RU2131010C1 - Prestressed ferroconcrete constructions - Google Patents

Abstract

FIELD: building industry, possibly manufacture or erection of prestressed ferroconcrete constructions with high demands for preventing cracking, especially operating in conditions of aggressive media, with high effort parameters of stressed reinforcement of beams, span structures of bridges, tunnels, reservoirs, reactor vessels, protective covers of nuclear reactors and so on. SUBSTANCE: uniform tension of rope strands is provided along the whole cross section of curvilinear passages. Jamming of slightly curved rope strands by means of sharply bent rope strands is prevented. When rope strands are pulled along passage of construction perforated spacing discs are used. Such discs are secured preliminarily to towing cable. Rope strands are passed through openings of discs. Supporting rollers are mounted on side surface of discs. EFFECT: improved design. 4 dwg

Description

 The invention relates to the field of construction and is intended for use in the manufacture or construction of prestressed reinforced concrete structures and structures with increased cracking requirements, especially those used in aggressive environmental influences, as well as with high stress parameters in prestressed reinforcement of beams, spans of bridges, tunnels, tanks, silos, hulls, protective shells of nuclear power plants, etc., in which high tensile reinforcement is used strong rope fittings laid in the form of beams of a rectilinear or curvilinear trajectory in the channels with their subsequent filling with cement mortar.

 A known method of prestressing reinforced concrete structures using rope or smooth wire high-strength reinforcement, without a protective sheath laid in the form of bundles in channels formed by channel formers of steel or thermoplastic material / pipe or sleeve /, followed by their filling / after prestressing / anticorrosive grease or cement solution / 1 /.

 Rope or smooth high-strength reinforcement for prestressed reinforced concrete structures without a protective anticorrosion sheath is subject to corrosion from the manufacturing stage to the stages of transportation, storage, bundle formation, which requires constant monitoring of the integrity of the reinforcing coating.

 Corrosion protection of the beam reinforcement after its installation is carried out in a building site, which does not fully guarantee that the beam reinforcement is not subject to corrosion throughout the life of the building structure.

 When the beams are tensioned in medium and high power channel formers with their curved path, the effect of pinching of some layers of the beam elements / in the bending plane / overlying layers occurs, which leads to uneven tension between the individual elements of the cable or wire reinforcement and the beam as a whole.

 This undesirable effect eliminates the possibility of tension or tightening of individual elements of the beam of prestressing reinforcement and requires tension of the beam with heavy equipment for the force in the whole beam.

 The unevenness of the stress state of the beam with a curved path leads to the factor of the length of the lower and upper layers of the strands of the beam lying in the plane of its bend.

 A known method of laying rope high-strength reinforcement in the construction of silos from prefabricated curved reinforced concrete panels in which channels with an orthogonal wiring system are arranged that extend along their entire length and width.

 At the construction site, during the assembly of the structure, the panels are installed with some clearance, and the channels stretch the reinforcement, which connects all the panels together, both in height and in the circumference of the silo.

 After joining the panels, concrete is laid at the joints between the prefabricated elements, while the concrete is pumped into the channels in which the reinforcement is laid / 2 /.

The presented constructive solution has the following disadvantages:
- The fittings laid in the channels must be protected from corrosion along the entire length, so the channels must be completely filled with concrete, which requires a complex control system for their filling.

 - Filling the channels with concrete is also required to ensure the joint operation of reinforcement with the reinforced concrete structure of the structure.

 The joint work of the reinforcement and concrete will be ensured only if the reinforcement is connected along the entire perimeter of the section with concrete pumped into the channels, which is difficult to do along its entire length.

 The closest technical solution to the proposed one is a prestressed reinforced concrete shell of a nuclear reactor containing reinforcing ropes with towing ropes located in the channels and tensioning mechanisms for ropes and ropes / 3 /.

 In this design, the rope tension mechanisms provide the pulling of the ropes in the channels and the tension of the ropes by the tension mechanisms. However, in the process of tensioning the ropes in the curved sections of the prestressed structure, the more curved strands of the rope are pinched by the less curved, the strands are unevenly tensioned in the rope, and the use of the rope section is not efficient enough.

 The objective of the invention is: to provide high aggregate strength of the reinforcing rope by uniformly tensioning its component parts - strands across the entire section in curved channel formers, and also to be able to tension or, if necessary, tighten individual strands in order to exclude powerful heavy devices / jacks / with full pulling force the force in the beam, using heavy devices with a magnitude of heavy force equal to the tensile force of an individual strand of the beam, and also provide corrosion resistance voltage my reinforcement beams by arranging a high-strength reinforcement in a polymer shell with lubricant.

 The task is achieved due to the fact that in a prestressed reinforced concrete structure containing a reinforcing rope located in the channel with a tow rope and rope and rope tension mechanisms, it is new that it is equipped with perforated disks axially mounted on the tow rope with support rollers on the side surface and the strands of the reinforcing rope are freely located in the holes of the disks.

 The reinforced concrete structure is supplied with perforated disks mounted on a tow rope to ensure uniform distribution of strands of rope along the channel section, and the remote arrangement of disks prevents the strand of the rope from touching each other and the channel walls during tension of the structure by the rope tensioning mechanism.

 Track rollers on the disks, in contact with the walls of the channel, help to avoid distortion of the disks when pulling the rope.

The invention is illustrated by drawings, where:
in FIG. 1 shows a strand of cable reinforcement in a polymer sheath with anti-friction protective grease;
in FIG. 2 - spacer disc in the channel;
in FIG. 3 is a transverse view of a channel with a spacer disc;
in FIG. 4 - installation of strands of cable reinforcement in a polymer shell with spacer discs in the channel of the prestressed structure.

 A prestressed reinforced concrete structure includes prestressing reinforcement in the form of ropes laid in channels 1 made in the body of structure 2. The number of ropes, as well as individual elements of strands 3 of the rope, their location is determined by the stress-strain state and layout design decision.

 The strand is made of high strength steel braided wire 4 located in the polymer protective sheath 5. Between the steel wire 4 and sheath 5 is an antifriction protective grease 6.

 Channels 1 for the passage of prestressed reinforcement, as a rule, are in the form of pipes made of metal or polymer material. The strained cable reinforcement in the form of strands 3 is laid in the channels 1 so that the strands 3 are evenly distributed over the entire cross-sectional area of the channel 1, and the gaps between the strands 3, the strands and the wall of the channel 1 are, if possible, the same. This is achieved by installing along the entire length of the rope spacing elements made in this technical solution in the form of disks 7 with holes 8 for passing reinforcing strands 3.

 The distance between the perforated discs 7 is determined by the stiffness of the strand 3, i.e. depends on the diameter of the cable fittings. The disks 7 in each channel 1 of the reinforced concrete structure are axially mounted on the towing cable 9 so as to prevent the strands 3 from touching each other and with the wall of the channel 1. In the working position, the towing cable 9 is connected to the mechanism 10 of its tension, and the strands 3 the rope is attached to the rope tensioning mechanism 11 and clamps 12 are fixed to them at the end surface of the perforated disk 7 from the side of the rope tensioning mechanism.

 To facilitate pulling through the channel 1 strands 3 of the rope on the side surface of the disks 7 of the spacing elements mounted rollers 13 with the possibility of flexibility.

 A fitting 14 is provided along the length of the channel 1 for filling it with cement mortar, as well as for air outlet as it is filled, as well as monitoring the filling of the channel along its entire length. The number of fittings 14 depends on the angle of the channels 1 to the horizon, its bend, the number of spacing elements along the length of the channel.

 To allow the flow of cement through the spacer elements in the disks 7, additional holes 15 are made in addition to those in which the strands 3 of the rope are installed.

 The prestressing of the reinforced concrete structure is carried out as follows, channels 1 are made in the body of the structure 2, which are made, as a rule, by means of channel formers of various types from metal, polymer, etc.

 Laying or pulling strands of 3 ropes with spacer elements can be performed both in channel 1, made in the body of the concrete structure, and in the channel former installed in the body before concreting the structure. As the main element for the purpose of prestressing the reinforced concrete structure, a wire rope 4 reinforcement having a protective coating in the form of a polymer sheath 5 is used. An antifriction protective lubricant 6 is provided between the polymer sheath 5 and the wire rope 4 of the reinforcement, which allows the rope to move freely relative to the polymer sheath 5.

 The set of rope also includes distant elements made in the form of perforated disks 7, installed along the entire length of the rope on the tow rope 9 and with a distance between each other depending on the stiffness of the strands 3 of the rope.

 The rope is stored in channel 1 by a cable tensioning mechanism 10, for example, a winch, at the end of the towing cable 9 located in the head of the rope.

 The distance elements are interconnected by a towing cable 9 into a continuous "garland" along the entire length of the rope.

 Thus, pulling the rope is carried out using the specified garland of spacing elements, in which the strands 3 are fixed with clamps 12. To reduce the resistance when pulling the rope in channel 1, the spacing elements are equipped with support rollers 13 interacting with the wall of channel 1.

 After installing the strands of 3 ropes in the design position, i.e. along the entire length of the channel 1, it is filled with cement mortar, which has increased strength and plasticizing properties and, if necessary, a delayed setting time.

 The supply and control of the density of filling of the channel 1 with cement mortar is carried out using fittings 14, which were removed during the installation of the channel former on the outer surface of the structure 2. After building strength of the concrete of the structure, as well as the cement mortar filling the channel 1, the rope reinforcement is tensioned. The tension is produced by the rope tensioning mechanism 11, for example, with a jack, sequentially of each of its strands 3. During the operation of the structure 2, it is possible, if necessary, to tighten each strand individually or the rope as a whole.

The application of this proposal as an element or component of the pre-stressing system of a building structure allows:
- to avoid the effect of pinching strands in curved beams with cable / or wire / reinforcement without a polymer sheath;
- to avoid the effect of uneven stress state for curved beams due to the diversity of the internal and external plane of bending of the elements - strands of the rope bundle;
- increase the coefficient of aggregate strength of ropes of stressed reinforcement;
- to tighten, if necessary, the strands of the rope element by element by the amount of effort depending on the relaxation properties of the reinforcing steel;
- to exclude the use of traction equipment / jacks / high power with a force on the rod equal to that calculated in the whole rope, using traction equipment with a force on the rod equal to that calculated in a separate strand of the rope;
- to increase the corrosion resistance of rope bundles of prestressing reinforcement through the use of rope reinforcement in a factory-made polyethylene sheath;
- Replace, if necessary, a single strand, and not the entire bundle.

Sources of information
1. USSR author's certificate N 684116, cl. E 04 H 7/00, 05.27.77.

 2. French patent N 2161298, cl. E 04 H 7/00, 11/15/71.

 3. Copyright certificate of the USSR N 1236800, cl. E 04 H 7/00, 02/08/08.

Claims (1)

 A prestressed reinforced concrete structure containing a reinforcing rope located in the channel with a towing rope and cable and rope tensioning mechanisms, characterized in that it is provided with axially mounted perforated disks and support rollers on the towing rope on the side surface, and the strands of the reinforcing rope are freely located in the openings of the disks .

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