FR2677694A1 - DEVICE FOR MAINTAINING TO THE ASSEMBLE STATE THE INDIVIDUAL TORONS OF A PRECONTRAINT MEMBER WITHOUT ADHERENCE. - Google Patents

Abstract

The invention relates to a device for maintaining in the assembled state the individual strands of a prestressing member without adhesion. This device is formed by a casing tube (2) which allows the concrete to pass through circular openings (3) and whose internal cross-sectional area is between 1.5 and 2.5 times the cross-sectional area of all the individual strands (1). Application in particular to the manufacture of reinforced concrete structures.

Description

The invention relates to a device for maintaining in the assembled state the

  individual strands of a prestressing member, to be embedded in the concrete over its entire

length, without adhesion.

  A known device of the type indicated (German Patent Application Publication No. 038 38 069) is constituted

  by a spacer, which houses individual and

  This is relatively complex especially from the point of view of the handling technique. It is generally possible to indicate, in detail, the following with respect to this device and the state of the art: In subsequent adhesion-preloading, envelope-tubes were embedded in the concrete, in which pre-stressing wires or strands of pre-stressing wires were inserted before concreting or

  after curing the concrete of the structural element

  The space of the tubes-envelopes, which is not occupied

  by the prestressing wires, is filled, after the precon-

  curing, by cement mortar The wall of the tube-

  the envelope must be leakproof so that no mixing water is

  The problem of this type of construction, in particular the protection of the prestressing wires against the concrete, does not penetrate the tubes and prematurely obstruct the tubes.

  corrosion, has been known for a long time.

  In the case of prestressing without adhesion,

  of which we speak in the context of the invention, we drown individually

  dually or beam, in concrete, so-called individual strands, which are placed in prestressing

  after curing the concrete of the structural element

  The clustering of individual strands

  for example, by means of star-shaped spacers (German Patent Application Publication No. 038 32 376) The individual strand bundles are

  prefabricated and inserted together with

  anchoring elements in the formwork of the building element (German patent application published under the

N 038 38 069).

  It is necessary to wind up longer beams for transport with a diameter of no more than 3 m, which poses some problems. These concern mainly the joining of the individual strands to the spacers and the reciprocal longitudinal mobility necessary during winding and unwinding We choose the distances between the individual strands between 2 and 3 cm so that the introduced concrete can completely wrap each individual strand In this way we obtain, for all the individual strands of a bundle, with respect to the prestressing strands used to a subsequent connection, which are located in a tube-envelope, a greater need in place in the cross section of the building element As has already been indicated, the mounting of said spacers involves significant expenditure of

workforce.

  The object of the invention is to indicate a device of the mentioned type, in which the manipulation of the prestressing member or of its individual strands clearly

fewer problems.

  To solve this problem, the invention indicates a

  device for holding in the assembled state the inner strands

  of a prestressing member, to be drowned

  in concrete over its entire length, without adhesion,

  sealed by a tube-envelope allowing the fresh concrete to pass

  formed and whose cross-sectional area

  thickness is 1.5 to 2.5 times the sum of

  cross section of all individual strands.

  Such a tube-envelope can be handled clearly

  This is valid irrespective of whether the individual strands are inserted into the permeable casing tube, before or after the installation of the strands into the formwork.

  is essential in this respect it is, in all cases, the

  indicated setting of cross-sectional areas; accordance

  At this setting, the cross-sectional area of the casing tube is always significantly greater than the sum of the cross-sections of the individual strands, which guarantees free insertion of the strands.

  no longer necessary to use spacers between the different

  individual strands.

  The last of freshly prepared concrete surprisingly realize a complete wrap of individual bundle strands, placed in the tube-envelope; likewise

  interspaces between the individual strands

  duels are filled automatically with a slurry of

  is lying. For the variants of implementation, there are several possibilities within the scope of the invention. Thus, as a material for the shell-tube, a sheet of steel is used, but also a plastic material or a steel wire. To some extent, it is better to

  make the shell tube into a perforated plate or

  In this respect, a particularly preferable embodiment of the invention is one in which the casing tube consists of a

  helically wound band with longitudinal edges

  at least in sections, for example by folding

  The best way to obtain the permeability of the tube-

  Envelope for freshly prepared concrete is to create openings as large as possible. Circular openings with a diameter of 20 to 40 mm separated by a distance of 40 to 50 mm are particularly assertive in practice; thus, all spaces, not occupied by the individual strands, inside the tube-envelope

  are safely filled with freshly

  As already indicated, the casing tube can also be made of a tubular network formed of a steel wire or a plastic wire. In any case, what is essential is that the casing tube has a sufficient inherent rigidity allowing the winding and unwinding and distances as large as possible of support from 0.8 to 1.3 m of the filled prestressing member

  partly by individual strands.

  meter of the tube-envelope according to the number of individual strands to be set up The sectional shape

  transverse is preferably circular; this form

  makes an irregular arrangement of the individual strands.

  But it is also particularly appropriate to have

  cross-sectional shape of a regular polygon

  to bind, in particular regular hexagon, whose length

  sides corresponds to a multiple of the diameter of the strands indi-

  viduals since it is possible to have a particularly tight storage of individual strands In any case it is necessary to choose the cross-sectional area

  of the tube-envelope so that it is always clean-

  above the sum of the cross sections of the

  strands, so as to guarantee free insertion of the dif-

individual strands.

  Moreover, as regards the tube-

  envelope, it should also be noted that the latter can be

  at any distance upstream of the anchor points No special arrangement is necessary in these locations The individual strands are separated in the usual manner and guided in a tube of

  upper diameter by means of an anchor plate.

  The features and benefits of this

  invention will emerge from the description given below

  Referring to the accompanying drawings, in which: Figure 1 shows a first device for holding in the assembled state the individual strands of a preload member without adhesion; and FIG. 2 represents a second form of

realization of such a device.

  The devices shown in the figures are used to maintain in the assembled state the individual strands 1 of a prestressing member to be embedded in concrete over its entire length, without adhesion. As can be seen in FIG. individual strands 1 consist of several steel wires placed in an envelope which is filled with grease as a corrosion protection agent

  the assembled state consists respectively of a tube

  casing 2, which passes the freshly prepared concrete and whose cross-sectional inner surface occupies between 1.5 and 2.5 times and, in the exemplary embodiment, approximately 1.9 times the sum of the cross-sectional areas

  cross-section of all individual strands

  envelope 2 is realized in the two examples of

  perforated steel sheet which is rolled in

  and is connected, at least in sections, to itself, at the neighboring longitudinal edges, which however is not shown in detail on

the figures.

  The casing tube 2 has circular openings

  3, which have a diameter of between 20 and 40 mm and are separated by a reciprocal distance of between 40 and 50 mm. It is obvious that the diameter and the distance

  are set one on top of the other so that it remains

  core of the bars between the openings 3.

  In the embodiment of FIG. 1, the casing tube 2 has a circular cross-sectional shape. In the embodiment of FIG.

  On the contrary, the tubular casing 2 has a transverse section

  a regular hexagon shape, the length of the sides of which is set to the diameter of the individual strands, so that the length 4 of the sides of the tube

  envelope 2 corresponds to three times the diameter of the individual strands

  The individual strands 1 can be arranged in

being more heavily packed.

Claims (5)

  1 Device for holding in the assembled state the individual strands of a prestressing member, in front of   be embedded in the concrete throughout its entire length, without   a shell-tube (2) which allows the freshly formed concrete to pass, and whose internal cross-sectional area occupies 1.5 to 2.5 times the sum of   cross-sectional areas of all individual strands duels (1).   2 Device according to claim 1, characterized   in that the jacket tube (2) is formed by a perforated plate or by a network of steel or plastic wires.   3 Device according to one of claims 1 or   2, characterized in that the shell tube (2) is formed   by a helically wound band with long edges   tudinals gathered at least in sections.   4 Device according to any one of claims 1 to   3, characterized in that the casing tube (2) has circular openings (3) having a diameter of 20 to 40 mm   and separated by a distance of 40 to 50 mm.   Device according to any one of Claims 1 to 4, characterized in that the jacket tube (2)   has a circular cross-sectional shape.   Apparatus according to any of the claims   cations 1 to 5, characterized in that the shell tube (2)   has in cross-section a form of regular polygon   to bind and in particular of regular hexagon, whose length (4) of the sides corresponds to a multiple of the diameter of the strands individual.