RU2528320C1 - Method to manufacture beam of bridge span - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method to manufacture a thin-walled beam of a span includes placement of stressed longitudinal reinforcement in the form as single-strand ropes K-7 of higher strength with tensile strength of at least 1860 MPa, insulation of ropes with stiff tubes from polymer material, fixation of detachable core drivers to a formwork, and core drives in place of their installation occupy at least 20% of the beam cross section, laying self-sealing dispersedly reinforced concrete mix into the form with formation of cavities arranged longitudinally along the length of the beam, from which at least two holes are arranged in the lower face of the beam for condensate drain in process of span operation. Core drivers are removed at least after 5 hours of concrete setting in the form.

EFFECT: reduced material and metal intensity due to reduced quantity of high-strength reinforcement with increased tension force.

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Description

The invention relates to the field of construction, mainly to bridge building, and can be widely applied in the manufacture of reinforced concrete structures used in the construction and reconstruction of bridges.

There is a method of creating a prestressed continuous continuous steel-reinforced concrete span of the bridge, including a reinforced concrete slab, combined with a steel beam using welded to the steel sheet, fastened to the belt of the steel beam with high-strength bolts through the holes arranged in it, and the stops fixed in the body of the plate. In this case, a plate is used, consisting of three separate blocks with homogeneous gaps between them, located on a steel sheet divided into three separate parts, and in its extreme parts, anchor devices for tension fittings made in the form of a bundle of high-strength carbon fiber elements (RU No. 2468143, 11/27/2012).

A known method of manufacturing a beam span bridge I-beam or tee profile, which is reinforced as follows - reinforced with the main working longitudinal reinforcement in the zone of maximum bending moment of the beam with individual rods, beams or ropes; in the zone of maximum cutting forces in the edge of the beam with frames made of longitudinal, transverse and inclined reinforcement; in the zone of the slab - with separate grids; in the zone of vut - with anti-shrink nets, in compliance with the corresponding value of the protective layer of concrete. In this case, the working longitudinal, transverse and inclined reinforcement are made of fiber reinforced plastic (RU No. 117929,10.07.2012).

The closest known is a method of manufacturing a reinforced concrete beam span of the bridge, in which two reinforcing ropes coated with preservative lubricant, which are coated with a thermoplastic polymer material, and a protective sheath of the reinforcing rope bundle is made of a thermoplastic polymer material of the same or different chemical composition, which covers at least the tangent contour of the sheaths of reinforcing ropes. When the beam is made of more than two reinforcing ropes, their longitudinal axes are positioned with a maximum offset from the plane passing through at least two of these axes by an amount not exceeding the diameter of the rope. When a beam is made of more than two reinforcing ropes, their longitudinal axes in the cross section of the beam can be arranged along a periodic curve. The shell of the reinforcing rope made of thermoplastic polymeric material and the protective sheath of the bundle of reinforcing ropes are interconnected during extrusion of the protective sheath (RU 2202683, 04.20.2003).

The technical task of this solution is to reduce the metal consumption by reducing the number of high-strength reinforcement with an increase in its tension force. At the same time, the use of single-strand beams makes it possible to increase the adhesion of high-strength reinforcement to concrete, more evenly and smoothly transfer the tensile force to concrete, which reduced (made it possible to use concrete with cement of a lower grade) the concrete strength necessary to absorb the transmitted forces from high-strength reinforcement. The use of self-compacting concrete (SUB) increases the quality of its laying and distribution in densely reinforced and thin-walled structures. Thus, they reduce labor and energy costs, improve surface quality. When using such a design and self-compacting concrete, concrete is exposed to 5–6 hours before removing the core formers, which intensifies the manufacturing process of the beam. The use of SMS allows you to reduce cement consumption without compromising strength. When using single-strand beams of increased strength with a temporary resistance of 1860 MPa, in the places of isolation they are made of a rigid PVC pipe of smaller diameter. The use of PVC tubes can also reduce labor costs for insulation of strands and improve product quality. The use of hollow core formers with temporary fastening to fixed formwork allows reducing concrete consumption on the beam by at least 20%, while technological devices are provided in the lower face of the core forming units for forming at least two openings for condensate drainage from the beam voids during operation span structure.

This is achieved by the fact that the method of manufacturing a thin-walled span beam includes placement in the form of a tensile longitudinal reinforcement in the form of single-strand K-7 ropes of increased strength with a temporary resistance of at least 1860 MPa, insulation of the K-7 rope with rigid pipes made of a polymeric material, preferably PVC, fastening to the formwork of removable core formers, occupying at least 20% of the cross section along the cross section of the beam at the installation site, laying in the form of a self-sealing dispersively reinforced concrete mixtures with the formation of cavities longitudinally spaced along the length of the beam, into which at least two holes are formed in the lower face of the beam for drainage of condensate during operation of the span, and the extraction of void formers is carried out after at least 5 hours of exposure of the concrete in the mold. In addition, in the manufacture of a thin-walled beam with a length of more than 31.5 m, after removing the core formers, a fixed formwork is installed, the reinforcing frame of the upper plate is placed on it and the upper plate is concreted.

The span beam contains single strand beams of increased strength with a temporary resistance of 1860 MPa as prestressing reinforcement. The beam is made of self-compacting concrete mixture with temporary fastening of the hollow formers to fixed formwork. Closed cavities after extracting the void formers occupy at least 20% of the cross section along the beam cross section. In this connection (and the hygroscopicity of concrete) technological devices are provided in the lower face of the hollow formers to form at least two openings (channels) in the areas under the hollow for creating condensate drainage from the beam cavities during operation of the superstructure. The frame assembly in the formwork is carried out with the installation of high-strength reinforcement (K-7 ropes). A feature is the use of dispersed high-strength reinforcement. The transition from traditional 4-strand bundles to single-strand bundles of increased strength with a temporary resistance of 1860 MPa made it possible to increase the tensile force and reduce the number of high-strength reinforcement. Applied plastic tubes that are worn on strands in places provided by the project. The use of single-strand beams made it possible to increase the adhesion of reinforcement to concrete, to more evenly and smoothly transfer the tensile force to concrete, which made it possible to reduce the concrete grade needed to absorb the transmitted forces from high-strength reinforcement. A feature of this beam manufacturing technology - high-strength reinforcement and thin-walled construction - does not allow the use of a vibrator during concrete laying. In this design, laying concrete in the usual "vibrational" way is impossible. The application of the SMS allowed to solve the problem of laying concrete in the structure with improving the quality indicators of concrete. Exposure of concrete before pulling out the void for 5-6 hours. A feature of beams longer than 31.5 m is two stages of concreting. The 1st stage is described above, and the 2nd stage begins after pulling out the void formers. Fixed formwork is installed. The frame is knitted and then the top plate is detonated. Technological devices are provided in the lower face of the hollow formers that allow two openings to be formed in the areas under the hollow for the removal of condensate from the hollow formers during the operation of spans.

The proposed technical solution significantly reduces concrete consumption and reduces the mass of the beam.

Claims (2)

1. A method of manufacturing a thin-walled span beam, including placement in the form of a tensile longitudinal reinforcement in the form of single-strand K-7 ropes of increased strength with a temporary resistance of at least 1860 MPa, insulation of the K-7 rope with rigid tubes of a polymeric material, preferably PVC, fixing to formwork removable hollow formers, occupying at least 20% of the cross section along the beam cross-section at the place of their installation, laying in the form of a self-compacting dispersively reinforced concrete mixture with the formation longitudinally spaced along the length of the beam cavities, of which the bottom face of the beam defining at least two openings for condensate during operation of the span, and blockouts extract produced no less than 5 hours curing concrete in the form. 2. A method of manufacturing a thin-walled beam span according to claim 1, characterized in that in the manufacture of a thin-walled beam more than 31.5 m long after removing the core formers, fixed formwork is installed, the reinforcing frame of the upper plate is placed on it and the upper plate is concreted.