EP1121492B1 - Guy cable deflector - Google Patents

Description

The present invention relates to a diverter for n-strand cable separated, of the type comprising at least one body which has two opposite faces at least approximately perpendicular to a longitudinal axis of the body, and which is pierced of n holes traversing the body from one side to the other of the latter and arranged according to a mesh network, each hole having an inner diameter corresponding to the diameter outside of a cable strand.

In a stay cable, the strands of the cable, seen in cross-section, are usually arranged in the form of a mesh network, for example, a network to triangular mesh. In the current part of the cable of stay, that is to say in the part of the cable extending between two anchors at the ends of the cable. the mesh should be as small and compact as possible so as to minimize the cable resistance to wind and reduce the cost of this running part, especially the cost of the cable sheath and the material injected into this sheath for the cable protection. On the other hand, at each anchor, the strands be separated from each other in such a way that one can juxtapose the jaws of tightening or the sleeves which are used to individually fix the strands to the head anchor. It is therefore usually provided with a deflator which makes it possible to pass the strands from the wide mesh of the anchor head to the compact mesh of the part current of the stay cable.

At the anchor head and at the deflector, the strands not undergo sharp angular deflection and should not touch each other in order to improve the fatigue behavior of the anchor. More generally, we seek to limit, or even eliminate, the metal-to-metal contacts because, in use, such contacts are likely to cause wear by small deflections, which those skilled in the art call "fretting corrosion".

A common technique is therefore to subject each strand a small angular deviation, which is generally less than 2 ° and usually about 1 °, in placing a deflector at a distance from the anchor head such as the deflection of most deviated strands, that is to say those on the periphery of the cable, either less than the angle indicated above.

In the case of individually wrapped strands, the deflector is usually constituted by a device of the collar type, which clamps the strands sheathed together. The strands then touch each other by their individual sheath.

In the case of strands not sheathed individually, the deflector is usually constituted by a plastic disk, which is pierced with as many holes as strands, each strand passing through a respective hole in the disc and each hole having an axis parallel to the longitudinal axis of the stay cable.

This known deviation technique, however, has a number disadvantages. In the case of unsheathed strands, when threaded, the strands must be guided from the anchoring head to the deflector, since these two parts are distant from each other and that each strand must pass through two holes which correspond in both rooms, that is to say which have the same position in the mesh network. In addition, in all cases, that is to say that the strands are sheathed or not, the deflector must be placed at a relatively large distance from the head anchor so the total length of the anchor area plus the area of deviation is itself important. As we will see later, with a deviator conventional, the distance between the deflector and the anchor head can reach 3.4 m in the case of a cable composed of 61 strands of the T15S type commonly used for cable cables, and about 2.6 m in the case of a cable consisting of 37 strands.

In addition, the coaxiality between the anchor head and the deflector must be guaranteed at the risk of introducing an additional angular deflection. Therefore, the deflector must be maintained by a rigid connection (possibly semi-rigid), which can be constituted for example by a formwork tube in a pylon or by a tube embedded in a screed. This link supports significant efforts to "the state ultimate limit ", which requires, in certain anchoring configurations, a mounting of the connecting tube all the more complex as the deflector is placed far anchor head.

For all the above reasons, it is desirable to reduce the distance between the deflector and the anchor head. One way to reduce this distance to reduce the distance between the adjacent strands in the anchor head, as is done in some anchoring processes to reduce dimensions the anchor head itself. However, reducing the distance between the strands adjacent, ie the reduction of mesh size of the mesh network formed by the strands in the anchoring head, is necessarily limited, on the one hand to because of the presence of the clamping jaws or spun sleeves which serve to fix individually the strands on the anchor head and which must be able to be juxtaposed on the latter, and secondly because holes too close together in the anchor head would weaken the anchor and would therefore adversely affect its mechanical resistance. It follows therefore that this known solution only allows one limited reduction in the distance between the deflector and the anchor head.

Cable anchoring systems are known in which each individual strands of the cable is brought to follow a curved path either in a kind deflector placed immediately before the anchor head or heads (US Pat. No. 4,473,915 and US Pat. FR - 1.328.971), or in the structure of the concrete structure (US-4,442,646, FIG. 4), still in the anchor head itself (US-4,442,646, FIG. 6, US-4,484,425). In all these known anchoring systems, which make it possible to reduce substantially the total length of the deflection and anchoring zone of the strands of the cable, the said strands pass individually in curved guide tubes which are embedded in a concrete matrix or cement grout.

In anchoring systems known from US Pat. Nos. 4,473,915 and 4,442,646. and US-4,484,425, the guide tubes have an inside diameter substantially larger than the outer diameter of the individual strands. A resin epoxy, mortar or grout is injected to fill the spaces gaps between each strand and the inner wall of the guide tube which surrounds it. With a such a known arrangement, it is not possible to obtain a deviation of the strands such the strands of the bundle of strands coming out of the deviator, on the side of the current of the cable, are arranged according to a mesh network having a very small mesh size. This is due to the accumulation of thicknesses of different materials involved in the manufacture of the deflector between any two adjacent strands of the cable, and the fact that concrete, mortar and grout are unable to withstand high tensile forces when they are used with weak thicknesses.

• du diamètre intérieur des tubes de guidage des torons,
• de deux épaisseurs de paroi de ces tubes de guidage,
• d'une épaisseur minimale du matériau enrobant les tubes de guidage et les maintenant en position, c'est-à-dire un coulis de ciment ou un béton selon la description du brevet US 4.473.915.

More specifically, in the short anchoring and deflection systems described in the aforementioned three US patents, the minimum mesh size is the sum:

• the inside diameter of the strand guide tubes,
• two wall thicknesses of these guide tubes,
• a minimum thickness of the material encasing the guide tubes and holding them in position, that is to say a cement slurry or a concrete according to the description of US Patent 4,473,915.

For a cable made of T15S strands, commonly used, the diameter inside of the guide tubes should be of the order of 22 mm to allow a good injection of the residual space between the strand and the tube with a grout of cement.

The thickness of the wall of the guide tubes depends of course on the nature of the material that constitutes them and their type; we can consider that this thickness is between 2 and 3 mm.

To withstand the pressure forces exerted by each strand on the wall of the coating material of the guide tubes, due to the curvature and tension of the strands, a value of 5 mm seems to be a minimum for the thickness of concrete or grout between two adjacent tubes.

Adding these values, we find that the minimum value of the mesh of a cable formed according to US Patent 4,473.15 is 31 mm.

Other known short anchoring and deflection systems with similar characteristics (US 4,848,425, US 4,442,646, FR 1,328,971) lead to comparable, and sometimes even higher, values. It is possible to say with these known systems, it is impossible to obtain a mesh size smaller than a value close to 30 mm in the current part of the cable.

If we take for example two cables commonly used in guying applications, one of 37 T15S strands, the other of 61 T15S strands, one and the other arranged in an equilateral triangular mesh around a central strand, one finds that the first cable fits into a circle of size clutter 196 mm, while the second cable fits into a circle of diameter 256 mm.

It follows that. in the running part of the cable, the cross-section overall bundle of parallel strands forming the cable has a relative diameter large, requiring the use of a protective cable sheath itself having a relatively large diameter adapted to that of the cable. This leads to a sheathed cable relatively expensive, because of the relatively large diameter sheath and because of of the largest amount of material to be injected for the protection of the cable. In addition, in the case where the cable is a cable of stay cable, it presents a relatively high wind resistance because of the relatively large diameter of its sheath. Finally, because an epoxy resin, a mortar or a cement grout is injected into the guide tubes, the strands can no longer be extracted from the said tubes after taking the injected material. As a result, it is not possible to carry out a strand-on-strand replacement if necessary, and that the cable must then be completely replaced as well as at least part of its anchoring systems.

In the anchoring system known from the aforementioned FR-1.328.971 patent, no material is injected into the guide tubes, so that, in use, the strands individuals can freely slide in said tubes. This allows to tighten later strands if they lost some of their tension, and replace if necessary one or more strands of the cable, strand by strand, without having to replace the entire cable and its anchors. However, in this last system known anchor, the strands of the bundle of strands leaving the deflector, on the side of the part of the cable are transversely spaced apart from one another relatively large distance compared to their mutual distance in the part current of the cable, in which the strands are much narrower like this is desirable. This is achieved by placing in front of the deflector a ring or frustoconical sleeve which tightens the strands towards the running part of the cable and, conversely. allows them to flourish towards their respective tubes guide in the deflector. The frustoconical sleeve or sleeve is therefore also diverter function and this known anchor system therefore actually comprises two deflectors placed end to end.

Although the anchoring system known from the FR-1.328.91 patent does not present the aforementioned disadvantages of the anchoring systems described in the three aforementioned US patents, it nevertheless has the disadvantage that the deflection of the strands must be provided by two successive diverters for the cable and its sheath protector have a diameter as small as possible in the current part of the cable.

Furthermore, with reference to FIG. 1 of patent FR-1.328.971, it can be seen that at minus the strands on the periphery of the cable undergo two bends or deviations relatively sharp angles (> 5 °) respectively in the regions of the two end faces of the frustoconical sleeve.

In addition, as the strands are not kept spaced from each other in the region of the smaller diameter end of the frustoconical sleeve, the relatively sudden bending that they undergo at this point causes them to come into contact with each other at least with respect to the strands located in the peripheral layers of the cable. Because of these relatively sudden inflections and resulting contacts between the strands in said layers peripherals, as well as between the outermost strands of the cable and the edge end of smaller diameter of the tapered sleeve and between the strands and the edge of curved guide tube openings, and because of the inevitable small displacements of the strands under the effect of the dynamic loads to which they are subjected in service, the strands are subject to fatigue and wear by small fretting corrosion in the above-mentioned regions.

The present invention therefore aims to provide a deflector allowing to achieve both a substantial reduction in the total length of the zone of deflection and anchoring strands of a guy cable, a mesh size also as small as possible for the mesh network formed by the strands in the current part cable, and the possibility of replacing one or more cable strands, strand by strand, and while avoiding subjecting said strands to angular deviations localized unacceptable.

For this purpose, the invention provides a deflector according to claim 1.

The curved path of each channel of the deflector has a predefined curvature, constant or non-constant, which is compatible with the strength of the strand and its resistance to fatigue, and which allows to pass the strands of the first mesh size at the second mesh size, respectively at the level of first and second faces of the body of the deflector, on a length of deflection which, as will be seen later, is much less than that which is necessary with the conventional deflectors placed away from the anchor head. For strands of the type T15, T15S or T16, which are commonly used to form guy cables, the radius of curvature (min of R) of the diverter channels that are located at the periphery of the mesh network have a preference value greater than or equal to 2 m and preferably for example, the value (min of R) is equal to 2.5 m.

Preferably, said first mesh size (m ₁ ) has a value that satisfies the relation: Φ + 1,5 mm ≤ m 1 ≤ Φ + 5 mm where Φ is the value of the inner diameter of the channels which itself satisfies the relation: φ + 0.4 mm ≤ Φ ≤ φ + 2 mm where φ is the diameter value of a cable strand.

In a first embodiment of the deflector according to the invention, usable with an anchor head whose holes have axes parallel to the longitudinal axis of the cable, each curved path of the deviator channels has two parts successive curved in opposite directions, namely, starting from the first face of the body of the deflector, a first part having a concavity turned towards the outside of the body, followed by a second part having a concavity turned towards the interior of the body.

In another embodiment of the deflector according to the invention, usable with an anchor head whose holes have axes that converge towards the axis length of the cable, each curved path of the deflector channels is curved monotonous way from the first to the second face of the deviator's body.

In both cases, the size of the mesh of the mesh network formed by the deviator channels on the second face of it (second dimension of mesh) can be chosen to match the mesh size of the holes in the anchor head. Under these conditions, the deflector can be attached to the anchor head to form a very compact set. In addition, as each channel of the deviator is contiguous to a corresponding hole in the anchor head and forms with it a path continuous for the strand that passes through them, threading the strands through the holes of the anchor head and the diverter channels is greatly facilitated and one can get pass guide tubes which, with some known deflectors located at a distance of the anchor head, should be provided between the deflector and the anchor head for guide the strands from one to the other of these two elements.

In addition, in the diverter according to the invention, each strand is in contact with the inner surface of the corresponding channel of the deflector over a length relatively large compared to a conventional deflector. Because of this relatively long contact length, and because of the curved shape of the path followed by each strand in the deflector, each strand is submitted in service, when it is stretched, to a frictional force in the corresponding channel of the deflector, in the where the strands are attached to the anchoring head by means of clamping jaws, the friction forces applied to the strands by the deflector make it possible to reduce the amplitude of the stresses of fatigue experienced by the strands in the clamping jaws anchor head. In this respect, the deflector according to the invention thus acts as a filtered.

• la figure 1 est une vue en partie en élévation et en partie en coupe longitudinale montrant un ancrage pour câble de hauban utilisant un déviateur classique ;
• les figures 2 et 3 sont des vues en coupe transversale respectivement suivant les lignes A-A et B-B de la figure 1 ;
• la figure 4 est un schéma permettant d'expliquer le calcul de la longueur de la zone de déviation qui est nécessaire pour dévier transversalement d'une quantité prédéterminée un toron d'un câble dans le cas du déviateur conventionnel de la figure 1 ;
• la figure 5 est une vue semblable à la figure 1 montrant un ancrage pour câble de hauban utilisant un déviateur selon l'invention, la figure 5 montrant en outre une première forme du trajet courbe des canaux du déviateur dans le cas où les trous de la tête d'ancrage ont des axes parallèles à l'axe médian longitudinal du câble ;
• la figure 6 est une figure semblable à la figure 5, également avec un déviateur selon l'invention, montrant une seconde forme du trajet courbe des canaux du déviateur dans le cas où les trous de la tête d'ancrage ont des axes qui convergent vers l'axe médian longitudinal du câble ;
• la figure 7 est un schéma permettant d'expliquer le calcul de la longueur de la zone de déviation qui est nécessaire pour dévier transversalement de ladite quantité prédéterminée un toron d'un câble dans le cas du déviateur de la figure 6 ;
• les figures 8 à 11 sont des vues en élévation latérale, avec arrachement, montrant quatre formes concrètes de réalisation d'un déviateur selon l'invention conforme à la figure 6.

Other features and advantages of the invention will become apparent from the following detailed description of various embodiments of the deflector, given with reference to the accompanying drawings in which:

• Figure 1 is a view partly in elevation and partly in longitudinal section showing an anchor for cable stay using a conventional deflector;
• Figures 2 and 3 are cross-sectional views respectively along the lines AA and BB of Figure 1;
• Fig. 4 is a diagram for explaining the calculation of the length of the deflection area which is necessary to transversely deflect a strand of a cable in a predetermined amount from the conventional deflector of Fig. 1;
• FIG. 5 is a view similar to FIG. 1 showing an anchor for stay cable using a deflector according to the invention, FIG. 5 further showing a first form of the curved path of the deflector channels in the case where the holes of the anchoring head have axes parallel to the longitudinal median axis of the cable;
• FIG. 6 is a figure similar to FIG. 5, also with a deflector according to the invention, showing a second form of the curved path of the deflector channels in the case where the holes of the anchor head have axes which converge towards the longitudinal median axis of the cable;
• Fig. 7 is a diagram for explaining the calculation of the length of the deflection area which is necessary to transversely deviate from said predetermined amount a strand of a cable in the case of the deflector of Fig. 6;
• Figures 8 to 11 are side elevational views, broken away, showing four concrete embodiments of a deflector according to the invention according to Figure 6.

Figure 1 shows a conventional anchor 1 for a guy cable multi-strand 2.

Although for the sake of simplicity and clarity of Figure 1, this one shows only two strands 3, the stay cable 2 usually has a large number of strands, for example 37 strands 3 as shown in FIGS. 2 and 3. Anchor 1 comprises an anchor head 4, which is pierced with n holes 5 (37 holes in the example shown) in each of which the strands 3 of the stay cable 2 are anchored individually in a known manner, for example by means of keys or conical jaws 6, in which case the holes 5 are partly cylindrical and partly conical. The holes 5 of the anchoring head 4 are arranged according to an arrangement forming a mesh network, for example equilateral triangle mesh (Figure 3), which has a given size of mesh, for example 33 mm in the case where we use T15S type 1770 or 1860 MPa strands (corresponding to a force guarantee at break of 265,500 or 279,000 N) which have a diameter of 15,7 mm. The mesh size is the distance between the axes of any pair of adjacent holes 5.

The anchor 1 shown in Figure 1 further comprises a deflector 7 pierced with n holes 8 (n = 37 in the example shown), which makes it possible to convert the arrangement of the strands 3 in the anchoring head 4 into an arrangement forming a mesh network (FIG. 2) which has a mesh size smaller than that of the network meshed holes 5 of the anchoring head 4, for example a mesh size of 18 mm, for the current part of the cable of guy 2. The current part of the cable of guy 2 is the part that extends between the anchor 1 shown in Figure 1 and another anchor (not shown) located at the other end of the stay cable 2, and which passes usually in a sheath 9 (only a very small part of this sheath is visible in Figure 1) constituted for example by a high density polyethylene tube (HDPE).

The deflector 7, made for example of HDPE, is attached to one end of a metal tube 11, itself fixed or embedded in a portion 12 of a structure to guy. The tube 11 supports and maintains the deflector 7 at a predefined distance l ₁ (FIG. 4) from the anchoring head 4. This distance l ₁ is usually chosen so that the angular deflection α produced by the deflector 7 remains lower or equal to a preset value usually 1 to 2 ° for all the strands 3 so that, in use, they are not subjected to too much fatigue at the point where they leave the deflector 7, that is to say at the exit orifices, holes 8 oriented towards the anchoring head 4, and possibly also at the point where they enter the anchoring head 4, that is to say at the inlet orifices of the holes 5 facing the deflector 7 if the axes of the holes 5 are parallel to the longitudinal central axis 13 of the anchorage 1.

Referring to FIG. 4, if d denotes the transverse offset experienced by any of the strands 3 of the cable 2 between the deflector 7 and the anchoring head 4. by e ₁ the distance between the axis 13 and the axis of the hole 8 through which the strand 3 passes in the deflector 7, and e ₂ the distance between the axis 13 and the axis of the hole 5 through which the strand passes in the anchoring head 4 , the distance l ₁ is then given by the following equation: l 1 = d tgα = e 2 - e 1 tgα

The distances e ₁ and e ₂ are themselves given by the following equations: e 1 = rm 1 e 2 = rm 2 in which m ₁ and m ₂ are respectively the mesh dimensions of the networks formed by the holes 8 and 5 respectively in the deflector 7 and in the anchoring head 4, and r is a number corresponding to the rank of the hole 8 or 5 considered relative to the axis 13. From the equations (1) to (3), the distance l ₁ can be expressed by the following equation: l 1 = r (m 2 - m 1 ) tgα

Since the strands 3 which undergo the strongest angular deflection α are those which are at the periphery of the mesh network of holes, in particular those which pass through the holes which are located at the vertices of the hexagon formed by the grating holes and which have the highest rank (the holes of rank 3 in the example shown in Figure 3), the distance l ₁ must be calculated for the holes of highest rank. For a cable 2 of 37 strands of the T15S type, with a mesh size m ₁ of 18 mm, a mesh size m ₂ of 33 mm, an angular deflection α of 1 ° and a value of r equal to 3, we obtain a distance l ₁ equal to 2.56 m. For a cable 2 of 61 strands, r is equal to 4 and with the same values of the parameters m ₁ , m ₂ and α, we obtain for the distance for the distance l ₁ a value of 3.44 m. From the foregoing, it can thus be seen that in the conventional anchor 1 shown in FIG. 1, the distance l ₁ must be relatively large. Thanks to the present invention, this distance can be considerably reduced as will now be seen.

Figure 5 shows an anchor 10 using a deflector 7 according to a first embodiment of the invention. The elements of the anchor 10 of FIG. 5 which are identical or which play the same role as those of the conventional anchor 1 of FIG. 1 are designated by the same reference numbers and will not be described again in detail. The deflector 7 of the anchor 10 of FIG. 5 is in the form of a body 14, for example cylindrical, which has an axial length greater than that of the deflector 7 of the conventional anchor 1 of FIG. and which comprises as many channels 8 as there are strands 3 in the cable 2. Each channel 8 preferably has an inside diameter Φ which satisfies the relation: φ + 0.4 mm ≤ Φ ≤ φ + 2 mm where φ is the outside diameter of a strand 3.

On the face of the body 14 facing the sheath 9, the mesh network formed by the channels 8 of the deflector 7 of FIG. 5 has a first mesh dimension m ₁ which may be the same as that of the mesh network formed by the holes of the 7 of Figures 1 and 2. On the opposite face of the body 14, which faces the anchoring head 4, the mesh network formed by the channels 8 of the deflector 7 of Figure 5 has a second dimension of mesh m ₂ which is greater than the first mesh size m ₁ and which is preferably equal to the mesh size of the network formed by the holes 5 of the anchor head 4. In these conditions, the deflector 7 and the head of anchorage 4 can be joined to each other as shown in Figure 5.

With the exception of the central channel 8 of the deflector 7, which is located on the axis longitudinal axis of the body 14 and which is straight, all the other channels 8 of the deflector 7 of the 5 extend between the two faces of the body 14 along a curved path, which has any point a curvature at most equal to a predefined maximum curvature. In this embodiment, the curved path of the channels located at the periphery of the network mesh have a stronger curvature than that of the channel paths closer to the longitudinal axis of the body 14, while remaining nevertheless less than the curvature predefined maximum. As stated above, this predefined maximum curvature is chosen so as to be compatible with the mechanical strength of the strands 3 and with their resistance to fatigue. With strands 3 of type T15S which are the most commonly used for guy cables, the minimum radius of curvature of the channel curve 8 is at least 1 m, preferably at least equal to 2 m, for example equal to 2.5 m.

In the embodiment shown in FIG. 5, in which the axes holes 5 of the anchoring head 4 are parallel or substantially parallel to the axis longitudinal median 13 of the anchor 10, the curved path of each channel 8 of the deviator 7 comprises two successive parts curved in opposite directions. More precisely, starting from the face of the body 14 which is turned towards the sheath 9, each channel 8 has a curved path that has a first part whose concavity is radially outwardly of the body 14, and a second part whose concavity is turned radially inwardly of said body 14, the two parts are connecting to one another continuously.

In the embodiment shown in FIG. 5, the length of the deflection zone of the strands 3 of the cable 2 is equal to the axial length of the body 14 of the deflector 7. Comparing FIGS. 1 and 5, in which the anchors 1 and 10 have been drawn to the same scale, it can be seen that the length of the zone of the deviation of the strands 3 in the anchorage 10 is significantly shorter than the length of the deflection zone of the strands 3 in the conventional anchoring 1, the length of this last zone corresponding to the distance l ₁ .

If we use an anchor head 4 having holes 5 whose axes converge towards the longitudinal median axis 13 of the anchor 10 towards the deflector 7, as shown in FIG. 6, the length of the deflection zone of strands 3, that is to say the length of the body 14 of the deflector 7, can be further reduced more. In the embodiment of Figure 6, with the exception of the central channel which has a rectilinear path, the other channels 8 of the deflector 7 have a curved path which is curved monotonically from one of the end faces of the body 14 to its opposite end face, each curved path having a concavity oriented radially outwardly of the body 14. Preferably each curved path has the shape of an arc of a circle, that is to say that it has a constant curvature, without this constitutes an imperative limitation of the invention. Indeed, every curve could have a curvature that varies from an end face to the face opposite end of the body 14, provided however that at each point of each curved path the curvature remains lower than the predefined maximum curvature above.

Referring to FIG. 7, which schematically illustrates the deflection of a strand 3 by the deflector 7 of FIG. 6 in the case where the curved path of the channels 8 has an arcuate shape, the length l ₂ of the deflector 7 is given by the following equation: ℓ 2 = R sinβ where R is the radius of the arc of the curved path followed by the strand 3 in the deflector 7, and β is the angle at the center of said arc. In this case, the transverse offset d experienced by the strand 3 between the input and the output of the deflector 7 is given by the following equation: d = e 2 - e 1 = R (1 - cosβ) wherein e ₁ represents the distance between the axis 13 and the center of the orifice of the channel 8, sheath side 9, and e ₂ represents the distance between the axis 13 and the center of the orifice of the channel 8, side anchor head 4. Taking into account that the values of e ₁ and e ₂ are again given by the equations (2) and (3) given above, and that the sum of the squares of the sine and the cosine of the angle β is equal to 1, the length l ₂ of the deflector 7 is then given by the following equation: l 2 = [2 r R (m 2 - m 1 ) -r 2 (m 2 - m 1 ) 2 ] 1/2

For a cable 2 consisting of 37 strands 3 of the T15S type, assuming that the value of the radius R is chosen equal to 2.5 m and with the same values of r, m ₁ and m ₂ as those indicated above for conventional anchoring 1 of FIG. 1, a value of 0.47 m is obtained for the length 1 ₂ of the deflector 7 of FIG. 6. For a cable of stay 2 consisting of 61 strands 3, the same is obtained for the length l ₂ a value of 0.54 m. In order to facilitate the comparison between the conventional anchorage 1 of FIG. 1 and the anchorage according to the invention of FIG. 6, the values of ₁ and 1 ₂ are summarized in the following table: Number of cable strands r l ₁ in m l ₂ in m l ₁ / l ₂ 37 3 2.56 0.47 5.4 61 4 3.44 0.54 6.4

As can be seen from the table above, for a cable of 37 strands, the length 1 ₂ of the deflector 7 according to the invention (FIG. 6) is 5.4 times smaller than the length ₁ of the the deflection area of the conventional anchorage 1 and, for a 61-strand cable, the length l ₂ is 6.4 times smaller than the length l ₁ . In the case of the embodiment of FIG. 5, the length l ₂ of the deflector 7 would be approximately equal to twice that of the deflector 7 of FIG. 6, the values obtained in this case remaining, however, significantly lower than those of the length ℓ ₁ .

7 with the diverter according to the invention, the length of the metal tube 11 which supports and keeps the deflector can be greatly reduced, since its length can be equal to the length l ₂ of the deflector as shown in Figures 5 and 6.

• guider les torons 3, lors de leur enfilage, depuis la zone courante du câble de hauban 2 dans la gaine 9 où les torons 3 sont disposés parallèlement les uns aux autres selon un réseau à maille étroite, jusque dans les trous 5 de la tête d'ancrage 4, qui sont disposés selon un réseau à maille relativement large, ou, vice-versa, depuis les trous 5 de la tête d'ancrage 4 jusque dans la zone courante du câble de hauban 2 ;
• imposer aux torons tendus un trajet courbe à l'intérieur du déviateur 7;
• et transférer les efforts radiaux (créés par la tension des torons du câble et par la courbure de leur trajet à l'intérieur du déviateur) jusqu'à un point fixe de l'ouvrage à haubaner, par l'intermédiaire du tube 11, tout en étant capable de résister aux efforts de traction et de compression auxquels le déviateur est soumis en service en raison de la tension des torons et des charges dynamiques appliquées aux câbles ou transmises par ceux-ci.

In the two embodiments of FIGS. 5 and 6, the functions of the deflector 7 according to the invention are as follows:

• guiding the strands 3, during their threading, from the current zone of the stay cable 2 into the sheath 9 where the strands 3 are arranged parallel to each other in a narrow mesh pattern, into the holes 5 of the head of the anchorage 4, which are arranged in a relatively wide mesh pattern, or, vice versa, from the holes 5 of the anchoring head 4 to the current zone of the stay cable 2;
• impose on the stranded strands a curved path inside the deflector 7;
• and transferring the radial forces (created by the tension of the strands of the cable and the curvature of their path inside the deflector) to a fixed point of the structure to be guyed, through the tube 11, all by being able to withstand the tensile and compressive forces to which the deflector is subjected in service due to the stress of the strands and the dynamic loads applied to or transmitted by the cables.

• d'un polymère ou d'une résine, par exemple du PEHD, une résine Epoxy, des polyamides, du polytétrafluroéthylène (PTFE), etc. ;
• ou d'un métal moins dur que l'acier, et tel que les particules d'oxydation ou d'usure ne soient pas abrasives vis-à-vis de l'acier, de préférence un métal plus électropositif que l'acier, par exemple du zinc ou un alliage d'aluminium.

In addition, the deflector 7 according to the invention is designed so as not to generate contacts likely to cause, in use, damaging wear of the strands 3, by friction by small deflections, particularly when the strands 3 are not sheathed. individually. For this purpose, the inner surface of each channel 8, at least in its zone where a strand 3 when stretched comes into contact with said inner surface, may be constituted:

• a polymer or a resin, for example HDPE, an epoxy resin, polyamides, polytetrafluoroethylene (PTFE), etc. ;
• or a metal less hard than steel, and such that the oxidation or wear particles are not abrasive with respect to steel, preferably a more electropositive metal than steel, by example of zinc or an aluminum alloy.

• du même matériau que la surface des canaux 8, à condition que ce matériau ait les propriétés mécaniques requises, notamment une résistance mécanique suffisante pour supporter les efforts susmentionnés, en particulier une résistance à la compression supérieure à 20 MPa et une résistance à la traction supérieure à 10 MPa (dans le cas où on utilise des résines pour former la matrice du corps 14, les résines peuvent contenir des charges appropriées comme par exemple des particules de silice ou de la poudre de zinc, la taille des particules de silice ou de zinc étant alors inférieure à la quantité (m₁ - Φ)/4) ;
• ou d'un matériau différent de celui qui constitue la surface des canaux 8, par exemple en acier.

The matrix, that is to say the material of the body 14, may consist of:

• of the same material as the surface of the channels 8, provided that this material has the required mechanical properties, in particular sufficient mechanical strength to withstand the aforementioned forces, in particular a compressive strength greater than 20 MPa and a higher tensile strength at 10 MPa (in the case where resins are used to form the matrix of the body 14, the resins may contain suitable fillers such as, for example, silica particles or zinc powder, the size of the silica or zinc particles being then less than the quantity (m ₁ - Φ) / 4);
• or a material different from that which constitutes the surface of the channels 8, for example made of steel.

The deflector 7 according to the invention (FIG. 5 or 6) can be manufactured from different ways, which will now be described with reference to Figures 8 to 11.

In the embodiment of FIG. 8, the body 14 of the deflector 7 is in a castable and curable plastic material, such as for example a resin possibly containing fillers or a mortar based on resin. Channels 8 are defined by cores, for example by curved tubes (not shown) and which respectively have predefined curvatures corresponding to the desired curvature of the path of each channel 8. The tubes may be plastic or metal. A sheet 15 made of a metal that is less hard and more electropositive than the steel constituting the cable strands, is placed around each tube or elongated core used to form each channel 8 and the tubes are placed inside a mold (not shown), which can be itself constituted in part by the tube 11 shown in FIG. sheet 15 may be for example zinc or aluminum alloy and it has example a thickness of about 5/10 mm (this thickness was strongly exaggerated in figure 8 for the clarity of the drawing).

The castable and curable resin intended to form the body 14 is then cast or injected into the mold. The tubes serving as cores for molding are removed from the body 14 after demolding, while the leaves 15 remain in the 8 channels to double their inner surface.

In the embodiment of FIG. 9, the body 14 of the deflector 7 is made by molding in the same manner as the embodiment of FIG. except that, in this case, the channels 8 are not internally lined with a sheet or other metal coating. In the embodiments of Figures 8 and 9, the cores for forming the channels 8 in the body 14 may have a skin and / or be coated with a material facilitating their removal from the body 14 after molding of it.

In the embodiment of FIG. 10, each channel 8 is machined in the material of the body of the deflector 7, for example by means of a tool 16 in the form of a half-diabolo, which has a curved profile corresponding to the desired curvature of the curved path of the channel 8. In this case, the deflector 7 is preferably constituted by several bodies, for example three bodies 14a, 14b, and 14c, pierced with n holes and arranged successively on the same longitudinal axis and preferably juxtaposed, the holes homologues of the three bodies 14a, 14b and 14c each defining a curved channel continuous 8 for a strand 3 of the cable 2. Each hole or channel 8 of the intermediate body 14b, which has an axial length greater than that of the two end bodies 14a and 14c can be drilled using the tool 16 from each of the two end faces intermediate body 14b, so that the two holes thus formed are join in the middle of the intermediate body 14b. In this case, the shoulders that appear at the interfaces of the three bodies 14a, 14b and 14c, because of differences in diameter of the holes 8 at these places, can be slaughtered by milling, as shown in 17, so as not to interfere with the threading of the strand in the aligned holes of the three body 14a-14c. These three bodies can be made of metal, preferably in a less hard metal and more electropositive than the steel constituting the strands, for example aluminum or an aluminum alloy. However, the three bodies 14a to 14c can also be made of steel, but in this case the surface of the channels 8 will preferably be lined with a layer of softer material than steel constituting the strands of the cable. If this layer is itself metallic, it can be deposited for example by an electrolytic deposition process or by any other appropriate method.

In the embodiment of FIG. 11, the deflector 7 is obtained by a mixed process combining the methods described above. For example, the diverter 7 can be constituted by two juxtaposed bodies 14a and 14d. The body 14a, whose holes 8 are the closest to each other, can be metal or material thermoplastic material, for example a material selected from the range of HDPE or 6. The body 14a can then be produced according to the machining technique. removal of material described with reference to FIG. 10, or according to a technique injection pressure. The body 14d can be produced according to the technique of molding a thermosetting plastic material described with reference to FIG. 9.

With the deflector according to the invention, and when using T15S strands, it is possible to adopt a mesh size m ₁ as small as 18 mm. For two cables constituted respectively of 37 and 61 strands, it is found that the first cable is part of a circle of space of diameter 124 mm, while the second cable is part of a circle of size 160 mm in diameter. The space saving on the current section of the cable obtained by virtue of the invention is therefore considerable, of the order of 37% in diameter, or 60% in section with respect to the cables provided with anchoring and deflection systems. short described in US Patents 4,442,646, 4,473,915 and 4,484,425.

It goes without saying that the embodiments of the present invention, which have been described above, have been given as a purely indicative example and not at all limiting, and that many modifications can be made by the man of the art without departing from the scope of invention as defined in the claims. For example, it is not absolutely essential that the deflector 7 according to the invention is attached to the head 4, although this provision is particularly favorable from the point of view the guidance of the strands 3 and the point of view of the total length of the anchor 10. In in addition, in the case where the deflector 7 is composed of several successive bodies, these are not necessarily attached to each other, but they can be slightly spaced apart from each other, for example a few dozen centimeters. In addition, the body 14 or the bodies 14a to 14c are not necessarily cylindrical, but they may be frustoconical or partly cylindrical and partly frustoconical, or they may have a non-circular section, for example a polygonal section.

Nor is it essential that the curved path of each channel 8 has a constant curvature (arc) throughout its length. The curvature of each curved path may indeed vary over all or part of the path length, provided that at any point of said path the value (min of R) of the radius of curvature remains within the limits indicated above.
For example, with the exception of the central channel of the mesh network, each channel may have a curved path portion, with the same curvature for all channels, but different curved path lengths (the channels at the periphery of the mesh network having the longest curved path portions, and channels near the middle of the mesh network having the shortest curved path portions), and a straight path portion following the curved path portion.

In addition, if desired, the free spaces between each strand and the wall of the corresponding channel of the deflector can be filled with a protective agent against corrosion such as, for example, a flexible viscoelastic resin, a wax oil, grease, or other soft materials that do not interfere with the possibility of replacement of one or more strands, strand by strand.

Claims (21)

1. Deflector for a stay cable (2) with n separate strands (3), including at least one body (14) which has two opposing sides at least approximately perpendicular to a longitudinal axis (13) of the body and which includes n channels (8) passing through the body from one side to the other side thereof and arranged according to a lattice network, and in which each channel (8) has an internal diameter Φ selected in such a way as to define, in operation, a radial play just sufficient for one strand (3) of the cable (2) to pass freely in the channel, the lattice network formed by the channels (8) has, on a first of the two opposing sides of the body (14), a first lattice dimension (m₁), and on the second side of the body (14) a second lattice dimension (m₂) larger than the first lattice dimension, and in which, apart from a central channel situated on the longitudinal axis of the body (14), each channel (8) runs between the first and second sides of the body along a curved course,
   the channels (8) which are situated at the periphery of the lattice network and which have, among all the channels (8), the curved course having the smallest radius of curvature (R min), having at every point of their course a curvature less than or equal to a maximum predefined curvature, characterised in that the body (14) is in a material capable of being shaped with thicknesses less than 2 mm and having compressive strength greater than 20 MPa and tractive resistance greater than 10 MPa, and in that said smallest radius of curvature has a value (R min) which satisfies the relation: 1 m ≤ (R mm) ≤ 5 m.
2. Deflector according to Claim 1, characterised in that said smallest radius of curvature has a value (R min) which satisfies the relation: 2 m ≤ (R min) ≤ 4 m.
3. Deflector according to either one of Claims 1 or 2, characterised in that said first lattice dimension (m₁) has a value which satisfies the relation: Φ + 1.5 mm ≤ m1 ≤ Φ + 5 mm    where Φ is the value of the internal diameter of the channels (8) which itself satisfies the relation: ϕ + 0.4 mm ≤ Φ ≤ ϕ + 2 mm    where ϕ is the value of the diameter of one strand (3) of the cable (2).
4. Deflector according to any one of Claims 1 to 3, characterised in that the body (14) is made from a resin which can be cast and hardened, which is cast or injected into a mould, and in that the channels (8) are defined by elongated and curved cores, which have respectively predefined curvatures and which are embedded in the material of the body (14) during moulding and removed from the body afterunmoulding thereof.
5. Deflector according to Claim 4, characterised in that the resin contains a charge.
6. Deflector according to Claim 5, characterised in that the charge is constituted by particles of silicon or by zinc powder, the particles of silicon or of zinc being smaller in size than the quantity (m₁ -Φ)/4.
7. Deflector according to any one of Claims 4 to 6, characterised in that the internal surface of each channel (8), at least in its zone where a strand (3), once stretched, comes into contact with said internal surface, is lined with a sheet (15) of a softer and more electropositive metal than steel, said sheet being placed around the elongated core serving to form the corresponding channel and being left in place in said channel after moulding of the body (14) and removal of said elongated core.
8. Deflector according to Claim 7, characterised in that said sheet of metal is made of zinc or aluminium alloy and has a thickness of approximately 5/10 mm.
9. Deflector according to any of Claims 1 to 3, characterised in that the channels (8) are machined in the material of the body (14).
10. Deflector according to Claim 9, characterised in that the body (14) is made of a softer and more electropositive metal than the steel constituting the strands (3) of the cable (2).
11. Deflector according to Claim 9, characterised in that the body (14) is made of steel and in that the internal surface of the channels (8) is lined with a layer of material less hard than the steel constituting the strands (3) of the cable (2).
12. Deflector according to any of Claims 1 to 11, characterised in that it includes several bodies (14a-14c) perforated by n holes and arranged successively on the same longitudinal axis (13).
13. Deflector according to Claim 12, characterised in that the bodies (14a-14c) are in contact two by two and their homologous holes define in each case a continuous curved channel (8) for a strand (3) of the cable (2).
14. Deflector according to Claim 13, characterised in that a first body (14a) of the bodies (14a and 14d) is made of metal and its holes are realised by machining, and in that a second (14d) of the bodies (14a and 14d) is made by moulding a plastic material.
15. Deflector according to Claim 13, characterised in that a first body (14a) of the bodies (14a and 14d) is made of a thermoplastic material and is realised by one of the two techniques consisting of injection under pressure and machining by removal of material, and in that a second (14d) of the bodies (14a and 14d) is made by moulding a plastic thermosetting material.
16. Deflector according to any of Claims 1 to 15, characterised in that it also includes a retaining tube (11), of the same length as the body (14) which tightly surrounds said body and which serves to fix the latter onto a structure (12) to which the stay cable (2) is anchored.
17. Deflector according to any of Claims 1 to 16, characterised in that each channel (8) has a curved course which includes two successive parts curving in opposite directions, to wit, starting from the first side of the body (14), a first part having a concavity turned towards the exterior of the body, followed by a second part having a concavity turned towards the interior of the body.
18. Deflector according to any of Claims 1 to 16, characterised in that each channel (8) has a course which curves monotonously from the first to the second side of the body (14).
19. Deflector according to Claim 18, characterised in that each curved course takes the form of an arc of a circle.
20. Device for anchoring a multi-strand stay cable, including an anchorage head (4) which contains n holes (5) in each of which the strands (3) of the stay cable (2) are individually anchored, and which are positioned according to an arrangement forming a lattice network which has a given dimension of lattice, and a deflector (7) allowing the arrangement of the strands (3) to be converted in the anchorage head (4) into an arrangement forming a lattice network which has a lattice dimension smaller than said given dimension of lattice, for a running part of said cable (2), characterised in that the deflector (7) is a deflector according to any one of claims 1 to 19.
21. Stay comprising a cable (2) composed of several separate strands (3), and two anchoring devices (1) situated at the extremities of the cable, characterised in that at least one of the two anchoring devices (1) is an anchoring device according to claim 20.

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