HK1038251B - Anchoring device for fixing a structural cable to a building element - Google Patents

Description

The present invention relates to anchorages for attaching structural cables to structural elements.

In particular, the invention is applied whenever it is necessary to attach a cable subjected to tensile stresses to equip structural elements such as drawbridges, suspension bridges or other bridges by connecting the tops of the pylons of these bridges to their fore-ends and anchorages.

The cables usually found in such construction elements comprise a plurality of strands which have each of the metal wires themselves wrapped together in a protective sheath, each of these protective sheaths being broken at a terminal slice so that the strands each have a bare end section.

The anchorages commonly encountered, and in particular in EP-A-0 323 285, include: a perforated block on which the bare end sections of the various strands are individually anchored,a span which is solid with the structural element and against which the perimeter of the perforated block is supported axially,a tube to which the perforated block is connected on the side of the span, the tube delimiting transversely a chamber within which the terminal slices of the strands are located and which is filled with a material to protect the bare end sections present in the chamber, and a press-stop which seals the chamber, opposite the anchorage block, and which is sealed through by the threaded gauges, the press-stop comprising: . at least two perforated plates, one of which, the inner plate, is placed on the side of the chamber and the other, the outer plate, is placed on the opposite side of the perforated block from the inner plate, and . at least one buckle cushion which is placed between the inner and outer plates.

In the known embodiments of the stoppers found in anchorages of the type in question, the inner plate of the stopper is fixed while the outer plate is movable and is drawn to the fixed plate by means of threaded rods through the perforated block and put into tension.

In order to ensure a good seal on the anchorage, the cushion of the press-stop can be compressed again by pulling on the outer plate if necessary, but the ends of the threaded rods screwed into the outer plate are on the cable side and are therefore not accessible to the operator without dismantling the entire anchorage.

Such an anchorage system therefore requires large and expensive maintenance operations since the mechanical parts are located in hard-to-reach places.

The purpose of the present invention is to remedy the above disadvantages by providing an anchorage device to facilitate maintenance operations.

To this end, according to the invention, an anchorage device of the type in question is characterised by the fact that the outer plate is fixed in relation to the chamber and that the device includes means of support on the inner plate.

Thus, thanks to these arrangements, all the components of the buffer are protected against corrosion and the elements which enable the buffer pad to be compressed are accessible from the side of the anchorage device opposite to the side from which the cables extend and therefore do not involve costly dismantling.

In preferred embodiments of the anchorage according to the present invention, one or both of the following arrangements are used in addition: The means of support on the inner plate consist of a compression rod with one end in a plug on the inner plate and the other end through a hole in the perforated block and is actuated from the side of the perforated block opposite the solid span of the structural element;the compression rod is a threaded rod and the hole is threaded, the rod being actuated by screw;the compression rod is actuated against an interposition plate mounted adjacent to the inner plate;the means of support consist of a plug which is solid in the tube and is located inside the tube at a distance from the outer face of the outer plate to the inside;the inside of the tube is narrowly slit;the inside of the tube is narrowly slit;the inside of the tube is narrower than the outside;the inside of the tube is narrower than the outside;the inside of the tube is narrower than the inside;the inside of the tube is narrower than the outside;the inside of the tube is narrower than the inside;the inside of the tube is narrower than the outside;the inside of the tube is narrower than the inside;the inside of the tube is narrower than the outside;the inside of the tube is narrower than the inside;the inside of the tube is narrower than the inside;the inside of the tube is narrower than the inside;the inside of the tube is narrower than the inside;the inside of the tube is narrower than the inside;the inside of the inside is narrower than the inside;the inside of the inside is narrower than the inside;the inside is defined by a narrower than the inside;the inside is defined by a narrower than the inside;the inside is defined by a narrower than the inside is defined by a narrower;the inside is defined by a narrower than the inside is defined by a narrower and the inside of the inside of the inside is defined by a narrower;the inside is defined by a narrower;the inside the inside is defined by a narrower and the inside of the inside is defined by a narrower;the inside is a narrower is defined by a narrower than the inside the inside of the inside is defined by a narrower; the The protective material is compressed in the chamber; and a hood is mounted tightly on the perforated block.The test shall be carried out in a chamber with exposed end strands protruding, the chamber being filled with the said protective material.

Other features and advantages of the invention will be shown in the following detailed description of two of its embodiments, given as non-limiting examples, in relation to the attached drawings on which: Figure 1 is a general schematic view of a suspension bridge whose cables are held in place by means of anchorages according to the present invention; Figure 2 is a cross-sectional view of a cable in Figure 1; Figure 3 is an enlarged view of one of the strands making up the cable in Figure 2; Figure 4 is a longitudinal view of a first mode of cable anchorage in Figures 2 and 3; Figure 5 is a longitudinal view of a second mode of anchorage to secure the cable in Figures 2 and 3; and Figure 6 is a longitudinal view of the enlarged press-cutting device in Figure 5.

The construction element 1 shown in Figure 1 is, for example, a suspension bridge, which typically consists of a deck 2, two pillars or pylons 3, two parallel support cables 4, one of which is visible in the figure, and a plurality of suspensions 4a which are attached to the cables 4 and which support deck 2.

The support cables 4 are stretched between two ground anchorages 9 at either end of the bridge and are supported by two pylons 3.

As shown in particular in Figure 2, the cable 4 in question is composed of a plurality of individual strands 5.

Each strand 5 is itself formed, as shown in Figure 3, of a plurality of 6 elementary wires, e.g. seven in number. These wires can be parallel or twisted and are made of galvanized or galvanized steel, for example. The whole of these wires is surrounded by a protective sheath 7 which is able to protect them throughout their life from corrosion due to weather or other external aggression, including moisture and handling. This sheath is made of a plastic material, such as polyethylene or polyamide, or a metal such as aluminum or stainless steel. The sheath is directly applied to the extrusion beam.

The sheath may also be made up of any other desirable coating of the strand 6, for example epoxy coated on it.

The spaces between thread 6 and sheath 7, if any, may or may not be filled with a protective substance 8 such as, for example, a resinous epoxy-type liner or wax or polybutadiene.

The 5 threaded wires thus defined are all identical with each other, are independent and remain so throughout the life of the cable 4 they constitute.

The threaded strands 5 of cable 4 are individually tensioned in a way that is known to itself on deck 1. For example, the mounting is done by means of threaded sleeves or, as shown in Figures 4 and 5, by tightening the ends of the threaded strands 5 into split strands 10.

For this purpose, each of the protective sheaths 7 of the 5 strands is broken at a terminal slice T so that each strand 5 has a striped end 11 section.

The bare end sections 11 are clamped in the split strands 10 which each have on the one hand a tapered cylindrical hole capable of joining the end of the anchorage strand and on the other hand a truncated outer surface capable of cooperating with a complementary housing fitted in a perforated anchorage block 15.

Each 5th beam is thus tensioned between, for example, a pillar 3 of bridge 1 and the solid perforated block 15 of, for example, one of the anchorages 9 of that bridge.

The perforated block 15 has two opposite faces: an outer face 16 and an inner face 17. The outer face 16 is facing the opposite side of the strands 5. The ends 12 of the end sections 11 protrude on this side. The inner face 17 is facing the side of the strands 5.

To protect end sections 11 of yarns 5 from corrosion, the T-terminal sections of each of these yarns are located inside a chamber 20 delimited by: at the first axial end, through the inner face 17 of the perforated block 15, transversely, by a rigid tube 22 which is for example cylindrical in shape with a circular base and which is screwed or welded at one end to be adjustable or fixed in relation to the inner face 17 of the perforated block 15; and at the axial end opposite to block 15, by a clamping press 25 which is seamlessly passed through by the threaded strands 5 and which is pressed seamlessly against the inner face 23 of the tube 22 by axial compression.

The plunger 25 is known to consist of three perforated plates 26, 27 and 28 between which are placed two cushions 29 and 30 made of elastomer or similar material.

The perforated plates 26 to 28 are rigid plates of plastic material and all the plates and cushions extend transversely to the 5 strands to be passed through them. The plate 26 is an outer plate located at the end of the tube 22 facing the current part of the cable i.e. the side from which the 5 strands extend towards the pylon 3. This plate is kept in a fixed position relative to chamber 20 being in a buttressed position against a return 32 saved at the end of the tube 22.

Plates 26 to 28 keep the cushions 29.30 in compression to inflate the cushion edges and ensure the desired sealing capacity.

In the first embodiment shown in Figure 4, the supporting means 35 consist of a perforated interposition plate 36 which is applied to the inner plate 28 and 37 threaded rods (one only shown in Figure 4).

A first end of the threaded rod or screw 37 is supported against the interposition plate 36 while the second end of the rod 37 passes through a grooved hole in the perforated block 15 so that the head 38 protrudes on the outer face 16 of that block.

The intermediate plate 36 is pushed back by screwing threaded rods or screws 37 during this compression, the interposition plate 36 moves the inner plate 28 closer to the outer plate 26 which remains fixed.

In order to immobilise the perforated block 15 in relation to anchorage 9, a tuning tube 40 is mounted solidly on the outer face of the tube 22 in the vicinity of the end of this tube adjacent to the perforated block 15 while a ring 41 is screwed onto an additional thread fitted to the tuning tube 40. This ring is axially supported against a ring span 42 forming part of the anchorage 9.

In addition, a hood 45 is mounted tightly on the outer face 16 of the punched block 15 and is held on it by means of a screw 46. This hood delimits a chamber 47 in which the ends 12 of the exposed end sections 11 of the strands 5 are located and which contains a flexible material to protect against corrosion of these ends.

Chamber 47 is filled for corrosion protection through an opening which is then closed by a plug 48. Chamber 47 communicates with chamber 20 by cleaning passages in perforated block 15 (not shown).

After tensioning the strands 5 and applying compression to the interposition plate 36 with the threaded rods or screws 37, both chambers 20 and 47 are filled with the material to protect the bare strands 5 from corrosion.

This arrangement allows each strand 5 to be independent throughout its length and can be stretched or loosened independently of its neighbours.

Similarly, cushions 29 and 30 can be periodically easily compressed to maintain good sealing by screwing the heads 38 of the screws which are easily accessible from the outer face 16 of block 15.

The second method of construction shown in Figures 5 and 6 differs from the previous method only in the shape of the supporting materials 35, the diameter of the clearance passages in the cushions 29 and 30, and the end of the tube opposite the anchorage block.

In addition, a 51-throw is inserted at the end of tube 22 which is opposite the anchor block 15. The tube 22 thus has at its end a section of inner diameter which is greater than the inner diameter of the rest of the tube. A 52-throw is defined by this change in diameter. The three perforated plates 26 to 28 and the 29th and 30th passages are inserted into this 51-throw by the end of the tube 22. The plates and the cushions are in a direct contact with the 52th and are held in contact with each other by means of a compression handle.

Alternatively, a perforated plate replaces the shutter sleeve and is screwed to the end of the tube 22.

When strands 5 are inserted into the stopper, the additional material from cushions 29 and 30 due to the reduced diameter of the passages 50 is compressed against the throat 51, which ensures a very good seal.

The sealing is further improved when inserts are removed and inserted into the press-stop so that the material of the cushions is pushed back even further.

In another variant, the material of chamber 20 is compressed so that the inner plate 25 of the press-stop is pushed back towards the outer plate which remains fixed.

Claims (10)

1. Anchoring device for securing a structural cable (4) to a building element (9), said cable (4) comprising a number of strands (5) each of which comprises metal wires (6) themselves enveloped together in a protective sheath (7), each of the protective sheaths (7) being interrupted at a terminal edge (T) so that the strands (5) each have a bared end portion (11), the anchoring device comprising:

   - a perforated block (15) in which the bared end portions (11) of the various strands (5) are individually anchored,

   - a bearing surface (42) which is secured to the building element (9) and against which the periphery of the perforated block (15) axially bears,

   - a tube (22) to which the perforated block (15) is attached on the bearing surface side, the tube (22) transversely delimiting a chamber (20) inside which the terminal edges (T) of the strands (5) are located and which is filled with a substance that protects the bared end portions (11) present in the chamber (20), and

   - a packing box (25) which seals the chamber (20), at the opposite end to the anchoring block (15), and which has the sheathed strands (5) passing in a sealed manner through it, the packing box (25) comprising

   . at least two perforated plates (26, 27, 28) of which one, known as the inner plate (28), is arranged on the same side as the chamber (20) and of which the other, known as the outer plate (26), is arranged at the opposite end to the perforated block (15) with respect to the inner plate (28), and

   . at least one piece of packing (29, 30) which is inserted between the inner plate (28) and the outer plate (26),

   characterized in that the outer plate (26) is stationary with respect to the chamber (20) and in that the device comprises means (35) for pressing on the inner plate (28).
2. Anchoring device according to claim 1, in which the means (35) for pressing on the inner plate (28) comprise a compression rod (37), one end of which is in abutment against the inner plate (28) and the other end of which passes through a hole made in the perforated block (15) and which can be actuated from the opposite side of the perforated block (15) to the bearing surface (42) secured to the building element (6).
3. Anchoring device according to claim 2, in which the compression rod (37) is a threaded rod and the hole is tapped, the rod being operable by screwing.
4. Anchoring device according to claim 2 or 3, in which the compression rod (37) is in abutment against an insert plate (36) fitted adjacent to the inner plate (28).
5. Anchoring device according to claim 1, in which the pressing means (35) comprise a stop (52) which is integral with the tube (22) and which is situated inside the tube at a distance from the outer face of the outer plate (26) that is more or less equal to the thickness of the packing box (25), and in which said at least one piece of packing (29, 30) is perforated with passages (50) of a diameter smaller than the diameter of the sheathed strands (5).
6. Anchoring device according to claim 5, in which the packing box (25) is placed in a groove (51) formed inside the tube (22) and the stop (52) is defined by the step between the groove (51) and the main part of the tube (22).
7. Anchoring device according to any one of claims 1 to 6, in which the outer plate (26) is in abutment against a stop sleeve (53) attached to the end of the tube (22) by screwing.
8. Anchoring device according to any one of claims 1 to 6, in which the outer plate (26) is in abutment against a perforated plate attached to the end of the tube (22).
9. Anchoring device according to any one of claims 5 to 8, in which the protective substance is compressed in the chamber (20).
10. Anchoring device according to any one of claims 1 to 9, in which a cap (45) is sealed onto the perforated block (15), delimiting a chamber (47) into which the bared end portions (11) of the strands (5) project, the chamber (47) being filled with said protective substance.