HK1038252B - Cable with parallel wires for building works structure, anchoring for said cable, and anchoring method - Google Patents

Description

The present invention relates to the field of reinforcement used in construction structures.

The invention relates in particular, but not exclusively, to such structures as are intended to equip drawbridge, suspension or other bridge.

In the known embodiments of reinforcements of the type in question, see for example EP-A-0855471, the various constituent wires are usually twisted around a central wire. This arrangement is used to make a yarn, also called a toron, from yarns of reduced diameters.

Winding the peripheral wires around a central wire binds the strands together and reduces the bending inertia of the assembly, thus producing a reinforcing unit from very high strength wires.

However, the production of the twisted or torsion thread requires a special torsion operation which is expensive, and which causes a differential elongation between the central wire and the peripheral wires, which means that the peripheral wires are less stressed than the central wire, inducing a lower apparent modulus of elasticity of the thread than that of each constituent wire.

In addition, the fatigue behaviour of a strand as defined above is less efficient than that of the yarn which constitutes it, since the differential elongation between the peripheral wires and the central wire causes differential movements with radial pressure and therefore friction between the wires which is not favourable to fatigue.

An additional disadvantage is the nuts resulting from the thinning which creates a stiff steel with residual internal stresses making it less ductile and therefore susceptible to creep or relaxation depending on the type of stress. To try to reduce this disadvantage, an operation is carried out by applying a high temperature of about 400°C. This operation is costly and can be tricky because it requires high temperature precision when the wires are galvanized or galvanized.

In addition, in order to obtain good corrosion protection, it is customary to extrude a plastic film onto the yarn. Prior to this extrusion operation, a spacer device allows the spaces between the threads around the central wire to be filled with a flexible product such as grease or wax.

The purpose of the invention is to remedy the aforementioned disadvantages by providing a reinforcement whose mechanical performance is equivalent or even equal to that of each of the wires which make up it.

To this end, according to the invention, a reinforcement of the type in question is essentially characterised by the fact that the wires are substantially parallel to each other to form a beam and that it comprises a plastic sheath which has a lobed inner wall which is fitted with hollows and protrusions, the peripheral wires being lodged in the hollow and the protrusions extending into the throats.

This arrangement preserves the cohesion of the resulting reinforcement while the mechanical characteristics of the reinforcement are equivalent or equal to those of a constituent wire.

In preferred embodiments of the reinforcement according to the invention, one or both of the following are also used: The full yarns are metal yarns; the full yarns are composite yarns; the sheath has a circular outer wall with a cross-section; the sheath has a lobed outer wall with a cross-section; the sheath has a substantially polygonal outer wall with a cross-section; the sheath and the yarns delimit gaps which are filled with a lubricant selected from the wax and grease; and the sheath and the yarns delimit gaps which are filled with a bonding device.

In addition, the invention also concerns a construction structure cable comprising at least two reinforcements as defined above.

The invention also concerns a process for conditioning a reinforcement as defined above by parallel winding on a lathe by completing a complete twist on a lathe.

Finally, the invention relates to a process for implementing a reinforcement as defined above in a construction work, consisting in stripping the full wires in at least one part of the reinforcement and anchoring the stripped wires to at least one part of the construction work so as to make the reinforcement work in tensile motion.

The advantage is that all the wires in the reinforcement are locked together in a mooring.

Other features and advantages of the invention will be shown in the following detailed description of several 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 comprising reinforcements according to the present invention; and Figures 2 to 6 are respectively cross-sectional views of a reinforcement according to a first, second, third, fourth and fifth embodiment.

The structure of building 1 shown in Figure 1 is, for example, a suspension bridge, which typically has a deck 2, two pylons 3, two parallel support cables 4, one of which is visible in the figure, and a plurality of suspenders 5 which are attached to the cables 4 and which support deck 2.

The support cables 4 are stretched between two ground anchorages 6 at either end of the bridge and are supported by two pylons 3.

Each cable 4 is made up of one or more reinforcements 10 according to a first embodiment of the invention as shown in Figure 2.

Each reinforcement 10 is made up of a set of full wires 11 that form a beam wrapped in a sheath 12. The reinforcement 10 thus formed is also called a strand, and can be joined to other strands to form the cable 4.

In a strand, the 11 wires are usually seven in number and include a central wire 13 around which six peripheral wires are arranged 14. The 13 and 14 wires are parallel to each other and are made of steel, for example.

The 13th and 14th wires are in contact with each other according to their generator. Only the central 13th wire is in contact with all the other 14th peripheral wires. The 14th peripheral wire is separated from each other by two and delimits gorges 15 that are facing outwards from the beam of 13,14th wire.

The entire set of wires 13 and 14 is extruded with sheath 12 which forms an outer shell of flexible plastic material which may be HDPE or amorphous polypropylene.

Sheath 12 is hollow cylindrical in shape and has an outer wall 16 and an inner wall 17.

In the first embodiment (Figure 2), the outer wall 16 is circular in cross-section while the inner wall 17 is lobed in cross-section, and thus has 18 recesses and 19 protrusions which alternate along the circumference of the inner wall.

Peripheral cables 14 are housed in the 18 slots and the 19 protrusions extend between the 14 cables in the 15 throats, so that the peripheral cables are firmly held by the sheath.

In a second embodiment, such as that shown in Figure 3, reinforcement 20 differs from reinforcement 10 only in the shape of the outer wall of the sheath or sheath 22.

The inner wall 27 is similar to the inner wall 17 of sheath 12 of the first embodiment and has hollows 28 and protrusions 29.

The reinforcement 30 of the third embodiment shown in Figure 4 differs from the reinforcement 20 described above only in that wires 13 and 14 are immersed in a matrix of elastomer 31 such as polybutadiene or similar, which occupies the spaces between the wires 13,14. The elastomer 31 adheres to the wires by surface adhesion, preferably by chemical bonding with the sheath 22 to increase this adhesion. Alternatively, the matrix may be a lubricant such as wax or grease to reduce friction between the wires and the sheath.

In the fourth embodiment, shown in Figure 5, the reinforcement 40 differs from the reinforcement 30 shown in Figure 4 by the outer shape of the sheath 42. The outer wall 46 of this sheath is no longer lobed in cross-section but polygonal in shape. This makes it easier to juxtapose the reinforcements or strands to form a cable 50 such as that shown in Figure 6.

Alternatively, 40 reinforcements with different diameters of wires can be juxtaposed.

The yarn thus obtained by one of the methods of production has a mechanical strength, elastic modulus, fatigue performance and ductility of values equivalent and equal to those of each yarn of which it is composed.

To be conditioned and transported to the construction site, the strand is rolled up on a tourniquet by completing a twist on a lathe, the step being of the order of one to three metres, so that residual stresses in the elastic field are stored in each constituent strand.

In addition, the reinforcement obtained by one of the methods of construction is implemented in the structure 1 to have the function of one of the cables 4 or the suspensions 5. For this purpose, a portion of the reinforcement, e.g. the end, is stripped by removing the sheath. The stripped wires are fixed by means of strands, e.g. in the ground anchors 6, and the rest of the reinforcement extends towards the pillars 3 so as to make the reinforcement work in tensile.

For example, all 13,14 wires are collectively stuck in the anchorage strands.

Claims (12)

1. Reinforcement (10; 20; 30; 40) for a structure of a permanent construction (1), comprising an assembly of solid wires (13, 14) forming a bundle comprising a central wire (13) and peripheral wires (14) surrounded by a sheath (12; 22; 42) made from plastic material, which peripheral wires (14) are tangential to the central wire (13) and mutually spaced to bound grooves (15), and the sheath (12; 22; 42) is made from flexible plastic material extruded onto the bundle, which sheath (12; 22; 42) has a cylindrical external shape, characterised in that the wires (13, 14) are substantially parallel with one another and the sheath (12; 22; 42) has a lobed internal wall (17; 27) incorporating hollows (18; 28) and projections (19; 29) so that the peripheral wires (14) are accommodated in the hollows (18; 28) and the projections (19; 29) extend through the grooves (15).
2. Reinforcement (10; 20; 30; 40) as claimed in claim 1, in which the solid wires (13, 14) are metal wires.
3. Reinforcement (10; 20; 30; 40) as claimed in claim 1, in which the solid wires (13, 14) are wires made from a composite material.
4. Reinforcement (10; 20; 30; 40) as claimed in claim 1, in which the sheath (12) has an external wall (16) with a circular shape in cross-section.
5. Reinforcement (10; 20; 30; 40) as claimed in claim 1, in which the sheath (22) has an external wall (26) with a lobed shape in cross-section.
6. Reinforcement (10; 20; 30; 40) as claimed in claim 1, in which the sheath (42) has an external wall (46) with a substantially polygonal shape in cross-section.
7. Reinforcement (10; 20; 30; 40) as claimed in claim 1, in which the sheath (12; 22; 42) and the wires (13, 14) bound interstices which are filled with a lubricant selected from wax and grease.
8. Reinforcement (10; 20; 30; 40) as claimed in claim 1, in which the sheath (12; 22; 42) and the wires (13, 14) bound the interstices which are filled by means of a bonding device.
9. Cable (4; 5; 50) for a structure of permanent construction comprising at least two reinforcements (10; 20; 30; 40) as claimed in claim 1.
10. Method of packaging a reinforcement as claimed in claim 1 by a parallel winding of the reinforcement (10; 20; 30; 40) onto a drum, making a full twist in one turn.
11. Method of employing a reinforcement as claimed in claim 1 in a permanent construction, characterised in that the solid wires (13, 14) are stripped in at least one portion of the reinforcement (10; 20; 30; 40) and the stripped wires are anchored to at least one constituent part (6) of the permanent construction (1) to make the reinforcement (10; 20; 30; 40) work under traction.
12. Method of employment as claimed in claim 11, in which the solid wires (13, 14) of the reinforcement (10; 20; 30; 40) are collectively clamped in an anchoring jaw as a unit.