EP4276243A1 - Verfahren zur lokalen wiederherstellung der spannung eines vorspannkabels und system zur überbrückung eines vorspannkabels mit diesem verfahren - Google Patents

Verfahren zur lokalen wiederherstellung der spannung eines vorspannkabels und system zur überbrückung eines vorspannkabels mit diesem verfahren Download PDF

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Publication number
EP4276243A1
EP4276243A1 EP23167487.0A EP23167487A EP4276243A1 EP 4276243 A1 EP4276243 A1 EP 4276243A1 EP 23167487 A EP23167487 A EP 23167487A EP 4276243 A1 EP4276243 A1 EP 4276243A1
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EP
European Patent Office
Prior art keywords
cable
prestressing
volume
bars
zone
Prior art date
Legal status (The legal status 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 status listed.)
Pending
Application number
EP23167487.0A
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English (en)
French (fr)
Inventor
Adrien ROIBET
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
IXO
Original Assignee
IXO
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Filing date
Publication date
Application filed by IXO filed Critical IXO
Publication of EP4276243A1 publication Critical patent/EP4276243A1/de
Pending legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
    • E01D22/00—Methods or apparatus for repairing or strengthening existing bridges ; Methods or apparatus for dismantling bridges
    • 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
    • E01D19/16—Suspension cables; Cable clamps for suspension cables ; Pre- or post-stressed cables

Definitions

  • the invention belongs to the field of public works structures, more particularly engineering structures such as bridges integrating one or more prestressing cables.
  • the invention aims at the maintenance of such structures, in particular when the prestressing cable(s) that they integrate have suffered damage, requiring correlative measures to be taken to safeguard the integrity of said structure.
  • prestressing cables external to concrete within engineering structures, and in particular bridges, is now widely used.
  • Such prestressing cables undergo wear or corrosion phenomena over time, likely to cause their rupture and, as a corollary, that of the engineering structure within which they are integrated.
  • This corrosion is generally not generalized over the entire cable, but concentrated at point defects, the vast majority either at connections of cable sheaths, or at so-called makeshift repairs dating from execution, or at the anchors.
  • This type of technique is defined as provisional, that is to say allows gentle relaxation of the cable without dynamic effect. It therefore allows the removal of the cable, generally with a view to its replacement, not its conservation. It is therefore common to replace a cable of more than 50 linear meters, while the corrosion defect on the same cable only exists over a length of the order of a meter.
  • the present invention aims to free itself from the installation of such jaws and therefore, as a corollary, to reduce the bulk necessary for their installation on the one hand, and on the other hand, to allow the conservation of the linear unbridged cable without requiring their removal.
  • the invention consists of ensuring the transfer by adhesion of the forces initially undergone by the cable, over a suitable covering length between the existing reinforcement(s) or cables and the bridging profiles or bars. prestressed, thus making it possible to benefit from the confinement effect inherent to the formwork.
  • This formwork is preferably typically made of semi-cylindrical metal shells, or even made of composite material incorporating glass fibers or carbon fibers for example, particularly if one wishes to avoid leaving metal elements permanently in an aggressive atmosphere. .
  • Anchoring by adhesion, and not by nailing provides system flexibility for different types of cables.
  • transfer by adhesion in a material only requires adaptation of the injected volume (length and section) to ensure the effective transfer of force between the cable and the bar bridging system.
  • composition of the confinement system is significantly simplified compared to a clamping jaw of the prior art, also taking up the axial forces of prestressing bars, since the mechanical operation of the confinement tube is intrinsically different and a fortiori less penalizing.
  • this containment system does not need to be geometrically adjusted to the type of cable encountered. It is possible to vary the dimensions of the outer envelope, typically by several centimeters for example, to adapt to the diameters of commercial tube products, or quite simply to the geometry constraints of the work, for example the distance to the facing closest to the cable.
  • the formwork is made up of two half-shells capable of being assembled together and of defining a substantially cylindrical volume, centered in relation to the cable in question.
  • the formwork also cylindrical, is temporary, and is therefore intended to be removed after the UHPFRC or resin has set.
  • metal hoops made of High Adherence (HA) steel of reinforced concrete are integrated into the volume defined by the formwork prior to the injection of the UHPC concrete or resin, and arranged around the cable and the prestressing bars provided with their sheath, these hoops being in the form of overlapping semi-circles mechanically overlapping at their two ends.
  • HA High Adherence
  • the figure 1 is a schematic representation of a work of art, in this case a box bridge partially represented.
  • a box bridge partially represented.
  • This sheath is typically made of PVC (polyvinyl chloride), HDPE (high density polyethylene), or steel, and traditionally surrounds the cable in question.
  • PVC polyvinyl chloride
  • HDPE high density polyethylene
  • the desired objective is to release the constituent reinforcements of the cable (2) in tension, in order to allow the adhesion of the future material, typically UHPC type or resin type, on these same reinforcements.
  • This removal or release of the filling material can be carried out by hydrodemolition, particularly in the frequently encountered case of structures injected with cement grout.
  • the cable without the sheath and its filling is generally in the form of a certain number of wires or metal strands, depending on the prestressing process used.
  • the cable (2) is generally made up of a bundle of smaller units.
  • the outermost wires or strands of the cable mask an interior volume containing non-accessible wires or strands, typically coated in cement grout; in this situation, it is appropriate to release as much of the peripheral strands as possible, then to adapt the length of the device of the invention to the adhesion surface actually available, via an approach similar to that of package anchoring length calculations. of bar for reinforced concrete steels, as specified in the Eurocode 2 corpus.
  • At least two prestressing bars (5, 6) are positioned on either side of said cable (2), said bars (5, 6) passing through the anchor head (1) previously drilled, typically by coring, for the purposes of to allow their insertion up to the level of the box within which the various prestressing cables pass, and in particular the weakened cable (2).
  • the bars (5, 6) are held in place on the one hand at the anchoring level, and on the other hand by stakes, for example metallic, preceding the half-cylindrical shells (7) described below.
  • These bars typically having a diameter of around 40 millimeters for common prestressing cables, they have significant rigidity and therefore only undergo very small deformations over several meters under their own weight, which facilitates their installation. implemented.
  • prestressing bars are initially provided with a PVC or HDPE sheath provided for in the technical advice of the prestressing supplier, which should be removed directly above the fragile zone of the damaged prestressing cable (2) of which we intend to carry out the bypass.
  • This stripping of the prestressing bars aims to allow their subsequent anchoring by adhesion in the UHPC concrete or in the resin, as will be described later. They are held in position by means of fixing or connecting members, for example hangers or stakes fixed to the nearest facing, such as for example illustrated on the figures 11 and 12 .
  • these connecting or fixing members are used to position, around the prestressing cable (2), not only directly above the cable damage zone, but also upstream and downstream of it.
  • a cylindrical metal shell (7) whose axis of revolution is, in this case, coincident with the cable (2).
  • An interface allowing slight sliding when tensioning is implemented between the shell (7) itself and the connecting or fixing members.
  • Such an interface is for example made up of a sheet of PTFE (polytetrafluoroethylene), or even a layer of grease.
  • a fiber-reinforced concrete advantageously of the UHPC type, in this case with ultra high performance.
  • SMART Up by the company VICAT
  • BSI reference “BSI”
  • This concrete can be replaced by a resin, for example marketed under the reference “Sikadur 52” by the company Sika.
  • This concrete or this resin will therefore occupy the entire volume defined previously, and come into contact respectively with the cable (2) and the prestressing bars (5, 6).
  • a concrete or resin of this type are such that it ensures extremely effective adhesion, on the one hand with the prestressing cable (2), and on the other hand with the prestressing bars (5, 6). He/she also makes it possible to protect the parts anchored by adhesion against corrosion or other attacks, and thus contributes to the long-term durability of the device.
  • the prestressing bars (5, 6) are then put under tension.
  • This tensioning is preferably carried out on the basis of computer-assisted control, based on the theoretical force of the cable and displacement measurements, for example via extensometer type sensors placed between fixed points on the structure. on the one hand, typically concrete core or slabs, and several points of the cylindrical shell and tension elements, prestressing bars (5, 6) and the cable (2), on the other hand.
  • the tensioning under hydraulic control is carried out in such a way that one can have up to one hydraulic channel per bar.
  • This dedicated control makes it possible to adapt the tensile force in each prestressing bar, and thus cover the effects of possible installation defects of said bars in relation to the cable.
  • the connection system illustrated by the figures 11 and 12 , contributes to recovering the effects of a foreseeable implantation fault which cannot be recovered satisfactorily by a simple difference in tension between the bars.
  • zone (10) corresponds to the section of the damaged cable and zone (11) corresponds to the section of the preserved cable.
  • the system of the invention is therefore positioned astride zones (10) and (11).
  • the prestressing bars (5, 6) pass through the wedging zone (1) and tension bolts (14) ensure the tensioning of the prestressing bars (5, 6) after the fiber concrete has set.
  • THE figures 7 to 9 represent another embodiment of the invention, in which the system of the invention is positioned on either side of the section (17) of the damaged cable, that is to say also partly at the level of the sections (16) where the cable is kept.
  • the system is suspended from the upper wall (3) of a box by means of hangers (18) fixed by any means, in particular by screwing.
  • the lower end of the hangers is connected to the cylindrical shells (7) intended to define the volume within which the fiber-reinforced concrete is injected.
  • the prestressing bars are anchored to the ends of the cylindrical shells, via a system of anchoring plates (22), commonly used in prestressing by bar.
  • the dimensions of these anchoring plates can be reduced taking into account the performance of the confined material, advantageously UHPC concrete.
  • the prestressing bars retain their sheathing (23) over the length of the cylindrical shells, without anchoring by adhesion to the confined material (24), advantageously of the UHPC type, with the aim of allowing them to be put under tension .
  • the cable (2) is always anchored by adhesion via this same material.
  • THE figures 16 to 18 represent a variant of the embodiment of the invention previously described.
  • a temporary formwork (29) is positioned, typically metallic, or even made of PVC according to the same location as that described in connection with the figures 7 to 9 , and this, using hangers (18).
  • These hoops are more or less regularly distributed, at a rate of around ten per meter of formwork.
  • hoops can for example be placed directly against the half-shells of the temporary formwork via covering wedges, a ligature on the tube, and longitudinal mounting steels, these arrangements avoiding a posteriori implementation of the creation of the formwork .
  • the covering of the hoops, as shown in the Figure 18 without any longitudinal steel, is improved by the use of UHPC compared to a traditional reinforced concrete situation.
  • This embodiment of the invention makes it possible to have an external UHPC skin directly at these levels, not requiring repainting or regular maintenance, and also allowing the detection of possible cracks on the system in as part of the routine monitoring of the structure in general, typically during periodic detailed inspections within the framework of a road bridge.
  • the invention is applicable in the case of detensioning of the cable (2) with a view to its replacement. To this end, we first choose the cutting point of said cable according to the constraints of access and protection of personnel.
EP23167487.0A 2022-05-05 2023-04-12 Verfahren zur lokalen wiederherstellung der spannung eines vorspannkabels und system zur überbrückung eines vorspannkabels mit diesem verfahren Pending EP4276243A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR2204263A FR3135283B1 (fr) 2022-05-05 2022-05-05 Procédé pour la reprise locale de la tension d’un câble de précontrainte et système de pontage d’un câble de précontrainte mettant en œuvre ce procédé

Publications (1)

Publication Number Publication Date
EP4276243A1 true EP4276243A1 (de) 2023-11-15

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EP23167487.0A Pending EP4276243A1 (de) 2022-05-05 2023-04-12 Verfahren zur lokalen wiederherstellung der spannung eines vorspannkabels und system zur überbrückung eines vorspannkabels mit diesem verfahren

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EP (1) EP4276243A1 (de)
FR (1) FR3135283B1 (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8959742B2 (en) * 2006-08-02 2015-02-24 Soletanche Freyssinet Method for demounting a tensioned cable, a system and associated devices
CN109137763A (zh) * 2018-10-29 2019-01-04 招商局重庆交通科研设计院有限公司 拉索切割装置及拉索拆除施工方法
FR3112561A1 (fr) 2020-07-15 2022-01-21 Soletanche Freyssinet Dispositif de pontage et procédé de détension et de découpe

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8959742B2 (en) * 2006-08-02 2015-02-24 Soletanche Freyssinet Method for demounting a tensioned cable, a system and associated devices
CN109137763A (zh) * 2018-10-29 2019-01-04 招商局重庆交通科研设计院有限公司 拉索切割装置及拉索拆除施工方法
FR3112561A1 (fr) 2020-07-15 2022-01-21 Soletanche Freyssinet Dispositif de pontage et procédé de détension et de découpe

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FR3135283B1 (fr) 2024-04-05
FR3135283A1 (fr) 2023-11-10

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