[0001] The present invention relates to a prefabricated wall panel and a structural system made with such a panel, and also to a method of manufacturing the prefabricated panel. The invention also relates to a load-bearing layer of the prefabricated panel.

[0002] In particular, the invention relates to a construction system for residential, commercial or industrial construction based on the manufacturing and use of prefabricated panels, in particular preassembled prefabricated panels, consisting of a plurality of layers, for making exterior and/or interior walls, and also floors. The panel comprises several layers of different materials which simultaneously serve the functions of structural and/or aseismic resistance, isolation and/or acoustic absorption and thermal-hygrometric protection. In particular, the panel comprises an innovative load-bearing layer.

[0003] Specifically, the present invention also relates to a preassembled wall panel, and also a dry construction method of the preassembled panel, in which the preassembling may take place in a factory far from the construction site or on site.

[0004] Multilayer wall panels are known for example, from CH69211A5, EP0921243A2, EP1273729A2, US6,625,948 B2, EP1892350A2. In addition to the known art, reference is made to the unpublished International Patent Application PCT/IB2018/058161 by the same inventor.

[0005] It is the object of the present invention to provide a load-bearing layer for a wall panel, a prefabricated or preassembled wall panel, a structural system comprising a plurality of the wall panels, and a method for manufacturing or prefabricating wall panels, having such features as to meet and better reconcile the needs to:

[0006] reduce the manufacturing times and costs,

[0007] increase the thermal-hygrometric protection performance of the wall panel and of the shell of the structural system,

[0008] increase the manufacturing versatility of structural systems, in particular dwellings, with reference to the sizes, number of levels and distribution of the interior spaces, and/or [0009] increase the standardization level of the materials and equipment and prefabricating and construction methods, and/or

[0010] facilitate the making of certified dwellings in compliance with the legislation on the matter of seismic, phonic and sound protection, and/or

[0011] increase the level of industrialization and reduce the use of labor and the execution times in making dwellings, and/or

[0012] create one or more empty cavities in a dwelling, which are suitable for guiding a flow of air originating from the outside toward the inside of the walls of the dwelling, eliminating moisture, impure air and gas, e.g. radon, which are among the main causes of the lack of living comfort and of the deterioration of the structures of the known art,

[0013] separate selected layers of the prefabricated panel or of a wall of the structural system to form an inner gap and thereby promote air circulation.

[0014] It is a further object of the present invention to provide a load-bearing layer for a wall panel, a prefabricated wall panel, in particular a preassembled prefabricated wall panel, a structural system comprising a plurality of the wall panels, and a method for prefabricating wall panels, having such features as to reconcile the needs of thermal protection with the features of structural resistance and mechanical resilience which are necessary for making aseismic and/or collapse-proof structural systems in response to increased vertical and lateral and/or cyclic stresses.

[0015] It is a further object of the present invention to provide a load-bearing layer for a wall panel, a prefabricated wall panel, in particular a preassembled prefabricated wall panel, and a structural system comprising a plurality of the wall panels with thermal cutting features, i.e. in the absence of significant heat bridges between separate climatic environments by means of the wall panels.

[0016] At least some of these objectives are achieved by a prefabricated wall panel, in particular a preassembled prefabricated wall panel, according to claim 1. The dependent claims relate to advantageous and preferred embodiments.

[0017] According to one aspect of the invention, a prefabricated wall panel for making a structural system defines a panel surface and a peripheral edge and comprises:

A) a plurality of material layers which are parallel to the panel surface and overlap one another, comprising:

- a load-bearing layer comprising a metal load-bearing structure,

- a protective layer formed on a first side (inner side) of the load-bearing layer and spaced apart from the load-bearing layer,

- a thermo-insulating layer formed on a second side (outer side) of the load-bearing layer opposite to the first side (inner side),

B) an air circulation gap formed between the load-bearing layer and the protective layer and which separates the load-bearing layer and the protective layer from each other, said air circulation gap being open on the peripheral edge,

C) a plurality of connectors-spacers, e.g. made of metal or synthetic material, extending in a direction transverse to the panel surface through said air circulation gap and having a first fastening portion fastened to the protective layer and a second fastening portion fastened to the load-bearing layer, wherein:

- said metal structure comprises a plurality of load-bearing columns spaced apart from one another and each having one or more metal tubular profiles which are parallel to one another and to the panel surface,

- the one or more metal tubular profiles of each of said load-bearing columns extend through one or more insulating blocks made of polymer resin of said load-bearing layer,

- the load-bearing layer between, respectively, two of said adjacent load-bearing columns is filled with an thermo-insulating material which is different from the material of the insulating blocks,

- the insulating blocks extend in a direction transverse to the panel surface, beyond the volume of the metal tubular profiles, and prevent a direct contact between the metal tubular profiles and layers of the prefabricated panel adjacent to the metal tubular profiles, in said direction transverse to the panel surface.

[0018] Moreover, the one or more metal tubular profiles of each of the load-bearing columns may be blocked and spaced apart from one another with one or more of the insulating blocks made of polymer resin.

[0019] The prefabricated panel is structurally load-bearing and resistant, thermally insulating, and allows a circulation of the air in the wall in a natural and continuous manner. Moreover, the prefabricated panel creates a so-called “thermal cutting”, i.e. a net and defined discontinuity of thermal conduction, between the middle metal, load-bearing and inevitably thermally conductive structure, and the layers of the panel arranged on the two sides of the middle metal structure.

[0020] The panel can be manufactured quickly and simply and affordably by means of metal carpentry assembly methods using widely standardized materials and processing which are widely available at contained costs.

[0021] The insulating blocks made of polymer resin, in which the metal tubular profiles are inserted, serve several synergistic functions: they form certain position references of the tubular profiles in preassembly step of the metal load-bearing structure and of the prefabricated panel. The insulating blocks made of polymer resin act as mutual connectors of the plurality of metal tubular profiles; they act as spacers between the individual metal tubular profiles of a same load-bearing column; serve the function of thermal insulators and finally, the insulating blocks made of polymer resin serve the function of connection bodies for fastening the adjacent layers of the panel to the load-bearing metal structure.

[0022] The invention also relates to the innovative load-bearing layer alone of the prefabricated or preassembled panel.

[0023] According to a further aspect of the invention, a structural system of a residential building comprises a plurality of prefabricated panels connected to one another, in which the air circulation gap continuously extends from one prefabricated panel to a respective adjacent prefabricated panel, and also a plurality of metal connection bodies each comprising:

[0024] - at least one flat supporting plate,

[0025] - two or more protrusions projecting from the supporting plate and connected by means of insertion with respective ends of the metal tubular profiles, so as to connect the metal tubular profiles to one another.

[0026] The connection bodies allow a quick and accurate assembly of the structural system, without specialized labor.

[0027] To better understand the invention and appreciate the advantages thereof, a description of certain non-limiting embodiments is provided below, referring to the drawings, in which:

[0028] Figures 1 and 1A are cross-section and perspective views of a detail of a prefabricated wall panel according to an embodiment.

[0029] Figure 1 B shows an enlarged detail in figure 1.

[0030] Figure 2 is a cross-section view of a detail of a structural system with two prefabricated wall panels joined to each other, according to an embodiment.

[0031] Figure 3 is a perspective view of an insulating block of the prefabricated wall panel according to an embodiment.

[0032] Figure 3A is a cross-section view of the insulating block in figure 3.

[0033] Figure 3B is a cross-section view of two adjacent insulating blocks of the prefabricated wall panel according to an embodiment, or of a double but monolithic insulating block of the prefabricated wall panel according to a further embodiment.

[0034] Figures 4 to 10 are perspective views of connection bodies of a structural system according to embodiments.

[0035] Figures 11 , 11 A, 11 B are perspective, side and cross views of a load-bearing column serving the function of beam in a prefabricated panel used as floor in the structural system, according to an embodiment.

[0036] Figures 12, 12A, 12B are perspective, side and cross views of a load-bearing column serving the function of beam in a prefabricated panel used as floor in the structural system, according to a further embodiment.

[0037] Figures 13A and 13B are perspective views of a connection node between load- bearing columns serving the function of structural beam of one or more prefabricated panels acting as floor of the structural system, in disassembled configuration and in assembled configuration, according to an embodiment.

[0038] Figures 13C and 13D are sectional views of certain parts of the connection node in figures 13A and 13B.

[0039] Figures 14, 14A, 14B are cross-section and top perspective views of details of the load-bearing structure of a prefabricated panel serving the function of floor of the structural system, said load-bearing structure having a plurality of load-bearing columns serving the function of main load-bearing beams and a plurality of secondary beams which are transverse to the load-bearing columns and are connected thereto by means of secondary connection bodies, e.g. made of polymer resin, according to an embodiment.

[0040] Figures 15, 15A, 15B are perspective, side and top views of the secondary connection body in figure 14, according to an embodiment.

[0041] Figure 16 is an exploded perspective view of a structural connection area between three horizontal load-bearing columns serving the function of floor beam, for example the beams in figure 11 , with a vertical load-bearing column, for example a load-bearing column in figure 1A, by means of a connection body, for example the connection body in figure 9, and to a foundation for the structural system.

[0042] Figure 17 is an exploded perspective view of a structural corner connection area between two horizontal load-bearing columns serving the function of floor beam, for example the beams in figure 11 , with two vertical load-bearing columns of two corner bordering prefabricated panels, such as for example in figure 2, by means of three connection bodies, for example the connection bodies in figures 5, 6, 7, and to a foundation for the structural system.

[0043] Figure 18 is an exploded perspective view of a structural connection area of two load-bearing columns belonging to two prefabricated panels arranged one on top of the other and belonging to two different levels of the structural system, with three load-bearing floor beams at a linear external wall, by means of three connection bodies, for example the connection bodies in figures 4, 10.

[0044] Figure 19 is an exploded perspective view of a structural corner connection area between two load-bearing floor beams, for example load-bearing beams in figure 11 , with first two load-bearing columns of two corner bordering prefabricated panels, such as for example in figure 2, of a first level of the structural system, and with second two load-bearing columns of two corner bordering prefabricated panels of a second level of the structural system, by means of four connection bodies, in particular the connection bodies in figures 5, 6, 7, 8.

[0045] Figures 20 and 20A are exploded perspective and vertical sectional views of details of the structural system at an external wall of a building, according to an embodiment.

[0046] Figures 20B and 20C are vertical sectional views of details of the prefabricated panels of the structural system shown in figures 20 and 20A.

[0047] Figures 21 A and 21 B are exploded and assembled views of a part of the structural system made by means of the prefabricated wall panels.

[0048] Figure 22 is a sectional view of parts of the load-bearing structure of the structural system with a floor lying on a foundation level and with a further intermediate floor between two levels (upper levels) supported by the load-bearing columns of the prefabricated panels forming the exterior walls of the structural system.

[0049] Figures 23A and 23B are exploded perspective and vertical sectional views of a structural node of the structural system according to an embodiment.

[0050] Figure 24 is an exploded perspective view of a structural node of the structural system according to a further embodiment.

[0051] Prefabricated panel 1

[0052] With reference to the figures, a prefabricated wall panel 1 for making a structural building system 2, e.g. a building, defines a panel surface 3 and a peripheral edge 4 and comprises:

A) a plurality of material layers 5, 6, 7 which are parallel to the panel surface and overlap one another, comprising:

- a load-bearing layer 5 comprising a metal load-bearing structure 8,

- a protective layer 6 formed on a first side (inner side 9) of the load-bearing layer 5 and spaced apart from the load-bearing layer 5,

- an thermo-insulating layer 7 formed on a second side (outer side 10) of the load-bearing layer 5 opposite to the first side (inner side 9),

B) an air circulation gap 11 formed between the load-bearing layer 5 and the protective layer 6 and which separates the load-bearing layer 5 and the protective layer 6 from each other, said air circulation gap 11 being open on the peripheral edge 4,

C) a plurality of connectors-spacers 12, e.g. made of metal or synthetic material, extending in a direction transverse to the panel surface through said air circulation gap 11 and having a first fastening portion 13 fastened to the protective layer 6 and a second fastening portion 14 fastened to the load-bearing layer 5, wherein:

- said metal structure 8 comprises a plurality of load-bearing columns 15 spaced apart from one another and each consisting of one or more metal tubular profiles 16 which are parallel to one another and to the panel surface 3,

- the one or more metal tubular profiles 16 of each of said load-bearing columns 15 extend through one or more insulating blocks 17 made of polymer resin of said load-bearing layer 5,

- the load-bearing layer 5 between, respectively, two of said adjacent load-bearing columns 15 consists of or is filled with a first insulating material 18 which is different from the material of the insulating blocks 17,

- the insulating blocks 17 extend, in a direction transverse to the panel surface 3, beyond the volume of the metal tubular profiles 16 and prevent a direct contact between the metal tubular profiles 16 and layers of the prefabricated panel adjacent to the metal tubular profiles 16, in said direction transverse to the panel surface 3.

[0053] The prefabricated panel 1 is structurally load-bearing and resistant, thermally insulating, and allows a circulation of the air in the wall in a natural and continuous manner. Moreover, the prefabricated panel creates a “thermal cutting”, i.e. a net and defined discontinuity of thermal conduction, between the middle metal structure 8, load-bearing and inevitably thermally conductive, and the layers of the panel arranged on the two sides of the middle metal structure 8.

[0054] Panel 1 can be manufactured quickly and simply and affordably by means of metal carpentry assembly methods using widely standardized materials and processing which are available at contained costs.

[0055] The insulating blocks 17 made of polymer resin, in which the metal tubular profiles 16 are inserted, serve several synergistic functions: they form certain position references of the tubular profiles 16 in preassembly step of the metal load-bearing structure 8 and of the prefabricated panel 1 , they act as mutual connectors of the plurality of metal tubular profiles 16, they act as spacers between the individual metal tubular profiles 16 of a same load- bearing column 15, and they serve the function of thermal insulators and finally, they serve the function of connection bodies for fastening cover layers of the load-bearing layer 5 itself and/or of layers of panel 1 adjacent to the load-bearing metal structure 8.

[0056] Preferably, the prefabricated panel 1 is flat and plate-shaped with the peripheral edge 4 generally having a polygonal rectangular shape, for example substantially rectangular or square.

[0057] According to an embodiment (figures 1 , 1A, 1 B), the connector-spacer 12 is an elongated metal sheet profile, for example having 1.5 mm thickness, for example bent in the shape of a “Z” or “omega” in cross section to the longitudinal extension thereof. Preferably, the first 13 and second 14 fastening portions are planar and parallel to the panel surface 3. Advantageously, the connectors-spacers 12 of a same prefabricated panel 1 are parallel to one another and parallel to the metal tubular profiles 16, delimiting a plurality of parallel air circulation channels 19 in the air circulation gap 11 , for example vertical or extending from a lower edge of panel 1 to an upper edge of panel 1 when panel 1 is in upright position.

[0058] The connector-spacer 12, for example the metal sheet elongated profile, is perforated in the first 13 and/or second 14 connection portions for a connection thereof, for example by means of screws, with the load-bearing layer 5 and with the protective layer 6, and may comprise transverse ventilation holes 20 (figure 1 B) which create air passages between adjacent air circulation channels 19.

[0059] According to an embodiment (figure 1 , 1A, 1 B), the load-bearing layer 5 comprises a first cover layer (inner cover layer 21) fastened to the insulating blocks 17 on the first (inner) side 9 of the load-bearing layer 5, and surrounding or covering the metal load-bearing structure 8 and the first insulating material 18 on said first side 9.

[0060] Preferably, the first cover layer 21 is continuous and has no through openings, with the exception of possible discontinuities along contact lines between bordering panels of cover layer. The first cover layer 21 may be of wood or of synthetic material or of composite material, with or without fiber reinforcement, preferably of multilayer wood (so-called “marine wood”), or of compacted particle wood, and may have a thickness from 10 mm to 30 mm, advantageously from 16 mm to 24 mm, preferably of 20 mm. [0061] Similarly, the load-bearing layer 5 comprises a second cover layer (outer cover layer 22) fastened to the insulating blocks 17 on the second (outer) side 10 of the load-bearing layer 5 and surrounding or covering the metal load-bearing structure 8 and the first insulating material 18 on said second side 10.

[0062] Preferably, the second cover layer 22 is continuous and has no through openings, with the exception of possible discontinuities along contact lines between bordering panels of cover layer. The second cover layer 22 may be of wood or of synthetic material or of composite material, with or without fiber reinforcement, preferably of multilayer wood (so- called “marine wood”), or of compacted particle wood, and may have a thickness from 10 mm to 30 mm, advantageously from 16 mm to 24 mm, preferably of 20 mm.

[0063] The first cover layer 21 and/or the second cover layer 22 is fastened to the insulating blocks 17 by means of screws 23, for example self-tapping screws, for example made of stainless steel.

[0064] The first insulating material 18 may comprise a layer or panel of fiber minerals, e.g. rock wool, and may have a thickness in transverse direction to the panel surface 3 from 240 mm to 360 mm, preferably from 280 mm to 320 mm, even more preferably of about 300 mm. [0065] Advantageously, as for example in the case of mineral fiber materials, the first insulating material 18 is selected from the group of materials with absorption and/or acoustic insulation features.

[0066] According to an embodiment, the metal tubular profiles 16 comprise rectilinear tubular profiles, preferably having circular cross section, for example having diameter of 76.1 mm and wall thickness of 2.9 mm, or having diameter of 60.3 mm and wall thickness of 2.9 mm, made of hot laminated steel or aluminum for example.

[0067] Advantageously, each load-bearing column 15 comprises exactly two parallel tubular profiles 16 spaced apart from each other, which middle longitudinal axes 32 define a column surface 33 which is orthogonal to the panel surface 3 (figure 1 B).

[0068] In order to increase the axial compression resistance of the load-bearing columns 15 and to avoid instability phenomena (buckling) of the individual metal tubular profiles 16, for example in the case of use of the prefabricated panel 1 as vertical load-bearing wall element, the individual (e.g. two) tubular profiles 16 of a same load-bearing column 15 are connected to one another by means of one or more metal connection plates 34, which preferably are planar and rectangular, having (e.g. two) holes 35 of shape and position compatible with the cross shape and the position of the tubular profiles 16, and the two or more tubular profiles 16 of the load-bearing column 15 are inserted into the holes 35 of the one or more metal connection plates 34.

[0069] Advantageously, the metal connection plate or plates 34 are positioned at and in contact with the insulating block or blocks and/or preferably:

[0070] - in a middle stretch, at about half the length or in the third of middle length of the load-bearing column 15, or

[0071] - so as to divide the whole length of the load-bearing column 15 (and of the tubular profiles 16 thereof) into substantially equal portions of length.

[0072] According to an embodiment, the insulating blocks 17 are made of a polymer material, preferably of polyamide, e.g. PA6, even more preferably made of “Akulon Supermid” material.

[0073] The insulating blocks 17 are preferably extruded with a constant and invariable cross section along a longitudinal extension thereof which corresponds to the longitudinal extension of the metal tubular profiles 16.

[0074] The insulating blocks 17 form a plurality of parallel inner longitudinal channels 36, 37 which comprise one or more, preferably 2, main channels 36 for receiving a tubular profile 16 and optionally but preferably, a plurality of auxiliary channels 37, respectively, for lightening the insulating block 17 and increasing the thermal insulating capacity thereof. [0075] The insulating blocks 17 further form a plurality of parallel outer longitudinal channels 38, 39 which comprise auxiliary outer grooves 38 for lightening the insulating block 17, reducing the contact surface with adjacent layers and increasing the thermal insulating capacity thereof, and/or outer cutting reference grooves 39 which act as reference for a cut or a planned break of the insulating block 17 into two semi-blocks 40 (figures 3, 3A), for example for a use as insulating blocks in prefabricated panels serving as floor (figures 11 , 12) which is described later.

[0076] The insulating blocks 17 may be arranged along the load-bearing column 15 in (for example two or three) discrete positions spaced apart from one another and alternated by stretches of load-bearing column with no insulating blocks 17 (figures 1A, 11 , 12).

[0077] Alternatively, the insulating blocks 17 may be arranged beside one another or have such a length as to extend along at least 80% of the length of the load-bearing column 15 and without stretches of load-bearing column with no insulating blocks 17 therebetween (figure 22).

[0078] The insulating blocks 17 may be connected to the tubular profiles 16 by means of interference coupling, friction, by means of screws, bolts or glue.

[0079] The insulating blocks 17 thus configured ensure a discontinuity of thermal conduction between the metal load-bearing structure 8 and adjacent layers (in particular the first and the second cover layer 21 , 22) of the load-bearing layer 5 and/or of the prefabricated panel 1 .

[0080] In order to increase the bending resistance of the load-bearing columns 15 outside the panel surface 3, for example in case of use of the prefabricated panel 1 as horizontal load-bearing floor element, the individual (e.g. two) tubular profiles 16 of a same load- bearing column 15 are connected to one another by means of one or more metal connection cores 41 (“webs”), e.g. a single rod, or two rods, having solid section and shaped like a coil or undulated, welded to the tubular profiles 16 (figures 11 , 11A, 11 B, 12, 12A, 12B).

[0081] Here, where it is not possible to thread the insulating blocks 17 onto the tubular profiles 16 up to the planned position thereof, the insulating blocks 17 are divided into two semi-blocks 40 and are positioned about the tubular profile 16 in the planned position and connected to the tubular profile 16 by means of screws, bolts (figures 12A, 12B) or glue. [0082] The load-bearing layer 5 thus formed may be quickly and affordably prefabricated, by means of the following steps:

[0083] - assembly of the metal load-bearing structure 8 on a horizontal surface,

[0084] - fastening of the metal load-bearing structure 8 to one of the first 21 and second 22 cover layers,

[0085] - with the metal load-bearing structure 8 and the cover layer connected thereto arranged horizontally and with the cover layer positioned below the metal load-bearing structure 8, filling from the top of the space between the load-bearing columns 15 by means of the first insulating material 18,

[0086] - positioning and fastening the other cover layer from the top on the metal load- bearing structure 8.

[0087] As a result of this preassembly step, the load-bearing layer 5 is obtained in the form of load-bearing and self-load-bearing panel, laterally delimited by the two first 21 and second 22 cover layers, which is easy to handle, transport and store in view of the further completion of the prefabricated wall panel 1.

[0088] The load-bearing layer 5 carries out the task of static and aseismic load. The air circulation gap 11 may be directly delimited by the load-bearing layer 5 and by the protective layer 6. [0089] According to an embodiment (figure 1 , 1A, 1 B), the thermo-insulating layer 7 is directly adjacent to and in direct contact with (the second outer cover layer 22 of) the load- bearing layer 5 and is made of thermal and acoustic insulating material, e.g. EPS (foam polystyrene), rock wool, wood fibers, cork, having thickness within for example, the range from 6 cm to 20 cm, preferably from 10 cm to 15 cm and optionally reinforced with plasticized mesh 24 or that can be reinforced with plasticized mesh 24 (on an outer side thereof opposite to the load-bearing layer 5), and suitable for receiving one or more outer colored whitewash layers 25.

[0090] The thermo-insulating layer 7 forms an outer thermal “jacket”, i.e. the face, of the structural system 2 made by means of the prefabricated panel 1 .

[0091] The thermo-insulating layer 7 may be glued or screwed to the (second supporting layer 22 of) the load-bearing layer 5.

[0092] Advantageously, when the prefabricated or preassembled panel 1 is being constructed or prefabricated, the thermo-insulating layer 7 is applied and fastened from the top, on the previously preassembled load-bearing layer 5 lying (with the panel surface 3) in horizontal position.

[0093] The protective layer 6 (which may be seen as an interior wall of the dwelling) may be a structure which in turn is multilayer, for example comprising an overlapping fiber- cement sheet 26 and a plasterboard sheet 29, of overall thickness which is less than the thickness of the load-bearing layer 5.

[0094] Alternatively, the protective layer 6 may comprise a reinforced-concrete sheet 26 (with reinforcing bar 27) or a fiber-cement sheet 26, of smaller thickness than the thickness of the load-bearing layer 5.

[0095] The protective layer 6 has a surface facing the first side 9 (inner side) of the prefabricated panel 1 and adapted to be painted or covered with indoor whitewash 28. The air circulation gap 11 is essential for the circulation of the air in the prefabricated panel 1 and therefore, of the dwelling that can be obtained. Moreover, the air circulation gap 11 allows the passage of the ducts (water, gas, air conditioner) and of electrical wires and Internet/Intranet networks, antenna cables, etc. for creating the residential engineering and infrastructural network without making holes in the load-bearing layer 5 or the load-bearing metal structure 8.

[0096] According to an embodiment (figures 1 , 1A, 17, 19, 22), the prefabricated panel 1 forms one or more tie rod channels 30, in particular consisting of one or more of the aforesaid metal tubular profiles 16 of the reinforcing layer 5. The tie rod channels 30 are adapted to each receive a tie rod 31 , for example made of steel or harmonic steel, which is pretensionable so as to join and tighten a plurality of prefabricated panels 1 (or one or more prefabricated panels 1 and one or more further structural elements, e.g. floors) to one another, and possibly precompress them with a level of precompression of choice. Advantageously, the tie rod channels 30 are parallel to one another and parallel to the panel surface 3.

[0097] According to embodiments (figures 20B, 20C), not only may the prefabricated panel be used as vertical wall of the structural system 2, for example of a residential building, rather also as horizontal floor.

[0098] Here, the protective layer 6, as described above or having a single layer or a double layer of plasterboard sheets, may form a suspended ceiling 42 (figure 20C). Alternatively, the protective layer 6, as described above or having an additional layer 43 of thermal insulating, may form a surface below the floor at foundation 57 of the structural system 2 (figure 20B). [0099] The air circulation gap 11 serves the same function already described above and may advantageously be in communication with the air circulation gap 11 of:

[00100] - one or more vertical bordering prefabricated panels 1 forming a load-bearing wall of the structural system 2, and/or

[00101] - one or more horizontal bordering prefabricated panels 1 together forming the horizontal floor of the structural system 2.

[00102] The thermo-insulating layer 7 may comprise a film 44 which is impermeable to fluids to prevent the passage of water from a room above panel 1 in the load-bearing layer 5 and towards a room below panel 1 . The thermo-insulating layer 7 may further comprise a floor layer 45 containing insulating material, for example a technical floor connected to the load- bearing layer 5 by means of a metal supporting structure or a traditional floor with parquet, tiles or other known floor coverings.

[00103] Using the prefabricated panel 1 as horizontal floor, similar advantages are obtained to the ones described with reference to the use as vertical load-bearing wall, in particular a ventilation and removal of harmful and stagnant substances, e.g. radon gas, from the structural system 1 , a thermal insulating, an acoustic absorption and insulation, a structural and aseismic resistance, the possibility of industrial preassembly and pre-manufacturing, and also quick, accurate and affordable assembly at the construction site.

[00104] Structural system 2 [00105] Figures from 4 to 10 show embodiments of connection bodies for joining the prefabricated panels 1 to one another to form the structural system 2.

[00106] Figures from 13 to 22 show embodiments, structural details and assembly steps of the structural system 2, using the prefabricated panels 1 described hereto.

[00107] The structural system 2 of a residential building comprises:

- a plurality of prefabricated panels 1 connected to one another, in which the air circulation gap 11 continuously extends from one prefabricated panel 1 to a respective adjacent prefabricated panel 1 , and also

- a plurality of metal connection bodies 46 each comprising:

- at least one flat supporting plate 47,

- two or more protrusions 48 projecting from the supporting plate 47 and connected by means of insertion with respective ends 49 of the metal tubular profiles 16, so as to connect the metal tubular profiles 16 to one another, and to connect the prefabricated panels 1 to one another.

[00108] The connection bodies 46 allow a quick and accurate assembly of the structural system 2, without highly specialized labor and without the need of welding at the construction site for connecting the load-bearing structures 8 of the prefabricated panels 1 to one another.

[00109] According to an embodiment (figures 4, 5, 6, 7, 8, 9, 10), the protrusions 48 consist of parallel and rectilinear metal tubular portions having preferably circular cross section and having at least one pair of holes 50, preferably two pairs of holes 50 spaced apart from each other in a longitudinal direction of protrusion 48, for housing bolts 51 for blocking the ends 49 of the tubular profiles 16 to the protrusions 48.

[00110] According to a further embodiment (figures 5, 8, second connection bodies 46”), the protrusions 48 comprise two groups of two protrusions 48, respectively, projecting in a same direction from a same planar supporting plate 47 to connect two tubular profiles 16 of two load-bearing columns 15 of two mutually bordering prefabricated panels 1 to each other, respectively.

[00111] According to a further embodiment (figures 5, 8, second connection bodies 46”), said two groups of two projecting protrusions 48, respectively, are arranged at an angle and the supporting plate 47 has a plan angle shape so as to connect two load-bearing columns 15 of two mutually bordering prefabricated panels 1 oriented orthogonally to each other. [00112] According to further embodiment (figure 4, first connection body 46’, figures 5, 8, second connection bodies 46”), the connection body 46 also forms a passage channel 52 for the passage of the tie rod 31 . The passage channel 52 advantageously extends through one of the tube-shaped protrusions 48 and through the supporting plate 47. This allows a rectilinear continuity of extension of the tie rod 31 along the tubular profile 16 of the prefabricated panels 1 and through the structural connection node therebetween, formed by means of the connection body 46.

[00113] According to a further embodiment (figures 6, 7, fourth connection bodies 46””, figures 9, 10, third connection bodies 46’”), the connection body 46 forms two transverse connection plates 53 connected, for example welded, at a right angle, to the supporting plate 47 and forming connection seats (connection holes 54, tie rod passage openings 55, housing seats 56) for a connection of the connection body 46 not only with the tubular profiles 16 of the load-bearing columns 15, but also with further connection bodies 46 or further parts of the structural system 2. This is particularly advantageous in the connection of the prefabricated panels 1 serving as horizontal floors, as seen for example in figures 16 to 20.

[00114] According to an embodiment (figures 9, 10, third connection bodies 46’”), the two transverse connection plates 53 and the supporting plate 47 jointly form a double-T profile, in which the two transverse connection plates 53 form the upper and lower flanges and the supporting plate 47 forms the vertical core of the double-T profile. In this embodiment with the connection body 46 mounted in position of use, the supporting plate 47 is oriented in a vertical plane, the transverse connection plates are oriented in parallel horizontal planes, the (preferably two) protrusions 48 are arranged one over the other and extend from a first side 58 of the supporting plate 47 along parallel horizontal directions. On a second side 59 of the supporting plate 47 opposite to the first side 58, (preferably two) “U”-shaped seats 60 or seats may be formed, having the shape of an open channel with horizontal longitudinal extension and extension perpendicular to the longitudinal extension to the protrusions 48, for example made by means of curved metal plates, welded to the supporting plate 47, to accommodate ends 49 of horizontal tubular profiles 16 which are perpendicular to the longitudinal extension of the protrusions 48 (and of the tubular profiles 16 inserted/threaded therein/thereon). The seats 60 are open in a direction opposite to the direction in which the protrusions 48 project to allow the insertion and housing of the ends 49 of the tubular profiles 16 in the extension direction of the protrusions 48 (figure 16).

[00115] Also the seats 60 may form holes 50 for housing bolts 51 for blocking the ends 49 of the tubular profiles 16 in the seats 60. The seats 60 of a same connection body 46 may have different lengths and different positions of the holes 50 to facilitate the housing of two ends of tubular profile arranged head-to-head and/or to facilitate the access to the holes 50 and to the bolts 51 to insert and tighten the latter.

[00116] According to an embodiment (figures 6, 7, fourth connection bodies 46””), with the connection body 46 mounted in position of use, the supporting plate 47 is oriented in a vertical plane, and the (preferably two) protrusions 48 are arranged one over the other and extend from a first side 58 of the supporting plate 47 along parallel horizontal directions. On a second side 59 of the supporting plate 47, opposite to the first side 58, the transverse connection plates 53 are oriented in parallel horizontal planes and project from the supporting plate 47 in a direction opposite to the direction in which the protrusions 48 project. The transverse connection plates 53 each form a tie rod passage opening 55 for allowing the extension of the tie rod 31 through the connection body 46.

[00117] According to an embodiment, two of these fourth connection bodies 46, 46”” may be arranged one beside the other with the protrusions 46 thereof oriented at an angle or parallel, and with the transverse connection plates 53 positioned at different heights and overlapping in vertical direction, with the vertically aligned tie rod passage openings 55 and with damper blocks 61 made of damping material, for example Neoprene or polytetrafluoroethylene (PTFE), interposed between one transverse connection plate 53 of the one and one transverse connection plate 53 of the other, respectively, of the two fourth connection body 46, 46”” (figure 17).

[00118] This configuration facilitates the dry assembly of the structural nodes of the structural system 2 and gives the structural system 2 an excellent seismic resistance.

[00119] Figures from 16 to 22 show details of the structural system 2 with a plurality of prefabricated panels 1 vertically oriented and arranged one above the other in a vertical wall plane (possibly with alternating floor elements) to form a vertical wall 64, and also one or more tie rods 31.

[00120] The tie rods 31 are anchored to the vertical wall at the anchoring ends 62 thereof and extend parallel to the panel surface 3 through the load-bearing layer 5 of the prefabricated panels 1 and through the connection bodies 46 interposed between two vertically adjacent prefabricated panels 1 , respectively, and may be blocked and/or locked or pretensioned, for example by means of a tensioning nut 63 screwed on the threaded end of the tie rod 31 and resting against the vertical wall 64, so as to keep it joined. [00121] The tie rods 31 may comprise one or more steel cables or steel bars threaded at the ends and having length substantially corresponding to the height of the vertical wall 64. The diameter of the tie rod 31 is selected according to the resistance to the traction required, preferably equal to or greater than 24 mm.

[00122] In addition to the one or more vertical walls 64, the structural system 2 may further comprise horizontal walls 65 connected with the vertical walls 64, and optionally also a plurality of horizontal tie rods 66 anchored to the vertical 64 or horizontal 65 wall at the anchoring ends 67 thereof and extending horizontally through the horizontal wall 65 and the horizontal tie rods 66 may be blocked and/or tightened or pretensioned, for example by means of a tensioning nut 63 screwed on the threaded end of the horizontal tie rod 66 and resting against the horizontal wall 65, so as to keep the structural system 2 horizontally joined.

[00123] Figures 23A and 23B and 24 show structural nodes of the structural system which note the possible and advantageous alternative embodiments compatible with the embodiments described above.

[00124] According to an embodiment, the tubular profiles 16 may be profiles having rectangular or square section. This is particularly advantageous for making panels 1 for floors and for fastening a secondary load-bearing structure to the tubular profiles 16.

[00125] According to a further embodiment, the connection core 41 may be formed from a flat metal perforated sheet provided with connection holes 68 for a connection by means of bolts of the load-bearing column 15 (serving for example as structural beam) to one or more of the metal connection bodies 46.

[00126] According to a further embodiment, one or more of the load-bearing columns 15 (serving for example as structural beam) may comprise metal end plates 69 welded to the ends of the metal tubular profiles 16 and adapted to be screwed to each other or with one or more of the connection bodies 46.

[00127] The load-bearing layer for wall panel, the prefabricated panel 1 and the structural system 2, and also the manufacturing method described are economically affordable, may be industrialized and repeated with dimensional and execution certainty at the construction site, and meet and conciliate the needs of structural and seismic resistance, healthiness and residential comfort.

[00128] Panel 1 according to the invention may be made as purely preassembled panel by means of dry assembly steps (typical of carpentry). [00129] Panel 1 , the structural system 2 and the method described allow making the panel without specifically fitted factories.

[00130] The layers forming the wall panel and the structure of the individual layers, especially the insulating features thereof, give the final wall an increased degree of thermal insulating, such as not to necessarily require a heating or conditioning system.

[00131] The structural system is particularly accurate and repeatable in the execution thereof. In particular, in addition to keeping them structurally joined, the conception of two plates (floor plates or treading floors) spaced apart by a series of pairs of tubular profiles (columns) prevents the deformation of the structure (of the dwelling, as though it were a box) and therefore are resistant to the seismic forces acting in any direction. This aspect is particularly important and is a significant advantage with respect for example, to homes which can be assembled with wood load-bearing structure.

[00132] Lastly, but not least importantly, the materials of the individual layers described and the layering order of panel 1 allow a minimum resistance to fire of 60 minutes (REI 60) and are also suitable for a fire resistance certification of 120 minutes.

[00133] Panel 1 and the structural system 2 are therefore suitable for making REI and aseismic certifiable buildings having an increased acoustic insulation, and also improved hygrometric and insulating features with respect to the prior art of the reference field.

[00134] Those skilled in the art, with the aim of meeting contingent and specific needs, can make further changes and variations, all falling within the scope of protection defined by the claims.