HK1022007B - Method, member, and tendon for constructing an anchoring device - Google Patents

Description

Method, member and cable for constructing an anchoring device

Technical Field

The present invention relates to an anchoring device for use in civil engineering, in particular a so-called concealed anchoring device accessible only from one side, and more particularly to a method of constructing such a device with more than one cable type and to an anchor member for constructing such a device. The invention also relates to a type of cable, one end of which is intended to be inserted into the anchoring cavity of such an anchoring device.

Background

For some anchoring devices with cable pre-stressed or un-pre-stressed anchor heads, it is not possible to access the anchoring device from the rear. This is particularly the case for submerged anchoring devices which are only accessible from the ground surface, or when the water-tightness or corrosion protection must be particularly careful, so that the rear side of the device must be closed. This requirement has prevented the use of conventional anchor plates, and thus the attachment of the cable to the plate, for example by means of an anchor cone, requires the development of new anchoring devices.

Us patent No.5,056,284 shows an anchoring device accessible only from one side, wherein the device described therein has the disadvantage that each cable, and therefore the pipe in which it is inserted, is held only by longitudinal adhesion, thus greatly limiting the traction stresses which such anchoring devices can withstand and resulting in the need for very large anchoring lengths to obtain a sufficient adhesion surface.

Similarly, U.S. patent No.4,043,133 provides a steel cable jacket that is secured to the surrounding ground by longitudinal adhesion only. The cables extend from the bottom of the sheath and are all attached to the anchor plate; but the method of inserting the plate into the cavity and the method of securing the wire rope to the plate are not described. Given that this embodiment can be made, the transmission of the anchoring force through the injected sheath to the ends of the cables in the surrounding ground is only generated by the longitudinal adhesion forces and does not benefit from the wedge effect described below in connection with the present invention.

Disclosure of Invention

It is an object of the present invention to provide a method for constructing an anchoring device accessible from one side only, without encountering the aforementioned technical drawbacks of the anchoring devices of the prior art, i.e. an anchoring device in which the cables are fixed in such a way that the traction stresses acting on each cable at the level of the anchoring device are taken up by the adhesion forces which have the advantage of constraints due to the overall shape of the anchoring device and of longitudinal mechanical blocking of the ends of the cables, which is achieved by the specific shape of these ends and their arrangement in a cavity which is substantially conical.

A further object of the invention is to provide an anchor member of a specific shape which, together with a plurality of cables also having a specific shape, makes it possible to construct such an anchoring device.

It is another object of the present invention to enable the construction of such anchoring devices without the direct use of anchor members.

The method according to the invention for constructing an anchoring device with more than one cable, said anchoring device being accessible from one side only, comprises the following steps: making a cavity in the surrounding structure around the anchoring device, said cavity having an elongated conical shape and two ends, the cross-sectional area at the accessible side end of the anchoring device being smaller than the cross-sectional area of the other part of the cavity, the cavity having an opening at the accessible side of the anchoring device, from which opening one end of each of the cables is inserted in succession, each of said cables consisting of a pull rod having a first cross-sectional area and an end part having a second cross-sectional area larger than said first cross-sectional area, the cavity being filled with an embedding material.

An anchor member according to the invention for use in the construction of an anchoring device having more than one wire, said anchoring device being accessible from one side only, characterized in that said anchor member is substantially of elongated conical shape and has two ends, a first end having a cross-sectional area smaller than the cross-sectional area of another part of the anchor member, said anchor member being substantially composed of a wall forming a cavity of substantially similar shape to said part, said anchor member having an opening with a first cross-sectional area at said first end of the anchor member and a bottom wall at the second end, another cross-section of said cavity having another cross-sectional area larger than the first cross-sectional area, said anchor member being intended to be applied with a predetermined number N of wires, each of said wires having an anchor cavity to be inserted into the anchoring device, one end of said wires consisting of a pull rod, the tie rod has an end portion at its end to be inserted into said cavity, the cross-sectional area of the end portion being greater than the cross-sectional area of said tie rod, the cross-sectional area of the opening of said anchor member cavity being greater than the area consisting of the sum of the cross-sectional areas of (N-1) tie rods plus the maximum cross-sectional area of the end portion of the wire rope, the difference between the cross-sectional area of the opening occupied by said predetermined number N of tie rods and the cross-sectional area of said opening being less than the cross-sectional area of an additional tie rod when said predetermined number N of tie rods are positioned.

The cable with one end to be inserted into the anchoring cavity of an anchoring device accessible from one side only through a longitudinal conduit according to the invention consists of a pull rod having an end portion at its end to be inserted into said cavity, the cross-sectional area of the end portion being larger than the cross-sectional area of said pull rod, characterized in that the end portion or end block has a projecting lower end portion.

Drawings

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which:

figure 1 shows a cross-sectional view of a preferred embodiment of an anchor member according to the present invention,

figure 2 shows a series of cross-sectional views (a-L) representing a sequence of steps of a method of constructing an anchoring device according to the invention,

figure 3A is a diagrammatic elevational view of a portion of the steel cord of the first embodiment of the present invention,

figure 3B is a diagrammatic elevational view of a portion of the steel cord of the second embodiment of the present invention,

figure 3C is a diagrammatic elevational view of a portion of the steel cord of the third embodiment of the present invention,

FIG. 3D is a diagrammatic elevational view, partially in section, of a portion of a fourth embodiment of the steel cord of the present invention.

Detailed Description

To accomplish the inventive method, a shaped anchoring cavity must first be obtained. The anchoring cavity is generally elongate and tapered in shape, having a first open end on an anchor-accessible side and a second closed end on an anchor-inaccessible side. Further, the cross-section of the first end of the anchoring device must be smaller than the other cross-section of the cavity, whether this other cross-section corresponds to the second end or to the middle part of the cavity.

Such cavities can be obtained by several methods or devices. The first method is to use an anchor member having a preformed internal cavity having the desired shape of the anchoring cavity. A preferred embodiment of such an anchor member is shown in fig. 1. The anchor member 1 consists essentially of a suitably thin wall 10 defining an internal cavity 11. The first end of the anchor member 1, i.e. the top end of the member as shown, is provided with an opening 12 and means 13 for securing a tubular sheath for protecting the wire rope, the purpose of which will be described below. The other end of the anchor member 1 is closed by a bottom wall 14. The outer shape of the anchor member 1, and thus the shape of the lumen 11, is generally conical, e.g. frustoconical or frustopyramidal, with a minimum cross-section adjacent the opening 12 and a maximum cross-section adjacent the bottom wall 14. An inlet 15 is adjacent the bottom wall 14 and a spray tube 16 is mounted or attachable to the inlet 15. Similarly, an outlet 17 is adjacent to the opening 12, and a discharge pipe 18 is fitted or attachable to the outlet 17. The use of the elements 15-18 will be described below.

The conical, frusto-conical or frusto-pyramidal outer surface of the anchor member 1 comprises one or more anchoring rings 19 located around the surface with the purpose of improving the transmission and distribution of the anchoring force to the surrounding structure. The embodiment shown in the figures comprises two such rings 19. The anchor member 1 may be made of synthetic material, metal or concrete, the dimensions of which are substantially dependent on the range of anchoring devices considered.

Fig. 2A illustrates a first step of the inventive method of constructing an anchoring device using such anchor members. When the surrounding concrete structure has not yet been made, the anchor member is placed in the exact position of the anchoring device to be constructed, with the opening 12 pointing in the direction of the future wire rope. The anchor member 1 is held in place by temporary scaffolding or, more suitably, by means of iron bars 20 of concrete reinforcement. Preferably, although not essential to the invention, one or more annular iron bars 21 forming one or more loops are placed around the anchor member to improve the bonding of the concrete at that location.

In fig. 2B it can be seen that the concrete structure 2 used to support the anchoring device is poured around the anchor member 1 in a conventional manner. Thus, the anchor member 1 is fully enclosed and secured in the concrete structure 2, except for its first end having an opening 12 flush with or slightly proud of the upper surface of the concrete structure 2 as shown, and the end of the injection and discharge pipe 18 which remains accessible outside the concrete structure 2.

It should therefore be noted that in the second step of the method, a shaped cavity 11 is made in the concrete structure 2. As described so far, the cavity 11 is made by using an anchor member 1 having a prefabricated cavity. Similar cavities 11 in the concrete 2 can also be made in other ways, for example by on-site manufacturing. For example, a form can be prepared which can be removed, which can be made of wood or other material and which has a shape corresponding to the desired shape of the cavity 11 and which is placed in the desired position, and the concrete structure 2 is subsequently poured around the form. When the concrete has hardened, the formwork is removed through the opening 12 and removed from the cavity 11 through the same opening. In a quite similar way an elastic inflatable element can be used which, after being inflated, has the desired shape of the cavity 11 and is placed in the desired position. After the concrete structure 2 has been poured, the inflatable element is deflated, thus leaving a cavity 11 of the desired shape in the structure 2. Another way of making the cavity 11 is by drilling such a cavity of the desired shape into an existing structure 2. Such drilling operations may be reserved for direct anchoring at the ground or for installing new anchoring means on the existing structure 2. The cavity 11 produced in either of the described methods has two important dimensions, the passage area of the opening 12 indicated at S12 and the maximum cross-sectional area indicated at S11 (see fig. 1).

In a third step, shown in fig. 2C, the structural element 3 to be prestressed is placed or concreted on the concrete structure 2 in a manner known per se, the structural element 3 preferably comprising a guide tube or sleeve 30, which is placed with one end opposite the opening 12 for attachment to the fixing means 13 connecting the opening 12. The cross-section of the sleeve 30 or the cross-section of the duct designed for the steel cord in the structural member 3 substantially corresponds to the cross-section of the opening 12 of the cavity 11. The tube 30 or corresponding conduit comprises at least one ejection port 31 connected to an ejection tube 32, the at least one port 31 being conveniently arranged near the end of the tube 30 close to the opening 12, and also comprises at least one outlet connected to a discharge tube, the at least one outlet being arranged near the other end of the tube 30 (not visible in the figures) so as to be near the structural member 3.

The fourth step shown in fig. 2D is to insert a wire rope. Reference is now made to fig. 3A-3D, which show, by way of non-limiting example, four designs of such a steel cord 4. The cable is substantially composed of a pull rod 40 and an end portion 41. The end portion 41 on the lever 40 is designed such that it has a cross-sectional area S41 that is greater than the cross-sectional area S40 of the pull lever 40 for reasons explained below. The other end of the rod 40 is free of such end portions and is configured for normal anchoring as is well known to those of ordinary skill in the art.

The pull rod 40 may be of any known type and may comprise either a complete strand or a plurality of strands helically assembled to form a single cable. The integral strand or strands making up the tie rod 40 may be steel, preferably steel having a high tensile strength, or a composite material, such as a carbon-fiber based or kevlar based composite material.

The end portion 41 may be an end block of metal or synthetic material firmly fixed to the end of the tie rod 40. The choice of material from which the end block is made and the method by which it is secured to the tie rod 40 depends essentially on the material and method of manufacture of the tie rod 40. The end-block basically comprises a central body 42 bounded by more than one portion 43 and a lower portion 44. The body 42 may be a right cylinder of circular cross-section or polygonal cross-section as shown in fig. 3A, or a truncated cone or truncated square cone of circular cross-section or polygonal cross-section as shown in fig. 3B. If tapered, the smaller cross-section portion is adjacent the upper portion 43. The two parts 43 and 44 are preferably domed and consist of inclined planes to facilitate sliding of the end part in mounting over the other end part already mounted, as will be seen below.

In another design, the end portion 41 may be formed by deforming or machining directly on the end of the tie rod 40. Fig. 3C and 3D show examples of this type of end portion. In fig. 3C, the tie rod 40 is made of a complete strand, the end portion 41 being obtained by deforming the end of the tie rod 40, for example by forging, die forming or pressing. Fig. 3D shows an example of an end portion 41 of a pull rod 40 made up of assembled multi-strand rope. In this example, the end of each strand is offset from its normal position, and a loop or a tie can be added just prior to the offset position to prevent the remaining cords from unwinding. The offset end of the strand may be held in place, or left free, by an additional retainer 45, such as a circular disk welded or otherwise secured to the underside of the offset strand. In a design not shown, the retainer for securing the displaced strand may comprise an element in the shape of two base-joining cones, wherein a first conical portion is inserted between the strands to displace them and a second conical portion serves the same purpose as the lower portion 44 described above. Thus, as previously mentioned, in any design of end portion 41, it may also have a circular or polygonal shape and include upper and lower portions 43 and 44.

The examples of the end block 41 or the deformed end portion 41 are not limited in their shape or the method of their manufacture; any method of increasing the cross-sectional area of the end portion of the tie rod 40 is contemplated. Although the following description refers to an end block, it should be understood that it may also be an end portion as described above.

Returning to fig. 2D, it will be seen that the first wire 4 has been pushed into the conduit 30 and then into the cavity 11 until its end block contacts the bottom face of the cavity 11. The second wire rope 4 is installed in the same way.

Figure 2E shows the use of possible dome or inclined shapes on the upper and lower parts 43, 44 of the end-block. When installing the wire 4, it is very well possible that its end block will abut against the end block of an already installed wire. Due to the domed or angled shape of these portions, the second end block is not captured by the first end block, but rather is moved away from and slid along the first end block until it reaches its final position on the side of the first end block.

Figure 2F shows that after a number of cables have been installed, a new end block to be installed may have no room at the bottom of the cavity 11 for its use. In this case, it is sufficient to push the end block as far as possible into the cavity until it bears against one or more already installed end blocks or against a side wall of the cavity, in order to enable the cable to complete its complete function later.

In order to anchor the wire rope or the prestressed element, a certain number N of wire ropes 4 must be inserted in the cavity 11. If it is known that the cross-sectional area of each tie rod 40 is S40 and the maximum area of the end block cross-section is equal to S41 (see FIGS. 3A, 3B, 3C, 3D), the following relationship should exist:

to allow the insertion of the last cable 4, i.e. to allow the last end block 41 to pass through the conduit 30 and the opening 12:

[(N-1)×S40]+S41＜S12

where S12 is the cross-sectional area of opening 12 (figure 1),

to allow the end-block 41 to be placed completely to the bottom of the cavity 11:

(N×S41)＜S11

where S11 is the maximum cross-sectional area with cavity 11 (fig. 1).

When all the cables 4 are pushed in through the conduit 30 with their end blocks received in the cavity 11 as described above, the next step can be performed as shown in fig. 2G. In this step, the liquid embedding material 50 is added through the ejection tube 16; the embedding material enters the cavity 11 through the inlet 15 and fills the space between the end block and the end of the tie rod 40 within the cavity 11 until it at least partially fills the cavity 11. In this operation, the outlet and discharge tube 18 functions to discharge the gas in the cavity 11 at the time of filling and to check the filling degree of the cavity 11. The cavity 11 is preferably filled with an amount of liquid that reaches the level of the outlet 17. The embedding material in the cavity 11 then hardens into a solid block with high mechanical strength, in which the end blocks 41 and the ends of the tie rods 40 are encased.

In the next step shown in fig. 2H, each wire 4 is subjected to a traction force until a specified pretension stress is reached. The traction is applied in a conventional manner by acting on the other end of each cable 4, i.e. each pull rod 40, which can be pre-tensioned simultaneously or sequentially. As shown in the figures, the cavity 11, and thus the truncated cone or pyramid shape of the hardened mass encasing the end blocks 41 and the ends of the tie rods 40 of the steel cables 4 therein, allows for an effective wedge-shaped anchoring in the surrounding concrete structure. In contrast to the aforementioned prior art devices, this wedge shape prevents any possible axial movement of the hardened mass 5 and allows the anchoring force to be transmitted to the surrounding structure 2 by axial compression rather than simple adhesion. Thus, the length of the anchoring device is advantageously reduced.

Additional anchoring reliability is ensured by the specific arrangement of the end-blocks in the cavity 11. Considering that the end-blocks 41 are arranged in a bundle in the cavity 11, the bundle forms a cross-sectional area of the outer shell of the combined end-block that is larger than the area of the opening 12 of the cavity 11. The bundle of end-blocks is thus blocked in the cavity 11.

Returning to the expression given above,

to be able to block the cables 4 in the cavity 11 by preventing the end blocks from coming out of the openings 12, which are blocked from each other, the relationship should be:

(N×S41)^*＞S12

wherein (NxS 41)^*The ensemble represents a face formed by a bundle of the outer shells of N composite end blocks, each end block having a cross-sectional area S41. Considering that one or both end blocks 41 may not find their proper position, as shown in fig. 2H, each section S41 and channel section S12 must be dimensioned to be able to block the end block when traction forces act on all cables 4 simultaneously.

It should be noted that the step of pre-tensioning the wire rope 4 as just described can be performed in different ways, in particular in the case of a single wire rope, not pre-tensioned.

In the last step of the method shown in fig. 2L, the space in the sleeve 30 or in the ducts made in the structural member 3 can be filled with a sealant 60 through one or more injection pipes 32 and one or more inlets 31 to maintain the tightness of the pretensioning system and prevent corrosion of the pretensioning member. This last step is optional depending on whether such protective material 6 is needed or necessary.

It should therefore be noted that a very effective anchoring device is obtained in this way, the longitudinal traction of each cable 4 being mainly borne by its end blocks or portions 41 and transmitted to the hardened block 5 of embedded material with high mechanical strength. Since the end block is firmly attached to the tie rod 40, an efficient transfer of this force is possible; since the attachment can be performed in a factory, the mechanical strength thereof is very high. This force is thus transmitted to the surrounding structure 2 through the inclined walls of the cavity 11. By arranging one or more anchoring rings on the anchor member 1, it is more likely that the anchoring effect on the surrounding structure 2 is improved. As mentioned, a ring 21 may be provided to further improve the bonding of the surrounding structure 2 in the vicinity of the cavity 11. In addition to the mentioned longitudinal strength-each end of the tie rods 40 is fixed in a block 5 of embedded material-each rod 40 is also fixed by radial compression.

This type of anchoring device is particularly useful for pre-stressed anchoring of the pre-stressed structural member 3. It also facilitates the anchoring of non-prestressed steel cables, such as steel cables supporting a mast or tower, in which case the steel cables do not need to be protected by the protective tube 30. Also, it is not necessary to design the cavity 11 in the concrete surround; alternatively, a borehole in the ground or rock may be provided by means of which the desired cavity can be obtained.

The foregoing description is of a cavity having a substantially vertical longitudinal axis with an opening 12 at the top. Other geometric arrangements are also possible; the dimensions of the cavity 11 should be adjusted to obtain an adequate filling of the cavity 11 with the embedding material 50.

Claims (29)

1. Method for constructing an anchoring device with more than one cable (4), said anchoring device being accessible from one side only, comprising the steps of:

making a cavity (11) in a surrounding structure (2) around the anchoring device, said cavity having an elongated conical shape and two ends, the cross-sectional area (S12) at the accessible side end of the anchoring device being smaller than the cross-sectional area (S11) of another part of the cavity, the cavity having an opening (12) at the accessible side of the anchoring device,

one end of each steel cord (4), each consisting of a tie rod having a first cross-sectional area (S40) and an end portion (41) having a second cross-sectional area (S41) greater than said first cross-sectional area (S40), is inserted in sequence from an opening (12), filling the cavity (11) with a burying material (50).

2. A method according to claim 1, wherein the cavity is formed by mounting an elongate conical anchor member (1) having two ends, a first end having a cross-sectional area smaller than the cross-sectional area of another part of the anchor member, said anchor member being formed by a wall (10) forming a cavity (11) of similar shape to said anchor member, said anchor member having an opening (12) at said first end of the anchor member having a first cross-sectional area (S12) and a second end having a bottom wall (14), another cross-section of said cavity having another cross-sectional area (S11) larger than the first cross-sectional area (S12), said anchor member (1) being embedded or concreted in the surrounding structure (2), said opening (12) being open.

3. Method according to claim 1, characterised in that the cavity (11) is made by installing a removable mould with an elongated conical shape, then pouring the surrounding structure (2) around said mould with concrete, then removing the mould through the opening (12), leaving an elongated conical cavity (11) and an opening (12) directed towards said cavity in the poured surrounding structure (2), the cross-sectional area (S12) of the part of said cavity close to the opening (12) being smaller than the cross-sectional area (S11) of the other part of said cavity.

4. Method according to claim 1, characterized in that the cavity (11) is made by mounting an inflatable elastic element which, once inflated, has an elongated conical shape, then casting the surrounding structure (2) around said inflated element with concrete, then deflating the element, leaving an elongated conical cavity (11) and an opening (12) directed towards said cavity in the cast surrounding structure (2), the cross-sectional area (S12) of the part of said cavity close to the opening (12) being smaller than the cross-sectional area (S11) of the other part of said cavity.

5. A method according to claim 1, characterized in that the cavity (11) is manufactured by drilling an elongated conical cavity in the surrounding structure (2), said cavity having an opening (12), the cross-sectional area (S12) of the part of said cavity near the opening (12) being smaller than the cross-sectional area (S11) of the other part of said cavity.

6. Method according to claim 1, characterized in that it comprises, after the step of making the cavity (11), a step of installing or pouring in concrete the structural element (3) to be prestressed, said structural element (3) comprising a longitudinal duct (30) passing through the wire (4), one end (13) of said longitudinal duct (30) being in communication with the opening (12) of the cavity (11) of the anchoring device.

7. Method according to any one of the preceding claims, characterized in that it comprises, after the step of filling the cavity (11) with the embedding material (50), a step of tensioning each steel cord (4).

8. Method according to claim 7, characterized in that it comprises, after the step of tensioning the steel cord (4), a step of filling the longitudinal ducts (30) of the prestressed structural element (3) with a sealant (60).

9. Anchor member (1) for the construction of an anchoring device with more than one wire, which anchoring device is accessible from one side only, characterized in that the anchor member is of elongated conical shape and has two ends, a first end having a cross-sectional area smaller than the cross-sectional area of another part of the anchor member, the anchor member consisting of a wall (10) forming a cavity (11) of similar shape to the said piece, the anchor member having an opening (12) with a first cross-sectional area (S12) at the said first end of the anchor member and a bottom wall (14) at the second end, another cross-section of the cavity having another cross-sectional area (S11) larger than the first cross-sectional area (S12),

said anchor member being intended to be used with a predetermined number N of wires, each of said wires having one end intended to be inserted into an anchor cavity (11) of the anchoring device, said wires consisting of a pull rod (40) having an end portion (41) at its end intended to be inserted into said cavity, the cross-sectional area (S41) of the end portion (41) being greater than the cross-sectional area (S40) of said pull rod (40),

the cross-sectional area (S12) of the opening (12) of the cavity (11) of the anchor member (1) is greater than the area made up of the sum of the cross-sectional areas (S40) of (N-1) tie rods (40) plus the maximum cross-sectional area (S41) of the end portion (41) of the wire rope (4), the difference between the cross-sectional area of the opening (12) occupied by the predetermined number N of tie rods (40) and the cross-sectional area (S12) of the opening (12) being less than the cross-sectional area of one additional tie rod (40) when the predetermined number N of tie rods (40) are positioned.

10. Anchor member according to claim 9, characterized in that the maximum cross-sectional area (S11) of a cavity (11) is larger than the sum of the maximum cross-sectional areas (S41) of the end parts (41) or end blocks inserted into the cavity.

11. Anchor member according to claim 9 or 10, characterized in that the cross-sectional area (S12) of the opening (12) of the cavity (11) is smaller than the area of the cross-section consisting of the cross-sectional areas (S41) of all end parts (41) or end blocks inserted into the cavity.

12. The anchor member of claim 9, having a frustoconical shape.

13. The anchor member of claim 9, having a frusto-pyramidal shape.

14. Anchor member according to claim 9, characterized in that it has an inlet (15) near its bottom wall (14), said inlet being connected or connectable to a tube (16) for spraying a liquid or semi-liquid product (50).

15. Anchor member according to claim 14, characterized in that it has an outlet (17) near its opening (12), said outlet being connected or connectable to a discharge tube (18).

16. Anchor member according to claim 9, characterized in that the opening (12) has means (13) for fixing a catheter (30) intended to receive the wire (4).

17. Anchor member according to claim 9, characterized in that it has at least one circumferential widening (19) on its outer side.

18. The anchor member of claim 9, wherein the anchor member comprises metal.

19. The anchor member of claim 9, wherein the anchor comprises a synthetic material.

20. An anchor member according to claim 9, wherein the anchor comprises concrete.

21. Cable (4) having one end to be inserted into an anchor cavity (11) of an anchoring device accessible from one side only through a longitudinal conduit (30), said cable consisting of a tie rod (40) having an end portion (41) at its end to be inserted into said cavity, the cross-sectional area (S41) of the end portion (41) being greater than the cross-sectional area (S40) of said tie rod (40), characterized in that the end portion (41) has a convex lower end portion (44).

22. Steel cord according to claim 21, characterized in that the end portion (41) or end block has a protruding upper end portion (43).

23. Tie rod according to claim 21, characterized in that the end part (41) consists of an end block fixed to the end of the tie rod.

24. Tie rod according to claim 21, characterized in that the end portion (41) is obtained by deforming an end of the tie rod (40).

25. Tie rod according to claim 24, wherein the tie rod (40) consists of a cable assembly of complete strands, the end portion (41) continuing by offsetting at least one of said complete strands, providing an additional element (45) for fixing said strand or strands in an offset position.

26. Steel cord according to claim 21, characterized in that the end portion (41) or end block has a bevelled central portion (42), the portion with the smallest cross-sectional area being close to the upper end portion (43) and the portion with the largest cross-sectional area being close to the lower end portion (44).

27. Steel cord according to claim 21, characterized in that the end portion (41) or the end block has an upright cylindrical central portion (42), the central portion (42) having a constant cross-section portion, which is bounded by an upper portion (43) and a lower portion (44).

28. The steel cord of claim 21 wherein the steel cord comprises metal.

29. The steel cord according to claim 21, wherein said steel cord comprises a synthetic material.