RU2782773C1 - Method for reinforcing a reinforced concrete truss - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction, and in particular to a method of reinforcing a reinforced concrete truss. The method for reinforcing a reinforced concrete truss is to install a tubular rack of two pipes, while steel plates, anchors, a metal plug, a metal sleeve, a ball valve, a concrete conduit are additionally used for reinforcement, and a concrete mixture is supplied. To install a tubular rack, the middle of the truss span is determined, the position of the upper and lower steel plates, and the axis passing through the crosshairs of the diagonals of the plates is aligned with the vertical axis passing through the lower chord of the truss in the middle of the span; perform anchoring to the base of the structure at the level of the finished floor of two steel plates pre-welded along the contour. A hole with a diameter greater than the diameter of the outer pipe is made in the upper plate at the crosshairs of the diagonals. Two steel plates pre-welded along the contour are fastened with anchors to the lower face of the lower chord of the truss, and a hole with a diameter greater than the diameter of the metal plug is made in the lower plate at the crosshairs of the diagonals. An external pipe with an internal thread pre-cut in the upper part is installed into the hole made in the upper steel plate attached to the base of the structure, a hole is made in the upper part of the inner pipe from the upper cut at a distance exceeding the length of the metal plug, followed by welding of the metal sleeve with a ball valve at the end. A metal plug is installed in the upper part of the inner pipe to a depth equal to two thirds of the length of the metal plug; the inner pipe is installed in the upper part of the outer pipe to achieve alignment with the holes in the steel plates of the base of the structure and the lower edge of the lower chord of the truss. The connections of the outer and inner pipes and the metal plug are adjusted until the pipes are immobilized; the concrete pipeline is installed to the ball valve in the upper part of the inner pipe, followed by the supply of the concrete mixture until the internal volume of the pipes is completely filled; the metal plug is unscrewed with the continuation of the concrete mixture supply until the required expansion force in the pipes is reached; the ball valve is closed, followed by stopping the supply of the concrete mixture and dismantling the concrete pipeline; a metal sleeve is sawn off from the upper part of the inner pipe after the concrete reaches the design strength.

EFFECT: increasing the bearing capacity of a reinforced concrete truss.

4 cl, 3 dwg

Description

The invention relates to construction, namely to the strengthening of building structures, and can be used to strengthen reinforced concrete trusses that require the restoration of the bearing capacity due to the impact of off-design loads on them during the operation of buildings and structures.

Currently, there are various technical solutions related to the strengthening of trusses of buildings and structures. The “Method of reinforcing the belt in the knot of a tubular truss” is known according to patent RU 2756260 C1 dated September 28, 2021. This method is implemented by creating a hole into which a protruding steel sleeve is inserted with subsequent welding, then a fabric bag is passed through the steel sleeve. After a series of technological operations, the specified bag is filled with a concrete mixture, which, when hardened, provides an increase in the rigidity of the assembly. At the same time, this solution does not allow to increase the bearing capacity in the middle of the truss span and, therefore, is of a private nature.

Known "Method of reinforcing centrally compressed rods of steel corner trusses of the coating" according to the patent for invention RU 2275483 C2 dated 04/27/2006. seams on the paired shelves of the corners of the main rods. The dimensions of these seams are provided in such a way as to be sufficient to create welding deflections equal in magnitude to the displacements of the centers of gravity of the sections that appear when additional elements are adjacent. This solution is also limited solely to the solution of the issue of strengthening private structural elements.

The "Method of reconstruction and strengthening of the supporting parts of reinforced concrete beams" is known according to the patent for invention RU 2754840 C1 dated 09/08/2021. , and a tensioner in the form of a clutch with a pin-stop. This method allows you to partially unload the beam, but does not fully reduce the value of internal forces that occur in the middle of the span of the structure.

The closest analogue, adopted as a prototype of the proposed method, is a technical solution for strengthening using the well-known "Device for reinforcing a beam with an intermediate rigid support" according to the patent for the invention RU 2711375 C1 dated February 18, 2019. This device includes a foundation, a combined sliding tubular rack with cantilever ledges, jacks and a package of steel plates. The rack in the specified device consists of two pipes - an internal fixed stationary and an external removable movable, moreover, base and distribution plates are welded to the ends of the inner pipe, two U-shaped consoles from sheets with a thickness of 6 ... 8 mm, located symmetrically with respect to the longitudinal axis of the pipe, while the working surface of the upper consoles is located 50 ... 80 mm above the end of the removable pipe, and the surface of the lower consoles is at the level of the end of this pipe.

The disadvantage of reinforcement using this device is an increase in the probability of collapse of the truss structure in the event of its strengthening using this solution in the event of a further decrease in the operational suitability of the truss with various off-design impacts on the structure. The lack of solutions in the specified device for the use of concrete is a limitation in achieving the required expansion force in the middle of the truss span.

The objective of the invention is to improve the reliability of building structures damaged during operation during various off-design impacts.

The technical result consists in increasing the bearing capacity and preventing the destruction of the reinforced concrete truss after the influence of dynamic loads by arranging a rack to obtain a spacer force.

The specified technical result is achieved in the following way. Common features of the prototype and the proposed method is that the reinforcement is to install a tubular rack of two pipes.

Distinctive features of the proposed method are:

1. additional use of 10 mm thick steel plates, anchors, metal plug, metal sleeve, ball valve, concrete pipeline and concrete mix supply;

2. advance determination of the middle of the span of the truss, the position of the upper and lower steel plates;

3. alignment of the axis passing through the crosshairs of the diagonals of the plates with the vertical axis passing through the lower chord of the truss in the middle of the span;

4. fastening with anchors to the base of the structure at the level of the finished floor of two steel plates 10 mm thick pre-welded along the contour;

5. early execution in the upper plate at the crosshairs of the diagonals of the hole with a diameter of 2 millimeters greater than the diameter of the outer pipe;

6. fastening with anchors to the lower edge of the lower chord of the truss of two steel plates pre-welded along the contour with a thickness of 10 millimeters;

7. early execution in the bottom plate at the crosshairs of the diagonals of the hole with a diameter of 2 mm more than the diameter of the metal plug;

8. the device of an external pipe with an internal thread pre-cut in the upper part into a hole made in the upper steel plate attached to the base of the structure;

9. arrangement of a hole in the upper part of the inner pipe from the upper cut at a distance exceeding the length of the metal plug by 30 millimeters, followed by welding of a metal sleeve with a ball valve at the end;

10. installation of a metal plug into the upper part of the inner pipe to a depth equal to two thirds of the length of the metal plug;

11. arrangement of the inner pipe in the upper part of the outer pipe to achieve alignment with the holes in the steel plates of the base of the structure and the lower edge of the lower chord of the truss;

12. adjusting the connection of the outer and inner pipes and the metal plug to ensure the immobility of the pipes;

13. installation of a concrete conduit to a ball valve in the upper part of the inner metal pipe, followed by the supply of concrete mixture until the internal volume of the pipes is completely filled;

14. unscrewing the metal plug with the continuation of the supply of concrete mixture until the required expansion force in the pipes is reached;

15. shutting off the ball valve, followed by stopping the supply of the concrete mixture and dismantling the concrete pipeline;

16. Saw off the metal sleeve from the top of the inner tube after the concrete had reached design strength;

17. making the thread pitch of the inner and outer pipes and the metal plug the same;

18. the presence of an internal thread in the upper part of the outer pipe, the presence of an external thread in the lower part and an internal thread in the upper part of the inner pipe, the presence of an external thread along the entire length of the metal plug;

19. threading on the outer and inner pipes and a metal plug to ensure a thrust between the base of the structure at the level of the finished floor and the lower edge of the lower chord of the truss.

The combined use of these distinctive features in the claimed method allows to obtain a positive effect, which consists in preventing the destruction of the reinforced concrete truss by increasing the bearing capacity after various off-design impacts by reducing the absolute value of the bending moment in the middle of the span of the truss.

The invention is illustrated by drawings.

The figure 1 shows the technological scheme of strengthening the reinforced concrete truss by the claimed method. The figure 2 shows a diagram of a section along the level of a metal plug with a view of the lower face of the lower chord of the truss (top view). The figure 3 shows a diagram of the supply of concrete mixture from the concrete pipeline through a ball valve and a metal sleeve to the outer pipe of the spacer.

In figures 1, 2 and 3, the following designations are used in Arabic numerals and Latin letters:

1 - upper steel plate attached to the base of the structure;

2 - lower steel plate attached to the base of the structure;

3a - anchor;

3b - the design position of the anchor after being screwed into the base of the structure through steel plates;

4 - nut;

5 - hole in the upper steel plate attached to the base of the structure;

6 - inner pipe;

7 - outer pipe;

8 - metal sleeve;

9 - ball valve;

10 - metal plug;

11a - anchor;

11b - design position of the anchor after screwing into the surface of the lower face of the lower chord of the truss;

12 - nut;

13 - hole in the lower steel plate attached to the lower face of the lower chord of the truss;

14 - upper steel plate attached attached to the lower face of the lower chord of the truss;

15 - lower steel plate attached attached to the lower face of the lower chord of the truss;

16 - concrete pipeline;

17 - reinforced concrete truss;

18 - section of the figure.

Since the strengthening of the reinforced concrete truss can be carried out by the repeatedly proposed method, this method is industrially applicable.

The application of the method of reinforcing a reinforced concrete truss after man-made impacts is carried out as follows. To create a spacer structure in the middle of the span of a reinforced concrete truss, a tubular rack of two pipes (6 and 7), as well as steel plates (1, 2, 14 and 15) 10 mm thick, anchors (3a and 11a), a metal plug (10) are used , metal sleeve (8), ball valve (9) and concrete pipe (16). In this case, the outer pipe (7) has an internal thread in the upper part, the inner pipe (6) has an external thread in the lower part and an internal thread in the upper part, and the metal plug (10) has an external thread along the entire length; the threads on the outer and inner pipes (7 and 6) and the metal plug (10) are applied in such a way as to provide space between the base of the structure at the level of the finished floor and the lower edge of the lower chord of the truss (17), and the thread pitch of the inner and outer pipes (6 and 7) and the metal plug (10) are the same.

At the first stage, for the installation of a tubular rack, the middle of the span of the reinforced concrete truss (17) is determined; a decision is made on the position of the upper and lower steel plates (1, 2, 14 and 15), and the axis passing through the cross of the diagonals of the plates (1, 2, 14 and 15) is aligned with the vertical axis passing through the lower chord of the truss (17) in the middle of the span.

At the next stage, anchors (3a) are attached to the base of the structure at the level of the finished floor of two steel plates (1, 2) pre-welded along the contour with a thickness of 10 millimeters. At the same time, a hole (5) with a diameter 2 mm larger than the diameter of the outer pipe (7) is made in the upper plate (1) in advance at the crosshairs of the diagonals to ensure unhindered passage of the outer pipe (7) into the resulting opening. Further, the anchors (11a) are fastened to the lower face of the lower chord of the truss (17) of two steel plates (14, 15) pre-welded along the contour with a thickness of 10 millimeters. At the same time, in the lower plate (15), a hole (13) is made in advance at the crosshairs of the diagonals with a diameter of 2 mm larger than the diameter of the metal plug (10). After these works are completed, the external pipe (7) is installed with an internal thread pre-cut in the upper part into the hole (5) in the upper steel plate attached to the base of the structure (1). Then, a hole is made in the upper part of the inner pipe (6) from the upper cut at a distance exceeding the length of the metal plug (10) by 30 millimeters. A metal sleeve (8) with a ball valve (9) at the end is welded to the specified hole. Next, the metal plug (10) is screwed into the upper part of the inner tube (6) to a depth equal to two thirds of the length of the metal plug (10). This action is performed to provide the possibility of changing the height of the formed tubular rack by rotating the metal plug (10). The next step is the installation of the inner pipe (6) into the upper part of the outer pipe (7) in order to achieve alignment with the holes in the steel plates of the base of the structure and the lower edge of the lower chord of the truss (1, 2, 14 and 15). After these operations, the connection of the outer and inner pipes (6 and 7) and the connection of the inner pipe (6) and the metal plug (10) are adjusted in order to ensure the immobility of the pipes closed between the steel plates (1,2, 14 and 15) of the base of the structure and the lower edges of the lower chord of the truss (17). After receiving the spacer structure, the concrete pipeline (16) is mounted to the ball valve (9) in the upper part of the inner pipe (6). Then the concrete mixture is supplied under pressure through the concrete conduit (16) until the internal volume of the pipes (6 and 7) is completely filled. If there is a difficulty in supplying the concrete mixture, the metal plug (10) is smoothly unscrewed with simultaneous supply of the concrete mixture at a lower speed in order to obtain the necessary expansion force in the pipes (6 and 7) of the resulting structure. If it is impossible to further supply the concrete mixture under pressure through the metal sleeve (8), the ball valve (9) is closed, the supply of the concrete mixture is stopped, and the concrete conduit is dismantled (16).

After the concrete reaches the design strength (28 days), the metal sleeve (8) located on the inner pipe (6) is sawn off.

Used sources

1. Patent for invention RU 2756260 C1 dated September 28, 2021 "Method of reinforcing the belt in the knot of a tubular truss".

2. Patent for invention RU 2275483 C2 dated April 27, 2006 “Method of reinforcing centrally compressed rods of steel corner roof trusses”.

3. Patent for invention RU 2754840 C1 dated 09/08/2021 "Method of reconstruction and strengthening of the supporting parts of reinforced concrete beams".

4. Patent for invention RU 2711375 C1 dated February 18, 2019 “Device for reinforcing a beam with an intermediate rigid support”. - prototype.

Claims (4)

1. A method of reinforcing a reinforced concrete truss, which consists in installing a tubular rack of two pipes, characterized in that steel plates 10 mm thick, anchors, a metal plug, a metal sleeve, a ball valve, a concrete conduit are additionally used for reinforcement, and a concrete mixture is supplied, while for installation of a tubular rack, the middle of the truss span, the position of the upper and lower steel plates are determined in advance, and the axis passing through the crosshairs of the diagonals of the plates is aligned with the vertical axis passing through the lower chord of the truss in the middle of the span; anchoring is carried out to the base of the structure at the level of the finished floor of two steel plates 10 mm thick pre-welded along the contour, and in the upper plate in advance at the crosshairs of the diagonals a hole with a diameter of 2 mm larger than the diameter of the outer pipe is made; two steel plates 10 mm thick pre-welded along the contour are fastened with anchors to the lower face of the lower chord of the truss, and in the lower plate a hole with a diameter of 2 mm larger than the diameter of the metal plug is made in advance at the crosshairs of the diagonals; an external pipe is installed with an internal thread pre-cut in the upper part into a hole made in the upper steel plate attached to the base of the structure; a hole is made in the upper part of the inner pipe from the upper cut at a distance exceeding the length of the metal plug by 30 mm, followed by welding of a metal sleeve with a ball valve at the end; a metal plug is installed in the upper part of the inner pipe to a depth equal to two thirds of the length of the metal plug; the device of the inner pipe is carried out in the upper part of the outer pipe to achieve alignment with the holes in the steel plates of the base of the structure and the lower edge of the lower chord of the truss; the connection of the outer and inner pipes and the metal plug are adjusted until the pipes are immobilized; installation of a concrete pipeline to a ball valve in the upper part of the inner pipe is carried out, followed by the supply of concrete mixture until the internal volume of the pipes is completely filled; the metal plug is unscrewed with the continuation of the concrete mixture supply until the required expansion force in the pipes is reached; the ball valve is closed, followed by stopping the supply of the concrete mixture and dismantling the concrete pipeline; a metal sleeve is sawn off from the upper part of the inner pipe after the concrete reaches the design strength. 2. The method of reinforcing the truss according to claim 1, characterized in that the outer pipe has an internal thread in the upper part, the inner pipe has an external thread in the lower part and an internal thread in the upper part, and the metal plug has an external thread along the entire length. 3. The method of strengthening the truss according to claim 1, characterized in that the threads on the outer and inner pipes and the metal plug are applied in such a way as to provide space between the base of the structure at the level of the finished floor and the lower edge of the lower chord of the truss. 4. The method of reinforcing the truss according to claim 1, characterized in that the thread pitch of the inner and outer pipes and the metal plug is the same.

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