WO2002081832A1

WO2002081832A1 - Stable self-balancing system for building component

Info

Publication number: WO2002081832A1
Application number: PCT/FR2002/001161
Authority: WO
Inventors: Vinicius Raducanu; René MOTRO
Original assignee: Centre National De La Recherche Scientifique (C.N.R.S.); Tissage Et Enduction Serge Ferrari
Priority date: 2001-04-09
Filing date: 2002-04-03
Publication date: 2002-10-17
Also published as: FR2823287A1; FR2823287B1

Abstract

The invention concerns a criss-cross system, comprising surface layers (1, 2), delimiting its opposite surfaces, each layer including a set of criss-crossed cables (3-4, 5-6) forming an organised network of nodes (7, 8) whereon are articulated the ends of rigid rods (9), providing the link between the layers, said rods, associated with pull wires (10), forming in the space between the layers a plurality of spacers. Each of the spacers comprises two bundles consisting each of at least two rods converging towards and assembled by one common end to a node of a layer, their opposite ends being linked to neighbouring nodes of the other layer. Furthermore, each pull wire is arranged between two nodes belonging to the two bundles, said pull wire being tensioned to exert on the rods a compressive force and likewise tension the criss-crossed cables at the nodes of the layers, globally providing the assembly with stable self-balance.

Description

Self-balancing system for building element

The present invention relates to a system comprising a crosslinked structure, in particular for a structural element of the frame type, panel or other similar assembly, in the general form of a plate or layer, the dimensions of which extend favorably in two directions of the space and which has a reduced thickness in a direction perpendicular to the other two, this structure comprising a repetitive internal composition in the plane defined by the first two directions, arranged so as to constitute a tenségπté system, statically coherent.

More particularly, the crosslinked structure considered is formed of unitary components, distributed contiguously according to a grid formed of repetitive meshes in the extent of the plate or layer, and in which these components are arranged so that they are placed in tensile when they are arranged outside the structure and in tension or compression inside the latter, these meshes being joined together in the extent of the layer so as to constitute a structurally coherent whole and the rigidity is the result of an autocontramte of these elements.

Tensegrity systems have been known in the art for many years, but have been mainly used in the field of plastic arts, or even to constitute models making it possible to better understand the biomechanical behavior of normal and pathological cells subjected to forces which are susceptible to cause significant change in the morphology of the cell and the organization of its cytoskeleton.

In the field of light construction structures applied to architecture, assemblies formed by the agglomeration of autonomous crosslinked cells have already been produced. With these known embodiments, prestressed but not self-stressed, it is in fact necessary to have support elements and foundation foundations essential for carrying out the prestressing of the elements of the structure, which is generally complex to produce and leads to high costs.

The present invention relates to a crosslinked structure, the design of which corresponds to this concept, in particular being arranged so that it is autonomous and transmits in a balanced manner, thanks to the mutual self-stress of its various components and to the established links. between them, the permanent and variable loads to which the structure is subjected from the outside, without requiring any additional tensioning device.

The invention also allows the realization of a structure in the form of a layer or panel, fixed or foldable, which can correspond to many variants, with variable curvatures, positive or negative, or with a thickness which is not everywhere the even in the extent of the layer.

To this end, the crosslinked system considered, in the general form of a grid, in particular for a structural element of an architectural construction, comprising two surface layers, delimiting the opposite faces of the system, each layer including a set of crisscrossed cables or equivalent, forming between them, at their mutual crossing points an ordered network of nodes on which are articulated the ends of bars or similar elements, rigid in compression, realizing the connection between the two layers, these bars, associated with other traction cables or similar, forming in the space between the layers a plurality of spacers, distributed in an orderly and repetitive manner in this space by forming elementary meshes, in which at any node of a sheet corresponds at least one spacer, is characterized, on the one hand in that each of the spacers comprises two beams each formed of at least two bars converging towards and joined by one end common to a node of a tablecloth, their opposite ends being connected to neighboring nodes of the other tablecloth, each of the nodes of convergence of the bars in the two bundles being arranged in a different ply, and on the other hand in that each traction cable associated with the bars is, in each bundle, disposed between two convergence nodes belonging to the two beams of a spacer, this traction cable being tensioned to exert on the bars a compression effort and also tighten the crisscrossed cables at the nodes of the layers in which they extend, by carrying out an overall assembly the in stable self-equilibrium, the coherence of which results from the arrangement of the spacers. The association in the spacers of the system of cables and compressed bars, leads to a rigid structure having the behavior of a tensegrity system, the bars which maintain the nodes which they connect at stable distances being only subjected to efforts compression, while all the cables, in the plies and between them, are exclusively subjected to tensile forces, these provisions precisely characterizing the structure and the behavior of such a system.

In it, the spacers are distributed in a coherent and repetitive manner throughout its extent according to the two directions of repetition of these spacers. Thanks to the mechanical connection produced by the bars between the nodes of the plies, all of these spacers achieves a statically stable structure, where the internal forces created in the bars and the cables are mutually compensated, that is to say placed in a state of self stress. The tensioning of the traction cables associated with the bars of any retractor in the system induces at each node in a sheet an effort which is distributed in the bars which end at this node, which transmit it to the convergence nodes of these same bars in the other layer, this effort being compensated mutually by those which are distributed in the crisscrossed cables of these layers interesting these nodes, by stabilizing moreover the relative position of these, thanks to the effect of self-stress thus created .

According to various secondary characteristics of the crosslinked system considered, the nodes formed by the cables crisscrossed in the two layers constitute regular networks, continuous or not, in the extent of each of these layers.

The networks of nodes in the two layers are identical or different.

The rigid bars in compression belonging to the two beams of any spacer are arranged two by two in distinct, non-parallel planes, defining two directions that are not confused for the repetitive distribution of all the spacers in the system.

Preferably, but not exclusively, the planes containing the rigid bars are orthogonal. The distribution of the spacers in the space delimited between the two layers is symmetrical or not. Likewise, the two surface layers may or may not be parallel.

In particular, the plies can be flat or curved, the curvature of these plies being able to be identical or different from one to the other. In each layer, the curvature may be regular or not.

In a preferred embodiment of the invention, the elementary meshes formed, on the one hand by the spacers between the layers, and on the other hand the cables crisscrossed in these layers, have a polyhedron geometry, whose edges between vertices consist of cables, the spacer bars being distributed along diagonals of the lateral faces of the polyhedron and / or diagonals connecting opposite vertices in two distinct faces.

In a particular case, simple and advantageous from a constructive point of view, the polyhedron of each mesh is constituted by a regular prism whose edges have equal lengths and in which the bars are only distributed in the lateral faces of the prism, these bars being oriented in a direction which connects in each face a vertex to another opposite, in an identical and repetitive configuration for each of these faces.

More particularly still in the above embodiment, the prism is constituted by a rectangular parallelepiped.

In an alternative embodiment, the prism has a triangular base.

In another variant, the regular prism is a cube in which the bars are distributed in two contiguous faces in two diagonal directions and arranged to be joined in a first common vertex, the second common vertex of the bars arranged in the other two faces of the cube being opposite the first, the two other vertices of the cube, devoid of connection with the bars in these faces being connected together by a complementary bar arranged along the internal diagonal of the corresponding cube. Other characteristics of a crosslinked system established in accordance with the invention will become more apparent from the following description of several exemplary embodiments, given by way of non-limiting example, with reference to the appended drawings in which: - Figure 1 is a schematic perspective view of a limited fraction of the structure considered, making it possible to illustrate the arrangement of a spacer formed from bars and cables and the mutual links established between these elements. - Figures 2, 3 and 4 are perspective views, relating to three examples of particular shapes of a mesh whose ordered repetition, in accordance with the invention, makes it possible to produce the envisaged structure. FIGS. 5 and 6 are respectively views from above and in axonometric perspective of a grid-shaped structure according to the invention, in which the elementary mesh formed by the spacers corresponds to the example of FIG. 2.

Figure 7 is an exploded axonometric perspective of the grid according to Figures 5 and 6.

- Figures 8 and 9 are views similar to those of Figures 5 and 6, but in which the elementary mesh corresponds to the example of Figure 3.

Figure 10 is an exploded axonometric perspective of the grid according to Figures 8 and 9.

Figures 11 and 12 are views similar to those of Figures 5 and 6, but in which the elementary mesh corresponds to the example of Figure 4.

Figure 13 is an exploded axonometric perspective of the grid according to Figures 11 and 12.

In the schematic view of Figure 1, the references 1 and 2 respectively designate two flexible plies here parallel, the nature of which does not directly matter to the characteristics of the invention and which delimit the external surfaces of the structure considered, these plies containing each two sets or sets of crisscrossed cables, respectively 3 and 4 in the ply 1, and 5 and 6 in the ply 2.

In the ply 1, the cables 3 and 4 form a regular network of nodes 7 distributed or arranged according to their crossing points, while in the ply 2, the cables 5 and

6 likewise form an analogous network in which the crossing points define nodes 8.

According to the invention, the nodes 7 and 8 formed at the crossing points of the cables in the two plies are joined by rigid bars in compression, the ends of which are articulated in these nodes, according to a particular arrangement.

Thus, any bar 9 is provided to always bring together a node 7 in the first layer 1 and a node 8 in the second layer 2, each node of a layer, here the node 7a for example, being joined to two bars 9b and 9c which also ensure the connection between this node and two nodes respectively 8b and 8c in the other layer.

As can be seen in the diagram, the assembly constituted by the two bars 9b and 9c is associated with a similar assembly, also formed by two other bars 9d and 9e which converge in a common node 8a in the second layer and connect the latter with two nodes 7b and 7c, neighbors but distinct from the first layer. The nodes common to the various aforementioned bars, opposite opposite in one and the other of the two plies, are moreover joined by a cable 10 provided with traction means (not shown) able to tension this cable by exerting a force of approximation between the nodes 7a and 8a, effort which is distributed in the structure by compressing the rigid bars 9 and by stretching the crisscrossed cables 3, 4, 5 and 6 in the two layers respectively.

In the example illustrated, the spacing and connecting bars 9b, 9c on the one hand, 9d, 9e on the other hand, constitute two bundles of a so-called spacer assembly, these pairs or pairs of bars being arranged here in two distinct and perpendicular planes, in the directions of which these beams are regularly and uniformly repeated over the entire extent of the structure, thereby forming a plurality of regularly entangled and symmetrical spacers, allowing to achieve a stable and stable whole in a state of self-stress, where the forces exerted on the structure are mutually compensated The bars 9 and the crossed cables 3 and 4 on the one hand, 5 and 6 on the other hand, finally the traction cables 10, form in addition repetitive elementary meshes of which Figures 2 to 4 illustrate different profiles, each of these meshes in the nonlimiting examples thus envisaged having a polyhedral external shape and more precisely here a form of regular prism.

In the example of Figure 2, the elementary mesh, called bi-directional, has the shape of a cube whose therefore all edges have the same length. These edges are formed by cables 3 and 4 in the first layer and by cables 5 and 6 in the second, the vertices of the cube constituting the nodes of the networks delimited by these cables in these layers.

In each mesh of this example, the bars 9 extend along diagonals of the lateral faces of the cube and are all oriented in the same direction when the four faces of the cube are traversed successively. The nodes 7 and 8 are thus connected two by two, all the bars 9 being symmetrical with each other relative to the center of the cube.

Figure 5 illustrates a top view of the grid structure produced using the symmetrical juxtaposition along the planes of their vertical faces of meshes conforming to that of Figure 2, this structure being shown in a horizontal position.

In this structure, all the horizontal cables 3,

4, 5, 6 in the two plies 1 and 2, as well as all the traction cables 10 between these plies present, once the structure is placed in self-stressing, a length which is everywhere the same, in the absence of external loads.

On the axonometric perspective view of Figure 6, appear the spacers produced as described above, these forming in two perpendicular directions and through all the juxtaposed consecutive meshes, stiffening members of the structure which provide it the desired geometric and mechanical stability, thanks to the mutual compensation of the forces in each mesh.

The cohesion of the whole results from this compensation, whereas, taken individually, each mesh has by itself no stability.

At the periphery of the structure and as an exception to the principle of regular and continuous repetition of the meshes formed by the tangle of spacers, each of the ends of the bars 9 is no longer connected except by oblique bracing cables 11 which leave from the ends of neighboring bars in both plies 1 and 2.

Note that the nodes located at the edge of the grid-shaped structure are not necessarily in the plane of the other nodes provided in the layers, these peripheral nodes being able to be salient or re-entrant with respect to the plane of these layers, implying in this case different lengths of the bars and cables in these edges compared to those which constitute the current part.

FIG. 7 completes the illustration of the grid thus produced, an exploded perspective view with the upper ply 1 illustrated at the top of the figure with its interlaced cables 3 and 4, the traction cables 10 between the nodes of the plies in each spacer, as well as the peripheral connecting cables 11, the bars 9 connecting the nodes 7 and 8 in the two plies, also provided between the latter, and finally the lower ply 2 with its cables 5 and 6. All of the spacer bars form, from a topological point of view, a structure comparable to a weaving of the taffeta type, with interwoven warp and weft, in which the self-stressing and the stiffening of this structure are obtained by reducing the lengths of the cables 10 for setting traction and / or by increasing the length of the bars 9.

Figure 3 illustrates a first embodiment where, in this case, the regular prism which constitutes the repetitive mesh of the network formed by the spacers, is a prism whose base is a possibly equilateral triangle, the mesh being said, in this case , three-way.

In this case, the bars 9 are distributed in the lateral faces of the prism, as in the previously described variant, extending along the diagonals of these faces, each node of the mesh cooperating with a bar thereof and of course another bar of the adjacent mesh juxtaposed. In this case too, the cables crisscrossed at the nodes of the two plies extend in these in directions forming between them an angle of 60 °, Figure 3 illustrating three cables of this kind marked 12, 13 and 14 for the upper ply, 15, lβ and 17 for the lower layer.

In this variant, the planes of the beams of the spacers form between them also an angle of 60 °.

Figures 8, 9 and 10 are views similar to Figures 5, 6 and 7 described above in relation to the triangular mesh, with the necessary adaptations due to the different profiles of the meshes in both cases. On the other hand, the traction cables 10 provided between the nodes 7 and 8 in the two layers remain identical, as do the peripheral connection cables 11.

The implementation of the spacers and the behavior of the structure, on the other hand, remain strictly the same, so that it is not necessary to describe them in more detail here. Figure 4 relates to another variant where, as in that of Figure 2, the repeating mesh of the structure is in the form of a regular prism and in particular a cube. In this case, however, the grid is four-way. Also in this variant, the spacers have a different configuration, the connecting bars in each mesh being arranged so that any bar 18, located in any side face, which converges towards a node 7 in the upper ply, is articulated at this same node with another bar 19 located in the next face, the bars 18 and 19 having symmetrical but opposite orientations.

The mesh comprises in the two other lateral faces of the cube, two other bars 20 and 21 which converge this time towards the node 8 of the lower ply, this node 8 being opposite diagonally to the previous one. The mesh is completed by a complementary bar 22, which extends along an internal diagonal of the tube and joins the other two nodes 7 and 8, opposite to those respectively connected by the bars 18 and 19 on the one hand, 20 and 21 d 'somewhere else .

Figures 11 to 13 illustrate, like Figures 5 to 7 for the first variant and Figures 8 to 10 for the second, the grid-like structure made with the planned four-way mesh, the two beams of each spacer in this case lying in planes forming an angle of 45 ° between them. All other structural and functional provisions are taken over with the necessary modifications.

A constructive system in the form of a grid is thus produced which meets the concept of tensegrity, having the advantages already mentioned.

Of course, it goes without saying that the invention is not limited to the only examples more particularly described and represented above, which have been given only for information, multiple variants that can be envisaged, without going beyond the ambit of it.

Thus, in these examples, the meshes have regular proportions in the three directions of space. However, the principles implemented according to the invention are preserved when the mesh size varies according to the extent of the surface of the layer, the lengths of the bars not being uniform from one mesh to the next, as well as the dimensions that separate the nodes in each of the layers, as well as from one layer to another. In particular, it is possible to produce such structures by leaving free in its current part areas devoid of bars, cables and nodes, on the sole condition that these free areas or holes of the structure have a shape wedged on an integer contiguous stitches. In this case, the edge of the hole is delimited by bracing cables arranged in a similar manner to those used at the periphery of the structure itself. Note also that, in such a case, the width of the grid between the edge of a hole and the outer edge closest to the structure must be equal to or greater than at least two meshes. According to other variants, the surface layers which delimit the grid-shaped structure can be flat or curved, this curvature can also vary so as to be regular or not and possibly be successively concave or convex. Likewise, the thickness of the structure between the two plies can vary, regularly or not, by varying the length of the cables of at least one ply and / or the length of the bars. In particular, provision may be made to produce a structure in the general shape of a lens. Also, the invention lends itself to the production of a complex structure in the form of a dihedral, by assembling two elementary grids along one of their common edges, formed by connecting bars belonging to spacers which are likewise common to both. faces of this dihedral. The layers can be continuous or not, and in particular consist of textile membranes in which the connecting nodes of the spacers are nevertheless individualized.

Claims

1 - Cross-linked system, generally in the form of a grid, in particular for a structural element of an architectural construction, comprising two surface layers (1, 2), delimiting the opposite faces of the system, each layer including a set of crisscrossed cables or the like

(3-4, 5-6) forming between them, at their mutual crossing points an ordered network of nodes (7, 8) on which are articulated the ends of bars or similar elements (9, 18 to 22), rigid in compression, providing the connection between the two plies, these bars, associated with other traction cables or the like (10), forming in the space between the plies a plurality of spacers, distributed in an orderly and repetitive manner in this space by forming elementary meshes, in which at any node of a sheet corresponds at least one spacer, characterized, on the one hand, that each of the spacers comprises two beams each formed of at least two bars converging towards and joined by one end common to a node of a ply, their opposite ends being connected to neighboring nodes of the other ply, each of the nodes of convergence of the bars in the two beams being arranged in a different ply, and on the other hand in that each traction cable associated with the bars is, in each bundle, disposed between two convergence nodes belonging to the two beams of a spacer, this traction cable being tensioned to exert on the bars a compressive force and also stretch the crisscrossed cables at the nodes of the plies in which they extend, overall producing a set in stable self-equilibrium, the coherence of which results from the arrangement of the spacers.

2 - System according to claim 1, characterized in that the nodes (7, 8) formed by the cables (3-4, 5-6) intertwined in the two layers (1, 2) constitute regular networks, continuous or not , in the extent of each of these layers. 3 - System according to claim 2, characterized in that the networks of nodes in the two layers are identical or different.

4 - System according to any one of claims 1 to 3, characterized in that the rigid bars in compression (9) belonging to the two beams of any spacer are arranged two by two in separate planes, not parallel, defining two directions not confused for the repetitive distribution of all the spacers in the system.

5 - System according to claim 4, characterized in that the planes containing the rigid bars are orthogonal.

6 - System according to any one of claims 1 to 5, characterized in that the distribution of the spacers in the space defined between the two plies (1, 2) is symmetrical or not.

7 - System according to any one of claims 1 to 6, characterized in that the two plies (1, 2) are parallel or not.

8 - System according to any one of claims 1 to 7, characterized in that the plies are flat or curved, the curvature of these plies may be identical or different from one to the other. 9 - System according to claim 8, characterized in that the curvature of the sheets is regular or not.

10 - System according to claim 1, characterized in that the elementary meshes formed, on the one hand by the spacers between the plies (1, 2), and on the other hand the crisscrossed cables (3-4, 5-6) in these layers, have a regular polyhedron geometry, the edges of which between vertices are formed by the cables, the bars (9, 18 to 22) of the spacers being distributed along diagonals of the lateral faces of the polyhedron and / or of the diagonals connecting opposite vertices in two distinct faces.

11 - System according to claim 10, characterized in that the polyhedron of each mesh is constituted by a regular prism whose edges have equal lengths and in which the bars are only distributed in the lateral faces of the prism, these bars being oriented in a direction which connects in each face a vertex to another opposite. 12 - System according to claim 11, characterized in that the prism is constituted by a rectangular parallelepiped.

13 - System according to claim 11, characterized in that the prism has a triangular base. 14 - System according to claim 11, characterized in that the regular prism is a cube in which the bars (18, 19) are distributed in two contiguous faces in two diagonal directions and arranged to be joined in a first common vertex (7) , the second common vertex (8) of the bars (20, 21) arranged in the two other faces of the cube being opposite to the first, the two other vertices of the cube, devoid of connection with the bars in these faces being interconnected by a complementary bar (22), arranged along the internal diagonal of the cube.