WO2016180485A1 - Selle de déviation de câble - Google Patents

Selle de déviation de câble Download PDF

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Publication number
WO2016180485A1
WO2016180485A1 PCT/EP2015/060478 EP2015060478W WO2016180485A1 WO 2016180485 A1 WO2016180485 A1 WO 2016180485A1 EP 2015060478 W EP2015060478 W EP 2015060478W WO 2016180485 A1 WO2016180485 A1 WO 2016180485A1
Authority
WO
WIPO (PCT)
Prior art keywords
saddle
curvature
flanking
central portion
radius
Prior art date
Application number
PCT/EP2015/060478
Other languages
English (en)
Inventor
Rachid Annan
Original Assignee
Vsl International Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vsl International Ag filed Critical Vsl International Ag
Priority to PCT/EP2015/060478 priority Critical patent/WO2016180485A1/fr
Publication of WO2016180485A1 publication Critical patent/WO2016180485A1/fr

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
    • E01D19/00—Structural or constructional details of bridges
    • E01D19/14—Towers; Anchors ; Connection of cables to bridge parts; Saddle supports

Definitions

  • the present invention concerns a cable deviation saddle.
  • Cable deviation saddles are used for example in cable-stayed bridges, stay bridges or other similar structures, for deviating the cables at the top of the towers of these bridges.
  • Such a cable deviation saddle can also be used for strands supporting other supported element than a bridge deck such as, among others, suspended roofs (stadium, ...), or any suspended parts of a civil engineering suspended structure.
  • a stay bridge is a type of bridge in which the deck (the load- bearing portion) is hung from stay cables.
  • the stay cables are suspended to towers, and they carry the weight of the deck below.
  • Cable deviating saddles are positioned on top of the towers; and these saddles support and hold the stay cables in position on the tower.
  • Saddles typically have a curved support surface on which the various strands that together build the cables are supported.
  • the cables are stressed in traction between their opposite ends which are usually anchored to the desk. They are conceived and selected so as to support the static forces caused by the weight of the suspended load, as well as the dynamic forces (also called service load) which may be caused by vehicles driving on the deck, by wind, or by other factors.
  • static loads should not exceed a value in a range between 1 5 and 30% of the breaking threshold of the cable, while dynamic loads should not exceed 1 5 to 30% of this breaking threshold.
  • dynamic loads should not exceed 1 5 to 30% of this breaking threshold.
  • the total load (static and dynamic) under service condition should not exceed 45%, or sometime 69%, of this breaking threshold.
  • the dynamic forces applied to both sides of the cable may be unbalanced, i.e. higher on one side of the saddle than on the other side. Therefore, in existing saddles, local slippage of the cable near exit or entrance may be caused be dynamic loads. This slippage may even occur with high balanced dynamic forces. This slippage creates some fretting; in the worst situation, the integrity of the cable might be compromised.
  • the radius of the curvature of the support surface of the saddle can influence the amount of fretting which occurs at the apex of the curved support surface. The smaller the radius of curvature, the higher the contract pressure between the cable and the curved support surface at the apex of the curved support surface. For a given amount of displacement, a higher contact pressure leads to an increase in fretting.
  • FR2968681 discloses in relation with Figure 3 a saddle comprising a smaller radius of curvature at both exits than in a middle portion of the saddle, thus resulting in a flared channel.
  • the invention starts from the realization that the problem of fretting is much both exits of the saddle than in the middle, where the local slippage is virtually inexistent even in the case of high unbalanced dynamic or static forces.
  • the risk of fretting depends on the pressure P between the strand and the support surface and on the relative displacement D between the strand and the support surface.
  • the fretting further depends on the type of contact surfaces.
  • the relative displacement D between the strand and the support surface depends on the elongation. Without friction, the displacement of each point would be proportional to its distance to a fixed point of the cable (for example at the apex in the case of symmetric forces). Due to the friction, this displacement is reduced, but nevertheless increases with the distance from the fixed point (for example at apex).
  • the radius of the saddle is reduced where the risk of fretting is reduced, i.e. in the central portion of the saddle where the relative displacement between each strand and the corresponding support surface is reduced.
  • the radius of the saddle is increased in order to reduce the pressure and the risk of fretting in the flanking portions where the displacement is more important.
  • a saddle virtually exempt from fretting may be achieved by means of a saddle according to claim 1 and any suspended (civil engineering) structure with such a saddle.
  • Some preferred features of the saddle are defined in claims 2 to 16.
  • the present invention concerns an assembly according to claim 17, a stay bridge according to claim 20 and a method of manufacturing a saddle according to claim 21 .
  • the expression "strand” is intended to designate not only isolated strands, but also strand bundles, ropes, cables or any other single or multiple elongated elements being tensioned between both ends.
  • Fig. 1 shows a section through a pylon and a saddle according to an embodiment of the present invention
  • Fig. 2 shows a cross section of a saddle comprising one channel according to a first embodiment of the present invention
  • Fig. 3 shows a cross section of a saddle comprising one channel according to a second embodiment of the present invention
  • Fig. 4 shows a cross section of a transition boy that may be arranged at the entry and exit pint of a saddle according to the present invention
  • Fig. 5 provides a perspective view of a housing for a saddle according to a further embodiment of the present invention. Detailed Description of possible embodiments of the Invention
  • Figure 1 shows a cross section of a saddle 1 for a stay bridge, according to an embodiment of the present invention.
  • the saddle 1 may comprise a tubular housing 20 and one or more channels 13 defined in a body 14 of the saddle 1 .
  • Each channel 13 supports and deviates one strand 90 of a stray cable 9.
  • the channels 13 may be arranged in a matrix form.
  • the saddle is usually mounted on top of a bridge tower 21 or on another type of pylons or mast (forming a
  • Each channel 13 of the saddle 1 comprises one support surfaces 2 on each of which one strand 90 of the cable 9 can rest.
  • the support surface 2 is defined by an inner surface 12 of the channel 13.
  • Each channel 13 of the saddle 1 may have a circular or
  • each channel is as described in international application WO2007/121782 and comprises pinching surfaces for pinching the strand when the traction increases, thus increasing the friction between the cable and the saddle.
  • the section of the channel 13 may be the same over the whole length of the channel.
  • the section of the channel is constant over its whole length, except for the two extremities 40a, 40b which are flared and therefore have a larger section.
  • the friction between the strand 90 and the channel 13 is adapted by selecting the section of the channels 13 and the material used for the inner surface 20 and for the strand 90.
  • This friction is preferably chosen so that the middle point of the strand at the apex of the saddle does not move relative to the saddle 1, even when the dynamic forces exerted on one side of the cable amount to the maximal admissible value for which the cable is designed, for example 1 5 to 30% of the cable breaking threshold. Therefore, the portion of the cable at the apex of the saddle never moves relative to the saddle, even when the tension in the cable is very high and unbalanced.
  • the portions of the strands at the entry and exit point of the saddle might however move relative to the saddle, due to variations in elongation.
  • the saddle 1 may comprise one or more additional support surfaces 2 for other strands.
  • the support surface 2 may be simply an external surface of the saddle or may be an inner surface of a tubular structure.
  • the support surface 2 is configured such that it has a central portion 3, and flanking portions 4a,4b on opposite sides of the central portion 3.
  • the central portion 3 is the portion of the support surface which extends between interfaces 5a and 5b; in many constructions, the central portion includes the highest point (apex) of the support surface 2.
  • flanking portion 4a is the portion of the support surface 2 which extends from the interface 5a to a free end 6a; and the flanking portion 4b is the portion of the support surface 2 which extends from the interface 5b to a free end 6b.
  • the central portion 3 of the support surface 2 is configured to have at least one radius of curvature 'r'.
  • the flanking portions 4a,b usually have equal curvature profiles; each flanking portion 4a,b is configured such that the radius of curvature increases in the direction from the interface 5a,b between that flanking portion 4a,b and the central portion 3 to the free end 6a,b of the flanking portion 4a,b so that each flanking portion 4a,b is configured to have a plurality of radii of curvature.
  • the increase could be linear or follows any other function.
  • at least one segment of the support surfaces 2 correspond to a Bezier curve.
  • the support surfaces 2 in the flanking portions 4a, 4b, or in a portion of the flanking sections 4a, 4b, and/or in the central section 3, may correspond to a Bezier curve.
  • at least one segment of the support surface corresponds to a portion of a spline curve, a Bezier curve, nurbs (Non-Uniform Rational Basis Splines) curve, or to a sinus curve.
  • R radius of curvature
  • the central portion 3 is configured such that all its radii of curvature "r" are smaller than all of the plurality of radii of curvature "R" of the flanking portions 4a,b, so that the support surface 2 is configured to have at least two different local radii of curvature "r" and "R".
  • the flanking portions 4a,b may alternatively be configured to have a single radius of curvature "R", i.e.
  • flanking portions 4a,b have a plurality of radii of curvature; however what is important is that the central portion 3 is configured such that its largest radius of curvature "r" is smaller than at least one radius of curvature "R" of the flanking portions 4a,b.
  • each flanking portion 4a,b may be configured such that their radii of curvature increases non-linearly in the direction from the interface 5a,b to the free end 6a,b of the flanking portion 4a,b.
  • a strand 90 of a cable 9 which suspends a deck of a stay bridge extends through the channel 13 defined in a body 14 of the saddle 1 .
  • the cable simultaneously rests on the central portion 3 and both flanking portions 4a,b of the support surface 2 such that the central portion 3 and flanking portions 4a,b of the support surface 2
  • the strand is thus guided along a curved path of curvature equal to the profile of the support surface 2.
  • the profile of the support surface 2 in the central portion 3 is configured such that all its radii of curvature "r" are smaller than the radii of curvature "R" of the flanking portions 4a,b.
  • the radius of curvature never decreases from the apex of support surface 2, in the middle of the central section, and both entry points 6a, 6b at the free ends of the flanking portions 4a, 4b. This ensures an overall reduction in the fretting of the strand.
  • the central portion 3 is configured to have a smaller radius of curvature "r” than the radius of curvature of the flanking portion 4a,b this reduces the size (i.e. the thickness "t") of the saddle 1 ; accordingly compared to the saddles of the prior art which have a support surface with a constant radius of curvature, a thinner tower is required to support the saddle 1 of the present invention.
  • Figure 3 illustrates another embodiment of a channel 13 for supporting and deviating a strand 90 of a cable 9.
  • This embodiment is similar to the embodiment described in relation with figure 2, except for the outer extremities 40a, 40b of both flanking portions 4a, 4b with are flared, forming a "bell mouth". Therefore, the section of the channel 13 expands in those flared extremities 40a, 40b.
  • This flared section avoids any contact between the channel 13 and the strand 90 at the entry and exit point of the strand 90 into the channel 13, and in particular avoids any contact between the strand and a sharp edge of the channel.
  • the length of the flared extremities is however limited, typically less than 200mm, possibly less than 100mm.
  • the local radius of curvature R' might be lower than all radius of curvatures "R" in the rest of the flanking portions 4a, 4b, and possibly even less than all or some radii of curvature "x" in the central portion 3.
  • the radius of curvature r, R never decreases from the apex of the support surface 2, in the middle of the central section, and both entry points 6a, 6b, except possibly in the flared extremities 40a, 40b. This local reduction of the radius of curvature has no impact on fretting, since the strand 90 is not supported by the channel 13 in those flared portions.
  • Figure 4 illustrates a transition box 60 that may be provided at both entry and exit point of the cable 9 into the saddle 1 . This transition box seals the cable inside the saddle and prevents introduction of water from the outside.
  • One transition box 60 may be provided at both
  • the illustrated transition box 60 comprises a front compression plate 61 , a transition pad 62, a sealing pad 63, a compression pad 64 and a rear compression plate 65. All those elements are perforated, the
  • the compression plates 61 , 65 may be metallic while the transition and compression pads 62, 64 may be made of hard plastic.
  • the sealing pad 63 ensures watertightness and is compressed by the
  • a bedding material such as a polyurethane, a grease, etc, is advantageously contained in the holes 66 and retained by the sealing pad 63; this bedding material, as well as possibly the pads 62, 64, have a damping effect on high frequency vibrations of the strand 90, which are attenuated at the entry point of the saddle, thus further reducing the risk of fretting caused by those high frequency vibrations.
  • this bedding material has an effect for filtering out bending stress of the strand 90.
  • each flanking portion 4a, 4b comprises a bedding material within said channel 13 for damping vibrations of the strand 90 and/or for filtering out bending stress of said strand 90.
  • the saddle 1 may further comprise a protective cover 20 which houses at least the saddle and the portions of the one or more cables which rest on a respective support.
  • the housing or protective cover 20 may be configured to have a curved profile which has a single radius of curvature only and is thus easier to manufacture.
  • the housing or protective cover 20 may have a plurality of radii of curvature, for example corresponding to the radii of the saddle.
  • the housing or protective cover 20 of Figure 5 can be used to deviate a cable 9, i.e. a bundle of strands, within the tube 27, or to deviate each individual strand 90 of the cable 9 in one individual independent channel 13 as described in relation with Figures 1 to 4.
  • the channels can be realized in a matrix material cast within the tube 27.
  • the housing 20 has a tubular structure with a curved profile so that the central portion 3 of the support surface 2 is configured to have at least one radius of curvature 'r' and that each of the flanking portion 4a,b has at least one larger radius of curvature 'R'.
  • the tubular structure 20 is composed of a metal form 25 which has been folded into the shape of a tube 27 having a rectangular or square cross section with rounded edges 26. It will be understood that the invention is not limited to having a tube 27 of rectangular or square cross section; the tube may have any suitable profile e.g. the tube may have a circular cross section.
  • a plurality of rib plates 28, each of which comprises a rectangular or square aperture 29, are distributed along the length of the tube 27.
  • the tube 27 is threaded through the square aperture 29 of each plate 28.
  • the plate 28 holds the folded metal form 25 in its folded position so that the tube-shape is maintained and that the forces are transmitted from the cable to the pylon.
  • a suitably shaped form typically made from metal, is folded into a substantially tubular shape of rectangular or square cross section. While maintaining its substantially tubular shape the folded metal form is then threaded through rectangular or square apertures 29 defined in a plurality of plates 28 and the plates 28 are arranged to be distributed substantially evenly along the length of the folded form. The plates 18 maintain the structure 20.
  • an alternative method of manufacturing the saddle 1 illustrated in Figure 5 may involve first cutting one or more metal forms with a laser to provide said central portion 3 and two flanking portions 4a,b, wherein each of the two flanking portions 4a,b are configured to have one or more radii of curvature and wherein the flanking portions 4a,b have equal curvature profiles, and wherein the central portion 3 has a radius of curvature 'r' which is smaller than all of the one or more radii of curvature 'R' of the flanking portions 4a,b. Then arranging the flanking portions 4a,b at opposite ends of the central portion 3 so that the flanking portions 4a,b flank the central portion 3. Once the flanking portions 4a,b are in position each flanking portion 4a,b is respectively welded to opposite ends of the central portion 3.
  • a transition box 60 as described in relation with Figure 4 may be arranged at one or at both extremities of the tube 27 within the housing of Figure 5.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Bridges Or Land Bridges (AREA)

Abstract

La présente invention concerne une selle (1) pour une structure suspendue, la selle (1) comprenant une ou plusieurs surfaces de support (2) sur lesquelles un brin (90), qui suspend un élément porté d'une structure suspendue, peut reposer, la ou chaque surface de support (2) étant configurée de telle sorte qu'elle a une partie centrale (3) et des parties de flanquement (4a,b) sur des côtés opposés de la partie centrale (3), à la fois la partie centrale (3) et les parties de flanquement (4a,b) de la surface de support (2) étant configurées de telle sorte qu'elles peuvent porter ledit câble en même temps; le rayon de courbure (r, R) de ladite surface de support (2) dans un plan dans lequel est inclus ledit brin (90) augmentant de la partie centrale (3) vers les parties de flanquement (4a,b). L'invention concerne en outre des procédés de fabrication d'une telle selle.
PCT/EP2015/060478 2015-05-12 2015-05-12 Selle de déviation de câble WO2016180485A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2015/060478 WO2016180485A1 (fr) 2015-05-12 2015-05-12 Selle de déviation de câble

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2015/060478 WO2016180485A1 (fr) 2015-05-12 2015-05-12 Selle de déviation de câble

Publications (1)

Publication Number Publication Date
WO2016180485A1 true WO2016180485A1 (fr) 2016-11-17

Family

ID=53191661

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2015/060478 WO2016180485A1 (fr) 2015-05-12 2015-05-12 Selle de déviation de câble

Country Status (1)

Country Link
WO (1) WO2016180485A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108914773A (zh) * 2018-08-24 2018-11-30 中铁第四勘察设计院集团有限公司 一种转角索鞍

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011116834A1 (fr) * 2010-03-26 2011-09-29 Vsl International Ag Perfectionnement pour un dispositif de guidage de brin
WO2012076815A2 (fr) * 2010-12-08 2012-06-14 Soletanche Freyssinet Dispositif de deviation d'un cable de structure tel qu'un hauban, et ouvrage ainsi equipe
CN202500087U (zh) * 2012-01-18 2012-10-24 柳州豪姆机械有限公司 单根可抽换式矮塔斜拉桥抗滑索鞍

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011116834A1 (fr) * 2010-03-26 2011-09-29 Vsl International Ag Perfectionnement pour un dispositif de guidage de brin
WO2012076815A2 (fr) * 2010-12-08 2012-06-14 Soletanche Freyssinet Dispositif de deviation d'un cable de structure tel qu'un hauban, et ouvrage ainsi equipe
CN202500087U (zh) * 2012-01-18 2012-10-24 柳州豪姆机械有限公司 单根可抽换式矮塔斜拉桥抗滑索鞍

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108914773A (zh) * 2018-08-24 2018-11-30 中铁第四勘察设计院集团有限公司 一种转角索鞍

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