EP0393013B2 - Tensioning-bundle comprising tensioning members - Google Patents

Description

The invention relates to a tension bundle according to the preamble of patent claim 1.

Until now, it was common to manufacture the bundles or strands individually with a plastic sheath, e.g. made of polyethylene, a grease coating (e.g. GB-A-2 140 480) or a galvanic coating (e.g. FR-A-1 044 844) and then bundle several such strands or wires. It is also known to galvanically coat or grease the strands or wires before coating them with plastic. Such strands or wires can move in the plastic jacket. The disadvantage of bundling the strands or wires covered with plastic is that a relatively thick bundle is achieved.

In the construction according to DE-OS 16 59 205, several smooth tensioning wires are enclosed parallel to one another by a tight-fitting plastic sheath, appropriate materials being used to reduce the friction between sheath and wire as far as possible and, if necessary, a lubricant can also be introduced. The preferred today, due to the higher flexibility and with the same preload thinner executable strands have a significantly rougher surface than wires, so that in accordance with the teaching of DE-OS 16 59 205 closely fitting on the entire surface of the tendon the desired mobility of the tendon in the plastic sheath would no longer exist, since the sheath would then also have penetrated into the surface structures which are gusset-shaped in cross section. According to a special embodiment, this document shows a bundle of wires running parallel to one another, which are individually sheathed in plastic. These sheathed wires are replaced by a second one Plastic cover held together in band form, but remain within this second cover loosely placed single tendons without a direct connection to each other.

In addition, tendons made of rods, wires or strands were guided individually or bundled in cladding tubes made of sheet metal or plastic, with the cavity between the tendons and the cladding tube being filled by means of cement or so-called permanent plastic masses by pressing in the filler material before or after tensioning the tendons.

The tendons were anchored at the ends and tensioned. They can be placed inside a structure or outside; in the latter case, the cladding tube itself must also be made of corrosion-resistant material.

The disadvantages of the known methods were often the corrosion protection, for which a separate operation was required, which resulted in a high expenditure of time and money. The risk of errors in protecting the tension members was also not insignificant. Not to be neglected disadvantages by touching the rods, wires or strands at deflection points of the tendons, which resulted in increased friction during prestressing and thus loss of prestressing forces and a reduction in strength, especially fatigue strength.

In WO88 / 09847 a tension member is described, which consists of steel ropes, a parallel wire or parallel strand bundle with a plastic sheath. This plastic sheathing results in a largely round surface of the bundle and the plastic can also fill the cavities between the individual wires or strands. However, strands would be in the compact Plastic matrix of WO88 / 09847 is not movable, since the plastic fills all cavities - ie also the surface structures of strands.

The object of the invention is to provide measures by which, while avoiding the above disadvantages, the smallest possible space requirement for the corrosion-protected tensioning bundle is achieved and the tensioning members can also be tensioned individually or jointly and can be moved within the casing in order to be relative to the other tendons as well Coat to be able to change their position or length. Touching or rubbing of the tendons should be avoided, i.e. that an orderly configuration should be maintained under all circumstances and over the entire course of the tension bundle.

This object is achieved by the characterizing features of patent claim 1. This solution has the advantage that the sheath has penetrated between the strands - with their higher elasticity and their smaller diameter with the same pretensioning force - and thus keeps them in a predetermined configuration at a distance that prevents mutual contact - and thus also friction. However, the surface structures of the strands are not filled with the material of the plastic sheath, so that the full flexibility of the strands in the sheath - and thus the independent tensionability of the individual tendons, which is not impeded by friction losses - is preserved.

According to a further feature of the invention, the strands are individually greased. As a result, the relative mobility to one another can be guaranteed even with the closest arrangement.

The sheath containing all the strands advantageously has at least one essentially flat surface, preferably two mutually parallel, essentially flat surfaces. This significantly simplifies the combination of several tendons according to the invention.

According to a further feature of the invention, the sheath is provided with at least one further sheathing made of plastic, which fits tightly on the outside of the sheath. This can compensate for deviations in the outline of the inner shell. The further casing can combine homogeneously with the first casing, so that a one-piece casing is produced.

Preferably, an inner sheath made of a soft plastic and an outer sheath made of a harder plastic are provided. Despite increased protection of the tendons, this ensures easy bending to small radii, so that the bundle can be rolled up to such small dimensions as it is e.g. is necessary for transport purposes.

In order to ensure the easy bending and rolling up of this tension bundle, a layer of a lubricant is advantageously provided between at least two sheathing according to a further feature of the invention.

According to a further feature of the invention, each plastic sheath consists of extruded material, which makes it particularly easy and economical to manufacture.

Further refinements according to the invention are apparent from the following description, in which exemplary embodiments for tension bundles designed according to the invention are explained in more detail with reference to drawings.

Fig. 1

einen bisher bekannten Aufbau für ein Litzenbündel mit kunststoffummantelten Einzellitzen im Querschnitt,

Fig. 2 und 3

je einen Querschnitt durch ein Litzenbündel gemäß der Erfindung,

Fig. 4 bis 9

Querschnitte durch weitere Ausführungsformen des Erfindungsgegenstandes dar, und

Fig. 10

ist eine Ausführungsform eines Endes eines solchen Bündels mit den Verankerungen.

In the drawings, the

Fig. 1

a previously known structure for a strand bundle with plastic-coated individual strands in cross section,

2 and 3

a cross section through a strand of strands according to the invention,

4 to 9

Cross sections through further embodiments of the subject matter of the invention, and

Fig. 10

is an embodiment of an end of such a bundle with the anchors.

Hiebei is shown in FIGS. 1 to 3 and 5 to 9, only one strand, while the other strands are simply indicated by a circle.

In Fig. 1, a known strand bundle is shown. This consists of individual strands 1, which are each provided with a plastic sheath 2. In the example shown, six such strands 1 are arranged parallel to one another around a central strand 1 '. Such a strand bundle requires a relatively large accommodation space when used as a prestressed strand bundle due to the sheath 2 applied separately to each strand 1 or 1 '.

The bundle shown in cross section in Fig. 2 has strands running parallel to each other, as is provided according to the invention, and is together with preferably soft plastic e.g. Polyethylene, has been extrusion-coated using an extruder, the plastic 3 both forming a coating and penetrating into the spaces between the strands 1. The strands can be dry before the sheathing with the soft plastic, but they can also, as shown, be provided with a coating 4 made of fat, a hard plastic or by galvanic application, which serves as corrosion protection. This coating can also fill the inner spaces between the tendons, especially if it is made of fat.

2 shows a ring of strands arranged around a central strand. But there is also the possibility to arrange any number of wreaths one above the other.

In Fig. 3, the bundle of strands 1 running in parallel is enclosed by a two-layer jacket or by two concentric jackets 3, 5. The sheathing is preferably carried out in two stages with two extruders. Hiebei it is advisable to fill the space between the strands 1 in such a way that the distance between the strands is greater than in the final state, the plastic also penetrating into the space between the inner strand and the surrounding strands, whereupon the strands are squeezed together so that the smallest possible diameter of the sheathed bundle is achieved.

In a second stage, the outer plastic sheathing 5 is applied, so that a round sheathed bundle is formed.

The two plastics can be chosen as desired, depending on the desired property of the coated bundle. There is the possibility of producing both shells from the same plastic or the inner sheath 3 from softer plastic than the outer sheath 5. This process is preferably carried out by successive extrusions of two extruders connected in series. Naturally, within the scope of the invention, the inner casing can be made of a harder plastic than the outer casing.

According to a further feature of the invention, a lubricant can be enclosed between the two sheaths 3 and 5, or better between the outer sheath 5 and a further concentric sheath, which makes it possible for the bundle with the inner sheath to be stretched when the bundle is tensioned can move relative to the outer casing. This type of sheathing can also be carried out in an extrusion process.

In many cases, however, it is necessary to arrange several strands next to one another. In this case, the strands 1 are at most enclosed by the sheath 4 and joined together to form a band by the plastic 3. In Fig. 4 the band consists of two and in Figs. 5 and 6 from four strands, Fig. 6 showing a band with a different shape of the sheath than Fig.5 In the embodiments according to Figs. 4 to 6 are Strands 1 separated from one another by longitudinal webs 7 of the sheathing.

However, there is also the possibility of arranging the strands in close contact with one another, so that the webs 7 are omitted.

It is up to the designer to arrange the strands lying parallel to one another also to other cross-sectional shapes of the strand bundles, as shown for example in FIGS. 7 to 9.

Within the scope of the invention is the number and the cross-sectional shape of the casings lying one above the other as well as the number of layers of lubricants between two jackets.

This allows the outer shapes of the bundles to be designed as desired and to be arranged in a space-saving manner both in the building and on the outer wall thereof.

Instead of strands, individual wires can also be combined into a bundle within the scope of the invention, the individual wires being able to be provided with a dry plastic, a galvanic coating or a coating of fat or thin hard plastic before the sheathing.

In the case of anchoring, the ends of the bundles produced in this way are freed from the plastic sheath, the surfaces of the strands are cleaned so that they can then be concreted, poured or clamped.

To anchor the strands, the end of the bundle can be slit open, as shown in FIG. 10, each end of the strand or the tensioning element being provided with its own anchor body 8. Of course, there is also the option of anchoring both ends in a common anchor plate. Although a bundle of only two strands is shown in the present case, bundles consisting of more than two tendons can be divided into individual members in the same way.

The bundles according to the invention are used, for example, for prestressing structures with external or internal arrangement of the bundles, for ground anchors or as inclined cables, e.g. applied to suspension bridges. Among other things, they have also the advantage that they can adapt to any desired course.

Claims (7)

1. A tensioning bundle composed of several tensioning members, running parallel with one another and collectively tightly enclosed by a plastic casing (3) and individually coated with a material (4) having the ability to slide, wherein the material of the casing (3) has also penetrated between the tensioning members, forming longitudinal webs (7), characterised in that the tensioning members are in the form of strands (1) and the casing (3) tightly encloses these strands (1), leaving the exterior surface structures thereof free, the said exterior surface structures being gusset-shaped in cross-section.
2. A tensioning bundle according to claim 1, characterised in that the strands (1) are individually lubricated.
3. A tensioning bundle according to one of the preceding claims, characterised in that the casing (3) containing all the strands (1) has at least one substantially plane surface, preferably two substantially plane surfaces extending parallel to one another.
4. A tensioning bundle according to one of the preceding claims, characterised in that the casing (3) is provided with at least one further casing (5) of plastic which closely fits the exterior of the casing (3).
5. A tensioning bundle according to claim 4, characterised in that an interior casing (3) of a soft plastic and an exterior casing (5) of a harder plastic are provided.
6. A tensioning bundle according to claim 4 or 5, characterised in that a layer consisting of a lubricant is provided between at least two casings (3, 5).
7. A tensioning bundle according to one of the preceding claims, characterised in that each plastic casing (3, 5) is composed of material which is applied by extrusion.

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