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Title:
RETICULAR STRUCTURE WITH NODES, RODS AND PANELS
Document Type and Number:
WIPO Patent Application WO/2018/234965
Kind Code:
A1
Abstract:
A reticular structure (1 ) comprises rods (10) that are connected at their own ends by nodes (20) and form polygonal meshes (2) to be covered by respective polygonal panels (50). Each node (20) comprises a body (21 ) whose peripheral region (22) has, in a same half-space (4), through holes (23) for receiving the end portions of the rods (10) at mutual inclination angles (λ,λ*). The body defines a central manoeuvre space (3) in which lock elements (12) for the rods are arranged. In an aspect of the invention, in the opposite side of the half-space (4) a stiff bridge element (31 ) extends between portions (24) proximate to non-adjacent, e.g. opposite through holes (23), restoring the node continuity so that forces can be exchanged between the corresponding rods, while maintaining a manoeuvre space (3) accessible for mounting operations. Advantageously, support elements (40) of the panels (50) are provided, each support element having a connection portion (41 ) on the peripheral region (22) between two adjacent through holes (23) and, at a predetermined distance (L), a support portion (42) for receiving a vertex (51 ) of a panel. This way, panels (50) are spaced from the rods (10), the panels can be arranged adjacent to each other and can be sealed at their edges, which makes it easier to obtain a simplifying the waterproof structure. In another aspect, the support elements (40) are slidably arranged with respect to the peripheral region (22) along bisectors (b) of the inclination angles (λ) of adjacent holes (23) and the connection portion (41 ) of each support element (40) in configured to abut against the vertex (51 ) of a respective panel (50). Lock means (43) are provided to lock the panel with respect to the peripheral region (22), in order to pre-compress the panels (50).

Inventors:
FROLI, Maurizio (Via Roma 86, Calci, 56011, IT)
LACCONE, Francesco (Via Ranieri Sardo 6, Pisa, 56122, IT)
Application Number:
IB2018/054454
Publication Date:
December 27, 2018
Filing Date:
June 18, 2018
Export Citation:
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Assignee:
UNIVERSITÀ DI PISA (Lungarno Pacinotti 43/44, Pisa, 56126, IT)
International Classes:
E04B1/32; E04B1/19
Foreign References:
FR2590375A11987-05-22
US3994106A1976-11-30
DE4224663A11994-01-27
DE4306746A11994-09-08
Attorney, Agent or Firm:
CELESTINO, Marco (ABM Agenzia Brevetti & Marchi, Viale Giovanni Pisano 31, Pisa, 56123, IT)
Download PDF:
Claims:
CLAIMS

1. A reticular structure (1 ) comprising:

a plurality of rods (10);

a plurality of nodes (20), each node connected to end portions (1 1 ) of at least three of said rods (10),

said rods (10) defining, between respective end nodes (20), a plurality of polygonal meshes (2);

a plurality of polygonal panels (50) locked at respective own vertices by corresponding support elements (40) of said nodes (20), and arranged to close at least one part of said polygonal meshes (2);

lock elements (12) of said rods (10),

wherein each of said nodes (20) comprises a main body (21 ) that extends about a central manoeuvre space (3) accessible to an operator, wherein said main body (21 ) has:

through holes (23) made along a peripheral region (22) of said main body (21 ) and having axes (23', 23") arranged in a same half-space (4) including a respective boundary plane (ττ) thereof, said axes (23', 23") forming predetermined mutual inclination angles (λ,λ*), wherein said at least three rods (10) are arranged within said through holes (23) with said end portions (1 1 ) locked by said lock elements (12) in said central manoeuvre space (3);

characterized in that a stiff bridge element (31 ) extends on the opposite side with respect to said half-space (4) between portions (24) of said peripheral region (22) of said main body (21 ) that are proximate to non- adjacent through holes of said through holes (23).

2. A reticular structure (1 ) according to claim 1 , wherein each of said support elements (40):

is configured to slide with respect to said peripheral region (22) of said main body (21 ) along a bisector (b) of a mutual inclination angle (λ) between said axes (23') of two adjacent through holes (23) of said through holes; is configured to engage in abutment against a vertex portion (51 ) of a respective polygonal panel (50) of said polygonal panels; and lock means (43) are provided for locking said support elements (40) with respect to said peripheral region (22) at a predetermined lock position of said polygonal panels.

3. A reticular structure (1 ) comprising:

a plurality of rods (10);

a plurality of nodes (20) each connected to end portions (1 1 ) of at least three of said rods (10),

said rods (10) defining, between respective end nodes (20), a plurality of polygonal meshes (2);

a plurality of polygonal panels (50) locked at respective own vertices by corresponding support elements (40) of said nodes (20), and arranged to close at least one part of said polygonal meshes (2)

lock elements (12) of said rods (10),

wherein each of said nodes (20) comprises a main body (21 ) that extends about a central manoeuvre space (3) accessible to an operator, wherein said main body (21 ) has:

through holes (23) made along a peripheral region (22) of said main body (21 ) and having axes (23', 23") arranged in a same half-space (4) including a respective boundary plane (ττ) thereof, said axes (23', 23") mutually oriented said axes forming predetermined mutual inclination angles (λ,λ*),

wherein said at least three rods (10) are arranged within said through holes (23) with said end portions (1 1 ) locked by said lock elements (12) in said central manoeuvre space (3);

characterized in that each of said support elements:

is configured to slide with respect to said peripheral region (22) of said main body (21 ) along a bisector (b) of a mutual inclination angle (λ) between said axes (23') of two through holes (23) adjacent to each other of said through holes; is configured to engage in abutment against a vertex portion (51 ) of a respective polygonal panel (50) of said polygonal panels; and in that lock means (43) are provided for locking said support elements (40) with respect to said peripheral region (22) at a predetermined lock position of said polygonal panels.

4. A reticular structure (1 ) according to claim 3, wherein a stiff bridge element (31 ) extends on the opposite side with respect to said half-space (4) between portions (24) of said peripheral region (22) of said main body (21 ) proximate to non-adjacent through holes of said through holes (23).

5. A reticular structure (1 ) according to claim 1 or 3, wherein each of said support elements (40) comprises:

a respective connection portion (41 ) to said main body (21 ), configured to clamp on said peripheral region (22) of said main body (21 ), between two through holes (23) adjacent to each other; a respective support portion (42), configured for receiving a vertex portion (51 ) of one of said polygonal panels (50) in a plane at a predetermined distance (L) from said connection portion (41 ), so that said polygonal panels (50) are arranged to cover respective polygonal meshes (2) converging to said each node (20), and are arranged at a predetermined distance from adjacent rods (10) of said rods inserted within said adjacent through holes (23).

6. A reticular structure (1 ) according to claims 1 or 4, wherein said non- adjacent holes (23), from a proximity (24) of which said stiff bridge element (31 ) extends, form a couple of non-adjacent holes (23) for whose axes (23") a mutual inclination angle (λ*) is maximum between said mutual inclination angles (λ,λ*) of said through holes (23).

7. A reticular structure (1 ) according to claim 5, wherein said support portion (42) defines a recess (44) configured for receiving said vertex portion (51 ).

8. A reticular structure (1 ) according to claim 7, wherein said recess (44) is defined between a base portion (45) integral to said connection portion (41 ) and a cover portion (46) that is removably arranged with respect to said base portion (45).

9. A reticular structure (1 ) according to claim 1 or 3, wherein said main body (21 ) of said each node (20) comprises a crown element (25), and said peripheral region (22) comprises:

hollow portions (26), in particular substantially cylindrical hollow portions, which define respective said through holes (23); connection portions (27) that are arranged in alternation with said hollow portions (26) and have trapezoid-shaped longitudinal sections, the oblique sides (28) of each of which forming angles that are equal to said mutual inclination angles (λ) formed by said axes (23') of said through holes (23) adjacent to each of said connection portions.

10. A structure according to claim 9, wherein said crown element (25) also comprises:

stiffening portions (29) located between non-adjacent hollow portions (26) of said crown element (25).

11. A reticular structure (1 ) according to claim 1 or 3, wherein said main body (21 ) of said each node (20) comprises a full-shell element (30), i.e. a cup element, in which said through hole are provided (23).

12. A reticular structure (1 ) according to claim 1 or 4, wherein a guide element (32) is arranged on said stiff bridge element (31 ), opposite to said peripheral region (22) of said main body (21 ), said guide element configured for retaining a cable (70), and for allowing said cable (70) to slide longitudinally with respect to said guide element (32).

13. A reticular structure (1 ) according to claim 12, wherein said guide element (32) comprises a saddle (33) or a groove (33).

14. A reticular structure (1 ) according to claim 13, wherein said groove comprises two separable halves (34', 34").

15. A reticular structure (1 ) according to claim 12, wherein said guide element (32) has an orientable longitudinal slide axis (35) of said cable (70), said longitudinal slide axis (35) rotatably arranged about a rotation axis (36') at an angle with respect to said longitudinal slide axis (35) and/or with respect to said stiff bridge element (31 ), in particular said rotation axis is orthogonal to said longitudinal slide axis (35) and/or to said stiff bridge element (31 ).

16. A reticular structure (1 ) according to claim 1 or 3, wherein said polygonal panels (50) are glass panels.

17. A reticular structure (1 ) according to claim 1 or 3, wherein said polygonal panels (50) have equilateral triangle shape, and said adjacent through holes (23) have axes (23') at an angle of 60° with respect to each other.

18. A reticular structure (1 ) according to claim 1 or 3, wherein said rods (10) are arranged along distinct sequences of consecutive segments (5) of lines having intersection points (6) laying on respective helices (9, 9', 9") arranged on a same cylinder (7), said helices forming at least three families of helices, in such a way that said rods (10) with said nodes (20) define a helical polyhedron (8) comprising triangular modules (2), said families having respective helix inclinations (α,β,γ) different from one another.

19. A reticular structure (1 ) according to claim 18, wherein each of said three families of helices comprises three helices (9).

20. A reticular structure (1 ) according to claim 12 and 18, wherein said cable is a stiffening cable (70) arranged along said helices (9) of a main family of helices having a maximum inclination (a), and said reticular structure (1 ) comprises lock means of said cable (70) for tightening and maintaining tightened said cable (70) about said reticular structure (1 ).

Description:
RETICULAR STRUCTURE WITH NODES, RODS AND PANELS

DESCRIPTION Field of the invention

[0001] The present invention relates to an improved structural node for connecting building envelope elements or, more in general, structure elements, such as opaque or transparent polygonal panels, in particular glass polygonal panels. More in detail, the node can be used to make hybrid shell structures, or structures having three-dimensional variously shaped polyhedron surfaces.

Description of the prior art and of the technical problem

[0002] IT1420093 (application n. MI2013A001496) describes a reticular structure in which polygonal panels, in particular glass polygonal panels, are connected to each other by nodes, each node comprising a plurality of clamp members i.e. support members, in particular six of these members. The support members are pairwise pivotally connected to each other about rotation axes, and each rotation axis is generally parallel to the adjacent edge of each of the two polygonal panels that are constrained about the axis itself. In an exemplary embodiment, the rotation axes are defined by hinges, comprising pins that can be integral to rods. These rods can be pre-stressed so that compression forces arise acting on the polygonal adjacent panels and on the support members supporting the polygonal panels at the end of each rod. The pivotable arrangement between the support members makes it possible to arrange the polygonal panels in such a way that the structure has the three- dimensional shape as desired by the designer. The rods can be tightened by nuts that are advantageously arranged in a central workspace of the node about which the support members are arranged. [0003] Other nodes of structures approximating free-form surfaces, in which a central space is provided for operating rod-tightening means, are described, for instance, in DE 42 24 663 and in DE 43 96 746.

[0004] In the above-mentioned nodes, the connection of the rods to a deformable or stiff crown element defining a central manoeuvre space, makes it easier to lock the rods and allows reducing encumbrances and protrusions out of the surface along which the structure extends. However, at each node, the structure is discontinued along the direction defined by two rods converging substantially opposite to the node itself, while along this direction forces are exchanged responsive to rod connections and to the external loads acting on the structure. This causes a stiffness decrease and a general structure weakening, which is compensated by oversizing the nodes and the connected rods, with respect to the ideal case in which no weakening is present at the nodes.

[0005] Moreover, in the above-mentioned structures, as well as in other known structures comprising polygonal panels and rods converging to nodes, the polygonal panels, for instance glass polygonal panels, must be arranged along the planes containing the axes of adjacent rods. The latter are therefore unaesthetically noticeable from outside the structure, as they mark discontinuities in the glass surface. Moreover, this connection method makes it more difficult to obtain a waterproof structure, if desired, since a sealing means must be arranged between such heterogeneous elements as the polygonal panels and the rods.

Summary of the invention [0006] It is therefore a feature of the present invention to provide nodes for a structure comprising rods groupwise converging to the nodes, and also comprising polygonal panels, in particular glass polygonal panels, cooperating with the rods, in which the nodes extend about a manoeuvre central space accessible to an operator, and have through holes to receive locking end portions of the rods into the central space, such as screw-threaded end portions, where the latter are coupled with node fastening elements like nuts, in which the nodes do not significantly weaken the structure along force directions defined by couples of opposite rods converging to each node, with respect to the prior art nodes in which such a central space is not provided.

[0007] It is also a feature of the invention to provide such a structure with nodes having a manoeuvre central space, which is transversally stiffer than the structures including prior art nodes, in particular generally vertical structures that are stiffer against horizontal loads.

[0008] These and other objects are achieved by a reticular structure comprising:

a plurality of rods;

- a plurality of nodes, each connected to end portions of at least three of the rods, the rods defining, between respective end nodes, a plurality of polygonal meshes;

a plurality of polygonal panels locked at respective own vertices by corresponding support elements of said nodes, and arranged to close at least one part of the polygonal meshes;

- lock elements of the rods,

wherein each of said nodes comprises a main body that extends about a central manoeuvre space accessible to an operator,

wherein the main body has:

- through holes made along a peripheral region of the main body and having axes arranged in a same half-space including a respective boundary plane thereof, the axes forming predetermined mutual inclination angles,

wherein the at least three rods are arranged within the through holes with the end portions locked by the lock elements arranged in the central manoeuvre space.

[0009] In a first aspect of the invention, a stiff bridge element is provided that extends on the opposite side with respect to said half-space, where the through holes of the main body are located, between two portions of the peripheral region of the main body that are proximate to two non-adjacent through holes.

[0010] This way, at each node, the continuity of the reticular structure is restored in the direction defined by the two rods that are arranged within the two non-adjacent through holes starting from which the bridge element extends, said rods converging substantially oppositely to the node itself, as exemplified hereinafter. Along this direction, the forces can be exchanged responsive to the external loads acting on the structure and to the compression of the polygonal panels within the respective meshes. The bridge element causes a general stiffening of the structure against these forces.

[0011] Accordingly, "lighter" structures can be manufactured, i.e. the size of the resistant elements can be reduced. In particular, the size and therefore also the noticeability of the nodes can be reduced, as well as the diameter or any transversal dimension of the rods. A lighter structure including the nodes according to the invention has a lower visual impact of the connections, with respect to any prior art structure having the same performances. This makes them more preferable for use in building envelopes to which a high transparency is required.

[0012] In a second aspect of the invention, each support element

is configured to slide with respect to the peripheral region of the main body along a bisector of a mutual inclination angle between the axes of two through holes adjacent to each other;

is configured to engage in abutment against the vertex portion of a respective polygonal panel,

and lock means are provided for locking the support elements with respect to the peripheral region at a predetermined lock position of the polygonal panels.

[0013] This way, each polygonal panel clamped by the node is prevented from relatively moving in any direction, apart from a translation movement along the bisector of the vertex angle in the disengagement direction.

[0014] This makes it possible to use successfully also materials that are not particularly resistant to traction, in particular glass, as they only receive compression contact forces. Preferably, the panels are made of glass or of another transparent material.

[0015] Like in the known systems, as described in IT1420093 and in IT1368859, the one-direction connection prevents the polygonal glass panels (or made of any other material) of the structure from receiving traction forces. On the contrary, if compression forces arise, the symbiotic combination provided by the node according to the invention promotes the cooperation between the rods and the polygonal panels, i.e. a novel way to operate these components is established, in which they mutually assist to resist to instability.

[0016] Advantageously, each node comprises support elements for polygonal panels, each having:

a respective connection portion to the main body, configured to clamp on the peripheral region of the main body, between two adjacent through holes;

a respective support portion, configured for receiving a vertex portion of one of the polygonal panels in a plane at a predetermined distance from said connection portion.

[0017] This way, the polygonal panels are arranged to cover respective polygonal meshes converging to the node and at a predetermined height with respect to adjacent rods inserted within adjacent through holes. This makes it possible to arrange the edges of the polygonal panels closely adjacent along each other, above the rods, and to substantially conceal the rods and the nodes to those who look at the reticular structure from the outside, i.e. from the side opposite to the rods and to the nodes with respect to the polygonal panels themselves. Moreover, as the edges of the polygonal panels can be arranged along each other, a sealing means can be more easily arranged between the polygonal panels, in particular, in order to provide a waterproof structure. In fact, this operation can be carried out by sealing the edges of the polygonal panels placed adjacent to each other, without involving the nodes and the rods.

[0018] In particular, the non-adjacent holes, from the proximity of which the stiff bridge element extends, form a couple of holes for whose axes the mutual inclination angle is maximum, with respect to any other couple of non-adjacent through holes.

[0019] Preferably, the support portion defines a recess configured for receiving the vertex portion, which easily provides the abutment engagement between the polygonal panel and the support portion, i.e. a one-direction connection between these elements. In particular, this recess is defined between a base portion that is integral to the connection portion and a cover portion that is removable from the base portion. This makes it easier to assemble and to disassemble the polygonal panel with/from the nodes arranged at the vertices of the same, when mounting or when replacing a polygonal panel, respectively.

[0020] In a preferred exemplary embodiment, the main body of each node comprises a crown element, and the peripheral region comprises:

hollow portions, in particular substantially cylindrical hollow portions, which define respective through holes;

connection portions that are arranged in alternation with the hollow portions and have trapezoid-shaped longitudinal sections, the oblique sides of each of these forming angles that are the same angles as the mutual inclination angles formed by the axes of the through holes adjacent to each connection portion.

The high void ratio of such a main body allows obtaining a very light and node, having a lower visual impact, which is an effect particularly important for structures that must be highly transparent and bright.

[0021] Advantageously, the crown element also comprises stiffening portions arranged between hollow connection portions of the crown element that are not adjacent to each other, for example in the form of walls contained a shell ideally defined by the peripheral portion of the crown element, i.e. by the sequence of hollow portions alternating with trapezoidal connection portions.

[0022] As an alternative, the main body of the node can comprise a full-shell element, i.e. a cup element, where the through holes are made.

[0023] In a preferred exemplary embodiment, on the stiff bridge element, opposite to the peripheral region of the main body, a guide element is arranged configured for holding a cable, and for allowing the cable to slide longitudinally with respect to the guide element.

[0024] The guide element can comprise a cylindrical groove or saddle made in two separable halves. This makes it easier to mount and to demount the cable to/from the nodes, when installing or replacing it, respectively.

[0025] Preferably, the guide element has an orientable longitudinal slide axis of the cable, the longitudinal slide axis rotatably arranged about a rotation axis that is at an angle with respect to the longitudinal slide axis and/or with respect to the stiff bridge element, in particular said rotation axis is orthogonal to the longitudinal slide axis and/or to the stiff bridge element. Typically, the rotation axis is perpendicular to the slide axis of the groove or saddle of the guide element, and normal to the outer surface of the bridge element.

[0026] For example, the polygonal panels have the shape of equilateral triangles, and the adjacent through holes have axes at an angle of 60° with respect to one another. This is the shape of the polygonal panels in structures having a tetrahelix or helical tower shape or, more in general, the shape of helical polyhedrons comprising triangular modules, as described hereinafter along with exemplary specific embodiments of the invention.

[0027] In a preferred exemplary embodiment, the rods are arranged along distinct sequences of consecutive segments of lines that have intersection points laying on respective helices ideally arranged on a same cylinder, the helices forming at least three families of helices. This way, the rods and the nodes define a helical polyhedron comprising triangular modules, the families having respective helix inclinations that are different from one another. In particular, each of the three families of helices comprises three helices. These shapes and, in particular, the tetrahelices, have relevant analogies with some forms of the nature, and are therefore particularly desired by the designers.

[0028] Advantageously, the cable is a stiffening cable, i.e. a tendon, tightened along the helices of a main family of helices having a maximum inclination, and the reticular structure comprises lock means for locking the cable in order to tighten the cable and to maintain it tightened about the reticular structure. This way, an external precompression force can be applied to the whole structure.

[0029] The bridge element provides therefore a support for the guide element, which makes it possible to install the tendon and to accomplish the external precompression while maintaining the hollow, or crown, or cup structure of the node of the main body, in which the manoeuvre means are housed for mounting the rods and, preferably, also for displacing and locking the support elements of the polygonal panels, so as to make these operations easier. [0030] A structure based on the use of such nodes is characterized by a high structural redundancy, since it associates the possibility of applying pretension forces on the whole structure by the tendons, which increases the stiffness of the latter, to the possibility of improve the exchange of the forces between the rods.

[0031] The sliding support elements of the second aspect of the invention and the stiff bridge element of the first aspect cooperate to ensure the static performances of the whole structure. In fact, the bridge element allows arranging the pre-tensioning cables with a preferred orientation, in order to reduce the compression stresses in the panels, which is possible thanks to the support elements. This way, both the rods and the panels cooperate to resist the external actions.

[0032] The safety level in the ultimate limit state and in the serviceability limit state is remarkably higher than in the node of IT1420093.

[0033] The supports of the bridge elements can also be used for mounting plant cables, such as power cables and data cables. Preferably, in this case, the supports of the bridge elements are configured for receiving conduits for these cables, which makes easier to install the plants normally present in civil or commercial or industrial buildings. Brief description of the drawings.

[0034] The invention will be now shown with the description of some exemplary embodiments, exemplifying but not limitative, with reference to the attached drawings, in which like reference characters designate the same or similar parts, throughout the figures of which:

- Figs. 1 and 2 are diagrammatical perspective views of two portions of reticular structures according to respective exemplary embodiments of the invention, comprising stiffening cables and without stiffening cables, respectively;

Fig. 3 is a perspective view of a zone proximate to a node of a structure according to the invention, comprising a bridge element; Fig. 4 is a perspective view of a zone proximate to a node of the structure of Fig. 1 , comprising a bridge element and a main body configured for receiving the support element shown in Figs. 9 and 10;

Fig. 5 is a perspective view of a zone proximate to a node of a structure according to the invention, comprising a bridge element and a guide element for a cable;

Fig. 6 is a perspective view of a zone proximate to a node of the structure of Fig. 2, comprising a bridge element with a guide element, and a main body configured for receiving the support element shown in Figs. 9 and 10;

Fig. 7 is an exploded perspective view of a zone proximate to a node of a structure according to the invention, including the support elements for polygonal panels shown in Figs. 9 and 10;

Fig. 8 is a partial section perspective view of a zone proximate to a node of the structure of Fig. 2 including support elements for polygonal panels shown in Figs. 9 and 10, and guide elements for a cable;

Figs. 9 and 10 are perspective views of a support element for polygonal panels according to an exemplary embodiment of the invention;

Fig. 1 1 is a cross sectional view of an end portion of a polygonal panel mounted to the support element shown in Figs. 9 and 10;

Fig. 12 is a partially exploded perspective view of a zone proximate to a node of the structure of Fig. 1 , before mounting the polygonal panels, including a bridge element and the support elements for polygonal panels shown in Figs. 9 and 10;

Fig. 13 is a partially exploded perspective view of a zone proximate to a node including the support elements for polygonal panels shown in Figs. 9 and 10 and a main body with stiffening portions between the rod connection seats;

Fig. 14 is a perspective view of a node of a structure according to the invention, similar to the node of Fig. 3, in which the main body comprises a full-shell element;

Fig. 15 is a perspective view of the node shown in Fig. 8, without the support elements of the polygonal panels;

Fig. 16 is an exploded perspective view of the node of Fig. 15; Figs. 17 and 18 are section views of rods of a structure as in Figs. 1 and 2, according to two exemplary embodiments;

Figs. 19, 20 and 21 are diagrammatical perspective views of structures, according to the invention, having a tetrahelical shape of order 3, 4 or of higher order.

Description of a preferred exemplary embodiment.

[0035] With reference to Figs. 1 and 2, a reticular structure 1 comprises a plurality of rods 10 that are generally connected to each other by nodes 20 and define a plurality of polygonal meshes 2. Each node 20 connects end portions 1 1 (Figs. 17 and 18) of at least three rods 10.

[0036] For example, nodes 20 shown in Figs. 3-8 and 12-20 connect six rods 10 to one another. More in detail, each node 20 comprises a main body 21 that has a peripheral region 22 in which through holes 23 are made, wherein the holes preferably have a cylindrical shape. As shown in Fig. 3, through holes 23 have axes 23', 23" arranged according to predetermined mutual inclination angles λ,λ * with respect to each other, i.e. they are arranged according to predetermined mutual inclinations λ,λ * . More in detail, mutual inclination angles λ between adjacent through holes are shown, i.e. the inclination angles between axes 23' of each hole 23 and of the adjacent hole, which is encountered travelling along peripheral region 22 in each of the two possible directions. Moreover, the maximum mutual inclination angle λ * is shown, formed by axes 23" of holes 23 that are, in general, not adjacent to each other.

[0037] The mutual inclination angles λ between axes 23' of adjacent through holes 23 can be different for each pair of adjacent through holes 23, even if in the exemplary embodiments of Figs. 3-8 and 12-20 these angles are equal to one another, and are 60°.

[0038] Still with reference to Fig. 3, through holes 23 are normally arranged in a same half-space 4 defined by a plane π closest to axes 23" having a maximum mutual inclination λ * with respect to any other pair of through holes 23. This way, meshes 2 define a locally convex portion of structure 1 about each node 20. In a particular exemplary embodiment, not shown, axes 23', 23" can lay in a same plane, which is the border of half-space 4, in which case meshes 2 (Figs. 1 and 2) are coplanar, and structure 1 has a locally flat portion.

[0039] Peripheral region 22 defines a central manoeuvre space 3, as still shown in Figs. 3-8 and 12-15. Rods 10 can be solid or hollow, and are connected to nodes 20 by inserting their own end portions 1 1 (Figs. 17 and 18) into through holes 20, until they protrude into central manoeuvre space 3, in which lock elements 12 are arranged for integrally connecting rods 1 1 to node 20. In particular, end portions 1 1 have an external or internal thread 13 and the lock elements are nuts or screws 12, respectively, that engage with the threads, thus fastening rods 10 to node 20. These lock elements are easily accessible to an operator for tightening/loosing the rods.

[0040] Rods 10 having screw-threaded end portions 1 1 are arranged along the edges of the surface of structure 1 '. In the exemplary embodiments described herein, rods 10 are fixed to node 20 simply by axially screwing. This connection is carried out in node 20 itself by one bolt element 12, which is screwed at the end portion of each rod 10. This way, the axial forces are properly exchanged, thus preventing any dangerous transversal weakening of the rod.

[0041] Node 20 can be easily manufactured by welding a plurality of pieces together, or as a single cast piece.

[0042] Meshes 2 (Figs. 1 and 2) can have the shape of a regular or irregular polygon with any number of sides, which is not necessarily the same number in all the meshes of a same structure. A node 20 is arranged at each vertex. In the exemplary embodiments described herein, however, each mesh 2 is defined by three rods 10 and has therefore the shape of a triangle, typically of an equilateral triangle. As described, in this case, mutual inclination angles λ between axes 23' of adjacent through holes 23 are 60 degrees angles.

[0043] Still with reference to Figs. 1 and 2, structure 1 also comprises a plurality of polygonal panels 50 arranged to close at least one part of polygonal meshes 2. Preferably, polygonal panels 50 have vertex portions 51 locked by support elements 40, which are in turn mounted to nodes 20. This is shown, for instance, in Figs. 7, 8 and 1 1 .

[0044] From another point of view, node 20 has a plurality of sectors, each comprising or configured for receiving a support element 40 for a respective polygonal panel 50.

[0045] With reference to Figs. 7-13, each support element 40 can include a connection portion 41 for mounting to main body 21 , said connection portion configured to clamp on peripheral region 22 of main body 21 between two adjacent through holes 23, and can also include a support portion 42, configured for receiving a vertex 51 of a polygonal panel 50, so as to position the latter on a plane at a predetermined distance L from the base of connection portion 41 (Fig. 1 1 ).

[0046] This way, as shown in Fig. 8, polygonal panels 50 cover respective polygonal meshes 2 converging to node 20, and are arranged at a predetermined distance L' from rods 10 inserted within through holes 23 adjacent to each other. Therefore, polygonal panels 50 are parallel to the plane of mesh 2 and shifted outwards with respect to the surface defined by nodes 20 and by rods 10. This leads to building envelopes 1 ,2 that have a continuous appearance, i.e. their look is not discontinued by rods 10, since the latter are concealed. Moreover, the building envelopes can be easily waterproofed, by a simple sealing along edges 5 of the adjacent panels.

[0047] In particular, as shown for instance in Figs. 7, 8 and 1 1 , a recess 44 of support portion 42 is configured for receiving a vertex 51 of a polygonal panel 50. With reference to Fig. 9, a removable cover 46 can also be provided that, along with a complementary base portion 45, defines recess 44, in order to allow the extraction of the vertex of polygonal panel 50 in a direction parallel to bisector b of mutual inclination angle λ of axes 23' of holes 23 that contribute to define mesh 2.

[0048] As shown in Figs. 3-6, 8, 12, 14-16, in a first aspect of the invention, on the opposite side of half-space 4 (Fig. 3), a stiff bridge element 31 or bridge 31 extends from zones 24 of peripheral region 22 of main body 21 that are close to non-adjacent through holes 23, and restores the continuity of node 20, while maintaining a free access to the central manoeuvre space 3 for operating lock elements 12, i.e. for tightening/loosing nuts or screws 12 that fasten rods 10 to nodes 20. This arrangement does not take up the room required to perform some manufacture steps, and makes it possible to replace easily and quickly any portion of structure 1 that may have been damaged.

[0049] In the exemplary embodiments described herein, bridge 31 extends between node portions that are close to through holes 23, which are a particular case of non-adjacent holes, whose axes 23" have a maximum mutual inclination angle λ * , with respect to mutual inclination angles λ of any other couple of through holes 23. Through holes 23, from the proximity 24 of which bridge 31 extends, can be made at regions diametrically opposite of peripheral portion 22 of main body 21 , i.e. holes 23 can be substantially opposite to each other.

[0050] With reference to Figs. 5, 6, 8, 15, in some exemplary embodiments of the invention, a guide element 32 is arranged on stiff bridge element 31 , at an opposite side with respect to main body 21 . Said stiff bridge element IS configured for retaining a cable 70, at a distance from node 20, which allows cable 70 to slide longitudinally along a slide axis 35.

[0051] In particular, in order to position and retain cable 70, guide element 32 can comprise a preferably cylindrical saddle 33 or groove 33, whose axis substantially coincide with slide axis 35. As shown in Figs. 8, 15 and 16, groove 33 can comprise two separable halves 34', 34".

[0052] Guide element 32 can be mounted to a support plate 37 preferably arranged in a substantially central region of bridge element 31 . For instance, guide element 32 can have a stem 36 arranged in a hole 37' of support plate 37.

[0053] Guide element 32 with saddle or groove 33 can be selectively orientable or freely rotatably arranged with respect to bridge element 31 . In the former case, stem 36 can be threaded externally, and engage with an internal thread of hole 37'. The mutual lock at various angular positions, which can maintain stem 36 and hole 37' in a predetermined relative angular position, ensures the selective orientation of guide element 32 with respect to bridge 31 . In the latter case, the stem is freely rotatably arranged within hole 37', and a means is provided, not shown, to limit the translation movement of stem 36 with respect to hole 37', so that guide element 32 cannot be removed from bridge 31 . In this case, the rotation axis of the guide element coincides with an axis 36' of stem 36, which can be at an angle but is preferably orthogonal, as shown in Figs. 8, 15 and 16, to longitudinal slide axis 35 or to stiff bridge element 31 , or to both of them.

[0054] With reference to Figs. 7, 12 and 13, in a second aspect of the invention, support elements 40 are configured to slide with respect to peripheral region 22 of main body 21 along bisectors b (Fig. 7) of mutual inclination angles λ of axes 23' of adjacent through holes 23. Moreover, connection portion 41 of each support element 40 is configured to internally engage in abutment against vertex portion 51 of a respective polygonal panel 50.

[0055] Preferably, vertex portions 51 of panels 50 and recess 44 are internal and external rounded surface portions, respectively, and engage in abutment on said surfaces portions. Moreover, a lock means 43 is provided for locking support elements 40 with respect to peripheral region 22 at a predetermined lock position of polygonal panels 50, as described more in detail hereinafter.

[0056] This way, the only polygonal panel 50 that is housed within support element 40 of node 20 is prevented from performing any relative movement, apart from a translation movement along bisector b (Fig. 7) of the vertex angle in the disengagement direction. Polygonal panels 50 can be made also of material not much resistant to traction, typically it can be made of glass, since they substantially receive only compression contact forces.

[0057] More in detail, node 20 of Fig. 7 does not include previously described bridge 31 , while node 20 of Fig. 12 includes both bridge 31 of the first aspect of the invention, and slidable support elements 40 comprising lock means 43 for locking the panels between nodes 20.

[0058] In the exemplary embodiment of Figs. 3-6, 13 and 15, main body 21 of node 20 consists of a crown element 25, whose peripheral region 22 comprises hollow portions 26, in this case cylindrical hollow portions, which are arranged in alternation with connection portions 27. In other words, crown element 25 comprises a number of sectors which is the same number as hollow portions 26, which is the same number as connection portions 27. Each hollow portion 26 defines a through hole 23 that receives a respective rod 10.

[0059] In this case, bridge element 31 is preferably located between two substantially opposite hollow elements 26, whose mutual inclination angle λ * is the maximum mutual inclination angle, as shown in Fig. 3.

[0060] The longitudinal cross section of connection portions 27 is preferably a trapezoid, in particular an isosceles trapezoid. In this case, as shown, in particular, in Figs. 3 and 7, the oblique sides, i.e. the hypotenuses 28 of each trapezoidal part, form an angle equal to a mutual inclination angle λ between axes 23' of through holes 23 of hollow elements 26 adjacent to connection portion 27. In other words, axes 23' are substantially parallel to the edges 28 of the two adjacent connection portions. Moreover, hollow portions 26 can have substantially the same length as edges 28.

[0061] With reference to Figs. 4,6,7,12,13,15,16, connection means 60,63 are now described of support element 40, which is slidably arranged and can be locked, along bisector b, with respect to the main body of node 20. From the long side of trapezoidal connection portion 27, a connection member 60 extends that is configured for receiving connection portion 41 of support element 40. In particular, the connection member extends parallel to trapezoidal connection portion 27 and has two lateral protrusion or teeth 61 that define a central recess configured for receiving connection portion 41 of support element 40. From the short side of trapezoidal connection portion 27, an abutment member 63 extends, preferably a flat abutment member, configured to engage in abutment against a rear face 49 (Fig. 10) of support portion 42 of support element 40. According to the second aspect of the invention, abutment member 63 has a screw-threaded hole 64 that houses an adjustment screw 43 configured to abut in turn against rear face 49 of support portion 42. This way, once panel 50 has been located with its vertices 51 into recesses 44 of the respective support elements, by screwing screws 43 into respective abutment members 63 beyond a certain limit, supports 40 are pushed towards the inside of mesh 2 causing panel 50 to turn into a compression state . [0062] As shown in Figs. 13 and 15, crown element 25 can also comprise stiffening portions 29, which are preferably inner walls 29 that connect pairwise non-adjacent hollow portions 26. In the case of the above pictures, the node comprises six hollow portions 26, and three stiffening portions 29 can be arranged to form a triangle sub-structure. Still in this case, the stiffening portions 29 have the same shape as connection plates or portions 27, typically a trapezoidal shape.

[0063] Instead, Fig. 14 shows a node 10 according to an alternative exemplary embodiment, in which main body 21 comprises a full-shell element, i.e. a cup element 30, along a peripheral portion 22 of which through holes 23 are provided. This node 10 can comprise or can be used in combination with support elements 40 of Figs. 9-1 1 and, preferably, in combination with connection means 60,63 configured for blocking panels 50 in a compression state.

[0064] Figs. 19-21 show particular reticular structures 1 that can be advantageously made using nodes 20 as described above. These structures comprise rods 10 arranged along distinct sequences of consecutive segments 5 of lines having intersection points 6 laying on respective helices 9, 9', 9" ideally arranged on a same cylinder 7, i.e. wound about a same axis 7'. In simpler words, rods 10 are arranged along helices 9, 9', 9" that are approximated or formed by segments 5. At each nodal point or intersection point 6 there is a node 20, to which pairs of segments 5 of helices 9, 9', 9" converge, each helix belonging to a same family, in other words, helices of the three different families meet at each nodal point 6, and in this case form angles of 60° with respect to one another.

[0065] Helices 9, 9', 9" form a plurality of arrays or families of helices. In structures 1 of Figs. 19-21 , three families of helices 9, 9', 9" are wound about common axis T. Each family of helices 9, 9', 9" has an own inclination with respect to a reference direction. This inclination can be an angle α,β,γ with respect to the direction of axis 7'. Inclinations α,β,γ are generally different from one another, i.e. the helices of three families 9, 9', 9" are differently slanted with respect to one another. Each family of helices 9, 9', 9" comprises at least three helices, as in the case of the reticular structure of Fig. 19, or more than three helices, for example it can comprise four helices, as in structure 1 of Fig. 20, or even more helices, as shown in Fig. 21 . Reticular structure 1 has the shape of a helical polyhedron or tetrahelix 8 comprising triangular modules 2. The higher the number of helices 9, 9', 9" of each family, the more closely tetrahelix 8 approximates cylinder 7.

[0066] Structures 1 of Figs. 19-21 , if arranged with axis T vertical, can be used to provide helical towers or "steles".

[0067] At the edges of the structures 1 , edge or closure nodes 20' are provided, where the number of converging rods 10 is lower, responsive to the constraint conditions.

[0068] Advantageously, nodes 20 of reticular structures 1 having a tetrahelix shape, like in Figs. 19-21 , comprise cable guide element 32, as shown in Figs. 5, 6, 8 and 15. Then, at least one stiffening cable 70 is arranged along helices 9 of the family comprising the most slanted helices, i.e. whose angle a is the narrowest angle, as shown in Figs. 2 and 8. The cable is tightened by conventional tightening means, not shown, arranged at the two ends of the cable itself. This way, rods 10 are compressed by a tightening force due to the tensile forces acting on cable 70, which further stiffens structure 1 . Guide elements 32 are arranged with the saddles or grooves 33 oriented so as to approximate the directions of rods 10 arranged along helix 9.

[0069] The foregoing description exemplary embodiments of the reticular structure and of the node according to the invention, and of the way of using the apparatus, will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiment without further research and without parting from the invention, and, accordingly, it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation.