The present invention relates to a cable anchorage system and a method for anchoring a cable at a construction, e. g. a civil engineering construction, according to the introductory part of patent claims 1 and 14.

Cables, like stay cables or cable hangers, are widely used for the design of civil engineering constructions like bridges, suspended roofs, cable stabilized building structures, stayed masts or towers and the like. The cables are usually realized by a plurality of twisted metal cable threads to provide the tensile force needed to absorb the heavy loads of the construction. One construction may require dozens of cables to achieve the strength and the statics involved in a cable construction design. The cables are anchored with one end at the construction and with the opposite end at a support, like a ground foundation, or at another part of the construction. Heavy duty anchor systems and tendons are used to mount a cable to the construction and then tension the cable to the tensile force required for the design of the construction. The application of the cables is problematic due to the very high weight and large dimensions of the cables, the high tensile forces required, and the overall size of the cable set up. Additionally outdoor environmental conditions impede the handling of the cables.

Existing solutions for anchoring and tensioning a cable use for example clevis components to attach the cable to a ground foundation or other structural components. After attaching the cable, stressing units are used to tension the cables to the necessary tractive force. Preferably, the traction can be adjusted during the service life of the cable. In general, two types of anchoring systems are known that use a rod or tube to anchor and tension the cable.

The first type uses a turnbuckle concept, wherein a rod features threads of opposite pitch at each extremity. One end of the rod is screwed into a support socket anchored with a clevis connection. The other end is screwed in a cable socket holding the cable. US 6,681 ,431 B2 shows an adjustable anchor for holding a cable hanger and bearing a civil engineering structure. The cable hanger is attached to an anchor pipe and a clevis is attached to a support. A linking part comprises threads with opposite pitches at each end. The linking part is screwed into the anchor pipe at one end and into the clevis at the opposite end. The clevis is mounted to the support by a pin that extends through oblong holes in the clevis forks with a play between the pin and the hole edges. A tension system pulls the whole unit set up by the anchor pipe with the cable hanger, the linking part and the clevis towards the support resulting in the play being located on the support side of the holes. By rotating the linking part, the clevis is pulled towards the anchor pipe and the play is located on the cable side of the holes, which tensions the cable. When the cable hanger has to be shortened or lengthened by a length greater than the play, this operation must be repeated several times.

The second type uses a bolt concept, wherein a threaded rod comprises a transfer head interacting with the clevis and a threaded end is threaded into a cable socket. For example, a cable anchorage system as shown in EP 3344817 B1 comprises a support socket attached to a structure by a clevis connection, an anchorage socket holding the cable and a coupling rod coupling the support socket with the anchorage socket. The coupling rod has a mounting head that is slidably located in an interior space of the support socket. The support socket space and the mounting head are provided with interacting abutments to prevent the coupling rod from disengaging from the support socket. To tension the cable the anchorage socket is pulled towards the support socket, wherein the coupling rod slides further into the interior space of the support socket creating a clearance between the interacting abutments. The coupling rod is threaded into the anchoring socket to reduce the clearance and keep the cable tensioned. Again, this process needs to be repeated several times in case the tensioning length of the cable is larger than the clearance.

Both solutions present the disadvantage of being subjected to high tensile and bending stresses acting on the location of the threaded connections. This forces the use of expensive solutions to manufacture such as threaded rods or tubes, both in the choice of high-performance material or in the choice of onerous methods of thread forming. In addition, both concepts present the disadvantage of aligning one component after the other; that is the clevis, the rod or tube for tension introduction or tuning, and the cable anchor. This leads to a long and bulky anchorage system. Finally, both concepts require a stage by stage stressing process, where the stroke of stressing or the threading cycle operation impacts directly on the length of the system assembly, making the stressing operations long and fastidious.

It is an object of the present invention to provide a cable anchorage system and method that overcome the identified disadvantages. In particular it is an object of the present invention to provide a cable anchorage system that is compact in length, comprises a robust design and is compatible with existing stressing applications. Further it is an object to provide a cable anchoring method that is safe and easy to apply, quickly anchors a cable with a required tensile strength, and reduces the steps for tensioning the cable.

These and other objects are fulfilled by a cable anchorage system for anchoring a cable at a construction and a method for tensioning such as a cable anchorage system according to independent claims 1 and 14. Advantageous features and preferred embodiments of the cable anchorage system and the method according to the invention are disclosed in dependent claims.

According to the present invention a cable anchorage system for anchoring a cable at a construction comprises an anchor head mounted to the cable, a construction socket attachable to the construction and a connector for connecting the anchor head to the construction socket. The anchor head, the construction socket and the connector are generally aligned along the same longitudinal direction, which basically corresponds to the longitudinal direction of the cable. The construction socket can be any unit or system that is designed for fixing the cable to a construction, while the cable is under tensile stress. Most commonly clevis-type fixations are used to attach cables or cable hangers to a construction. The construction is for example a basement, a ground foundation, parts of a civil engineering structure or the like.

The construction socket comprises an opening for at least partially receiving the anchor head in a movable manner. For example, the construction socket comprises a section for being mounted to the construction at one end and another section providing the opening at the opposite end. The anchor head can slide or rotate within the opening, while the cable anchorage system is in a pre- anchoring position before the systems takes up the load of the cable stress. The opening of the construction socket has an internal thread. The connector comprises an external thread for engaging with the internal thread of the construction socket. Further, the connector is movably arranged along the anchor head while the cable anchorage system is in the pre-anchoring position. By engaging with the internal thread of the opening of the construction socket the connector provides a longitudinally adjustable stop for the anchor head. The stop can be positioned within the opening along the longitudinal direction of the system by screwing it into the opening. The anchor head comprises a radially extending shoulder, which abuts against the stop of the connector when the connector is adjusted to take a cable tensioning position at the construction socket. Thus, the connector acts as a stop for moving the anchor head away from the construction socket when the cable exerts a tensile force on the anchor head.

The cable anchorage system can easily be transferred from a preanchoring mode, wherein the anchor head can freely move in the opening of the construction socket, to a cable tensioning mode, wherein the anchor head is blocked from movement relative to the construction socket by the connector stop, by screwing the connector into the opening to the required tensioning position. This design provides a high level of flexibility during the tensioning process, enables the cable anchorage system to quickly pick up the tensile forces after tensioning the cable with a traction force required for the construction and allows for simple adjustment of the system.

Preferably, the connector is completely detachable from the construction socket, so that it can slide along the anchor head before it is screwed to the construction socket. This ensures a large degree of freedom to move the anchor head along the longitudinal direction of the system before fixing the cable in the tensioning position.

The method for tensioning the cable anchorage system according to the present invention uses a stressing unit for stressing the cable. The stressing unit comprises a socket bracket attachable to the construction socket, at least one stressing jack attachable to the anchor head and stressing bars connecting the socket bracket and the at least one stressing jack. For stressing the cable and transferring the cable anchorage system from a pre-anchoring mode to a cable tensioning mode, the at least one stressing jack is driven to slide along the stressing bars towards the construction socket exerting a stressing force on the anchor head and causing the anchor head to slide into the opening of the construction socket until the cable tensioning position is realized. In the cable tensioning position of the anchor head the connector is screwed into the opening until the anchor head abuts against the stop of the connector.

By using the method for tensioning a cable with the cable anchorage system the stressing of the cable is easily done in a one-step tensioning process. The cable is stressed by pulling the anchor head mounted to the cable to the required tensioning position and the connector is adjusted to stop the anchor head from releasing the cable stress. It is not required to repeat the tensioning process several times to achieve the required cable tension as it is necessary in the above-described prior art concepts. After setting up the cable anchorage system in the cable tensioning position the stressing unit can be detached from the system and used to stress another cable anchorage system.

In one embodiment of the cable anchorage system according to the present invention the construction socket and the connector are overlapping in axial direction such as in a retractable telescopic manner, for instance when in the cable tensioning mode of the system. However, in the pre-anchoring position the connector may not overlap with the construction socket and may be located outside the opening of the construction socket. The anchor head/connector and the construction socket can be held in relative position to each other by the stressing unit. Once the connector is inserted into the opening of the construction socket, these two elements are overlapping in axial direction such as in a retractable telescopic manner. Preferably, also the connector is overlapping axially with the construction socket and the anchor head in the cable tensioning mode. Prior to the tensioning of the cable and adjusting the connector stop, the construction socket, the connector and the anchor head can be telescopically moved relative to each other along the longitudinal direction of the cable anchorage system. In a further embodiment of the cable anchorage system, the connector comprises an accessible tip for positional adjustment in relation to the construction socket. For example, the connector may have attachment points, like holes or small protrusions, at its back end for attaching a rotator device for turning the connector 4 around its longitudinal axis.

In a further embodiment of the cable anchorage system, the anchor head comprises a flat surface, axially orientated, as a bearing for the extension.

In a further embodiment of the cable anchorage system, the extension is an integrated element with the anchor head or a separate piece serving as a tool for moving the connector. In other words, the extension may not be essential to form as an integrated piece with the anchor head.

To this end, it is disclosed in a further embodiment that when the extension is a separate piece, it serves as a tool for moving the anchor head, allowing (subsequently) to adjust the connector.

In a further embodiment of the cable anchorage system, there is a further method by removing the extension from the cable anchorage system when the cable is anchored.

In a further embodiment of the cable anchorage system, further comprising a step of connecting the stressing jack to the extension via a stressing bracket.

In a further embodiment of the cable anchorage system the anchor head comprises a longitudinal extension as a bearing for the connector. For example, the anchor head can be designed by a cable block in which the cable is firmly attached at a front end of the anchor head and the extension can be a sleeve or tube extending from that cable block at a back end of the anchor head. The extension may extend around the cables that end in the cable block.

In an advantageous embodiment of the cable anchorage system the connector comprises an elongated tubular shape. For example, the connector is designed as a sleeve, nut or tube that is slidably arranged around the anchor head. Particularly, the tubular connector can slide along an extension of the anchor head. Preferably, the tubular connector sits on the extension in a form fit which allows the connector to slide longitudinally but prevents the connector from moving radially relative to the anchor head. For example, the anchor head or its extension and the tubular connector are of cylindrical shape. The tubular connector sits on the outer contour of the extension and can rotate thereon. This design facilitates the position of the anchor head, the connector and the construction socket relative to each other and avoids high stresses on these elements during the stressing process of the cable anchoring system.

Further, an outer diameter of the extension may be smaller than the inner diameter of the opening by as much as to leave a radial gap between the extension and the opening when the anchor head is located in the opening. Preferably, the radial dimension of the gap corresponds to the thickness of the connector engaging between the extension and the opening. Thus, the connector perfectly fills the gap and prevents radial movements of the anchor head within the opening. Advantageously, the diameters are designed such that the outer thread of the connector automatically engages with the inner thread of the opening when the connector is screwed into the construction socket. For example, the inner thread is at least arranged at the entry end of the opening and may extend longitudinally towards a bottom end of the opening. The outer thread of the connector may be arranged at least at the connector section oriented towards the construction socket. Preferably, the outer thread may extend along the full length of the connector.

Additionally or alternatively, an outer contour of the radially extending shoulder of the anchor head may comprise an approximate form fit with an inner contour of the opening of the construction socket. For example, the outer diameter of the cable block of the anchor head may correspond to the inner diameter of the opening of the construction socket. Such a cylindrical arrangement allows for simple longitudinal alignment of the anchor head in the opening. The form fit prevents radial movement of the anchor head in the opening and avoids stressing forces on the anchor head and the mounting of the cable.

Matching diameters of the anchor head, the opening of the construction socket and the connector will support the alignment of these separate elements of the cable anchorage system during the cable tensioning process and allows for a compact and robust design of the system.

In one embodiment of the cable anchoring system according to the invention the stop of the connector is realized by a radially arranged edge at an end of the connector oriented towards the construction socket. The opposite end of the connector is oriented towards the cable. The radial edge can be defined as the stopper edge of the connector. When the connector is screwed into the opening of the construction socket the stopper edge moves towards the anchor head until it abuts against the radially extending shoulder of the anchor head. In this position the cable anchoring system is in the cable tensioning mode.

In still a further embodiment of the cable anchorage system the opening of the construction socket comprises a bottom that serves as abutment for the anchor head in direction towards the construction socket. For example, the cable block of the anchor head can be pulled into the opening until its front end hits the opening bottom. In this position the anchor head is in a cable tensioning position providing the strongest stressing of the cable. After adjusting the connector stop in the opening to block the anchor head at its radial shoulder the cable anchoring system in a cable tensioning mode with its maximum cable stressing capacity.

However, the anchor head does not need to be inserted all the way to the bottom of the construction socket opening. The connector stop can block the anchor head in a cable tensioning position with some distance towards the bottom, which corresponds to a lesser stressing of the cable.

In an advantageous embodiment of the cable anchorage system according to the present invention the construction socket includes a clevis coupler for coupling the system to the construction. For example, the clevis coupler comprises a gusset flange, a fork element, and a connection pin. The gusset flange is anchored in the ground or mounted to a structure. The fork element is extended from the opening section of the construction socket. The gusset flange and the forks of the fork element have holes for assembling the clevis coupler. When the forks embrace the gusset flange all holes are aligned and the connection pin is inserted into the passage created by the holes to assemble the clevis coupler.

The present invention further provides a civil engineering construction comprising at least one cable, which is attached with at least one end to the construction by a cable anchorage system as described above. The civil engineering construction is set up quickly by using the cable anchoring system. The statics of the structure can be fine-tuned in a simple manner by taking advantage of the tensioning method according to the invention.

In summary, the cable anchoring system of the present invention is much more compact in length compared with existing solutions. Each of the adjustable elements of the system are located inside each other when the system is in a cable tensioning mode. Advantageously, they can be arranged relative to each other in a telescopic manner for the tensioning process. They do not need to be aligned one after the other as in the prior art concept. The cable anchoring system of the invention is much more robust because tensile and bending stresses occurring during the tensioning are mostly affecting the construction socket, which is the widest and therefore strongest element of the system. In addition, the critical location of high fatigue stress in the system is not located on a threaded surface but mostly on a plain surface free of indentations, permitting the use of simpler machining and more cost-effective material for manufacturing. The cable anchoring system can be applied to any tendon technology because the interface between the anchor head and the construction socket is a simple bearing interface and not a complex interface structure.

An exemplary embodiment of the invention will be illustrated in the following drawings, which merely serves for explanation and should not be construed as being restrictive. The features of the invention becoming obvious from the drawings should be considered to be part of the disclosure of the invention both on their own and in any combination. The drawings show:

Fig. 1 : a schematic longitudinal view of a cable anchoring system according to the present invention with a stressing unit in a pre-anchoring mode,

Fig. 2: a schematic longitudinal view of the cable anchoring system according to Figure 1 during a cable stressing process, and

Fig. 3: a schematic longitudinal view of the cable anchoring system according to Figures 1 and 2 in a cable tensioning mode,

Fig. 4: a schematic longitudinal view of the cable anchoring system according to Figures 1 to 3 after disassembly of the stressing system,

Fig. 5: a schematic longitudinal view of the cable anchoring system according to Figures 1 to 4 at an earlier stage before installation of the stressing system and insertion of the anchor head in the construction socket.

In the following description of the cable anchoring system and method for tensioning the same certain terms are used for reasons of convenience and are not intended to limit the invention. The terms “up”, “down”, “front”, and “back” are referred to directions in the figures and during the tensioning process. Also, spatially relative terms, such as "below", "lower", "above", "upper", and the like, may be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions and orientations of the elements in use or operation in addition to the position and orientation shown in the figures.

To avoid repetition in the figures and the descriptions of the various aspects and positions of the described embodiment, it should be understood that many features are common to many aspects and variants. Omission of an aspect from a description or figure does not imply that the aspect is missing. Instead, the aspect may have been omitted for clarity and to avoid prolix description. If, in order to clarify the drawings, a figure contains reference signs which are not explained in the directly associated part of the description, then it is referred to previous or following description sections. Further, for reason of lucidity, if in a drawing not all features of a part are provided with reference signs it is referred to other drawings showing the same part. Like numbers in two or more figures represent the same or similar elements.

Figures 1 - 5 illustrate a cable anchoring system according to the present invention in different stages during a tensioning process for stressing a cable 1 by the tensioning method according to the invention using a stressing unit. The cable 1 is schematically represented by several cable threads. However, the cables used for civil engineering constructions comprise a plurality of strands intertwined to realize a heavy-duty cable for holding large constructions like bridges, towers and the like as explained before.

The cable anchoring system comprises an anchor head 2 mounted to the cable 1 , a construction socket 3 attachable to the construction (not shown) and a connector 4 for connecting or coupling the anchor head 2 to the construction socket 3. The construction socket 3 comprises an opening 5 for at least partially receiving the anchor head 2. The elements of the cable anchoring system are aligned in direction of a longitudinal axis of the system and the cable, respectively. Further, in the illustrated embodiment the elements have a cylindrical shape and are generally symmetrical around the longitudinal axis. However, in other embodiments of a system according to the present invention the elements may have a different shape. The construction socket 3 is for example fixed to a ground foundation or a structure (not shown) by a clevis coupler comprising a gusset flange 100, a clevis fork 101 and a connection pin 102. The clevis coupler functions as known from the state of the art for example as describe above.

In Figure 1 the cable anchoring system is shown in a pre-tensioning mode, wherein the anchor head 1 is not inserted into the opening 5. In Figure 1 the anchor head 1 is located just above the opening 5. However, it could be located at a larger distance towards the opening 5 depending on the cable conditions prior to stressing the cable. The opening 5 comprises an internal thread 6 at an upper end of the construction socket, which represents an entry end for receiving the anchor head 2. In the illustrated embodiment, the internal thread extends over about 1/4 or 1/3 of the longitudinal length of the opening. However, the internal thread may cover a larger portion of the opening.

The connector 4 has an elongated tubular shape and is realized as an elongated sleeve or nut. It comprises an external thread 7 for engaging with the internal thread 6 of the opening 5, as will be described below. The connector 4 is movably arranged along the anchor head 2 and detached from the construction socket 3. The connector 4 provides a longitudinally adjustable stop 8 for the anchor head 2, as will also be explained below.

In the shown embodiment of the cable anchoring system, the longitudinal extension 9 may extend from the stressing bracket 204 to the flat surface 15 of the anchor head 2. To this end, it is noted that the stressing bracket 204 could be considered as a part of the stressing jack 201 . In the technical field of the present invention, jacks (hydraulic cylinders) are typically differentiated from steel structures, such as the stressing bracket 204, for example. The outer diameter of the extension 9 corresponds to the inner diameter of the connector 4. Thus, the extension 9 can serve as a bearing for the connector 4 and the connector 4 can slide and rotate on the extension 9 of the anchor head 2. Further, the anchor head 2 comprises a radially extending shoulder 10 for interacting with the stop 8 of the connector 4. The shoulder is provided by a radial step or edge at a front section of the anchor head 2, for example at the anchorage block. An outer contour of the front section of the anchor head 2 stretching from the shoulder 10 to the front end of the anchor head comprises a form fit with an inner contour of the opening. That means, the outer diameter of the anchor head 2 corresponds to the inner diameter of the opening 5.

A stressing unit for stressing the cable 1 and thereby pulling the anchor head 2 towards the construction socket 3 is attached to the anchor head 2 and the construction socket 3. The stressing unit comprises a socket bracket 200 attachable to the construction socket 3, at least one stressing jack 201 attachable to the anchor head 2 or to an extension 9 and stressing bars 202. The socket bracket 200 may for example be attached to the construction socket 3 by providing a bracket pin 203 through the connection pin 102 of the clevis coupler. Additionally or alternatively, the socket bracket 200 may for example be attached to the gusset flange 100 or structural elements of the construction socket 3. The at least one stressing jack 201 is coupled with the rear end of the extension 9 of the anchor head 2. The stressing jack 201 may for example be connected to the extension 9 via a stressing bracket 204 as shown in figure 1 . The at least one stressing jack 201 is slidably arranged on the stressing bars 202, wherein the stressing bars serve as a guide for the longitudinal movement of the stressing jack 201 and the anchor head 2, respectively.

A protection pipe 11 is located outside the stressing unit above the stressing jack 201 . The protection pipe 11 may slide over the cable anchoring system once the stressing unit is detached from the anchor head and the construction socket as shown in figure 4. For example, after tensioning the cable and when the cable anchoring system is in a cable tensioning mode.

In Figure 2 the cable anchoring system is shown after the stressing unit pulled the anchor head 2 into the opening 5 of the construction socket 3 by pushing the stressing jack 201 along the stressing bars 202 towards the socket bracket 200. The front end of the anchor head 2 is moved all the way to a bottom 12 of the opening 5 and abuts against it. The form fit between the inner contour of the opening 5 and the outer contour at the shoulder 10 of the anchor head 2 prevents radial movement of the anchor head 2 in the opening 5. Thus, the anchor head 2 simply slides along the inner wall of the opening 5 and is prevented from misalignment in the opening 5.

As can be seen in Figure 2, the connector 4 slides upwards along the extension 9 of the anchor head 2 during the cable stressing process and remains outside the opening 5 of the construction socket 3, while the anchor head 2 enters the opening 5. The connector 4 sits on the internal thread 6 at the entry end of the opening.

Compared to the pre-anchoring position of the anchor head 2 relative to the bottom 12 of the opening 5 as shown in Figure 1 , the anchor head 2 travelled a large distance towards the bottom 12 for tensioning the cable 1 and is now in the cable tensioning position as shown in Figure 2. The travelled distance of the anchor head 2 is much larger as a stressing distance allowed in any of the prior art concepts. The tensioning process does not create any bending or rotating stresses acting on the anchor head because all elements are aligned in longitudinal direction during the entire cable stressing.

As illustrated in Figure 2 an outer diameter of the extension 9 is smaller than the inner diameter of the opening 5 and leaves a radial gap 13 between the extension 9 and the opening 5. Advantageously, the radial dimension of the gap 13 corresponds to the radial thickness of a wall of the connector 4 engaging between the extension 9 and the opening 5. Thus, the connector 4 fits in between the extension 9 of the anchor head 2 and the inner wall of the opening 5 of the construction socket 3.

In Figure 3 the cable anchoring system is shown in a cable tensioning mode. The external thread 7 of the connector 4 has been screwed into the internal thread 6 of the opening 5. The connector 4 has an accessible tip 14 for turning the connector 4 around its longitudinal axis. For example, the connector 4 may have attachment points, like holes or small protrusions, at its back end for attaching a rotator device. The stop is realized by a radially arranged stopper edge corresponding to the front end of the connector 4 oriented towards the construction socket 3. The connector 4 is inserted into the opening 5 until this stop 8 abuts against the shoulder 10 of the anchor head 2. The connector 5 is in a snug fit with the inner wall of the opening 5 and the outer contour of the extension 9, and closes the radial gap 13. Thus, the anchor head 2 is tightly secured in the construction socket 3 in its cable tensioning position.

Now the socket bracket 200, the at least one stressing jack 201 and the stressing bars 202 can be detached from the cable anchoring system. The protection pipe 11 may be pushed over the anchor head 2 and the construction socket 3 protecting the cable anchoring system from weathering and vandalism.

In the cable tensioning mode of the cable anchoring system the anchor head 2, the connector 3 and the opening 5 of the construction socket 4 are overlapping in axial and/or radial direction such as in a retractable telescopic manner. The cable anchoring system has a compact and robust design, wherein plain surface absorbs a large portion of the stressing forces in the system. This reduces the amount of material and resources required for producing the system and provides a strong foundation for the stressed cable.

In the cable tensioning mode of the cable anchoring system as shown in Figures 1 -3 the anchor head is pulled all the way to the bottom of the opening. However, the cable tension required for the construction may not require that the cable is stressed that much. The anchor head can be pulled only partially into the opening to provide lesser cable tension. Consequently, the connector is screwed a shorter distance into the opening until the stop hits the shoulder of the anchor head. The traction force of the cable will securely keep the anchor head at the stop. Thus, the adjustable stop can be arranged according to a required tension of the cable.

Figures 4 and 5 show an example where the cable anchorage system without stressing unit (e.g., stressing jack and stressing bar), for instance the stressing unit is removed after anchorage has been established (Figure 4) or before anchorage is begun (Figure 5).

This description and the accompanying drawings that illustrate aspects and embodiments of the present invention should not be taken as limiting the claims defining the protected invention. In other words, while the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Various mechanical, compositional, structural, and operational changes may be made without departing from the spirit and scope of the claims. For example, the cable anchoring system can be coupled to a structure or ground foundation in other ways than using a clevis coupling, and the cable anchoring system can be tensioned using other stressing units than illustrated in the example embodiment. Also, the cable anchoring system does not need to be oriented in the illustrated up/down configuration. The system can take any orientation in space as needed by the design of the construction, which should be tensioned by the cable anchoring system. Thus, it will be understood that changes and modifications may be made by those of ordinary skill within the spirit of the following claims. Furthermore, in the claims the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single unit or step may fulfil the functions of several features recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Reference Numbers

1 cable

2 anchor head

3 construction socket

4 connector

5 opening

6 internal thread

7 external thread

8 stop

9 extension

10 shoulder

11 protection pipe

12 bottom of opening

13 radial gap

14 accessible tip

15 a flat surface

100 gusset flange

101 clevis fork

102 connection pin

200 socket bracket

201 stressing jack

202 stressing bar

203 bracket pin

204 stressing bracket