EP2489809B1 - Method for manufacturing a structural element and elements thus manufactured - Google Patents

Description

The subject of the invention is a method for producing a structural element which can be applied to the construction of buildings.

The invention allows, in general, all kinds of elongated structural elements intended to rest on two spaced apart supports, such as beams or posts.

DE10 2004 059 178 A1 discloses a beam comprising two plates separated by wooden pieces.

The roof of a building normally includes a covering, for example of slate, tiles or other materials, resting on a frame supported on the walls. The elements of the frame must therefore have a span corresponding to the distance between the supports.
It is interesting, for medium spans, for example 10 to 12 meters, to use structural elements light enough to avoid the use of heavy lifting equipment. For example, when there is no plan to build a storey under the eaves, the frame of a detached house can consist of prefabricated wooden trusses, which can be installed by a few men.

However, such elements only allow the construction of conventional roofs, with one or two slopes.

We also proposed, in the document FR-A-955616 , to produce light structural elements comprising at least two superimposed and curved thin blades, assembled by spacers and bearing on a tie rod.

Such relatively light structural elements form kinds of curved trusses making it possible, for example, to produce a slightly vaulted roof. However, the curvature of this arch depends on the resistance to bending of the wooden slats. In addition, they must be supported at their ends on a tie rod which extends between the supports, across the covered space.

However, even if the houses currently built remain fairly standard, with a roof with one or two slopes, there is a tendency, now, to seek more originality by calling on an architect who will eventually design frameworks and roofs of forms varied, everything trying to make the best use of the covered space.

Such constructions are, however, more expensive because there are no structural elements on the market having the desired shapes.
Admittedly, the technique known as "glued-laminated" makes it possible to produce wooden structural elements whose profile can be varied, for example for the production of a curved roof, possibly with reverse curvature. However, the glulam technique requires relatively large and expensive equipment and, therefore, is only used in practice for industrial or commercial buildings or, for example, motorway toll stations but is not economically applicable to the construction of medium-sized buildings.
To solve such problems, the invention relates to a new type of wooden frame elements which can have any desired shape, for example curved, such a method, particularly simple and economical, being profitable even for the production of elements of low or medium range, for example for the construction of individual houses.
The invention therefore relates, in general, to a method according to claim 1 of a structural element extending along a longitudinal axis over a certain length and consisting of at least two thin plates joined by rows spaced spacers which are interposed between two neighboring plates and fixed respectively on their opposite faces, so as to form an integral assembly capable of resting on two spaced apart supports. In this process, in accordance with the invention, a first plate cut in a shape desired for the element, with two longitudinal sides and two transverse sides, is applied and fixed, by an internal face, on a first series of battens distributed over a flat support, then the whole of this plate provided with cleats on its internal face is turned over and applied, by its opposite smooth external face, to a rigid support having a desired profile for the element to be produced, a second assembly comprising a second plate provided with a second series of cleats is then produced in the same way on the flat support then turned over, applied and fixed on the first series of cleats of the first plate taking the form of the rigid support and so on until at laying and fixing on a last series of battens, an external closure plate not provided with battens, in order to produce an element which is then moved away from the support while retaining the shape of the latter. In addition, the various plates thus assembled are cut so as to present the same external profile with two longitudinal sides, having a desired profile and said longitudinal sides are aligned during the assembly of the plates, along two lateral faces and, when the place of the element thus produced, the plates thereof are arranged vertically and rest on edge on the supports, so that the element has two faces, respectively lower and upper having a desired profile, the number of plates, their thickness and the thickness of the cleats being determined so as to give the element the desired resistance, while limiting its own weight.

Each plate, as well as the cleats, can be made of a homogeneous, resistant and relatively flexible material, such as wood or the like, and the spaced cleats are fixed by nailing or screwing on the plates between which they are interposed, so as to form a united and resistant whole.

Furthermore, in a particularly advantageous manner, each plate consists of at least two superposed layers each consisting of several sheets placed one after the other in the longitudinal direction of the element, the transverse joints between the ends adjacent consecutive sheets being offset longitudinally from one layer to another.

It should also be noted that to increase the resistance of the element, the two external plates may have a greater thickness than the intermediate plate or plates.

In addition, the two series of cleats fixed respectively on the two faces of the same plate are preferably offset longitudinally relative to each other.

In a first embodiment, the rigid support on which the various plates are successively applied after turning, has a curved application face in the form of a regulated surface and the cleats are placed so as to be arranged, after application on said curved face , according to the generators thereof, so that the assembly of each plate with its cleats remain flexible enough to take the form of the rigid support which thus constitutes a template for the production of an element having a desired curved profile.

In a variant of the method, the rigid support on which the various plates are applied successively, after turning over, has a flat application face in order to produce, after fixing the closure plate, a rectilinear element limited by two flat faces.

However, the invention also presents other possibilities and makes it possible, for example, to produce a building frame comprising a set of beams for supporting a floor or a roof resting on vertical posts, in which the beams and the posts consist of laminated elements produced by the method according to the invention and assembled in such a way that the plates constituting a beam overlap between the plates constituting a post, the assembly being secured by bolting.

• La figure 1 est une vue, en perspective, d'un élément de structure ne faisant pas partie de l'invention.
• La figure 2 montre, en coupe longitudinale, la réalisation d'une plaque munie de tasseaux.
• La figure 3 montre, en coupe longitudinale, les étapes de réalisation d'un élément à quatre plaques, sur un gabarit courbe.
• La figure 4 montre schématiquement l'élément réalisé après assemblage des différentes plaques.
• La figure 5 montre, en coupe longitudinale, la réalisation d'un élément à double courbure.
• La figure 6 montre, en perspective, un élément de grande largeur ne faisant pas partie de l'invention.
• Les figures 7 à 10 montrent respectivement, en perspective, différentes formes de poutres courbes réalisées par le procédé selon l'invention.
• La figure 11 montre, en perspective, la réalisation d'un élément sur un gabarit feuilleté.
• La figure 12 est une vue en élévation d'une maison comportant une charpente réalisée selon l'invention.
• La figure 13 est une vue de détail d'un appui de charpente ne faisant pas partie de l'invention.
• La figure 14 montre, en perspective, la réalisation d'une charpente avec chien assis.
• Les figures 15 à 18 montrent encore d'autres formes d'éléments de structure ne faisant pas partie de l'invention.
• La figure19 est une vue de détail montrant l'assemblage de deux éléments selon l'invention.
• La figure 20 montre, en perspective, une ossature de bâtiment constituée d'éléments selon l'invention.

Other advantageous characteristics of the invention will appear in the description which follows, of certain particular embodiments, given by way of example and represented in the appended drawings.

• The figure 1 is a perspective view of a structural element not forming part of the invention.
• The figure 2 shows, in longitudinal section, the production of a plate provided with cleats.
• The figure 3 shows, in longitudinal section, the steps for producing an element with four plates, on a curved template.
• The figure 4 schematically shows the element produced after assembly of the various plates.
• The figure 5 shows, in longitudinal section, the production of a double curvature element.
• The figure 6 shows, in perspective, a large element that is not part of the invention.
• The figures 7 to 10 respectively show, in perspective, different shapes of curved beams produced by the method according to the invention.
• The figure 11 shows, in perspective, the production of an element on a laminated template.
• The figure 12 is an elevational view of a house comprising a frame produced according to the invention.
• The figure 13 is a detailed view of a frame support not forming part of the invention.
• The figure 14 shows, in perspective, the creation of a frame with a seated dog.
• The figures 15 to 18 still show other forms of structural elements not forming part of the invention.
• The figure19 is a detail view showing the assembly of two elements according to the invention.
• The figure 20 shows, in perspective, a building frame made up of elements according to the invention.

On the figure 1 , there is shown, in perspective, a structural element such as a beam 1, intended to rest on two spaced apart supports A ₁ , A ₂ represented symbolically and which can be, for example, two walls of a building or two beams transverse resting on pillars.

This beam 1 consists, in the example shown, of four superimposed plates 10, separated by three rows of battens 2. Its thickness e depends on the number of plates 10, their thickness e ₁ and the thickness e ₂ of the battens 2.

This thickness e is determined to give the beam 1 the necessary resistance, taking into account the span L between the supports A ₁ , A ₂ and the load to be supported.

The length L ₁ of the beam is at least equal to the span L but its width depends essentially on the weight that one wishes to give to the beam, taking into account the lifting means available.

Indeed, the wooden beam thus made up of several separated sheets, can have a moment of inertia large enough to give it the desired resistance, while having a weight limited enough to allow the handling and installation by a few men, even for a range of several meters.

Such a beam can be produced very simply by means of the method according to the invention which will now be described with reference to figures 2,3 , and 4 .

In a first step of the process, represented on the figure 2 , a first series of cleats 21 are distributed on a fixed flat support 3, then a first plate 101 is applied, by an internal face 15, to this series of cleats and fixed to each of them, by nails or screws 4 which are easily placed on the side of its external face 14.

In a second step, represented on the figure3 , this plate 101 provided with cleats 21 is turned over and applied to a rigid support 3 ′ having an upper face 31 which has the desired profile for the element.

In the example shown, this profile is cylindrical and the cleats 21 distributed on the flat support 3 are parallel to each other, the plate 101 having a rectangular shape with a longitudinal axis perpendicular to the direction of the cleats 21. Therefore, if this longitudinal axis is parallel to the axis of the cylindrical surface31, the cleats 21 are parallel to the generatrices of the cylinder and the assembly of the thin plate 101 with its cleats 21 remains flexible enough to take the shape of this surface 31.

In a third step, a second plate 102 provided with cleats 22 is produced in the same way on the planar support 3 but the cleats 22 are offset by half a step relative to the cleats 21 of the first plate101.

However, the end strips 22 'are placed along the transverse edges of the plate 102.

This second plate 102 is also turned over and applied by its external face 142 to the upper faces of the cleats 21 of the first plate and fixed to the latter by nails 42 or screws which are laid and fixed easily on the plate 102 due to the offset of the battens. A third plate 103 is produced in the same way on the flat support 3 but it is provided with cleats 23 offset by a half-step relative to the cleats 22 of the second plate 102 and, consequently, in the same position as the cleats 21 of the first plate 101.

This third plate 103 is turned over and fixed on the cleats 22 of the second plate 102 by nails or screws 43.

An external plate 104 not provided with cleats is then applied and fixed by nails or screws 44 on the cleats 23 of the third plate 103.

A laminated element with four layers 101, 102, 103, 104 was thus produced, separated by three series of battens 21, 22, 23, of the type shown in the figure 4 , by simply using wooden plates and cleats fastened by nails or screws.

As indicated above, each set of a thin plate 10 provided on one face with battens 2 is flexible enough to take the shape of the template 3 'as soon as the battens are directed along the generatrices of the application surface 31. In on the other hand, after fixing the plates and cleats, the connection made by nails or screws withstands very well the detachment and shearing forces and the element 1 thus formed retains its shape when it is moved away from the support 3 ′ and even has a excellent resistance to bending which essentially depends on the thickness e of the element. In fact, the number of plates, their thicknesses and the thickness of the cleats can be determined so as to obtain the desired resistance, taking into account the range between supports, without excessively increasing the weight of the element 1. It should be noted that, contrary to the provision of the document FR-A-955616 mentioned above, there is no need to connect the ends of the element to each other by a retaining tie. In addition, the shape given to the element depends only on that of the template 3 '.

Therefore, according to an essential characteristic of the invention, such a method makes it possible to give the element a straight or curved shape, with a curvature turned upwards or downwards, or even with a double curvature, as shown in the examples of figures 4, 5 , 7 .

Furthermore, the structural elements thus produced consist only of wooden plates and cleats which can be cut to size and brought to the site to be assembled manually. It suffices, in fact, to produce on the site, for example in concrete, a flat slab 3 for fixing the plates to the cleats and a rigid support 3 ′ with an assembly face 31 having the desired profile, to superimpose and fix one on the other, the plates fitted with cleats.

But we can also make in the workshop, either plates with cleats which will be assembled on site, or complete elements which, due to their relatively low weight, can be stacked on a transport platform and delivered in desired number on site .

Indeed, such a beam may have a weight of the order of 100 kg for a span of 7 to 8 meters, while having a relatively high resistance to bending, due to its thickness and the connection between the plates 10 and cleats 2.

Even for a greater range, from 10 to 12 meters, such an element remains light enough to be able to be handled and set up by means of a small crane or other lifting device of low power or, even, manually, by a team scaled down.

On the other hand, the width of the element must be sufficient to give it a certain base and distribute the load on the supports, for example on a sand plate formed at the top of a wall or a partition. , as shown on the figure 12 .

An element of small width relative to its range can constitute a support beam for a floor or a roof.

However, this width can be arbitrary and, for example, can cover a large area.

Such an element, of the type represented on the figure 6 and which is not part of the invention, can then constitute a floor slab or a roofing element of vaulted form.

In this case, the upper face 501 may be covered with a sheet forming a sealing skin, for example made of zinc or of synthetic material. Furthermore, whatever the width I of the element 5, its lateral faces 56 can be closed by walls having edges 57, 57 ′ cut according to the profile of the curved plates 501, 504.

As a simple example, the figure 12 shows a single house with a roof 6.

We note the originality of such a construction whose curved cover allows, for example, to increase the internal volume. As indicated above, the use of very light laminated beams requires only a reduced material and, despite their lightness, such beams can have a fairly large span, for example of 12 meters, making it possible to produce a cantilevered awning. It is also possible to use beams covered with a roof.

As the figure 13 , the beams 6 for supporting the roof can be placed on a plate 61 resting on the posts 60. Of course, it is possible, as required, to adapt the number of plates and row of battens to the reach of l element and the desired resistance. Likewise, the curvature of the element can be varied, depending on the range.

In any case, the invention is not limited to the exemplary embodiments which have just been described, other provisions and equivalent means which can be used while remaining within the protective framework defined by the claims.

In particular, in a variant of the method, the rigid support on which the plates provided with cleats are assembled, has a flat application face on which the plates are placed flat.

These plates are cut along the same external profile with two longitudinal sides 16, 16 'which, when the plates 10 are assembled, are aligned along two lateral faces 17, 17' of the element. This is then put in place so that the plates 10 are directed vertically and rest on edge on the supports A ₁ , A ₂ , as shown in the figure 8 , with a lower face 17 and an upper face 17 'made up of all of the longitudinal sides 16, 16'.

In this case, to make a beam having a desired profile, one can cut along this profile the longitudinal sides 16, 16 'of the various plates which are placed on edge as shown in the figure 9 . Moreover, the two faces, respectively lower 17 and upper 17 'of the element 1 can then have different profiles.

For equal weight, the flexural strength of the beam also placed on edge can be increased by simply playing on the width of the plates 10, that is to say the height of the beam, which determines the moment of inertia of this one.

It should be noted that, as shown in the figure 11 the template 3 'used to assemble a curved beam of the type of Figures 4 and 5 , could be achieved in the same way, by superimposing several flat plates separated by cleats and whose longitudinal sides 18 are cut according to the profile to be given to the element produced, as before, by assembling plates 101, 102 provided with cleats 21, 22.

Furthermore, when the elements are placed on edge and have planar lateral faces, it is possible to use a single plane support 3 which first serves to produce in advance the desired number of plates (101, 102 .. .), each fixed on a series of cleats then, after turning the plates, fix them one on the other by resting on the same support 3.

However, in this process making it possible to produce elements to be placed on edge, it is also possible to use, for the assembly of the plates, a rigid support 3 ′ having a curved shape making it possible to give the element a desired profile not straight.

The figure 10 , for example, shows such an element intended to be placed on edge but whose vertical side faces are curved, for example to produce a facade element with a projection of the bow-window type. In this case also, the lower and upper faces 17, 17 'of the element are not necessarily planar, the longitudinal sides 16, 16' of the plates 10 can be cut according to a desired profile.

As the figure 12 , laminated elements with reverse curvature, of the type of figure 7 , allow to realize a seated dog 65. But, for this, we can also use elements assembled flat and placed on edge, as shown on the figure 14 .

It can therefore be seen that multiple variants can be envisaged, the invention making it possible to give the architect great freedom of design and the structural elements thus produced can find multiple applications.

Indeed, it should be noted that, the elements being made of wood, it is possible to apply to them the usual techniques of assembling a frame.

For example, after carrying out an element of the type of figures 4, 5 , 7 , it is possible to saw all the end plates and cleats in order to produce bearing faces having the desired orientation. This is how the figure 17 , which is not part of the invention, shows the mounting of a slightly vaulted element 1, with inclined end faces bearing on abutment parts 71 mounted on side walls 72 which oppose the separation of the ends under the effect of the applied loads.
Other forms could, of course, be envisaged.
For example, the laying lines of the elements need not necessarily be parallel, the process allowing the production of any non-cylindrical set surface. In this case, in fact, the cleats can be arranged so as to be parallel to the corresponding generatrices of the template, the plates thus produced remain flexible enough to be applied to the template which may have the profile of a portion of a cone, d hyperboloid or hyperbolic paraboloid with two lines of pose making between them a certain angle.

Such an arrangement would therefore make it possible to give particularly original forms to roofs or to certain facade elements of the type of figure 10 .

On the other hand, the method according to the invention makes it possible to produce such structural elements on the site of the construction site with very reduced equipment since it suffices to have a flat slab for fixing the plates to the battens and a rigid support having the desired shape, for superimposing and fixing these plates one on the other, such supports that can be produced on site in reinforced concrete. It will therefore be sufficient to bring wooden plates and cleats to the site, all the rest of the construction being carried out on site.

However, it is also possible to produce in advance, in the factory, sets of plates provided with cleats in order to shape them and assemble them on site.

Thus, the invention gives great freedom of choice, not only for the design of a house but also for the construction site which can possibly be difficult to access for vehicles.

Furthermore, the rectilinear elements of the type shown in the figure 8 can be arranged vertically so as to constitute posts or pillars, the laminated structure of the various elements making it possible to assemble them easily in the manner shown on the figure 19 . Indeed, if the plates 10 and the cleats 21 of a horizontal element 1 have, respectively, the same thicknesses that the cleats 21 'and the plates 10' of a vertical element 1 ', their ends can be threaded one inside the other and be fixed by bolts 19 or other means of assembly, in order to constitute a gantry structure.

Thus, from light elements, easy to handle and possibly made on site, we can build, as shown on the figure 20 , a complete frame of a building comprising vertical posts 1 ′ on which horizontal beams 1 are fixed which can support floor or roof elements 6.

Claims (7)

1. Method of producing a structural element extending along a longitudinal axis over a certain length (L) and consisting of at least two thin plates joined by rows of spaced apart spacer bars interposed between two adjacent plates (101, 102) and fixed respectively on their facing faces (13, 14), so as to form an interdependent assembly capable of resting on two spaced apart support (A1, A2), characterized by the fact that a first plate (101) cut into a desired shape for the element (1), with two longitudinal sides and two transverse sides, is applied and fixed, by an internal face (15), on a first series of spacers (21) distributed on a flat support (3), that the whole of this plate (101) provided with spacers (21) on its inner face (15), is turned over and applied, by its opposite smooth outer face (14), on an application face (31) of a rigid support (3'), that a second assembly comprising a second plate (102) provided with a second series of spacers (22) is made in the same way on the flat support (3) and then turned over, applied and fixed on the first series of spacers (21) of the first plate (101) while taking the form of the rigid support (3'), and so on until the installation and fixing on a last series of spacers (23) of an external closing plate (104) not equipped with spacers, in order to make an element (1) which is then removed from the rigid support (3') while keeping its shape, a method in which the various plates (101, 102... 104) thus assembled are cut in such a way as to have a same external profile with two longitudinal sides (16, 16') having a desired profile, and said longitudinal sides (16, 16') are aligned, during the assembly of the plates, along two lateral faces (17, 17') and, when the element (1) thus made is placed, the plates (101, 102...) of the latter are arranged vertically and rest on edge on the supports (A1, A2), so that the element (1) has two faces, respectively lower (17) and upper (17') with a desired profile, the number of plates, their thickness and the thickness of the spacers being determined in such a way as to give the element (1) the desired strength, while limiting its own weight.
2. Method according to claim 1, characterized by the fact that the rigid support (3') on which are successively applied the various plates (101,102... 104) after turning, presents a plane application face (31) in order to realize, after fixing of the closing plate (104), a rectilinear element limited by two plane faces.
3. Method according to claim 2, characterized by the fact of using the same plane support (3) on which are firstly realized in advance the desired number of plates (101, 102...) fixed each one on a series of spacers (21), the said plates (101, 102...) being then fixed one on the other by applying to the same support (3).
4. Method according to claim 1, characterized by the fact that the rigid support (3') on which are assembled the plates (101, 102... 104) provided with spacers (21) presents a curved form making it possible to give to the element (1) a no rectilinear desired profile.
5. Method according to claim 4, characterized by the fact that the rigid support (3') on which are successively applied the various plates (101, 102... 104) after turning, presents a curved application face (31) in the form of a surface generated by a straight generating line and on which the spacers (21, 22) are placed in order to be laid out, after application on the said curved face (31), according to the generating lines of this one, so that the whole of each plate (101, 102...) with its spacers (21, 22) remains enough flexible to take the form of the support (3') which thus constitutes a gauge for the realization of an element (1) limited by two curved vertical side faces.
6. Method according to one of the preceding claims, characterized by the fact that each plate (101, 102...) is made out of a homogeneous, resistant and relatively flexible matter, such as wood or analogue and that the spacers are fixed by nails or screws making it possible to resist the efforts of separation and shearing.
7. Method according to one of the preceding claims, characterized by the fact that each plate (101, 102,... 104) consists of at least two superimposed layers made up each one of several sheets (11, 11', 12, 12') posed one following the other in the longitudinal direction of the element (1), transverse joints between the adjacent ends of the consecutive sheets being shifted longitudinally from one layer to another.

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