EP2868829B1 - Method for reinforcing a timber construction element by assembling a reinforcement module placed under post-tension - Google Patents

Description

The present invention relates to the field of reinforcement of wooden construction structures (solid or glued laminated). Said wooden construction structures preferably extend between at least two support points and preferentially work in flexion, traction, compression, buckling or spill.

Over time, such structures are likely to degrade for various reasons, such as water infiltration, causing degradation of the material constituting the structure, ground settlement phenomena causing a movement of the building foundations, a modification of the building after its construction, an overload of the structure causing breaks etc ...

Permanent or occasional overloads due to the exploitation, can also be applied to the structure of wooden construction, which requires to increase its carrying capacity by increasing its inertia. The evolution of structural design standards may also require compliance of the building structure imposing to increase its inertia.

In known manner, the restoration of wood structures, floor type, beam, etc ..., with cracks, degradations or deformations, can be achieved by replacing the degraded or broken elements requiring scaffolding, or even a deconstruction and a partial reconstruction or total of the work. Such processes affect the surrounding structures and impose significant constraints in terms of operation and implementation, including the time of immobilization of the building and the cost, and do not allow to reinforce overloaded or degraded structures, in any case. reliability and safety, for a reasonable cost.

It is possible to use subtended cables or tie rods attached to each end of the beam to be reinforced and to a metal element arranged perpendicular to the beam to be reinforced.

However, such a reinforcement system has a large footprint thus reducing the operating space around the beam to be reinforced. In addition, the necessary metallic materials have poor fire resistance.

It is also possible to use reinforcement modules to be added on one of the faces of the beam to be reinforced.

Thus, the building elements of solid wood or laminated wood are reinforced by the integration of reinforcing modules or prostheses of wood or glue-laminated for example on the lower surface, called the intrados, of the building element. strengthen.

Such a prosthesis may be of constant or variable height and its length is often limited to the central zone of the beam where the bending moments are high.

The prosthesis thus contributes to increasing the inertia of the reinforced beam and can be added to it either directly, in which case the prosthesis is active only after overloading the beam, or after a so-called jacking stage consisting in creating a counter-arrow, given to the beam at the time of its strengthening with the help of jacks, so that the prosthesis is immediately in tension during the deverinage of the whole.

However, although such reinforcement modules have good fire resistance, they require the use of shoring ladders to give them a counter-arrow that requires to have a large operating space around the beam to strengthen.

In addition, it is not possible to increase their stiffness without increasing their size.

EP0034224A2 discloses a method of reinforcing wood beams comprising at least the following successive stages: contacting the two beams to be joined together with intercalation of a layer of fibers; drilling a plurality of anchor holes through the two beams and the fiber layer; introduction of reinforcing rods into the holes thus obtained; sealing the joints between the two beams; and introducing by casting or injection of an epoxy resin or a mixture of epoxy resins into said anchor holes until they are completely filled and until the total impregnation of the fiber layer.

The object of the invention is therefore to overcome these disadvantages and simplify the implementation of the reinforcement by facilitating its installation on a solid wood building element or laminated wood that may have deformed compared to its original shape , for example a beam flexed. The object of the invention is therefore to provide a counter-arrow to the reinforcement module without using a tower ladder shoring, thus reinforcing beams even in the most difficult to access spaces.

Another object of the invention is to bring end-to-end reinforcement modules to be assembled directly on the site, for example under the beam to be reinforced, in order to ensure the mechanical continuity of the traction forces that the assembled reinforcement must take up. . According to claim 1, the invention relates to a method of reinforcing a structural element made of solid wood or glulam, in which at least one of the faces of said construction element is fixed via at least one connector, at least one reinforcement module made of solid wood or laminated wood. At least one housing provided in the reinforcement module is inserted into at least one strand, said strand is post-tensioned by a post-tensioning system, and said strand is fixed by an anchoring device.

In one embodiment, the anchoring device comprises a support plate attached to each end of the reinforcement module and a clamping device comprising a conical jaw capable of clamping each end of the corresponding strand.

In one embodiment, at least one of the faces of the construction element is fastened with at least two adjacent reinforcement modules made of solid wood or laminated wood bonded by the post-tensioned strand.

Advantageously, a first support plate is fixed at a first end of the first reinforcement module, the second end of the first reinforcement module is joined to a first end of the second adjacent reinforcement module and a second support plate is fixed to a second a second end of the second reinforcement module.

For example, wooden fire protection means may be positioned around the support plates.

According to another embodiment, the anchoring device is a binder capable of sealing at least part of the strand inside the housing provided in the reinforcement module (s).

The connectors may be screws, studs sealed by a binder (not shown) such as for example a resin or glue simultaneously in the beam and the reinforcement module, or reinforcements constituted by rods or rigid bars, for example fiberglass, carbon, steel or other ....

The binder may be a resin, for example of the epoxy type, or an adhesive, for example of the cyanoacrylate, polyurethane, formaldehyde type or any other suitable adhesive or resin.

The strand may be made of metal material, synthetic material, composite material or mineral.

In one embodiment, the housing for the strand is machined in the reinforcement module (s).

In another embodiment, the housing for the strand is made by leaving gaps between the lamellae (s) module (s) reinforcement laminated wood during its manufacture.

Advantageously, a sheath is inserted into the gaps forming a housing before the application of a pressure force necessary for the manufacture of the laminated wood reinforcement module. Thus, it avoids the obstruction of the gaps by the glue during the pressure force applied to the superposition of wooden boards and layers of glue. The sheath may have internal and external surfaces which may be smooth or annealed depending on the degree of adhesion required between the wood and the sheath and between the strand and the sheath.

The housing may be substantially inclined relative to the longitudinal axis of (the) reinforcing modules to give the strand a substantially parabolic shape.

Advantageously, the reinforcement module is fixed to the beam to be reinforced by gluing.

In one embodiment, at least one hooping reinforcement is positioned in a hole made respectively in the reinforcement module (s) and the beam to be reinforced.

• la figure 1 représente une vue en coupe d'un élément de construction renforcé selon le procédé de renforcement selon un mode de réalisation de l'invention,
• la figure 1a illustre schématiquement un détail de la figure 1 ;
• la figure 2 représente une vue en coupe II-II de l'élément de construction renforcé selon la figure 1 ;
• la figure 3 représente une vue en coupe d'un élément de construction renforcé selon le procédé de renforcement selon un deuxième mode de réalisation de l'invention ;
• la figure 4 représente une vue en coupe d'un élément de construction renforcé selon le procédé de renforcement selon un troisième mode de réalisation de l'invention ; et
• la figure 5 représente une vue en coupe d'un élément de construction renforcé selon le procédé de renforcement selon un quatrième mode de réalisation de l'invention.

Other advantages and characteristics will appear on examining the detailed description of some embodiments taken as non-limiting examples and illustrated by the appended drawings, in which:

• the figure 1 represents a sectional view of a reinforced structural element according to the reinforcement method according to one embodiment of the invention,
• the figure 1a schematically illustrates a detail of the figure 1 ;
• the figure 2 represents a sectional view II-II of the reinforced structural element according to the figure 1 ;
• the figure 3 is a sectional view of a reinforced structural element according to the reinforcing method according to a second embodiment of the invention;
• the figure 4 is a sectional view of a reinforced structural element according to the reinforcing method according to a third embodiment of the invention; and
• the figure 5 is a sectional view of a reinforced structural element according to the reinforcing method according to a fourth embodiment of the invention.

On the figure 1 is represented a beam 1, for example of solid wood or glued laminated, having a lower surface, said lower surface or convex plane 1a, and to be reinforced either because of a degradation of its mechanical properties, or because of an increase the load she has to bear.

A reinforcement module 2 made of solid wood or laminated wood is fixed on the lower face 1a of the beam 1 by means of a plurality of connectors 3. As illustrated, the connectors 3 are screws, to the number of six, arranged inclined with respect to the longitudinal direction of the beam to be reinforced 1. Alternatively, the connectors 3 could be arranged substantially perpendicular to the longitudinal direction of the beam to be reinforced 1. It will be noted that one could provide a number of connectors greater than or equal to one.

In a variant, it will be noted that the connectors 3 may be studs sealed by a binder (not shown) such as, for example, a resin or a glue simultaneously in the beam and the reinforcement module, or else reinforcements constituted by rods or bars. rigid, for example fiberglass, carbon, steel or other ....

To assemble the reinforcement module 2 to the beam 1, the connectors 3 are positioned in bores 1b made respectively in the first reinforcement module 2 and in the beam 1 to be reinforced.

The lower surface 1a of the beam 1 to be reinforced is bonded by a binder 4, such as for example glue, with the reinforcement module 2. Thus, the reinforcement module is assembled by gluing and screwing or by gluing and stitching.

As illustrated on figures 1 and 2 , the reinforcement module 2 comprises two housings 5a, 5b provided to each receive a strand 6a, 6b.

The reinforcement module 2 is made of laminated wood glued by the superposition of several layers of wooden boards (not shown), while leaving gaps to form a passage 5a, 5b for the corresponding strand 6a, 6b. Alternatively, it could be provided to drill in the reinforcement module 2. It could also be provided that the reinforcement module 2 is made of solid wood.

Note that one could provide a housing and strand number greater than or equal to one.

The strand is made of metal material for example with high elastic limit of type T15, carbon fiber, fiberglass, aramid fiber, mineral fiber or any other synthesized material based on polymer. The strand may also be made of composite material such as carbon-epoxy, glass-epoxy, glass-vinylester, aramid-epoxy rods, etc.

It will be appreciated that a plurality of strands could be provided to form one or more cables.

Each of the strands 6a, 6b is post-tensioned by a post-tensioning system 10 illustrated in detail in FIG. figure 1a .

A first anchoring means 7 is attached to a first end of each of the strands 6a, 6b and a second anchoring means 7 is attached to a second end of each of the strands 6a, 6b. The two anchoring means 7 are identical to each other and only the anchoring means 7 located at one end of the 6a is illustrated in detail on the figure 1a and will be described. As illustrated in detail on the figure 1a the second anchoring means 7 is connected to a post tensioning system 10 such as for example a hydraulic cylinder outside the reinforcement module 2 and whose displacement according to the arrows F causes the tension of the strands 6a, 6b between the two anchoring means 7.

Each of the anchoring means 7 comprises for example a support plate 8 disposed at each end of the strands 6a, 6b and is provided with a passage 8a for the corresponding strand 6a, 6b.

As illustrated, each of the anchoring means 7 further comprises a clamping device 9 comprising, for example, a cylindrical body 9a and a conical jaw 9b having an outer surface of conical shape cooperating with a bore 9c of corresponding shape formed in the cylindrical body 9a. The cylindrical body 9a has on its outer surface of revolution a threaded portion 9d intended to cooperate with a screwing means 9e. The corresponding strand 6a passes into a passage (not referenced) provided inside the cylindrical body 9a of the clamping device 9 and is clamped between the conical jaws 9b, respectively disposed at one end of the corresponding strand, by the screwing means 9e . Any other means could be provided for anchoring each end of the strands 6a, 6b.

As illustrated, a hydraulic jack system 10 comprises a tubular body 10a surrounding the clamping device 9 and bearing axially on only one of the support plates 8. The tubular body 10a has an opening (not shown) so that to allow screwing of the clamping device 9. It will be noted that several screwing openings could be provided on the tubular body 10a.

The tubular body 10a is extended by a jack 11 fed by a hydraulic pump (not shown) intended to inject a fluid through the passage 11a in order to move the jack 11 according to the arrow F. The hydraulic jack system 10 also comprises a clamping 12 is disposed at one end of the corresponding strand 6a. The clamping device 12 comprises a conical key 12a intended to cooperate with a jaw 12b of corresponding shape. Note that one could provide any other means for clamping and tensioning the strand.

The hydraulic jack system 10 stretches the strand 6a, then the clamping device 9 anchors the strand 6a in the extended position to ensure the post tension of the strand. The prestressing force of each of the strands 6a, 6b is transferred to the reinforcement module 2 by means of the support plates 8 of the anchoring device 7. The prestressing is used here to maintain the reinforcement module 2 in a limited traction state, even compressed, and thus increase its tensile strength and bending.

As illustrated on figures 1 and 2 , reinforcements 13, such as for example screws or rods, are positioned at the ends of the reinforcement module 2 on either side of the housing 5a, 5b for the strands 6a, 6b. As illustrated, the hooping frames 13 are three rows of three frames. Alternatively, one could provide a single row of hooping frame having at least one hooping frame. By way of non-limiting example, the reinforcements may be made of metallic material.

These reinforcements 13 are intended to ensure the hooping of the reinforcement module 2 and the beam to be reinforced 1. In practice, these rods or shrinking screws 13 are inserted into holes (not referenced) made perpendicularly to the strands 6a, 6b in the module reinforcement 2 and in the beam to be reinforced 1.

Alternatively, one could provide to position these rods or shrink screw 13 in bores substantially inclined relative to the axis perpendicular to the strands 6a, 6b.

These screws or hooping rods 13 make it possible to prevent the formation of cracks in the reinforcement module 2 at the interface between the reinforcement beam 1 and the reinforcement module 2, in horizontal axes and parallel to the strands 6a, 6b when the beam to be reinforced is subjected to a large bending force. Since the concentration of shear stress is maximal at the ends of the reinforcement module, it is necessary to position the hoop reinforcements close to the ends. Alternatively, one could not provide reinforcement frames between the reinforcement module and the beam to be reinforced.

Note that one could provide as reinforcement frame, self drilling screws that do not require the creation of a drilling beforehand.

It will be noted that provision could be made to position wood protection means against the fire 14 around each of the support plates 8. It should also be noted that the thickness of the wood around each strand can be calculated according to the desired fire resistance.

The embodiment illustrated on the figure 3 , in which the same elements have the same references, differs from the embodiment illustrated in FIG. figure 1 by anchoring the strands 6a, 6a in the corresponding housing 5a, 5b.

After having post-tensioned the strands 6a, 6b via the hydraulic system 10 described with reference to FIG. figure 1a , the strands 6a, 6b are held in tension by the clamping devices 9 disposed at each end of the strands 6a, 6b.

A binder 15 is then injected into the housings 5a 5b for the strands 6a, 6b in order to bind the strands 6a, 6b to the reinforcement module 2. The binder can be injected under pressure in the axis of the housings, or via lateral openings (not shown) opening into the housing 5a, 5b and allowing the flow of the binder by gravitation. The binder may be a resin, for example of the epoxy type, or an adhesive, for example of the cyanoacrylate, polyurethane, formaldehyde type or any other suitable adhesive or resin. The binder can be thixotropic or fluid.

After post-tensioning performed and after curing of the binder 15, the stresses applied to the strands 6a, 6b are transmitted to the reinforcement module 2 by separating the clamping means 9 and the external jack system 10. The binder 15 plays here the role of anchoring means of the strands 6a, 6b. The force of the strands 6a, 6b is thus transmitted to the reinforcement module 2 via the binder 15.

It will be noted that the binder 15 can be placed only on part of the strand 6a, 6b to be sealed.

Alternatively, it is possible to combine the embodiments of the figures 1 and 3 in order to obtain as anchoring means strands 6a, 6b the combination of binder 15 and anchoring devices 7.

The embodiment illustrated on the figure 4 , in which the same elements have the same references, differs from the embodiment illustrated in FIG. figure 1 by the number of reinforcement modules 2.

As illustrated on the figure 4 several adjacent reinforcing modules 2, 2n, 2 (n + 1), for example three in number, made of solid wood or laminated wood are fixed on the underside 1a of the beam to be reinforced 1 via a plurality of connectors 3 identical to the connectors with reference to the figure 1 .

In a manner identical to the reinforcement method illustrated in the Figures 1 to 3 , to assemble the reinforcement modules 2, 2n, 2 (n + 1) to the beam 1, the connectors 3 are positioned in bores 1b made respectively in each of the reinforcement modules 2, 2n, 2 (n + 1) and in the beam 1 to strengthen.

The lower surface 1a of the beam 1 to be reinforced is bonded by a binder 4, such as for example glue, with each of the reinforcement modules 2, 2n, 2 (n + 1), to resume the efforts shearing between the beam to be reinforced 1 and the reinforcement modules 2, 2n, 2 (n + 1).

As illustrated on the figure 4 , the reinforcement modules 2, 2n, 2 (n + 1) are connected by two post-tensioned strands 6a, 6b respectively inserted in a corresponding housing 5a, 5b provided in each of the reinforcement modules 2, 2n, 2 ( n + 1).

Each of the strands 6a, 6b is post-tensioned by the post-tensioning system 10 and anchored by the anchoring means 7 illustrated in detail in FIG. figure 1a . The post-tensioning of the strands 6a, 6b will not be further described.

In order to link the reinforcement modules 2, 2n, 2 (n + 1) to each other, a first support plate 8 is fixed at a first end of the first reinforcement module 2, the second end of the first reinforcement module is joined to 2 at a first end of the second adjacent reinforcement module 2n, the second end of the second reinforcement module 2n is joined to a first end of the third adjacent reinforcement module 2 (n + 1) and a second support plate 8 is fixed. at a second end of the third reinforcement module 2 (n + 1). In other words, the support plates 8 are arranged at the ends of the strands 6a, 6b, independently of the number of reinforcement modules.

The strands 6a, 6b thus come to press the two reinforcement modules 2, 2n, 2 (n + 1) against each other.

It is possible to first assemble the reinforcement modules 2, 2n, 2 (n + 1) with each other, then to fix the assembly on the lower surface 1a of the beam to be reinforced 1.

Alternatively, it is possible to fix the lower surface 1a of the beam to reinforce each of the reinforcement modules 2, 2n, 2 (n + 1), then to insert the strands 6a, 6b in the corresponding housing 5a, 5b and to apply prestressing.

In the same way as the reinforcement method according to the figure 3 it may be provided that the anchoring means are made by the binder alone or the combination of the binder and the anchoring device 7 illustrated in detail on the figure 1a .

In a manner similar to the method described with reference to figure 1 it is possible to position a wooden protection means (not shown) against the fire around the bearing plates 8. It would also be possible to provide hoop reinforcements at the ends of each reinforcement module or only near the ends of the strands.

The embodiment illustrated on the figure 5 , in which the same elements have the same references, differs from the embodiment illustrated in FIG. figure 1 by the shape of the housing 5a, 5b for the strands 6a, 6b.

The housing 5a, 5b for the corresponding strand 6a, 6b is produced by leaving gaps between the lamellae of the laminated-wood reinforcement module during its manufacture, so as to form a housing substantially inclined with respect to the longitudinal axis reinforcement module 2. Thus the strand inserted in this housing will have a substantially parabolic shape.

During the known manufacture of the reinforcement module of laminated wood, is successively stacked a wooden blade and a layer of glue, then creates a pressure force. The creation of gap is achieved by the superposition of wood blades of different lengths. The pressure required to manufacture the laminated wood reinforcement module will overflow the glue and thus come to obstruct the gaps. A sheath (not shown), preferably annealed, can be inserted into each of the housing 5a, 5b formed by the gaps before the application of the pressure force to prevent clogging of the gaps. Under the action of the pressure force, the glue, present during the manufacture of the reinforcement module, will come to be distributed around the sheaths. Thus, each of the strands 6a, 6b can be easily inserted into the corresponding sheath.

Note that the reinforcing process is not limited to the use of one or two or three reinforcement modules. As a variant, it would be possible to use a number of reinforcement modules greater than three, in order, for example, to repair a large area or length of a damaged beam.

Alternatively, one could fix the reinforcement modules on the upper face or on a side face of the beam to be reinforced.

It will be noted that the reinforcements 13 and the fire protection means 14 illustrated in FIG. figure 1 can be used in all the embodiments described above.

The invention is suitable for any structure whose surface must be repaired, both during reinforcement work and at the end thereof.

Thanks to the invention, it is possible to restore resistance to bending, tensile, compressive, buckling or spilling to the beam of wood or glued laminated which is damaged by, on the one hand, fastening via at least one connector, supplemented or not by an injection of resin or glue, reinforcement modules of wood or laminated on at least one surface of the damaged beam and secondly by a linear assembly of the modules of reinforcement between them.

The damaged wooden beam is thus restored directly on site thanks to the reinforcement method described.

Claims (15)

1. Method for reinforcing a construction element (1) of solid wood or of glued-laminated wood, in which

   - at least one reinforcing module (2, 2n, 2(n+1)) of solid wood or of glued-laminated wood is fixed to at least one of the faces (1a) of said construction element (1) via at least one connector (3), characterized in that

   - at least one strand (6a, 6b) is inserted into at least one housing (5a, 5b) provided in the reinforcing module (2, 2n, 2(n+1)),

   - said strand (6a, 6b) is post-tensioned by a post-tensioning system (10), and

   - said strand (6a, 6b) is fixed by an anchoring device (7, 15).
2. Reinforcing method according to Claim 1, in which the anchoring device (7) comprises a bearing plate (8) fixed to each end of the reinforcing module (2, 2n, 2(n+1)), and a clamping device (9) comprising a conical jaw (9b) able to clamp each end of the corresponding strand (6a, 6b).
3. Reinforcing method according to either one of Claims 1 and 2, in which at least two adjacent reinforcing modules (2, 2n, 2(n+1)) of solid wood or of glued-laminated wood, which are connected by the post-tensioned strand (6a, 6b), are fixed to at least one of the faces of said construction element (1).
4. Reinforcing method according to Claims 2 and 3, in which a first bearing plate (8) is fixed to a first end of the first reinforcing module (2), the second end of the first reinforcing module (2) is juxtaposed with a first end of the second adjacent reinforcing module (2n) and a second bearing plate (8) is fixed to a second end of the second reinforcing module (2n).
5. Reinforcing method according to Claim 2 or 4, in which fire-resistant wooden protection means (14) are positioned around the bearing plates (8).
6. Reinforcing method according to any one of the preceding claims, in which the anchoring device is a binder (15) able to seal at least one portion of the strand (6a, 6b) within the housing (5a, 5b) provided in the reinforcing module(s) (2, 2n, 2(n+1)).
7. Reinforcing method according to any one of the preceding claims, in which the connectors (3) are screws or pins which are or are not sealed by a binder.
8. Reinforcing method according to Claim 6 or 7, in which the binder (15) is a resin or a glue.
9. Reinforcing method according to any one of the preceding claims, in which the strand (6a, 6b) is made of metallic material, of synthetic material, of composite material or of mineral material.
10. Reinforcing method according to any one of the preceding claims, in which the housing (5a, 5b) for the strand (6a, 6b) is machined in the reinforcing module(s) (2, 2n, 2(n+1)).
11. Reinforcing method according to any one of Claims 1 to 9, in which the housing (5a, 5b) for the strand (6a, 6b) is produced by leaving gaps between the laminations of the reinforcing module(s) (2, 2n, 2(n+1)) of glued-laminated wood during the manufacture thereof.
12. Reinforcing method according to Claim 11, in which a sheath is inserted into the gaps forming a housing prior to the application of a pressure force necessary for the manufacture of the reinforcing module of glued-laminated wood.
13. Reinforcing method according to any one of the preceding claims, in which the housing (5a, 5b) is substantially inclined with respect to the longitudinal axis of the reinforcing module(s) (2, 2n, 2(n+1)).
14. Reinforcing method according to any one of the preceding claims, in which the reinforcing module (2, 2n, 2(n+1)) is fixed to the beam (1) to be reinforced by gluing.
15. Reinforcing method according to any one of the preceding claims, in which at least one binding reinforcement (13) is positioned in a drilling made respectively in the reinforcing module(s) (2, 2n, 2(n+1)) and the beam (1) to be reinforced.

Images