HK1044580B - Device for anchoring a structural cable - Google Patents

Description

The present invention relates to devices used to anchor structural cables used in the construction of works of art. It applies in particular to hoists, pre-stress cables and suspended bridge cables.

The hoods are cables generally intended to transmit tensile forces between two points in a structure where they are anchored, so they are in theory straight if we ignore the external effects that tend to bend their trajectory.

The chain effect due to the own weight of the hood, the wind effect (external cross-pressure), the slight rotational movements of the structural elements supporting the hood anchors, the effects of temperature variations are factors leading to angular deviations at the ends of the hoods, i.e. at the exit of the anchors.

For other cables, significant deviations from the anchorage exit are also possible due to the path imposed on them or the transverse actions they undergo.

The anchorages are generally so constructed that only the tensile force is adequately absorbed; the local bending moments caused by the angular deflections mentioned above which might be applied to the anchorage are filtered by means of a continuous or isolated guide at the exit of the anchorage and located at a sufficient distance to be sufficiently effective.

The principle of anchoring is based on the individual locking of each of the strands making up the cable, which requires a certain cross-spacing of the strands at the anchorage block level to allow sufficient space for the individual locking devices, which are usually truncated staple strands.

In the case of hoists, a diverter assembles the strands in a compact arrangement at a certain distance from the anchorage, in order to minimize the overall cross section of the hoist in the running part. Generally, the guide that filters the bending moments is located at the level of the diverter that assembles the strands in a compact formation (see for example EP-A-0 323 285). The relatively large distance between the guide and the anchorage block (typically more than one meter) is needed to limit excessive angular deviations of each strand, which would risk damaging it and result in additional bending moments at the anchorage block level.

GB-A-2 157 339 describes a crankcase anchorage device in which a deflector is mounted in two parts in a solid tube of the anchorage block. The farthest part of the anchorage block avoids the contact of the external torons with the tube, while the closest part of the anchorage block avoids the friction of the torons with each other when cyclic loads are applied to the crankcase.

In other arrangements, the hood passes downstream of the anchorage through an opening which leaks out towards the running part, and which allows an overall angular deviation of the hood by taking back the bending forces along the length of the hood support zone in the opening (see for example GB-A-2 097 835).

One purpose of the present invention is to propose an anchorage system which limits the bending stresses of the cable to acceptable values as soon as the anchorage is removed. Another purpose is to make possible the possible elimination of an additional external device to take over the bending forces due to changes in the cable's path.

The invention thus proposes a structure cable anchorage device, comprising an anchorage block traversed by holes each receiving a strand of cable and a means of locking the strand, a support for the anchorage block, and means of guiding the strings between the anchorage block and a running part of the cable, connected to the running part and having for each strand of cable an individual guide conduit allowing an angular deflection. Each guide conduit escapes in the direction of the running part of the cable. The guide conduits have a transverse distribution in the direction of the anchorage block aligned with that of the anchorage block openings.

The overall design of the anchorage is greatly simplified by directly linking the guiding means to the anchorage device. The cable strands are guided individually, so that the inertia of the flexing element is significantly less than the inertia of the entire cable. This results in effective filtering of bending moments at the anchorage block level, even if the distance between the anchorage block and the guiding means is relatively small.

The advantage is that each guide line runs towards the current part of the cable along a fairly constant radius of curvature in a plane passing through the axis of the said line.

In a preferred arrangement of the device, the guiding means shall include at least one guiding organ housed in a tube connected to the support, through which the guiding ducts of the strands are formed.

The guide organ may be located just behind the anchorage block, or be spaced at a certain distance from the anchorage block. In the latter case, the cable strands may be expected to be individually protected torons in the current part, with the individual protection of each strand being interrupted in a chamber between the guide organ and the anchorage block, with sealing devices placed between the said chamber and the guide organ to form a watertight separation between the chamber and the current part of the cable and to contain a filler and protective product injected into the chamber. The location optionally includes a second guide organ arranged between the anchorage block and the sealing devices.

The guide body may be of a rigid or deformable material. In the latter case, it is advantageous to leave a groove, in the direction of the running part of the cable, between the circumference of the guide body and the tube in which it is housed, in order to allow an angular deviation of all the strands of the cable by deformation of the material of the guide body. The shape of this groove is optimized so as to provide a regular curvature.where the tube has a cylindrical inner face, the play may result from a narrowing of the periphery of the guide organ towards the current part of the cable, according to a radius of curvature that is substantially constant in a plane passing through the tube's axis. Another possibility is that the play may result partly from a narrowing of the periphery of the guide organ towards the current part of the cable, and partly from an evaporation of the inner face of the tube towards the current part of the cable.

The advantage of the deformable guide organ is that it has a viscosity which provides cushioning of the cable when it oscillates; this viscosity may be inherent in the deformable material of the organ and/or result from a viscous substance contained in cavities in the organ.

The deformable guide organ may have, between the guide conduits, inserts of decreasing inertia in the direction of the current part of the cable, which allows to control the curvature of the cable through the organ.

Other features and advantages of the present invention will be described in the following description of non-limiting embodiments, with reference to the attached drawings, in which: Figures 1 to 4 are schematic longitudinal views of anchorages made in accordance with the invention; andFigure 5 is a longitudinal view of a form of a guidance organ.

The invention is described below in its application to hoods, without limitation.

The hood anchored by one of the following devices is made up of a beam of bolts 1 of which only one is shown in Figure 1. In the example herein, bolts 1 are of the individually protected type: the assembly of bolted metal wires is covered with a corrosion-protective product (e.g. grease) and contained in an individual plastic sheath 2 (e.g. high-density polyethylene (HDPE)).

The anchorage device consists of an anchorage block 3 applied to a supporting piece 4 following a surface which is appreciably perpendicular to the general direction of the hood.

The anchorage block 3 is crossed by holes 5 which have a truncated profile which leaks out towards the side of the block opposite the support piece 4. Each of the holes 5 receives a toron 1 as well as a truncated bit 6 which ensures the trapping of the toron in the orifice.

To achieve a reliable anchorage of the individually protected torsion, the individual protection of each torsion in the current portion is interrupted in a chamber 7 located behind the anchor block 3. Thus, the nozzles 6 directly grip the metal wires of the torsions. To protect the metal of the torsions in chamber 7 and in anchor block 3 from corrosion, a filler (e.g. oil wax, grease or resin) is injected into chamber 7 and into the gaps left free between the torsions and the block 3. To prevent this filler from spreading to the current portion of the hat, the end of chamber 7 is closed to the anchor block 3 by a type 8 seal device which can be used to seal the inside of each chamber, such as the 8A-10-02 pressure-pressure tube, which is located at the opposite end of the chamber.

At a certain distance from the anchorage, a deflector 11 brings the torons 1 together in a more compact formation than in the anchorage, in order to minimize the overall cross-section of the hood in the running part.

The anchorage device shown in Figure 1 has a guide 12 housed inside the above tube 10. This tube 10 is connected to the support 4. It may for example be of a single support with this part 4, as shown, or with parts 4 and 3, or attached to an anchorage cap.

In the example in Figure 1, the guide organ 12 consists of a rigid cylindrical block (e.g. HDPE) inserted into the tube 10 without any gaps.

On the side facing anchorage block 3 (this side is located just behind the rear face of the sealing device 8 in the example shown), the ducts 13 are circular with a diameter corresponding to that of the individually protected torons 1 and their cross-sectional distribution is the same as that of the holes 5 in anchorage block 3.

In the direction of the running part of the hood, each guide tube 13, whose general shape is that of a revolution, runs along a profile which, in a plane passing through the axis of the tube, has a constant radius of curvature R. This curvature allows the angular deflection of the toron towards the deflector organ 11 and also allows overall bending movements of the hood.

In the devices shown in Figures 2 and 3, the guide 15, 17 is made of a deformable material such as neoprene. This material can have advantageous viscoelastic properties to help dampen the vibrations of the cable, the viscosity providing a dissipation of vibrational energy.

The 16 tubes saved for the torons in the guiding organ of deformable material 15, 17 evaporate to the running part of the hood following a radius of curvature R2 which may be greater than the radius R of the shape of the figure 1. This radius R2 is determined by the angular deflection due to the convergence of the torons to the diverting organ 11.

To tolerate the angular deviations due to the bending movements of the hood and to take up the corresponding moments, a J-switch is present between the inner face of tube 10 and the periphery of the guiding organ 15, 17 in the direction of the running part of the hood, and this over the entire circumference of the organ 15, 17.

The set J is preferably defined by a constant radius curvature R1 (in a radial plane passing through the tube's axis 10) at the interface between the periphery of the Neoprene guide organ and the inner face of the tube 10. This radius R1 is determined, with length L, according to the magnitude of bends to which the hood can be subjected. When the hood is deflected and its strands are grouped, these strands have a maximum radius of curvature R3 defined by a combination of R1 and R2, such that R3 < R1 and R3 < R2.

In the example in Figure 2, the radius curvature R1 is formed on the inner revolution face of tube 10 which escapes towards the running part of the hood, the periphery of the guide 15 being cylindrical.

In another variant, not shown, the J-set results from a combination of curvatures of the inner face of the tube 10 (Figure 2) and the periphery of the organ in deformable material (Figure 3).

In the example in Figure 4, the guiding means consist of two deformable material organs, one 20 placed between anchorage block 3 and the sealing device 8 and the other 22 placed beyond the sealing device 8. Each guide conduit receiving a toron then has a cylindrical portion 21, of a diameter corresponding to that of the toron, formed in organ 20, and a portion 23 formed in organ 22 and which runs according to the current part of the harness to the escape radius R2.

The organ 20 is housed in the cylindrical tube 10 which holds it in place on the side of block 3 and towards the current the periphery of the organ 20 tightens according to the radius of curvature R1 to resume bending movements. The organ 22, which can be attached to the sealing device 8, has the portions of the pipe 23 which drain along the radius of curvature R2 to the current to allow the torons to converge towards the deflector organ 11.

In the example shown in Figure 4, the J-joint is created in the same fashion as in Figure 3, by curving inward the periphery of the deformable organ; in one variant, the J-joint could be created, in whole or in part, by curving outward (as shown in Figure 2) the inner face of tube 10 to the right of the organ 20 adjacent to the anchorage block.

In the embodiment shown in Figure 5, the tube connected to the support piece 4 has two successive portions 10a, 10b. The cylindrical portion 10a contains the sealing device. The retractable portion 10b contains the deformable guide organ 15 which may have a similar constitution to that in Figure 2. The inertia of this portion 10b decreases in the direction of the running part of the crank, which allows a gradual bending of the cable and the guide organ.

In the variant shown in Figure 6, the gradual bending of the cable and the deformable guide 25 results from the decreasing inertia towards the running part of the hood of inserts 27 placed in the deformable material between the guide lines 26.

Claims (14)

1. A device for anchoring a structural cable, comprising an anchor block (3) having orifices (5) therethrough, each accommodating a tendon (1) of the cable and a means (6) of immobilizing said tendon, a bearing piece (4) for the anchor block, and means (12; 15; 17; 20, 22; 25) of guiding the tendons between the anchor block and a running part of the cable, wherein the guide means are connected to the bearing piece and comprise an individual guide passage (13; 16; 21, 23; 26) for each tendon of the cable, characterized in that each guide passage widens toward the running part of the cable so as to allow angular deflection of the tendon accommodated in said passage, and in that the guide passages have, in the direction of the anchor block, a transverse layout aligned with that of the orifices in the anchor block.
2. The device as claimed in claim 1, wherein each guide passage (13; 16; 23; 26) widens toward the running part of the cable with a radius of curvature (R; R₂) that is substantially constant in a plane passing through the axis of said passage.
3. The device as claimed in claim 1 or 2, wherein the guide means comprise at least one guide member (12; 15; 17; 20, 22; 25) housed in a tube (10; 10a, 10b) connected to the bearing piece (4), through which the tendon-guiding passages (13; 16; 21, 23; 26) are formed.
4. The device as claimed in claim 3, wherein the guide member (12; 15; 17; 22) is spaced away from the anchor block (3).
5. The device as claimed in claim 4, wherein the tendons (1) of the cable are strands individually protected in the running part, wherein the individual protection (2) of each tendon is interrupted in a chamber (7) lying between the guide member (12; 15; 17; 22) and the anchor block (3), wherein sealing means (8) are placed between said chamber and the guide member so as to form a sealed separation between the chamber and the running part of the cable, and wherein a filler product is injected into the chamber.
6. The device as claimed in claim 5, comprising a second guide member (20) lying between the anchor block (3) and the sealing means (8).
7. The device as claimed in any one of claims 3 to 6, wherein the guide member (15; 17; 20, 22; 25) is made of a deformable material.
8. The device as claimed in claim 7, wherein, in the direction of the running part of the cable, a clearance (J) is left between the circumference of the guide member (15; 17; 20, 22) and the tube (10) in which it is housed, so as to allow the collection of tendons of the cable an angular deflection by deformation of the material of the guide member.
9. The device as claimed in claim 8, wherein the guide member (15) has a cylindrical periphery and the clearance (J) results from a widening of the inner face of the tube (10) toward the running part of the cable, with a radius of curvature (R₁) that is substantially constant in a plane passing through the axis of the tube.
10. The device as claimed in claim 8, wherein the tube (10) has a cylindrical inner face, and the clearance (J) results from a narrowing of the periphery of the guide member (17) toward the running part of the cable, with a radius of curvature (R₁) that is substantially constant in a plane passing through the axis of the tube.
11. The device as claimed in claim 8, wherein the clearance (J) results partly from a narrowing of the periphery of the guide member toward the running part of the cable and partly from a widening of the inner face of the tube toward the running part of the cable.
12. The device as claimed in any one of claims 6 to 11, wherein the guide member (15; 17; 20, 22; 25) has a viscosity.
13. The device as claimed in any one of claims 6 to 12, wherein the guide member (25) comprises, between the guide passages (26), inserts (27) of an inertia that decreases toward the running part of the cable.
14. The device as claimed in any of claims 6 to 13, wherein the tube (10b) in which the guide member (15) is housed has an inertia that decreases toward the running part of the cable.