EP0323285A1 - Stay cables and their anchorage - Google Patents

Abstract

The cable lines (1) forming the stay cable, mounted so as to be able to work and to be dismantled independently of one another, each consist of an assembly of parallel or twisted steel wires, surrounded by a sheath (3) in polyethylene, polyamide or a corrosion-resistant metal, with interposition of a filling material, such as an epoxy-type resinous pitch, or a wax. The ends of the cable lines (1), stripped of their sheaths (3) for their individual anchoring on a perforated block (6) are embedded in a protective grease. The grease chamber (A), formed by a sleeve (7) connected to the anchoring block (6), is closed by a stuffing-box seal (8) traversed by the cable lines (1), which are sheathed again, and comprising an outer plate (82) which, controlled by clamping rods (10) which can be actuated from outside the anchoring block (6), presses an elastomer cushion (83) against an inner plate (81) bearing on spacer rings (11) arranged in the chamber (A). <IMAGE>

Description

The invention relates to assemblies comprising on the one hand cables or shrouds having a high tensile strength and composed of a plurality of strands themselves formed individually by sets of parallel or twisted metal wires and on the other hand anchoring structures for the ends of these shrouds.

It is more particularly, but not exclusively, among these assemblies, those which are intended to equip the cable-stayed bridges by connecting the tops of the pylons of these bridges with their decks and their anchor blocks.

It also targets the strands making up said shrouds.

In the known embodiments of guy wires of the type in question, the various constituent strands are generally brought together in a common protective envelope and linked together transversely by a protective binder which fills the intervals between the strands and the envelope.

This binder is generally a grout of injected cement hardened after injection.

This formula has a certain number of drawbacks such as the high weight and the stiffness of the shroud, the risks of cracking of the hardened grout and especially the fact that the shroud constitutes a one-piece assembly: it is therefore not possible to individually replace the strands which compose it in the case where only some of these strands are damaged, for example following an impact of a vehicle or vehicle loading against the shroud.

According to another formula, the protective binder is a grease or the like.

The aim sought by this other formula is to make possible the individual replacement of the strands.

But in practice such an operation proves to be very difficult because it is necessary each time to empty the envelope of its fat and then reload it with fat: in particular, this fat tends to flow out at the lowest end. shroud when opening it, but this natural flow is not enough to clear the envelope and make possible in good conditions the establishment of the new cable strand after clearing the used strand.

The object of the invention is, above all, to remedy these drawbacks.

To this end, the assemblies of the type in question according to the invention also comprise, in a manner known per se, a perforated block on which the stripped ends of the different strands making up the shroud are individually anchored, an annular bearing against which is applied axially. the periphery of the block, and a sleeve to which said block is connected on the side of said bearing surface, the chamber formed inside this sleeve being filled with a grease or similar material ensuring the protection of the bare portions of strands present in this chamber , and they are essentially characterized in that the different strands are protected by sheathing independently of each other and are mounted so that they can work and be dismantled independently of each other, in that the protective sheath of each strand is interrupted at the level of a terminal slice at a small distance from each end of this strand and in that the grease chamber contains the edges hes terminal sheaths and is closed in a sealed manner, on the shroud side, by a cable gland crossed in a sealed manner by sheathed portions of the strands.

In preferred embodiments, we have in addition to one and / or the other of the following provisions:
- the cable gland includes clamping rods passing through the perforated block and actuable from the side, of this block, furthest from the stay,
the various sheathed strands making up the stay slightly converge from their bared ends anchored to a guide collar beyond which they are joined together so as to form a bundle of parallel sheathed strands,
each strand is constituted by a set of steel wires embedded inside a protective sheath, in particular made of polyethylene, polyamide or metal, with possibly the interposition of a filling material, such as a resinous pitch of epoxy type or a wax.

The invention includes, apart from these main provisions, certain other provisions which are preferably used at the same time and which will be more explicitly discussed below.

• La figure 1, de ce dessin, montre, moitié supé­rieure en coupe axiale schématique et moitié inférieure en vue extérieure, la tête d'un hauban établie selon l'invention.
• La figure 2 montre en coupe axiale à plus grande échelle une portion terminale d'une tête semblable à la precédente.
• La figure 3 est une coupe transversale agrandie d'un hauban du genre de celui coupé selon III-III, figu­re 1.
• La figure 4 est une coupe transversale agrandie de l'un des brins constitutifs dudit hauban.

In what follows, we will describe preferred embodiments of the invention with reference to the accompanying drawing in a manner of course not limiting.

• Figure 1 of this drawing shows, upper half in schematic axial section and lower half in external view, the head of a shroud established according to the invention.
• Figure 2 shows in axial section on a larger scale a terminal portion of a head similar to the previous one.
• Figure 3 is an enlarged cross section of a guy like that cut along III-III, Figure 1.
• Figure 4 is an enlarged cross section of one of the strands constituting said stay.

The shroud considered is composed of a plurality of individual strands 1.

The number of these strands is generally less than 100, preferably being between 15 and 70.

Each strand 1 is itself formed by a plurality of elementary wires 2, for example 7 in number in the embodiment illustrated in FIG. 4.

These wires can be parallel or twisted: in the latter case, the corresponding strands are generally designated by the name of "strands".

The wires 2 are for example made of drawn and galvanized steel.

All of these wires are surrounded by a protective sheath 3 which is able to protect them during their whole life against corrosion due to bad weather or other external aggressions, and in particular to humidity and handling.

This sheath is for example made of a plastic material, such as polyethylene or a polyamide, or a metal such as aluminum or stainless steel.

It can be directly attached to the bundle of wires by extrusion.

The sheath in question can also be constituted by any other desirable coating of the wire bundle 2, for example by an epoxy paint coated on it.

The intervals between the wires 2 and the sheath 3, if they exist, may or may not be filled with a protective substance 4 such as, for example, a resinous pitch of the epoxy type or a wax.

Each strand 1 is manufactured in the factory and it is available at the exit of this factory in the form of a site coil.

We therefore provide for the thickness of the sheath 3 a value low enough to make it possible to wind the strand: if it is a metal, we give at said thickness a value of the order of 1/10 mm.

The sheathed strands 1 thus defined, all identical to each other, are autonomous and remain so throughout the life of the stay they constitute.

The assemblies of these sheathed strands on the anchoring structures are ensured individually in a manner known per se, for example using spun sleeves or, as illustrated, by clamping the stripped ends of said strands in split jaws 5 : each jaw 5 has, on the one hand, a cylindrical internal bore suitable for contiguously surrounding the end of the strand to be anchored, and, on the other hand, a frustoconical external surface suitable for cooperating with a complementary housing hollowed out in an anchoring block 6.

The terminal section T of each sheath 3 beyond which the stripped end of the corresponding strand 1 begins is located inside a chamber A delimited:
- at an axial end, by block 6,
- transversely, by a rigid sleeve 7 extending the periphery of the block 6 and fixed thereon using screws 18,
- And at the axial end opposite to the block 6, by a cable gland 8 crossed in a sealed manner by the sheathed strands 1 and applied radially in a sealed manner against the inner face of the sleeve 7.

This cable gland 8 comprises two transverse perforated plates 8₁, 8₂ between which is interposed a cushion 8₃ of elastomeric material or the like, and means suitable for bringing the two plates closer together, which causes the cushion to swell while ensuring the desired tightness.

These approximation means work in particular by screwing, then comprising nuts 9 accessible from outside the block 6 and mounted on threaded rods 10 themselves fixed on the plate 8 plaque la further away from said block, the plate 8₁ closest to this block being kept away from the latter by spacer rings 11 surrounding the rods 10.

Chamber A communicates by a channel 12 with a chamber B provided outside of block 6 and delimited by a cover 13 applied contiguously against this block, by tightening screws 14.

The assembly of the two chambers A and B is filled at the end of the anchoring of all the strands 1 on the block 6 with a grease or similar material having simultaneously the following properties: flexibility, weak adhesion with respect to the strands and their bare ends, protection of these ends against corrosion.

Around the sleeve 7 or of the block 6 is added, in particular by screwing along complementary threads of these two elements, a ring 15 suitable for resting itself axially against an annular bearing 16 forming part of a structure 17 for anchoring the guy line, structure such as a pylon top or a solid mass on the ground.

The portions, stretched strands 1, which are arranged outside of the grease box A, B, can be parallel to each other and be directly vented.

However, it is preferable to make them converge slightly from block 6, to a point arranged at a distance generally between 1 and 3 m from the block, using a guide collar 19 located at this point: au- beyond said point, the strands 1 are combined into a bundle of contiguous strands, as can be seen in FIGS. 1 and 3.

So that the collar 19 can be easily disassembled, which makes it possible to spread the various strands 1 apart, it is advantageously constituted by two half-shells which can be assembled and separated at will.

The beam can be left in the open air or itself be protected by an envelope 20 of any desired nature and size, for example made of polyethylene.

We still see:
- In Figure 1, a number of tubes and fittings, some of which have frustoconical sections, connecting, some, such as 22, the sleeve 7 to the casing 20, and the others 23,24,25, the bearing 16 around the envelope 20,
- And in Figure 2, sockets or furs 26 of plastic, in particular polyamide, interposed between the stripped portions of the strands 1 and the bores hollowed out in the block 6 to allow relative sliding, and a perforated plate 27 crossed by the stripped ends of the strands and interposed axially between the enlarged bases of the sockets 26 and the shims 11.

It should be noted that the only metal-metal contacts made between each strand 1 and its environment are located at the level of the individual anchors (jaws 5 in the illustrated case): the other elements which are in contact with these strands are the furs 26 and 8₃ cushions.

Each strand can therefore be considered completely autonomous over its entire length and can be stretched or relaxed independently of its neighbors.

In the case where such individual relaxation of each strand 1 is envisaged, it may be useful to give the free ends 21 (FIG. 2) of these strands, which protrude beyond the anchoring members, a greater length. than that shown, to facilitate the taking of these ends.

As a result of which, and whatever the embodiment adopted, there is finally a guy wire whose constitution and assembly result sufficiently from the above.

This guy has a number of advantages over those previously known and in particular the following:
each of the individual strands 1 that make up the stay can be replaced independently of the others, that is to say even when all the other strands remain taut, which makes it possible to intervene on the structure equipped with said stay without interrupting the operation of this structure, and in particular the traffic if it is a bridge,
the weight of the shroud is relatively low, given the removal of grouts or other hardened binders from previous embodiments,
- the longevity of the shroud is increased, given the elimination of the risks of cracking inherent in the grouts and the high quality which can be conferred in the factory to the individual protective sheaths of the strands.

As is obvious, and as already follows from the foregoing, the invention is in no way limited to those of its modes of application and embodiments which have been more especially envisaged; on the contrary, it embraces all its variants.

Claims (10)

1. Assembly constituted by a stay and its anchoring structure, said stay being composed of a plurality of strands (1) themselves constituted individually by sets of parallel or twisted metal wires, and the structure comprising a perforated block ( 6) on which the bared ends of the different strands are individually anchored, an annular bearing surface (16) against which the periphery of the block is applied axially, and a sleeve (7) to which said block is connected on the side of said bearing surface, the chamber ( A) formed inside this sleeve being filled with a grease or similar material ensuring the protection of the bare portions of strands present in this chamber, characterized in that the different strands (1) are protected by sheathing (3) independently from each other and are mounted so that they can work and be dismantled independently of each other, in that the protective sheath (3) of each strand (1) is interrupted at a end section (T) at a small distance from each end of this strand and in that the grease chamber (A) contains the end sections (T) of the sheaths and is closed in a sealed manner, on the guy side, by a press -throat (8) tightly crossed by sheathed portions of the strands. 2. Assembly according to claim 1, characterized in that the cable gland comprises clamping rods (10) passing through the perforated block (6) and actuable from the side, of this block, furthest from the stay. 3. Assembly according to claim 2, characterized in that the stuffing box comprises two perforated plates (8₁, 8₂) between which is interposed a packing cushion (8₃), the rods being fixed on the outer plate (8₂), and freely crossing the other plate (8₁) as well as rigid spacer rings (11) interposed axially, directly or indirectly, between this other plate and the perforated block (6). 4. Assembly according to any one of the preceding claims, characterized in that the various sheathed strands (1) which make up the stay slightly converge from their bared ends anchored to a guide collar (19) beyond which they are joined together so as to form a bundle of parallel sheathed strands. 5. Guy line comprised by an assembly according to any one of the preceding claims, characterized in that each strand (1) is constituted by a set of steel wires (2) embedded inside a protective sheath (3 ) with the interposition of a filling material (4). 6. Guy line according to claim 5, characterized in that the filling material (4) is a resinous pitch of epoxy type. 7. shroud according to claim 5, characterized in that the filling material (4) is a wax. 8. shroud according to any one of claims 5 to 7, characterized in that the sheath (3) is made of polyethylene. 9. shroud according to any one of claims 5 to 7, characterized in that the sheath (3) is made of polyamide. 10. Guy line according to any one of claims 5 to 7 'characterized in that the sheath (3) is made of a corrosion-resistant metal.

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