WO2022058695A1

WO2022058695A1 - Reinforcing cage for strengthening a concrete beam

Info

Publication number: WO2022058695A1
Application number: PCT/FR2021/051600
Authority: WO
Inventors: Romain MESNIL; Jean-François Caron; Sébastien MAITENAZ; Paul ONFROY; Nicolas METGE
Original assignee: Ecole Nationale Des Ponts Et Chaussees; Vinci Construction
Priority date: 2020-09-21
Filing date: 2021-09-20
Publication date: 2022-03-24
Also published as: EP4214374A1; FR3114330A1; FR3114330B1

Abstract

The invention relates to a reinforced structure (39) for a concrete element, comprising at least two longitudinal reinforcements (36, 37) and at least one transverse reinforcement (8) formed in a single piece of concrete reinforcement bar. At least one transverse reinforcement (8) comprises two parallel flat portions (9, 11), each having a general shape corresponding to the letter U or V and comprising a first and a second straight limb; each first limb is prolonged by a first side elbow (13, 13'), said first side elbows (13, 13') are connected by a connecting portion (12); each first limb is connected to a second limb by a central elbow (16, 16'); each second limb is prolonged by a second side elbow (18, 18'); and at least a first and a second longitudinal reinforcement (36, 37) are parallel to each other and perpendicular to the transverse reinforcement (8); the first and second longitudinal reinforcements (36, 37) are rigidly connected to the first and second side elbows (13, 13', 18, 18'), respectively, of the transverse reinforcement (8) by welding or binding.

Description

Title: Reinforcement cage for a concrete beam

TECHNICAL AREA

The invention relates to reinforcement elements of the reinforcing steel type which are embedded in concrete structural elements in order to improve their mechanical strength.

PRIOR ART

In FIG. 1, a structure 1 for the mechanical reinforcement of a concrete beam is intended to be installed inside a formwork in which concrete is poured to form a so-called reinforced beam.

This reinforcement structure 1 constitutes a trellis including longitudinal reinforcements 2 linked to each other by transverse reinforcements 3, each reinforcement being made up of a reinforcing bar, that is to say a steel bar with a face external ribbed.

The four longitudinal reinforcements 2 are rectilinear bars parallel to a main direction AX, and they are arranged along the four vertices of a square when viewed along this main direction AX.

Each transverse reinforcement 3 has the shape of a frame extending along a plane normal to the main direction AX and surrounding the longitudinal reinforcements 2, these longitudinal reinforcements being regularly distributed along the main direction. Each longitudinal reinforcement 2 rests on an internal side of a vertex of each transverse reinforcement 3, being rigidly secured thereto, by welding or by a wire ligature.

When the beam supports a load, it is stressed in bending, the two lower longitudinal reinforcements stretch to increase its mechanical strength, while the two upper longitudinal reinforcements compress. In the event of stress under shear forces, for example when the ends of the beam are subjected to vertical forces from opposite directions, the transverse reinforcements increase the resistance to these shear forces.

In practice, when the beam is stressed in bending, it also undergoes shear forces, so that the transverse reinforcements also contribute to increasing the mechanical strength of the beam in bending.

As illustrated by the reinforcements 4, 6 and 7 shown in Figure 2, there are multiple possibilities with regard to the geometry of the transverse reinforcements, conditioned by the desired mechanical strength, and the building codes in force. The transverse reinforcements are generally bent in the form of frames, stirrups, loops, U, or the like.

Such structures are made from lattices, coils, or straight bars of bent reinforcing bars, then assembled. The assembly is carried out on a production site before transport to a construction site, or directly on the site from the reinforcements previously transported to it.

One possibility is to have a table to hold the transverse reinforcements and insert the longitudinal reinforcements therein, before welding them together. Another possibility is to install the longitudinal reinforcements on trestles to thread the transverse reinforcements around the latter, before assembling them.

In all cases, the significant flexibility of the longitudinal reinforcements makes the positioning of the assembly before assembly complex to implement, whether in the factory or on site.

It follows that the positioning of the transverse reinforcements requires a significant amount of time, otherwise the transverse reinforcements have oblique orientations as illustrated in FIG. 3, so that they do not have the required geometric conformity.

The object of the invention is to provide a solution making it possible to remedy this drawback, and more generally, to facilitate the assembly of such a reinforcement structure. DISCLOSURE OF THE INVENTION

To this end, the subject of the invention is a reinforcing structure for a concrete element, comprising at least a first and a second longitudinal reinforcement made of concrete iron, characterized in that:

- It comprises at least one transverse reinforcement formed by bending the same reinforcing steel bar;

- this transverse reinforcement comprises at least two planar portions having the same shapes and extending in parallel planes spaced apart from each other, each planar portion comprising an undulation including a first and a second rectilinear branch connected to each other the other by a central elbow;

- each first rectilinear branch is extended by a first lateral bend, these first lateral bends being connected to each other by a connecting portion extending from the plane of the first portion to the plane of the second portion;

- Each second straight branch is extended by a second lateral bend extending in the opposite direction to the first lateral bend; and in that :

- The first and second longitudinal reinforcements are oriented perpendicular to the transverse reinforcement and are secured respectively to the first and to the second lateral bends of the transverse reinforcement by welding or binding.

With this solution, the fact that the transverse reinforcements extend in two planes ensures that they spontaneously position themselves perpendicular to the longitudinal reinforcements, so that the reinforcing structure which results therefrom has better geometric conformity.

The invention also relates to a structure thus defined, comprising a third longitudinal reinforcement perpendicular to the transverse reinforcement which is secured to the central elbows of the transverse reinforcement. The invention also relates to a structure thus defined, in which the first lateral bends and the second lateral bends of each transverse reinforcement are each extended by a straight lateral branch.

The invention also relates to a structure thus defined, in which each planar portion comprises several undulations connected to each other and extending in the same plane, the second lateral elbow of an undulation forming the first lateral elbow of the next wave.

The invention also relates to a structure thus defined, having a transverse reinforcement comprising more than two plane portions.

The invention also relates to a method for assembling a structure thus defined, comprising the steps of:

- Install on a support a first and a second longitudinal reinforcement parallel and high relative to the ground;

- deposit on these longitudinal reinforcements of the transverse reinforcements to place them in support by their first lateral elbows on the first longitudinal reinforcement and in support by their second lateral elbows on the second longitudinal reinforcement;

- secure the transverse reinforcements to the longitudinal reinforcements at the level of the first and second lateral elbows.

The invention also relates to a method thus defined, comprising, after removal of the transverse reinforcements on the first and on the second longitudinal reinforcement, a step of depositing at least one third longitudinal reinforcement resting on the central elbows of the transverse reinforcements.

The invention also relates to a method for assembling a structure thus defined comprising the steps of:

- place the third longitudinal reinforcement on the ground;

- Place transverse reinforcements on the ground aligned one behind the other resting on their first lateral elbows and on their second lateral elbows on either side of the third longitudinal reinforcement; - deposit the first longitudinal reinforcement so that it rests in the first lateral bends;

- deposit the second longitudinal reinforcement so that it rests in the second lateral elbows;

- lift the third longitudinal reinforcement so that it comes to rest against the central elbows of the transverse reinforcements;

- secure the transverse reinforcements to the longitudinal reinforcements at the level of the elbows against which these longitudinal reinforcements rest.

- deposit transverse reinforcements on the ground so that they rest in support on their first lateral elbows and on their second lateral elbows, by arranging them aligned one behind the other;

- deposit the first longitudinal reinforcement so that it rests in the first lateral bends;

- Engage the third longitudinal reinforcement between the first lateral elbows and the second lateral elbows of the transverse reinforcements and lift it so that it bears against the central elbows of the transverse reinforcements;

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is an overall perspective view of a known reinforcement structure;

Figure 2 shows several types of transverse reinforcement seen from the front; Figure 3 is an overall perspective view of a known reinforcement structure comprising positioning defects of its transverse reinforcements;

Figure 4 is a perspective view of a transverse frame according to the invention;

Figure 5 is a perspective view of an assembly bench of a reinforcement structure according to the invention;

Figure 6 is a perspective view of the assembly bench supporting two longitudinal reinforcements in accordance with the invention;

Figure 7 is a perspective view of the assembly bench supporting two longitudinal reinforcements themselves supporting transverse reinforcements in accordance with the invention;

Figure 8 is a perspective view of the assembly bench supporting two longitudinal reinforcements themselves supporting transverse reinforcements which themselves support a third longitudinal reinforcement according to the invention;

Figure 9 is an enlarged view showing a transverse reinforcement supported by two sections of longitudinal reinforcement and supporting a third section of longitudinal reinforcement;

Figure 10 is a perspective view of a variant of transverse reinforcement according to the invention;

Figure 11 is a perspective view of another variant of transverse reinforcement according to the invention.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

According to the invention, a form of transverse reinforcement is used extending in two separate parallel planes, and having a geometry that spontaneously ensures its orientation when it bears on two parallel longitudinal reinforcements. Such a transverse reinforcement, marked 8 in FIG. 4, is an element formed from a single piece of rebar, comprising a first flat portion 9 extending in a first plane PI, extended by a second flat portion 11 s extending in a second plane P2 parallel to the first, these two portions having identical shapes.

The portion 9 has a general undulating shape corresponding to that of the letter U or V, the ends of the branches of which are extended by external flaps each forming a bearing elbow on a longitudinal reinforcement.

More particularly, the portions 9 and 11 are joined by a connection portion 12 having here a semicircular shape extending from the plane PI to the plane P2. This connection portion 12 is extended on one side by a first lateral bend 13 having a curved arcuate shape and, this first bend being extended by a first rectilinear branch 14 itself extended by a central bend 16 of curved shape which is extended by a second straight branch 17, itself extended by a second lateral bend 18.

The whole of this first portion 9 is a planar curved shape extending in the plane PI, and it is symmetrical with respect to an axis of symmetry AS1 extending in this plane while being equidistant from the two rectilinear branches 14 and 17. The two branches 14 and 17 which deviate from each other from the central elbow 16 to the first and second lateral elbow 13 and 18 correspond to the longest portions which define the general shape corresponding to the letter U or V of the transverse reinforcement. The first lateral bend 13 and the second lateral bend 18 are coplanar with the V-shape defined by the two rectilinear branches 14 and 17, and they extend outwards from this V-shape of which they each extend one branch. In other words, the first side bend 13 and the second side bend 18 extend in opposite directions.

As visible in Figure 4, on the one hand, the first and second lateral elbows 13 and 18 extend outwards from this V-shape, and on the other hand the concavity of the central elbow is turned towards the concavities of the first and second side elbows. The concavity of the central elbow is thus oriented opposite to the concavities of the first and second lateral elbows.

The second portion 11, which as indicated above is identical to the first, extends the connection portion 12, it comprises a first lateral elbow 13 'extended by a first branch 14' extended by a central elbow 16 'extended by a second branch rectilinear 17' extended by a second lateral elbow 18'.

The second portion 11 corresponds to the orthogonal projection of the first portion 9 on the second plane P2, the first branches 14 and 14' being parallel to each other, the second branches 17 and 17' also being parallel to each other. one to another.

The first portion 9 is connected to the second portion 11 by the connecting portion 12 which is curved and extends in a third plane perpendicular to the planes P1 and P2. The assembly formed by the first portion and the second portion connected to each other is formed from a single-piece concrete reinforcing bar, being for example obtained by bending to form the various elbows and the connecting portion.

As illustrated in FIGS. 5 to 8, an assembly bench for a reinforcement structure according to the invention, identified by 21, can consist of a mechanically welded structure, which can for example itself be made from iron bars. concrete to facilitate implementation on site.

In the example of the figures, the bench comprises two beams 22 and 23, parallel to each other and resting on the ground to constitute its base, to which are fixed high supports 24, 26, 27 and 28, here at number of four, and low supports 29, 31, here two in number. These supports are spaced from each other along these beams.

As can be seen in FIG. 6, these supports are rectangular frames extending in planes normal to the general direction of the beams, and each frame being fixed to the beams, advantageously in a removable manner. The upper edge of the high supports is at a greater height than the upper edge of the low supports, the difference in height of these supports corresponds to the height of a transverse reinforcement, i.e. the distance separating the central elbow of a portion, of the first or second lateral elbow of this portion along its axis of symmetry.

The maintenance of the two high supports 24 and 28, located at the ends, is reinforced by two oblique frames 32, 33 each connecting an upper part of a support to the beams to prevent the support in question from tilting. Each high support 24, 26, 27, 28 has an upper portion which is interrupted at its center so as to form a passage, these passages being marked 34. The low supports 29 and 31 are simple rectangular frames, c ie whose upper portion or edge is continuous.

In the example of the figures, the assembly of the reinforcing structure according to the invention is carried out by ensuring in the first place the positioning of two longitudinal reinforcements 36, 37 on the assembly bench, resting on the various high supports, of on either side of their central passages 34. In this situation, illustrated in FIG. 6, the reinforcements 36, 37 extend parallel to each other while being at a constant distance from each other, above the ground by being carried by the high supports.

Once the two upper longitudinal reinforcements 36 and 37 are in position, the transverse reinforcements 8 are installed on them. More particularly, each reinforcement 8 is presented above the reinforcements 36 and 37 and is lowered, in such a way that its first lateral elbows 13 and 13' come to rest by their interior sides on the first reinforcement 36, and that its second elbows lateral 18 and 18 'come to bear by their inner sides on the second longitudinal reinforcement 37.

In this situation, which appears more clearly in FIG. 9, the four elbows 13, 13', 18, 18' of the transverse reinforcement 8 bear against the longitudinal reinforcements, so that this transverse reinforcement 8 is positioned spontaneously in an orientation normal to the direction of the longitudinal reinforcement. In other words, the first portion 9 and the second portion 11 of the armature 8 each extend perpendicular to the armatures 36 and 37.

Once the first transverse reinforcement 8 has been installed, other reinforcements 8 are installed in the same way, being distributed along the reinforcements 36 and 37, for example in a regular manner as illustrated schematically in Figure 7.

When the various transverse reinforcements are in place, they constitute V-shaped open upwards and each extending essentially between the two reinforcements 36, 37. This situation makes it possible to install a third longitudinal reinforcement 38, or lower reinforcement by positioning it longitudinally , above the central passages 34, then lowering it to pass it through these passages in order to deposit it on the inner sides of the central elbows 16, 16' of the various transverse reinforcements. In this situation which corresponds to figure 8, all the reinforcements are correctly positioned, so that it essentially remains to fix these reinforcements to each other, by welding or by means of wire ligatures, at the level of the elbows, to form the reinforcing structure 39 according to the invention.

In general, the assembly method which has been described in relation to FIGS. 5 to 9 can be implemented manually, for example on a construction site, or else automatically in a factory by means of manipulator arms or the like capable of manipulating the various armatures to position them relative to each other.

Alternatively, it is also possible initially to deposit the third longitudinal reinforcement 38 on the ground, then to deposit transverse reinforcements 8 one behind the other on the ground resting on their first lateral elbows 13, 13' and on their second lateral bends 18, 18', these bends being respectively on either side of the third longitudinal reinforcement 38.

The first longitudinal reinforcement 36 can then be deposited to rest in the first lateral elbows 13, 13', and the second longitudinal reinforcement 37 can also be deposited to rest in the second side bends 18, 18'.

The third longitudinal reinforcement 38 can then be raised to bear against the central elbows 16, 16' of the transverse reinforcements 8, so that the various reinforcements are then in position relative to each other.

At this stage, the transverse reinforcements 8 can be secured to the longitudinal reinforcements 36, 37, 38 at the level of the elbows against which these longitudinal reinforcements 36, 37, 38 bear.

It is still possible initially to deposit transverse reinforcements 8 on the ground so that they rest in support on their first lateral elbows 13, 13 'and on their second lateral elbows 18, 18', by arranging them aligned with each other behind the others.

A first longitudinal reinforcement 36 can then be deposited to rest in the first lateral elbows 13, 13', and a second longitudinal reinforcement 37 can also be deposited to rest in the second lateral elbows 18, 18'.

At this stage, a third longitudinal reinforcement 38 is engaged between the first lateral elbows 13, 13' and the second lateral elbows 18, 18' of the transverse reinforcements 8 before being raised to bear against the central elbows 16, 16' transverse reinforcements 8, so that the different reinforcements are then in position relative to each other.

Under these conditions, the transverse reinforcements 8 can be secured to the longitudinal reinforcements 36, 37 at the level of the elbows against which these longitudinal reinforcements 36, 37, 38 rest.

One like the other of these arrangement and assembly methods can be improved in order for example to be automated on a production site by means, for example, of robotic manipulator arms and also automated welding heads.

The manufacture of a transverse reinforcement consists in turn, from a rectilinear concrete reinforcing bar, in bending it in its center by a value of 180° in order to to form two parallel sections joined by the connecting portion 12. After this first operation, a second bending operation makes it possible to jointly form the first two lateral elbows 13, 13', a second bending operation makes it possible to jointly form the central elbows 16 , 16', and a third bending operation makes it possible to jointly form the second lateral bends 18 and 18'.

The shape of each transverse reinforcement portion 8 appearing in FIGS. 4 to 9 corresponds to an embodiment of the invention, this shape being able to be declined or adapted. For example, in the case of Figure 10, the first lateral bend 13 of the first portion 9 is extended by a straight side branch 41, and the second bend 18 of the first portion 9 is extended by another straight side branch 42, so that the assembly has a general shape resembling the letter M. In this case, the first lateral elbows of the first and of the second portion are connected to each other via their branches lateral rectilinear themselves joined by the connecting portion 12.

Furthermore, FIGS. 4 to 10 show examples of transverse structures, each portion of which comprises a single corrugation, but the corrugation pattern can be repeated instead of being unique. For example, and as illustrated in FIG. 11, each portion may comprise two undulations extending in the same plane, the second lateral bend of one of the undulations constituting the first lateral bend of the other undulation. In this case, each portion has a shape resembling the letter W, which makes it possible to constitute a transverse structure intended to be deposited on three upper longitudinal reinforcements, and able to receive two lower longitudinal reinforcements.

As visible in this figure 11, the transverse reinforcement 8 may comprise more than two planar portions, namely for example three planar portions, marked here by 43, 44 and 45, which extend in three parallel planes marked by P1, P2 and P3.

In general, the invention makes it possible to simplify the manufacture of reinforcing structures for reinforced concrete elements, whether this manufacture is robotic or manual. It makes it possible to assemble reinforcement structures by manipulating the reinforcements essentially in the vertical direction from top to bottom to achieve a reinforcement structure having a high level of geometric conformity, because the transverse reinforcements are spontaneously oriented perpendicular to the longitudinal reinforcements. .

The invention thus provides a gain in precision, and a simplification of the assembly of rebar reinforcements, the assembly being carried out only by moving the longitudinal and transverse reinforcements vertically from top to bottom.

Claims

1. Reinforcing structure (39) of concrete element, comprising at least a first and a second longitudinal reinforcement (36, 37) of concrete iron, characterized in that

- it comprises at least one transverse reinforcement (8) formed by bending the same rebar bar;

- this transverse reinforcement (8) comprises at least two planar portions (9, 11; 43, 44, 45) having the same shapes and extending in parallel planes (Pl, P2) spaced from each other, each flat portion comprising an undulation including a first and a second rectilinear branch (14, 14', 17, 17') connected to each other by a central elbow (16, 16');

- each first rectilinear branch (14, 14') is extended by a first lateral elbow (13, 13'), these first lateral elbows (13, 13') being connected to each other by a connection portion ( 12) extending from the plane (PI) of the first portion (9) to the plane (P2) of the second portion (11);

- each second straight branch (17, 17') is extended by a second lateral bend (18, 18') extending in the opposite direction to the first lateral bend (13, 13'); and in that :

- the first and second longitudinal reinforcements (36, 37) are oriented perpendicular to the transverse reinforcement (8) and are secured respectively to the first and to the second lateral elbows (13, 13', 18, 18') of the reinforcement transverse (8) by welding or binding.

2. Structure according to claim 1, comprising a third longitudinal reinforcement (38) perpendicular to the transverse reinforcement (8) which is secured to the central elbows (16, 16 ') of the transverse reinforcement (8).

3. Structure according to claim 1, in which the first lateral elbows (13, 13') and the second lateral elbows (18, 18') of each transverse reinforcement (8) are each extended by a rectilinear lateral branch (41, 42 ).

4. Structure according to claim 1, wherein each planar portion (9, 11) comprises several corrugations connected to each other and extending in the same plane, the second lateral bend of a corrugation forming the first lateral bend of the next wave.

5. Structure according to claim 1, having a transverse reinforcement (8) comprising more than two planar portions (43, 44, 45).

6. A method of assembling a structure according to claim 1 comprising the steps of:

- Install on a support a first and a second longitudinal reinforcement (36, 37) parallel and high relative to the ground;

- deposit on these longitudinal reinforcements (36, 37) transverse reinforcements (8) to place them in support by their first lateral elbows (13, 13 ') on the first longitudinal reinforcement (36) and in support by their second lateral elbows ( 18, 18') on the second longitudinal reinforcement (37);

- securing the transverse reinforcements (8) to the longitudinal reinforcements (36, 37) at the level of the first and second lateral elbows (13, 13', 18, 18').

7. Method according to claim 6, comprising, after removal of the transverse reinforcements (8) on the first and on the second longitudinal reinforcement (36, 37), a step of depositing at least a third longitudinal reinforcement (38) in support on the central elbows (16, 16') of the transverse reinforcements (8).

8. A method of assembling a structure according to claim 2 comprising the steps of:

- Place on the ground the third longitudinal reinforcement (38);

- depositing transverse reinforcements (8) on the ground aligned one behind the other bearing on their first lateral elbows (13, 13') and on their second lateral elbows (18, 18') on either side of the third longitudinal frame (38);

- deposit the first longitudinal reinforcement (36) so that it rests in the first lateral bends (13, 13');

- deposit the second longitudinal reinforcement (37) so that it rests in the second lateral bends (18, 18');

- lifting the third longitudinal reinforcement (38) so that it bears against the central elbows (16, 16') of the transverse reinforcements (8);

- Secure the transverse reinforcements (8) to the longitudinal reinforcements (36, 37) at the level of the elbows against which these longitudinal reinforcements (36, 37, 38) rest.

9. A method of assembling a structure according to claim 2 comprising the steps of:

- depositing transverse reinforcements (8) on the ground so that they rest on their first lateral elbows (13, 13') and on their second lateral elbows (18, 18'), arranging them aligned one behind the others ;

- engage the third longitudinal reinforcement (38) between the first lateral elbows (13, 13') and the second lateral elbows (18, 18') of the transverse reinforcements (8) and lift it so that it comes to rest against the elbows centers (16, 16') of the transverse reinforcements (8); - Secure the transverse reinforcements (8) to the longitudinal reinforcements (36, 37) at the level of the elbows against which these longitudinal reinforcements (36, 37, 38) rest.