stressbar hydraulic cylinder (20) is either mounted directly on one of the clamping devices (100, 100’), or on a stressing chair (22) which in turn is bearing against this clamping device (100, 100’) located on at least one side of the portion (12) of the object (10) to be clamped for de-tensioning.

11. The de-tensioning system (1 ) according to claim 10, wherein the object (10) to be de-tensioned is a tendon formed of multiple wires, in particular more than 7 wires.

12. The de-tensioning system (1 ) according to claim 11 , wherein the tendon is a locked coil cable.

13. The de-tensioning system (1 ) according to one or more of the claims 10 to 12, wherein one or more clamping devices (100, 100’) are provided to each side of the portion (12) of the object (10) to be de-tensioned.

14. A method for de-tensioning a portion (12) of an object (10) to be de-tensioned, comprising the following steps: a) Positioning at least one clamping device (100, 100’) on at least one side of the portion of the object (10) to be de-tensioned if another side of the portion (12) is anchored to an anchored structure, or placing a first clamping device (100) and a second clamping device (100’) on either side of the portion (12) of the object (10) to be de-tensioned, wherein the clamping device (100, 100’) comprises a body (110) defining an elongated cavity (130) with a gradually declining width along the longitudinal axis (X) and a gripping assembly (120) at least partly receivable and movable within the cavity (130), which gripping assembly (120) forms a substantially elongated inner bore (170) to receive the object (10); b) Joining the clamping device (100, 100’) arranged on at least one side of the portion (12) of the object (10) with at least two stressbars (210), bearing plates (220), washers (230), and / or nuts (240); c) Exerting a clamping force to the at least one clamping device (100, 100’) until reaching approximately the same or slightly below an original load carried by the object (10); d) Cutting the portion (12) of the object (10) while the load and strain of the object (10) is hold by the de-tensioning system (1 ).

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