FR2783266A1 - Replaceable anchor for concrete structure pre-stressing cable has funnel, tube and anchoring assembly with cap - Google Patents

Abstract

A replaceable anchor for a concrete structure prestressing cable consists of a funnel (5) forming part of a tunnel (7) embedded in a block (4) and connected to an extension tube (6), and an anchoring assembly (16) for a multi-strand cable (13). The anchor consists of a funnel (5) forming part of a tunnel (7) embedded in a block (4) and connected to an extension tube (6), and an anchoring assembly (16) for a multi-strand cable (13). The funnel has an orifice (9) for injecting a self-setting protective product (30) such as cement mortar, and a cap (19) to retain grease (22), and the other end of the tube (6) is connected to a sleeve (3) by a coupling (12).

Description

The invention relates to the field of prestressing

  exterior of concrete or similar structures.

  In this field, the invention is exposed relative to the external prestressing by cable. However, the invention is also applicable to external prestresses by wires or bars, although

  that they are not described further.

  So thereafter, the term "cable" is used to designate in general terms, a prestressing element

any exterior.

  Current external prestressing techniques use: steel cables, with a variable number of strands, the latter comprising twisted wires; and - anchoring members, ensuring the individual blocking of each strand, with wedging structures, housed

in tapered holes.

  The invention aims more specifically to provide: - a replaceable anchor member; - a mixed protection device, for such an anchoring member; - a replaceable external prestressing system; and - a structure such as a bridge or building, provided with at least one

such organ, device or system.

  The operation of the external prestress is dependent on that of the anchoring members. Ideally, these components should both: resist corrosion; - protect the cables against corrosion; continue to perform their function in the event of occasional overvoltages; and - allow disassembly and subsequent replacement of cables. The techniques currently used currently are: - rigid protection, by injection of cement grout; - flexible protection by injection of grease or special wax; or

- mixed protection.

  The rigid protection responds well to the requirements of protection against corrosion. However, this technique

  limits the phenomenon of cable self-anchoring.

  To ensure disassembly with such techniques, a double casing is necessary in the crossing of the concrete of the anchor blocks. This makes these techniques complex and

therefore expensive.

  As for flexible protection, it generally responds well to the problems of protection, of the ability to recover

overvoltages and dismantling.

  On the other hand, this technique is expensive because of the cost and the quantities of flexible products injected and the means

  necessary for their implementation.

  Mixed protection is in theory a good compromise, but is little used in practice, due to the limitation of the volume allocated to one or the other type of protection, as well as to the difficulty of establishing in a simple way of

  watertight barriers in contact with the strands.

  For illustration, let us quote the document FR-A-2.741.097 which describes an anchoring piece for flat cable, intended for

  ensure the prestressing of a concrete structure.

  This document provides for a perforated block and a trumpet which form a single molded piece, of cast iron, intended to be

  embedded in the concrete of the structure to be prestressed.

  A grease or a protective wax for the stripped ends of the strands is introduced into a sleeve of the trumpet. Document FR-A-2.690.189 describes an internal prestressing using greased sheathed strands, all of the strands

  possibly being positioned in a tube.

  This document does not provide for disassembly.

  The invention aims to overcome the drawbacks of

known techniques.

  It aims to allow a removable and replaceable external prestress, and which can react effectively

occasional overvoltages.

  A first object of the invention is an anchoring member, for at least one cable or the like, intended to ensure the

  external prestressing of a structure.

  This anchoring member provides external prestressing via an anchor block and comprises at least: - a trumpet forming part of a tunnel, intended to be embedded in the anchor block; - An extension tube forming another part of the tunnel, projecting longitudinally from the front of the trumpet, and intended to be extended forward to the outside of the anchor block; - an outer rear face of the trumpet, substantially planar; - An anchoring head rigidly pressed against the external face of the anchoring member, the cable comprising several strands united in a sheath and having to be fixed to the anchoring member by this head; - a cover, covering the anchor head, being fixed to the trumpet; and - a separator tube, for at least one cable, extended longitudinally projecting from the rear face towards the rear, up to beyond a front end of the extension tube. The member is arranged so that each strand of a cable slides in a separator tube on the part corresponding substantially to the tunnel formed by the combination of the trumpet and the extension tube, and so that the protection of the strands and the member anchoring is ensured both by injecting a flexible protective product into the separator tube, and a product

  rigid protection around this tube.

  Other characteristics of this body provide: - that the trumpet has an injection hole for the rigid protection product, one end of which opens onto the external face of the trumpet and the other

  end opens into the tunnel formed by the trumpet.

  - that the organ is arranged so that the rigid protective product is injected into the tunnel of the trumpet and the

extension tube.

  - that the member is arranged so that the flexible protective product is injected in a clearance between the walls of each strand and the internal surface of the separator tubes

  corresponding, and inside the hood.

  - that the trumpet includes means allowing an injection device for the flexible protection product to be fixed and connected to the trumpet, to individually supply the flexible protection product

around each strand.

  - that the anchoring head comprises an anchoring block positioned against the external face of the trumpet, and provided with at least one anchoring orifice allowing the passage of

  strands and the attachment of a separator tube.

  - That a front part of at least one anchoring hole in contact with the tunnel of the trumpet, is shaped so as to receive and fix a corresponding part of the separator tube, the other rear part of this anchoring hole being of frustoconical shape for example allowing the introduction of at least one key shaped

  substantially complementary in this orifice; the key -

  and in keyways - allowing

  keep the strands in a fixed position.

  - that the separator tube and / or the extension tube are made of synthetic material, for example high density polyethylene (HDPE), of metal, of composite material,

ceramic, or the like.

  - that a heat-shrinkable sleeve, for example, ensures

  the seal between the trumpet and the extension tube.

  A second object of the invention is an external prestressing device comprising at least one cable and at

  minus an anchoring member as mentioned.

  The cable consists of several strands joined in a sheath connected to the anchoring member by a connection sleeve. The rigid protection product is injected into at least

part of the sheath.

  According to one characteristic, at least one connection sleeve has an injection pipe in order to diffuse

rigid protection product.

  In one embodiment, at least the sheath and / or a connection sleeve is made of synthetic material, for example high density polyethylene (HDPE), of metal, of material

  composite, ceramic, or the like.

  While at least one sleeve, for example heat shrink, provides sealing between the extension tube and the connection sleeve and / or between the

  connection sleeve and sheath.

  A third object of the invention is a replaceable external prestressing system, which comprises at least one anchoring member and / or at least one device for

  protection as mentioned above.

  This system comprises at least one anchor block, in

  which is embedded the anchor member.

  A fourth object of the invention is a structure such as a bridge or building, which comprises at least one anchoring member and / or at least one protection device and / or at least one external prestressing system

  replaceable, as mentioned above.

  The invention will be better understood from the description

  detailed below, with reference to the accompanying drawings,

  given by way of nonlimiting example.

  In these drawings, FIG. 1 is a schematic view of part of the external prestressing system in section along a longitudinal axis X, during the cable placement phase. FIG. 2 is a schematic view of part of the external prestressing system in section along the X axis, in

operating phase.

  Figure 3 is a schematic view of an anchoring member removed from the external prestressing system in section along the axis X. Figure 4 is a schematic view of part of the external prestressing system in section along the axis X, in

reassembly phase.

  Figure 5 is a schematic section of an anchor block, along a plane transverse to the axis X. And Figure 6 is a schematic view similar to Figure 2, in which is illustrated a system with a

  section reducer at the front duct outlet.

  In the figures, this axis X defines a longitudinal direction. The invention is described here with reference to this longitudinal direction X. The constituents of the invention are described in their current positions and orientations of use. But it goes without saying that they can take various positions or

directions.

  This is particularly the case for the storage positions and orientations of the constituents of the invention, which can

be different.

  It is specified here that the terms "rear" and "front" are considered respectively to indicate a location located on the clamping and / or injection side according to the

  longitudinal direction X, and an opposite location.

  And that the terms "radial" and "transverse" refer to directions orthogonal to the X axis, corresponding. An external prestressing system 1 comprises at least one anchoring member 2 and at least one sheath 3, visible on

Figure 1.

  Each system 1 also has an anchor block 4, for

concrete example.

  The anchoring member 2 for its part comprises at least: - a trumpet 5 embedded in the concrete of the anchoring block 4, and - an extension tube 6 extending from the

  trumpet 5 to the outside of the anchor block 4.

  In FIG. 1, the block 4 forms an integral part of a structure A, to which an external prestressing must be applied. In certain embodiments, at least one massif 4 is distinct from the structure A. It appears from the embodiment of FIG. 3, that the trumpet 5 has: - a tunnel 7 substantially extended along an axis X; an external face 8, substantially planar and substantially perpendicular to the axis X, and

  - an injection orifice 9 arranged in the trumpet 5.

  Note that here the trumpet 5 is obtained by molding a metal such as cast iron. But embodiments of the invention provide for trumpets 5 made of metal parts

mechanically welded or the like.

  You can also make the trumpet 5, in terms of

  synthetic and / or composite and / or ceramic.

  The external face 8 of the trumpet 5 is substantially parallel to and flush with an rear external surface 10a

of the anchor block 4.

  Still in FIG. 3, the reference 10b designates a face

outer front of this massif 4.

  The injection orifice 9 has a rear end 9a, opening onto the external face 8 of the trumpet 5 and a second front end 9b, opening inside the

tunnel 7.

  The trumpet 5 has, at the opposite front end of its external face 8, an end 11 shaped to ensure the connection between the trumpet 5 and the extension tube 6 extending substantially along the axis X. In FIG. 6, a reducer 11a is arranged between the extension tube 6 and the sheath 3. This reducer 11a is arranged at the front outlet of the sheath, to allow the junction of this tube 6 with the sheath 3 of radial diameter less than

that of tunnel 7.

  This reducer thus makes it possible to limit the quantity of product injected, such as grout, and to make the system less expensive. This extension tube 6 is in the example illustrated for example in high density polyethylene called "HDPE". This material in particular, makes cutting easy during disassembly. In embodiments not shown, the tube 6 is in

  metal, composite material, ceramic, or the like.

  In FIG. 1, 2 or 4, it can be seen that the junction between the anchoring members 2 and the sheath 3 is provided by a

connection sleeve 12.

  This sleeve 12 connects a front end of the sheath 3 to the rear external end 6a of the extension tube 6. A number of strands 13 pass through the sheath 3 and the anchoring members 2, substantially along the axis X. Indeed, it can be seen in these figures in particular that the strands 13 undergo towards their rear end, a slight

  radial outward inflection, just like tunnel 7.

  This aims for good accessibility at the rear, in

  particularly during the assembly and disassembly steps.

  A part of each strand 13 is positioned in a separator tube 14 which projects rearwardly from the external face 8 of the trumpet 5, up to at least the end of the

extension tube 6.

  These tubes 14 are also, in the embodiments illustrated,

made of HDPE.

  As for tube 6, in embodiments not shown, the tube 14 is made of metal, of material

  composite, ceramic, or the like.

  Sleeves 15, for example heat shrinkable, are positioned between the trumpet 5 and the extension tube 6 between the extension tube 6 and the connection sleeve 12, the connection sleeve 12 and the sheath 3, the separator tubes 14 and the strands 13 correspondents, to ensure watertightness at the junction

of these different constituents.

  An anchoring block 16 is positioned against the external face 8 of the trumpet 5, and is provided with anchoring holes 17 allowing the passage of the strands 13 and the

fixing the separator tubes 14.

  The part 17a of these anchoring holes in contact with the tunnel 7 of the trumpet 5, is shaped so as to receive and fix a part of the separator tubes 14, the other part 17b of these anchoring holes is of form allow the introduction of keys 18 of substantially complementary shape, into these anchoring holes 17. The shape of the part 17b of these anchoring holes is by

substantially frustoconical example.

  The keys 18 make it possible to hold the strands 13 in

a fixed position.

  Figures 3, 4 or 6 show a cover 19, which is positioned above the anchor block 16 and is fixed, by

  example by screwing, with a trumpet 5.

  In FIG. 2, a seal 20 seals between the

cover 19 and the trumpet 5.

  For the installation of the prestress, means 21 for injecting the flexible protective product 22 comprise, as illustrated in FIG. 1: - a distribution block 23 of the flexible protective material 22; - A seal 24 between the anchor block 16 and the distribution block 23; - Means 25 for fixing the distribution block 23 to the trumpet 5 and for clamping the distribution block 23 against the anchor block 16; and

  - a pump of which only a pipe 29 is shown.

  The distribution block 23 has, on its front face 23a in contact with the anchoring block 16, distribution orifices 26 corresponding to the anchoring orifices 17 of the

anchor block 16.

  The latter (16) is part with either the distribution block 23, or the cover 19, of an assembly called anchor head 33, visible in Figure 2 in configuration of use. The other rear face 23b, longitudinally opposite the distribution block 23 is provided with holes 27 corresponding to the distribution orifices 26, in which are fixed

  lubricators 28 acting as a valve.

  The pump is provided with the injection pipe 29 which is shaped to be able to be adapted on the, and connected in

  communication of fluid to, lubricators 28.

  The flexible protective product 22, for example grease, is injected between each strand 13 and the corresponding separator tube 14, as well as inside the

cover 19.

  A rigid protective product 30, for example cement grout, is injected into the cavity formed by the interior of the tunnel 7, the trumpet 5, the extension tube 6, the connection sleeve 12 and the

sheath 3.

  This product 22 is thus diffused from the orifice

injection 9 of the trumpet 5.

  Note that the strands 13 are on the other hand locally separated from the product 30 by the separator tubes 14, which

act as a reservation.

  The disassembly of the tensioned cable is done by cutting to the right of the connection sleeve 12, at the end of the tubes

separators 14.

  The sectioning carried out, the strands 13 and the anchoring members 2 can be separated, after dismantling the

  substantially frustoconical keys 18.

  The anchoring members 2 can thus be reused. The rigid protective product 30 is then no longer injected through the injection orifice 9 of the trumpet 5, but through the

new connection sleeve 12.

  As illustrated in Figure 4, is provided for this purpose on

  this sleeve 12 an injection pipe or event 31.

  Figure 1 shows a phase of implementation of the device. At the start, the trumpet 5 and the extension tube 6 are mutually linked and jointly poured into the massif

anchor 4.

  The anchoring block 16 is fixed in position by plating against the face 8 of the trumpet 5, and the separator tubes 14 are fixed in their housings 17a arranged

in the anchor block 16.

  The strands 13 are threaded from the rear, one by one, by a

end, in the sheath 3.

  On the side opposite to the threading, they are introduced into their corresponding separator tubes 14, through the opening 32 located between the extension tube 6 and the sheath 3,

not connected.

  The strands 13 are respectively threaded into the tubes 14

  correspondents, they are traditionally put under tension.

  The strands 13 are kept in tension thanks to the keys 18 placed in the orifices 17b of the anchoring block 16. The injection phase of the flexible protective product 22

follows these implementation phases.

  We first proceed with an injection phase of the

  flexible product 22 around the strands 13.

  The distribution block 23 is fixed to the trumpet 5 and pressed against the anchoring block 16. The flexible protective product 22 is injected by a pump, around each strand 13 into the space which exists between the edges of the strands 13

  and the inner face of the corresponding tubes 14.

  This flexible product 22, is thus channeled by the tubes

separators 14.

  This individual injection is done by adapting the

  pump successively on each lubricator 28.

  The operation is interrupted when the product leaves at

  the end of the separator tubes 14.

  The distribution block 23 is then separated from the trumpet 5, and the cover 19 is fixed to this trumpet 5,

  instead of the distribution block 23.

  The previous operation is completed by the protection of the anchor head 33 itself by filling the cover 19

  by the flexible protective product 22.

  This filling of the cover 19 can be carried out, for example, before the fixing of the cover 19, by filling this cover 19 with an excess of flexible protective product 22. By fixing the cover 19, the excess product, rejected to the outside,

is evacuated.

  Figure 2 shows the device in the operating phase. The sheath 3 and the extension tube 6 were connected via the connection sleeve 12 and the rigid protection product 30 was injected through the orifice

injection 9.

  We understand from this figure that the invention allows because of the flexibility provided by the product 22 in

  organ 2, a resistance of the prestressing system 1 -

  and in particular cables - with occasional overvoltages.

  This offers another advantage to the invention.

  FIG. 3 represents an anchoring member 2, such as after

  disassembly of the prestressing cables.

  The cutting was carried out at the sleeve of

  connection 12 at the end of the tubes 14.

  The anchor block 4, the trumpet 5, the extension tube 6 and the tubes 14 form in this state a unitary assembly, embedded in the concrete of the anchor block 4 on the one hand (radially outside), and in the rigid protective product 30 on the other hand (inside radially). Figure 4 shows an example of reuse of a

  anchoring member 2 as shown in FIG. 3.

  An anchoring block 16 is fixed to the anchoring member 2 and strands 13 are threaded in the sheath 3 then in the

separator tubes 14.

  The system is tensioned and the injection of the

  flexible protective product 22 as previously described.

  The injection of the rigid protective product 30 is carried out here by an injection pipe 31, fixed on the sleeve of

connection 12.

  There are therefore here two zones of rigid protection product 30 - that 30a, resulting from the previous implementation; and

- the newly injected 30b.

Claims (15)

  1. Anchor member (2) for at least one cable or the like, intended to ensure the external prestressing of a structure (A) via an anchor block (4), the member (2) being characterized in that that it comprises at least: - a trumpet (5) forming part of a tunnel (7), intended to be embedded in the anchor block (4); - An extension tube (6) forming another part of the tunnel (7), projecting longitudinally from the trumpet (5) and intended to be extended to the outside of the anchor block (4); - an outer face (8) of the substantially flat trumpet (5); - An anchor block (16) rigidly pressed against the external face (8) of the anchor member (2), the cable comprising several strands (13) united in a sheath (3) and having to be fixed to the 'anchoring member (2) by this block (16); - a cover (19) covering the anchoring body (16) being fixed to the trumpet (5); and - a separator tube (14) extended longitudinally projecting from the rear face (8) to beyond a front end of the extension tube (6); the member (2) being arranged so that each cable strand (13) slides in a separator tube (14) on the part corresponding substantially to the tunnel (7) formed by the combination of the trumpet (5) and the extension tube (6); and so that the protection of the strands (13) and of the anchoring member (2) is ensured both by injecting a flexible protective product (22) into the separator tube (14), and d '' a rigid protection product (30) around this tube (14).   2. Anchoring member (2) according to claim 1, characterized in that the trumpet (5) has an injection orifice (9) of the rigid protective product (30), one of the ends (9a) of which opens onto the external face (8) of the trumpet (5) and the other end (9b) opens into the   tunnel (7) formed by the trumpet (5).   3. Anchoring member (2) according to claim 1 or 2, characterized in that it is arranged so that the rigid protective product (30) is injected into the tunnel (7) of   the trumpet (5) and the extension tube (6).   4. Anchor member (2) according to one of claims 1 to   3, characterized in that it is arranged so that the flexible protective product (22) is injected into the clearance between the walls of each strand (13) and the internal surface of at least one corresponding separator tube (14), and to inside the cover (19).   5. Anchoring member (2) according to one of claims 1 to   4, characterized in that the trumpet (5) comprises means allowing a device for injecting the flexible protective product (22) to be fixed on the trumpet (5) to individually supply the protective product   flexible (22) around each strand (13).   6. Anchoring member (2) according to one of claims 1 to   , characterized in that an anchoring head (33) comprises an anchoring block (16) positioned against the external face (8) of the trumpet (5), and provided with anchoring holes (17) allowing the passage of the strands (13) and the fixing of each separator tube (14).   7. Anchor member (2) according to claim 6, characterized in that the part (17a) of the anchor holes (17) in contact with the tunnel (7) of the trumpet (5) is shaped so as to receiving and fixing a part of the separator tube (14), the other part (17b) of these anchoring holes (17) being of a shape allowing the introduction of keys (18) of substantially complementary shape in these holes (17) ; the keys (18) allowing the strands (13) to be held in a fixed position.   8. Anchoring member (2) according to one of claims 1 to   7, characterized in that each separator tube (14) and / or the extension tube (6) are made of synthetic material, for example high density polyethylene (HDPE), of metal   or of composite material, ceramic, or the like.   9. Anchor member (2) according to one of claims 1 to   8 characterized in that a sleeve (12), for example heat-shrinkable, provides sealing between the trumpet (5) and the extension tube (6).   10. External prestressing device comprising at least one cable and at least one anchoring member (2) according to   one of claims 1 to 9, the cable comprising   several strands (13) united in a sheath (3) connected to the anchoring members (2) by connection sleeves (12), characterized in that the rigid protection product   (30) is injected into at least part of the sheath (3).   11. External prestressing device according to claim 10, characterized in that at least one connection sleeve (12) has an injection pipe (31) so   to provide the rigid protection product (30).   12. External prestressing device according to claim 10 or 11, characterized in that at least the sheath (3) and / or a connection sleeve (12) is made of synthetic material, for example high density polyethylene (HDPE), metal, composite material, ceramic, or the like.   13. External prestressing device according to one of   claims 10 to 12, characterized in that at least one   sleeve (12), for example heat shrinkable, provides sealing between the extension tube (6) and the connection sleeve (12), and / or between the sleeve connection (12) and the sheath (3).   14. Replaceable external prestressing system (1), characterized in that it comprises at least one member   anchor (2) according to one of claims 1 to 9 and / or to   at least one device according to one of claims 10 to 13.   15. Work (A) such as a bridge or building, characterized in that it comprises at least one member (2) according to one of   claims 1 to 9 and / or at least one device according to   one of claims 10 to 13 and / or at least one system   (1) replaceable external prestress, according to the claim 14.