REINFORCEMENT ANCHORING DEVICE

Abstract

A device for anchoring prestressing reinforcement(s) or a structural cable such as a guy, for structural works, in particular made of concrete, including an anchor block having at least one housing configured to receive a clamping jaw for clamping a reinforcement, and an anchor sub-block, having a bearing face on which the anchor block rests and an arched shape, the concave portion of which is oriented toward the structural works.

Claims

1. A device for anchoring prestressing reinforcement(s) or a structural cable such as a guy, for structural works, comprising: an anchor block having at least one housing configured to receive a clamping jaw for clamping a reinforcement, an anchor sub-block, having a bearing face on which the anchor block rests and an arched shape, the concave portion of which is oriented toward the structural works, an element for distributing forces in the structural works on which the anchor sub-block rests.

2. The device as claimed in claim 1, wherein the anchor sub-block comprises a cementitious material.

3. The device as claimed in claim 2, wherein the cementitious material of the anchor sub-block being high performance concrete or ultra-high-performance tuber concrete.

4. The device as claimed in claim 1, wherein the element for distributing forces in the structural works comprises a cementitious material.

5. The device as claimed in claim 4, wherein the cementitious material of the sub-block is directly in contact with the cementitious material of the distribution element.

6. The device as claimed in claim 5, wherein the contacting surfaces are complementary and/or at least one out of the sub-block and the distribution element being produced with small reliefs configured to be crushed under the effect of the compression of the sub-block on the distribution element, and upon being crushed, allows more intimate contact between the sub-block and the distribution element, and/or the device comprising at least one element inserted between the sub-block and the distribution element, this element being made of non-cementitious material, selected to be crushed under the effect of the compression of the sub-block on the distribution element.

7. (canceled)

8. (canceled)

9. The device as claimed in claim 6, wherein the non-cementitious material or materials present at the interface between the cementitious material of the sub-block and that of the distribution element correspond to the shell of one or more lost molds used to mold the sub-block or the distribution element.

10. The device as claimed in claim 1, wherein the angle of opening of the concave portion of the sub-block, defined by the half-angle (a) at the apex of the cone which bears on the edge of the concave face furthest from the anchor block, and which is perpendicular to the concave surface at this edge, being between 15 and 90.

11. The device as claimed in claim 5, wherein the interface between the sub-block and the distribution element is such that the sub-block can slide in the distribution element under the effect of the compression and become more wedged therein, and at least one divider element intended to facilitate this sliding is arranged at the interface between the cementitious material of the sub-block and that of the distribution, and/or the interface between the sub-block and the distribution element having an incline such that the angle (b) formed between the interface and the tangent to the concave face at the interface is acute, and/or the surfaces of the sub-block and of the distribution element intended to bear against one another being given a shape such as to ensure that, despite the manufacturing tolerances, the distribution of the stresses remains favorable to the good mechanical strength of the sub-block and of the distribution element.

12. (canceled)

13. (canceled)

14. The device as claimed in claim 5, the distribution element having a compressive strength greater than that of the concrete of the structure, having a shape widening toward the structural works, and/or being without a strengthening reinforcement.

15. (canceled)

16. (canceled)

17. The device as claimed in claim 1, wherein the bearing face of the anchor sub-block being concave toward the anchor block and the anchor block having a convex inner face of complementary shape.

18. The device as claimed in claim 1, the anchor block being made of cementitious material or the anchor block being made of metal and the bearing face being flat, and/or the anchor sub-block being without reinforcement, and/or the anchor block having a plurality of housings for receiving clamping jaws for clamping the reinforcements.

19. (canceled)

20. (canceled)

21. (canceled)

22. Structural works made of concrete comprising at least one prestressing reinforcement, in the concrete structure of the structural works, kept under tension by means of an anchoring device as defined in claim 1.

23. The structural works as claimed in claim 22, a concrete structure in which the distribution element is embedded and/or a duct opening via a flared portion onto the distribution element.

24. (canceled)

25. A method for anchoring at least one prestressing reinforcement or structural cable of structural works, comprising: anchoring of the reinforcement within an anchor block of an anchoring device as defined in claim 1.

26. The method as claimed in claim 25, comprising tensioning the reinforcement or reinforcements by means of a cylinder bearing on the anchor block or on the sub-block.

27. A method for manufacturing a device for anchoring prestressing reinforcement(s) or a structural cable for structural works, a device as claimed in claim 1, the device comprising: an anchor block having at least one housing configured to receive a clamping jaw for clamping a prestressing reinforcement or a structural cable, an anchor sub-block comprising a cementitious material, having a bearing face on which the anchor block rests and an arched shape, the concave portion of which is oriented toward the structural works, in which method the anchor sub-block is produced by means of equipment for molding or extrusion of cementitious material.

28. The method as claimed in claim 27, the anchor sub-block being produced in an on-site workshop and/or being arranged at least partially in a recess in the structural works, the anchor block or the sub-block is counter-molded on the other and/or the anchoring device comprising a distribution element, in which method either the sub-block or the distribution element is counter-molded on the other.

29. (canceled)

30. (canceled)

31. (canceled)

32. A system for anchoring prestressing reinforcements, for an anchoring device as claimed in claim 1, comprising clamping jaws for clamping the reinforcements and an anchor block made of UHPFC, having housings, for receiving the jaws and ensuring the reinforcements are wedged under the effect of the tension therein, the anchor block having a face through which the forces are transmitted to the structure, this face being convex toward the structure.

33. The system as claimed in claim 32, the housings for receiving the jaws comprising metal inserts having at least one portion of conical shape, and/or the system comprising as many housings for the reinforcements as there are reinforcements, and/or the anchor block comprising a bursting reinforcement at its periphery, on the side away from the face that transmits the forces, and/or the anchor block comprising a bursting reinforcement at its periphery, on the side away from the face that transmits the forces, and/or having an outer surface widening toward the face that transmits the forces.

34. (canceled)

35. (canceled)

36. (canceled)

37. An anchor sub-block for a device for anchoring prestressing reinforcement(s) or a structural cable such as a guy, for structural works, this device comprising: an anchor block having at least one housing configured to receive a clamping jaw for clamping a reinforcement, an anchor sub-block, having a bearing face on which the anchor block rests and an arched shape, the concave portion of which is oriented toward the structural works, the sub-block being made of HPC or UHPFC, comprising a bearing face for receiving the anchor block for anchoring prestressing reinforcements, passages for the prestressing reinforcements, a force-transmitting peripheral portion and a central portion defining, on the side opposite to the bearing face, a concave portion, the peripheral portion having an end face joined, forming an acute angle (b) with the tangent to the concave surface having the concave portion, and/or the sub-block having an outer shape of revolution or with axial symmetry about the axis (X) along which the tension is applied in the reinforcements, and/or the bearing face being concave in shape, and/or the bearing face being flat, and/or the sub-block consisting exclusively of UHPFC, without integrated reinforcement.

38. (canceled)

39. (canceled)

40. (canceled)

41. (canceled)

42. A distribution element, for an anchoring device as defined in claim 1, comprising a body made of HPC, traversed by a central opening for the passage of the prestressing reinforcements, having a surface receiving an anchor sub-block and a peripheral outer surface which widens in the direction away from the surface, and/or the central opening having a cross section that increases toward the anchor sub-block.

43. (canceled)

44. An anchoring device for concrete structural works, comprising an anchor block serving to keep under tension prestressing reinforcements or a structural cable, an anchor sub-block on which the anchor block rests, and a distribution element to be embedded at least partially in the concrete structure of the structural works, the anchor sub-block and the distribution element being made at least partially of cementitious materials of compressive strength greater than that of the concrete of the structure, the compressive strength of the anchor sub-block being greater than that of the distribution element, the anchor sub-block, and/or the distribution element, wherein the system is a system for anchoring prestressing reinforcements, that comprises clamping jaws for clamping the reinforcements and an anchor block made of UHPFC, having housings, for receiving the jaws and ensuring the reinforcements are wedged under the effect of the tension therein, the anchor block having a face through which the forces are transmitted to the structure, this face being convex toward the structure; wherein the anchor sub-block is an anchor sub-block for a device for anchoring prestressing reinforcement(s) or a structural cable such as a guy, for structural works, the device comprising: an anchor block having at least one housing configured to receive a clamping jaw for clamping a reinforcement, an anchor sub-block, having a bearing face on which the anchor block rests and an arched shape, the concave portion of which is oriented toward the structural works, the sub-block being made of HPC or UHPFC, comprising a bearing face for receiving the anchor block for anchoring prestressing reinforcements, passages for the prestressing reinforcements, a force-transmitting peripheral portion and a central portion defining, on the side opposite to the bearing face, a concave portion, the peripheral portion having an end face joined, forming an acute angle (b) with the tangent to the concave surface having the concave portion, and/or the sub-block having an outer shape of revolution or with axial symmetry about the axis (X) along which the tension is applied in the reinforcements, and/or the bearing face being concave in shape, and/or the bearing face being flat, and/or the sub-block consisting exclusively of UHPFC, without integrated reinforcement; and wherein the distribution element comprises a body made of HPC, traversed by a central opening for the passage of the prestressing reinforcements, having a surface receiving an anchor sub-block and a peripheral outer surface which widens in the direction away from the surface, and/or the central opening having a cross section that increases toward the anchor sub-block.

Description

[0074] A better understanding of the invention may be gained on reading the following detailed description of non-limiting embodiments of the invention, and on examining the attached drawing, in which:

[0075] FIG. 1 schematically and partially shows concrete structural works having an anchoring device according to the invention,

[0076] FIG. 2 shows, in axial section, an alternative anchoring device according to the invention,

[0077] FIG. 3 shows an alternative embodiment of a sub-block, with the anchor block shown placed on top,

[0078] FIG. 4 is a view similar to FIG. 2, of an alternative embodiment of the anchoring device,

[0079] FIG. 5 shows an example of a relief that may be produced on the face of the anchor sub-block intended to bear on the distribution element,

[0080] FIG. 6 shows the use of a divider element at the interface between the anchor sub-block and the distribution element,

[0081] FIG. 7 is an example of a lost mold which may be used for molding the anchor sub-block and,

[0082] FIG. 8 shows the possibility of replacing the distribution element with a corresponding shape produced directly on the structural works.

[0083] FIG. 1 partially shows structural works comprising a concrete structure 1 within which at least one anchoring device 10 according to the invention is integrated.

[0084] This anchoring device 10 serves to keep under tension (anchor) reinforcements 3 constituting cables, for example cables formed from a bundle of substantially parallel strands, of all grades of steel, galvanized, greased and/or sheathed individually. Each strand of the cable may itself be made up of multiple wires. The cable formed by reinforcements 3 connected to the same anchoring device may be made up, for example, of from 1 to 61 strands, better still from 2 or 3 to 61, each strand being, for example, a T15.7 strand. The number of reinforcements may be even higher for a guy, for example up to 200.

[0085] The reinforcements 3 are not limited to cable strands, and may be wires or threaded bars, in which case they are tensioned by tightening a nut engaged on the thread of the bar.

[0086] The reinforcements 3 may or may not be bonded to the structure 1, depending on whether the prestressing is bonded or unbonded.

[0087] The reinforcements 3 pass through the structure 1 by means of a duct 8, which may be covered internally with a sheath 58, for example made of a thermoplastic material or a ribbed (ringed) metal strip. The reinforcements 3 may be embedded within the duct in a grease, in the case of unbonded prestressing, or in a cement grout which sets, in the case of bonded prestressing.

[0088] The structural works 1 preferably have, as shown, a recess 2 for receiving a seal or a cap (not shown) for protecting the anchoring device 10, after fitting and tensioning of the reinforcements 3.

[0089] The concrete of the structure 1 has a conventional compressive strength, typically of the order of 30 to 35 MPa, for example between 20 MPa And 45 MPa.

[0090] The anchoring device 10 comprises, in the example shown, an anchor block 20, a sub-block 30 and a distribution element 40, also known as a trumplate by analogy with existing distribution elements.

[0091] The anchor block 20 serves to retain the ends 3a of the reinforcements 3, by virtue of jaws 21 of conical shape, each made up of keys and a retention ring 59, in a conventional manner.

[0092] The jaws 21 are received in metal inserts 22, themselves arranged in housings 29 of complementary shape in the anchor block 20. The inserts 22 have a conical shape where the jaws 21 are received, such that traction on the reinforcement 3 engaged in the jaw 21 is accompanied by radial clamping and indentation of the jaw 21 on the reinforcement, this being stronger the more intense the traction.

[0093] In the example shown, only three reinforcements 3 are visible, but the invention is not limited to a particular number of prestressing reinforcements, or to a particular arrangement of these reinforcements with respect to the axis X of the anchoring device 10.

[0094] In the example of FIG. 1, the anchor block 20 is made of UHPFC, with a bursting reinforcement 23 in the upper part, at its periphery, in the form of a metal hoop.

[0095] The anchor block 20 has a base 25 widening toward an inner face 24, which is convex toward the structure 1. The base 25 has, for example, a frustoconical peripheral outer surface, of revolution or not about the axis X, preferably with axial symmetry. The reinforcements 3 may be arranged in a hexagonal configuration around a central reinforcement (or a central triplet), for example.

[0096] The lower face 24 has, for example, the shape of a spherical cap.

[0097] The sub-block 30 is also made of UHPFC, in the example shown.

[0098] It has a body traversed by as many holes 31 as reinforcements 3. These holes are each lined with a sheath 57 in the example shown.

[0099] The sub-block 30 has a bearing face 32 of concave shape, complementary to the convex face 24 of the anchor block 20, for example in the shape of a spherical cavity of revolution about the axis X.

[0100] The sub-block 30 has a general shape of an arch, and bears on the distribution element 40 via a peripheral portion 33.

[0101] The arched face 34 of the sub-block 30, within the peripheral portion 33, is concave toward the distribution element 40 and defines under the central part of the sub-block 30 a cavity 38, into which the holes 31 for the passage of the reinforcements 3 open.

[0102] The distribution element 40 is hollow and has a central opening 41 which flares toward the sub-block 30 and which is traversed by the cables 3. In the example in question, the opening 41 is frustoconical.

[0103] The arched face 34 is for example, as shown, spherical of revolution about the axis X, but may advantageously be otherwise concave, as will be described below.

[0104] The peripheral portion 33 bears on a surface 49 of the distribution element 40 via an annular bearing surface 36 which converges toward the structure 1 and which is for example frustoconical, as shown. The bearing surface 36 is, for example, oriented substantially perpendicular to the arched face 34, as shown.

[0105] The concave portion 38 may have an opening, given by the half-angle a at the apex of the cone passing through the outer edge of the concave portion 38 and perpendicular to the concave surface 34 at this edge, of between 15 and 90, and preferably between 30 and 90.

[0106] The surface 49 of the distribution element has the same orientation as the surface 36 of the sub-block, being of complementary shape, and being at least as wide as the surface 36.

[0107] The edge 53 of the opening 41 may be located, as shown, substantially at the junction between the arched face 34 and the bearing surface 36.

[0108] The distribution element 40 has a shape that widens, i.e. flares, within the structure 1, with for example an outer surface 46 of frustoconical shape, in the extension of the sub-block 30 toward the inside of the structure 1

[0109] The distribution element 40 may be made of a material with a compressive strength in between that of the concrete of the structure 1 and that of the sub-block 30, preferably high-strength concrete HPC. A plurality of force transmission elements are thus arranged between the anchor block 20 and the concrete of the structure 1, the strength of which is decreasing from the reinforcements 3 to the element 40 in contact with the concrete of the structure, and the size (in particular the largest dimension) of which may be increasing, as shown.

[0110] The distribution element 40 may have an end face 47 perpendicular to the axis X, as shown in FIG. 1, that is to say perpendicular to the direction in which the stress is exerted in the structure 1.

[0111] To use the device of FIG. 1, the distribution element 40 is positioned in the extension of the duct 8, and the concrete of the structure 1 is poured. The opening 41 in the distribution element 40 may be connected to a sheath 52 lining the duct 8 by a transition element (not shown) of generally conical shape, also called a trumpet, which may simply be a flared tube. After the concrete of the structure 1 has been poured, set and the formwork removed, the reinforcements 3 are inserted into the duct 8 and through the distribution element 40.

[0112] The sub-block 30 and the anchor block 20 are then put in place with the jaws 21.

[0113] A cylinder, preferably a hydraulic cylinder, is then used for tensioning the reinforcements 3, which are anchored under tension in the anchor block 20 by wedging the jaws 21 on each reinforcement 3.

[0114] The sub-block 30, made of UHPFC, and the distribution element 40, made of HPC, may be cast or extruded on site, i.e. in a workshop located close to the construction site (typically less than 50 km). The same applies, where appropriate, to the anchor block 20 when the latter is made of UHPFC. The various metal inserts may be put in place in a suitable formwork, followed by casting or extrusion of the concrete and placing in an oven.

[0115] In order to obtain a good form fit of the bearing surfaces 36 of the sub-block 30 and 49 of the distribution element 40, they may be molded in contact with one another.

[0116] The dimensions of the anchor block 20, of the sub-block 30 and of the distribution element 40 may be parameterized as a function of the strength and the geometry of the structure 1 for which the anchoring device 10 is intended, for a given prestressing force to be distributed therein.

[0117] In particular, when the size of the distribution element 40 is sufficient, it may not be necessary to integrate, in the structure 1, passive reinforcements, in particular distribution and hooping reinforcements, close to the anchoring device 10, in particular under the latter and around the distribution element 40.

[0118] However, it is possible to integrate into the structure 1, around the duct 8, a helical reinforcement 51, as shown, to take account of the fact that the reinforcements 3 may be stressed radially by the duct 8.

[0119] The shapes given to the anchor block 20, the sub-block 30 and the distribution element 40 make it possible to stress the cementitious material of which they are composed predominantly in compression, under the effect of the tension force prevailing in the prestressing reinforcements 3. In particular, the tensile stresses in the cementitious material of these elements preferably never exceeds 1/20 of the compressive strength of the cementitious material concerned.

[0120] The sub-block 30 transmits, by its internal arched shape, the force received from the anchor block 20 via predominantly compressive internal stresses.

[0121] The distribution element 40 and the structure 1 may be molded with a duct 60 for the passage of a pipe for injecting a grease or a cement grout into the duct 8.

[0122] In the example of FIG. 1, the anchor block 20 is made of UHPFC.

[0123] In the alternative embodiments of FIGS. 2 to 4, the anchor block 20 is made of metal, being for example made of steel, and its face 24 resting on the anchor sub-block 30 is flat and perpendicular to the axis X.

[0124] In this case, the anchor sub-block 30 has a flat bearing surface 32 which is also perpendicular to the axis X.

[0125] FIG. 2 shows the possibility for the concave face 34 to be non-spherical, in this case parabolic. The concave portion 38 is thus deeper, which makes it possible to accentuate the arch function, thereby further preventing the occurrence of tensile stresses in the sub-block 30.

[0126] The angle a defined as the half-angle at the apex of the cone in which the face 36 is inscribed, is less open than the angle a in the example of FIG. 1.

[0127] The face 36 of the peripheral portion 33 makes an acute angle b with the tangent to the concave surface 34 taken at the outer edge of the concave portion 38. This angle b is, for example, of the order of 30, preferably between 15 and 90 (upper limit excluded), and better still between 20 and 60.

[0128] FIG. 3 shows the possibility for the sheaths 57 to protrude beyond the side of the concave portion 38. It is not in fact necessary to cut the sheaths to the exact profile of the concave portion, given that these sheaths 57 are closed off during the casting of the cementitious material of the sub-block 30.

[0129] The alternative embodiment of FIG. 4 differs from that of FIG. 2 in that the distribution element 40 is shallower, and by the shape of the concave portion 38.

[0130] In this case, the structure 1 may comprise surface and/or bursting reinforcements, under the distribution element 40.

[0131] It is desirable for the sub-block 30 to bear on the distribution element 40 in a relatively homogeneous manner over the entire width of the surface 36.

[0132] However, manufacturing tolerances may lead to defects in terms of evenness or slope, detrimental to a homogeneous transmission of forces.

[0133] In order to prevent disparities in the shape of the surfaces 36 and 49, the sub-block 30 may be counter-molded on the distribution element 40, or vice versa. Likewise, the anchor block 20 may be counter-molded on the sub-block 30, or vice versa.

[0134] In the absence of counter-molding, it is possible to produce on the sub-block 30 and/or the distribution element 40, striations 65 as shown in FIG. 5. These striations 65 have fragile ridges which break under the pressure exerted and which are crushed where the stresses are locally the strongest, levelling out the degree of stress across the entire surface and compensating for manufacturing tolerances. It consists in a sort of hammering of one or both of the facing surfaces.

[0135] It is also possible, as shown in FIG. 6, to insert at least one divider element 70 between the sub-block 30 and the distribution element 40.

[0136] This divider element 70 may be crushed under the pressure of bearing of the sub-block 30 on the distribution element 40 and thus absorb, by local deformation, the highest stresses by the redistribution effect.

[0137] The divider element 70 may be a strip of a ductile metal, for example lead, or a sheet of a polymeric material.

[0138] The divider element 70 may also promote the sliding of the sub-block 30 relative to the distribution element 40 when an acute angle of wedging b exists.

[0139] FIG. 7 shows the possibility of producing the sub-block 30 using a lost mold 80. The latter may have an opening 81 on the side for filling. In this case, the wall of the mold 80 constitutes an element which is inserted between the surface made of cementitious material of the sub-block and that of the distribution element 40 and which may play the role of the aforementioned divider element.

[0140] The distribution element 40 may also be produced using a lost mold, as may the anchor block 20.

[0141] Naturally, the invention is not limited to the examples that have just been described.

[0142] For example, the shape of the anchor block, the anchor sub-block and the distribution element may be modified to give them another shape, while still allowing the cementitious material of which they are composed to be stressed predominantly in compression.

[0143] The anchor sub-block may have a shape without symmetry of revolution, with or without axial symmetry, with, for example, multiple, substantially radial or non-radial arches starting from the central body.

[0144] The arched face 34 of the sub-block 30 may or may not have one or more ridges, with one or more facets, in the form of an ogive, a cone, a quadric, a pointed arch. Preferably, however, the presence of ridges will be avoided.

[0145] Also preferably, the shape of the arched face is such that it has an inclination (slope) with respect to the plane normal (orthogonal) to the axis X at its apex, which increases away from this plane, preferably continuously. The variation in the slope is thus monotonous. The curve (not being inverted) may or may not be regular.

[0146] The anchor sub-block 30 may be made with a peripheral portion 33 which is not solid and continuous in an annular shape but has apertures, which extend for example as far as the distribution element 40 so as to form separate legs for bearing on the latter.

[0147] The surface 36 of the sub-block 30 may be indented, and the distribution element 40 is thus advantageously indented in a complementary manner. Such a form fit may be relatively easy to create when the sub-block 30 is molded in contact with the distribution element or vice versa.

[0148] The bearing face 32 of the sub-block intended to receive the anchor block 20 may be non-spherical, for example in the form of a cone, an ogive, a quadric, in particular a paraboloid.

[0149] The outer peripheral surface of the anchor block or sub-block may be of revolution or not, preferably with axial symmetry. For example, the shape of the block, of the sub-block or of the distribution element is generated by n repetitions of the same pattern by rotating by an angle of 360/n, n being equal to 3, for example, in particular in the case of a hexagonal mesh for the bundle of reinforcements 3.

[0150] FIG. 8 shows the possibility of replacing the distribution element 40 by a corresponding complementary shape made directly within the structural works 1. This is possible when the cementitious material of the structural works has sufficient mechanical strength, for example a concrete of strength class C80/95 or greater.

[0151] The complementary shape has, as shown, a cone for receiving the anchor sub-block 30, against which the face 36 of the anchor sub-block bears.

[0152] Although the invention is particularly suitable for concrete structural works, the invention may also be applied to a masonry or mixed, for example steel/concrete, structure.

[0153] Although a cementitious material is preferred for producing the anchor sub-block, it is also possible, as an alternative, to use materials less expensive than steel, such as cast iron, or a polymer-based composite material.