ELEMENTS

Technical field

The present invention relates to a building structure provided with vertical walls that comprise a thermoplastic polymer, and which is provided with reinforcement elements.

Background Art

It is known that houses in common use, that is to say built using common construction materials like reinforced concrete or bricks, exhibit considerable drawbacks.

The most notable drawbacks consist in long construction times (often several months), complex construction techniques, the high cost of the raw materials used, reduced resistance to seismic events, low thermal retention and the high cost of construction and purchase.

In order to overcome these drawbacks, building structures have been developed the walls of which comprise panels of expanded polystyrene.

An example of a building structure made using walls of this type is disclosed in US 6,519,904.

More specifically, US 6,519,904 discloses a method for building supporting walls of building structures. These walls comprise an insulating panel positioned inside a metallic containment structure inside which concrete is poured.

The poured concrete forms a supporting layer of considerable thickness that rests against the insulating panel.

The layer of concrete defines the outer face of the corresponding wall, while the insulating panel is directed toward the inner face of the same wall.

The layer of concrete, within which a metallic net and stiffening bars are immerged, interrupts the insulating panel in some regions, thus creating discontinuities where supporting vertical columns are provided.

The containment structure consists of substantially C-shaped containment elements arranged mutually so as to define a closed rectangular profile. The vertically arranged containment elements are provided with a plurality of through slots into which the concrete is inserted, thus becoming anchored to the containment structure.

Building structures made using the construction method disclosed in

US 6,519,904 are not free from drawbacks, including the fact that the rigidity of the structure is due solely to the layer of reinforced concrete, and so the insulating panels have no structural function and therefore do not contribute to absorbing the stresses to which the corresponding wall can be subjected. Walls provided in this way thus have a static behaviour that is just like the concrete walls in common use. Furthermore, the behaviour of these walls under dynamic stresses is not homogeneous throughout their extension, and in particular on their opposite faces, due to their nonsymmetrical structure.

US 6,519,904 does not disclose, furthermore, how the various walls that constitute an entire dwelling are connected to each other, and thus how the stresses acting on the building structure thus provided are distributed.

Another drawback of building structures of this type consists in the lengthy construction times that they require, which are also due to the extensive use of concrete.

In order to overcome these drawbacks this Applicant has developed an improved building structure of the type disclosed in WO2010/060857A1.

Thanks to the contrivances adopted, in fact, it is possible to provide building structures with multiple floors or levels, while at the same time increasing - among other advantages - the mechanical strength of the building structure, its energy level and its screening against magnetic fields.

In particular, in such a building structure, each internal environment is surrounded by a concrete structure incorporating a metallic net that wraps the entire environment and, in turn, is wrapped by an insulating layer formed by the insulating panels. The whole is anchored to the further metallic net which surrounds the structure externally, and is also encased in the concrete covering structure.

In order to improve the building structure as disclosed in WO2010/060857A1 , and in particular in order to provide building structures with multiple levels or floors, the applicant has concentrated attention on a number of studies aimed at increasing the reproducibility of the structure, its safety including anti-seismic requirements, and its structural strength, especially in the join regions.

tn recent times, in the field of construction in fact, the necessity both to cater to pressing needs to contain the energy consumption of dwellings and also to ensure capacity for resistance of the buildings to seismic events, has strongly driven research into types of construction that are increasingly thermally insulated and increasingly "lighter" in structural terms than traditional construction systems.

At the same time, the need to intervene in the economic factors of the process of producing buildings has led to the development of innovative construction solutions that are increasingly geared toward prefabrication. This technique however does not always succeed in meeting construction- related needs in that, while it certainly speeds up the steps of providing the building, by reducing them, especially at the structural level, to simple assembly operations, it poses a series of problems both economic and design-related which are linked to the necessity to have a fixed facility for producing elements and also to the design restrictions imposed by the modularity of those elements.

Disclosure of the Invention

The aim of the present invention is to eliminate the drawbacks of the known art and to improve the distribution of the static loads on the building structure, by providing a building structure that is offered as being half-way between the two construction types, that is to say, traditional construction and prefabricated construction, and which makes it possible to provide a building construction system that is rapid and simple to execute, highly reliable and with high performance levels that, without requiring special parts and specific technologies or apparatuses, is based on the use of materials that are readily available on the market in standard formats and, at the same time, is compatible with all types of finishing and with all technological systems used in the construction field.

Within this aim, an object of the invention is to be able to simplify and speed up the construction process, without making it necessary to have a specific production facility, without requiring the use of expensive site machines and apparatuses for mobilizing the elements and, at the same time, ensuring the highest energy and structural performance levels and much higher than those of both traditional and prefabricated systems.

Another object of the invention is to provide light construction systems in steel and polystyrene that are easily transported and have reduced spatial encumbrance and, at the same time, offer high resistance to stresses, static or dynamic, due for example to seismic events.

Another object of the invention is to provide a building structure that, once finished, is aesthetically and functionally entirely similar to a structure of the traditional type, already plastered, ready for any type of surface treatment or finishing, but which at the same time offers high capability for saving energy and, therefore, lower environmental impact.

Another object of the present invention is to provide a simple structure, that is easy and practical to implement, safe in use and effective in operation, and of low cost.

This aim and these objects are all achieved by the present building structure provided with reinforcement elements which comprises a plurality of vertical walls arranged on multiple levels, each wall comprising at least one first substantially continuous panel made of a thermoplastic polymer and a pair of layers of cement plaster which are arranged on the opposite sides of the corresponding first panel and define the opposite faces of the corresponding vertical wall; the vertical walls of the lowest level being fixed below a reference plane and the vertical walls of each level being mutually connected in order to delimit one or more closed perimeters; at least one covering wall, which is fixed in an upper region to the vertical walls of each one of said levels in order to define one or more closed volumes and mutually separate said levels, the covering wall of the highest level defining the roof of said building structure; and a metallic structure for connecting at least the vertical walls of each one of said levels and the face of said covering wall that is directed toward them, said metallic structure delimiting each closed volume, substantially without discontinuities; characterized in that it comprises at least one ridge that rests on said vertical walls of each level and supports the vertical walls of the level that lies above it, said ridge comprising at least one surface for resting said covering wall, which defines a further reference plane for said upper level.

Brief description of the drawings

Further characteristics and advantages of the present invention will become better apparent from the detailed description of a preferred, but not exclusive, embodiment of a building structure provided with reinforcement elements, which is illustrated for the purposes of non-limiting example in the accompanying drawings wherein:

Figure 1 is a side elevation view of a building structure, according to the invention, in a vertical cross-section;

Figure 2 is an enlarged-scale view of a detail of Figure 1 ;

Figure 3 is an exploded front view of the detail in Figure 2;

Figure 4 is an enlarged-scale view of another detail of Figure 1;

Figure 5 is a view of a first step of constructing a vertical wall, according to the invention;

Figure 6 is a view of a second step of constructing a vertical wall, according to the invention, in which first horizontal elements and angular elements are positioned on a corresponding first panel of thermoplastic polymer;

Figure 7 is a view of a third step of constructing a building structure, according to the invention, in which a ridge is positioned on the first horizontal elements;

Figure 8 is a view of a fourth step of constructing a building structure, according to the invention, in which second horizontal elements are positioned on the ridge;

Figure 9 is a view of a fifth step of constructing a building structure, according to the invention, in which the covering wall of the first level is positioned so as to rest on the resting surface of the ridge;

Figure 10 is a view of a sixth step of constructing a building structure, according to the invention, in which a vertical wall defining the second level and the further ridge for supporting the roof are positioned;

Figure 11 is a view of a seventh step of constructing a building structure, according to the invention, in which the roof of the structure is positioned.

Ways of carrying out the Invention

With reference to the figures, the reference numeral 1 generally designates a building structure according to the invention.

The building structure 1 comprises a plurality of vertical walls 2 arranged on multiple levels, where the term "levels" is intended to mean the floors arranged at different heights with respect to each other inside the building structure.

Each vertical wall 2 comprises at least one substantially continuous central first panel 3 of a thermoplastic polymer, preferably polystyrene, and a pair of layers 4 of cement plaster arranged on the opposite sides of the corresponding panel 3 and defining the opposite faces of the corresponding vertical wall 2.

The layer 4 of cement plaster comprises, specifically, a mixture of a cement mortar that is fiber-reinforced with inorganic fibers of the known type, which once hardened becomes self-supporting.

The vertical walls 2 of the lowest level (that is to say of the ground floor) of the building structure 1 are fixed below a reference plane 5 that is provided, for example, in concrete, as will become better apparent hereinbelow, using anti-seismic fixing and/or anchoring means.

More specifically, the vertical walls 2 of the lowest level are fixed to the reference plane 5 by means of a plurality of threaded elements 6 that engage with a metallic plate 7 arranged resting on the reference plane.

The vertical walls 2 of each level are mutually connected in order to delimit one or more closed perimeters.

The building structure 1 thus comprises at least one covering wall 8 fixed in an upper region to the vertical walls 2 of each level in order to define one or more closed volumes and in order to mutually separate the levels of the building structure 1.

The covering wall of the highest level defines the roof 8a of the building structure 1.

According to the invention, the building structure 1 comprises, furthermore, a metallic structure 50 connecting at least the vertical walls 2 of each level.

For the anti-seismic fixing of the building structure 1, metallic rods

51 can be provided embedded in the concrete defining the reference plane and protruding therefrom and adapted to be fixed to the vertical walls 2, for example by way of fixing using threaded elements to the metallic structure 50 or embedding in adapted cement castings formed in adapted spaces in the walls or in the metallic structure 50.

Specifically, the peculiarity of the invention consists in that it comprises at least one ridge 52 that rests on the vertical walls 2 of each level and supports the side walls 2 of the level that lies above it.

The ridge 52 comprises, furthermore, at least one surface 53 for supporting the covering wall 8 defining the upper level. From structural calculations and experimental tests it has been shown that the ridge 52 supports the vertical walls 2 of the two levels between which it is interposed and the covering wall 8 corresponding thereto, considerably increasing the mechanical strength of the structure thus formed, with respect to a structure in which the ridge is not provided.

In particular, by subjecting conveniently selected samples of vertical walls 2 assembled with a covering wall 8 by way of the above mentioned ridge 52 to shear tests, flexion tests, unconfined compression tests, in-plane compression and shear tests and out-of-plane compression and shear tests, surprising results were achieved in terms of resistance of the structure, which are not possible with classic construction systems.

Furthermore, the breakages found at the maximum breakage load have exhibited a minimal detachment of cement material, and in small granules, from the vertical walls and from the covering walls, the cement material used remaining stably anchored to the metallic structure 50 and to the ridge 52, despite the extreme stresses to which the sample was subjected.

This finding is of particular interest to the anti-seismic use of the building structure 1.

The ridge 52 comprises, advantageously, at least one metallic longitudinal member 54 the transverse cross-section of which is substantially Ω-shaped.

The shape of the longitudinal member 54 is such as to lighten the structure of the ridge 52, which is internally hollow, and at the same time to provide an excellent resistance to compression and to the stresses of various types to which it could be subjected.

The ridge 52, specifically, comprises a plurality of longitudinal members 54 connected to each other at their ends.

The structure 1 comprises, furthermore, at least one angular element 55 for the end-to-end connection of at least two of the longitudinal members 54 defining the ridge 52 which are mutually incident.

Specifically, the structure 1 comprises a plurality of angular elements

55.

Each angular element 55 comprises at least one column 56, for example made of press-formed metallic material, provided with a foot 57 for resting on the vertical wall 2 of each level and a flat support 58 defining a resting surface for the vertical wall 2 of the level that lies above it.

The structure 1 comprises, furthermore, at least one plurality of adjustment elements 59, for example comprising metallic profiles provided with slot-shaped holes for registering the position, for adjusting the mutual distance between the head of the longitudinal members 54 and the angular element 55 and which can be fixed to them by means of threaded elements, of the type of self-tapping screws and/or bolts that can be inserted into the slot-shaped holes.

Advantageously, the metallic structure 50 comprises, for each vertical wall 2, a pair of first metallic nets 9 integrally mutually associated by means of metallic connectors 10 and interposed between the sides of the corresponding first panel 3 and each one of the corresponding layers 4 of plaster.

Preferably, the first metallic nets 9 directed toward the incident faces of two vertical walls 2 connected to each other, are integrally mutually associated, for example by welding of their lateral ends or by means of threaded connections.

The metallic structure 50 comprises, furthermore, for each one of the vertical walls 2, at least one pair of first metallic vertical elements 11a, C- shaped and substantially without discontinuities, positioned at the lateral ends of the corresponding vertical walls 2 and defining an accommodation seat for a lateral end of the corresponding first panel 3,

The first vertical elements 1 1a, constituted for example by metallic plate profiles, have an elongated shape and the corresponding accommodation seat extends vertically.

Preferably, the metallic structure 50 comprises angular columns 1 1c, made of metallic material, for example press-formed sheet metal, and internally hollow, inside which the adapted space is defined for containing the concrete embedding the anti-seismic rods.

The first vertical elements 1 la in proximity to the angle of the vertical walls 2, advantageously, are integrally associated with the angular columns 11c.

Preferably, the metallic structure 50 also comprises, for each vertical wall 2, a plurality of first horizontal metallic elements l i b, which are C- shaped and associated at their ends substantially without discontinuities, arranged at the upper end of the corresponding vertical wall 2 and fitted on top of the corresponding first panel 3.

The first horizontal elements l ib, constituted for example by metallic plate profiles, have an elongated shape and the corresponding accommodation seat extends horizontally.

Conveniently, the first vertical elements 11a and horizontal elements l i b are integrally associated with at least one of the first metallic nets 9 of the corresponding vertical wall 2, for example by means of bolts or welds.

Advantageously, the first vertical elements 1 la of two vertical walls 2 mutually joined at the respective lateral ends are integrally mutually associated, for example by welding, screws or bolts or other fixing means.

For vertical walls 2 characterized by a horizontal extension that is perceptibly longer than the vertical extension, the corresponding first panel 3 is vertically separated into two parts, at the lateral ends of each one of which a pair of first vertical elements 11 a are positioned. The first vertical elements 1 1 a arranged at the region of separation of the first panel 3 are mutually opposite and integrally associated with each other.

For a vertical wall 2 connected with a lateral end thereof to a face of another vertical wall 2, the latter comprises, at the connection region, two first vertical elements 11a which are mutually opposite and connected to the first vertical element 11a arranged at the incident lateral end of the vertical wall 2.

The metallic structure 50 also comprises, for each level of the building structure 1 , a plurality of second horizontal metallic elements 12, which are shaped like an inverted letter C and associated at their ends substantially without discontinuities, integrally mutually associated in order to define a closed profile and a seat for the containment of the corresponding vertical wall 2 of the upper level.

The second horizontal elements 12, constituted for example by metallic plate profiles, have an elongated shape and the corresponding accommodation seat extends horizontally and directed upward.

Advantageously, the ridge 52 is fixed, by means of threaded elements of the type of self-tapping screws and/or bolts, to the first and second horizontal element, respectively l ib and 12.

In particular, the two horizontal base portions 52a of the Ω-shape rest on the first horizontal element, the central horizontal portion 52b that is directed upward acts as a resting element for the second horizontal element and the surfaces directed upward of the two horizontal base portions 52a define the resting surface 53 for the covering wall 8.

Preferably, the first metallic nets 9 directed toward the faces of the vertical walls 2 of the various levels of the building structure 1 that externally delimit the building structure are integrally mutually associated or even partially overlapping, if greater resistance to shearing of the structure should be necessary.

Conveniently, the covering walls 8 of the intermediate levels, that is to say not including the roof 8a, also comprise a layer of polystyrene 13.

They also comprise a layer-like structure, like the vertical walls 2, in which the layer of polystyrene rests on the resting surface 57 and on intermediate beams 60, which are also made by means of C-shaped metallic plate and are adapted to be fixed at the ends to the ridge 52.

The concavity of the C of the intermediate beams 60 is such as to be directed toward the layer of polystyrene to be supported, and in fact the intermediate beam fits over the layer.

Furthermore the covering wall 8, just like the vertical walls 2, comprises a pair of metallic nets 9, fixed to the ridge 52 and/or to the intermediate beams, and arranged on the opposite side (from the corresponding upper and lower faces) of the layer of polystyrene.

The metallic nets 9 are furthermore intended to be enveloped in respective layers 4 of cement plaster.

Specifically, each closed volume defines an inner environment of the building structure 1 and exhibits to view a layer 4 of cement plaster delimiting all the walls and the ceiling, inside which a metallic net 9 for each wall is embedded. The metallic nets are mutually stably linked by optional mutual overlaps and by elements for fixing to the metallic structure 50 defined by the ridges 52, the angular columns 56, the C-shaped profiles thus forming a continuous and closed cage that is such as to ensure excellent mechanical strength and elasticity of the structure 1 , which is optimal for the anti-seismic characteristics of the building structure.

Preferably, the roof 8a of the building structure 1, shown in cross- section in Figure 3, comprises a pair of second panels 14 of thermoplastic polymer which are arranged mutually inclined and around which a cornice 15 of cement plaster is provided.

Inside the cornice 15 a second metallic net 16 is positioned that surrounds the entire profile of the corresponding second panel 14, on one side and on the other side of the panel (above and below it).

Advantageously, the metallic structure 50 comprises means, for example a metallic bracket, of fixing the second metallic net 16 of the roof 8a to at least one of the first metallic nets 9 of the vertical walls 2 connected in a lower region to the roof. The roof 8a is covered in an upper region by a waterproofing membrane and by a covering mantle as is known to the person skilled in the art.

The metallic structure comprises, furthermore, a further ridge 61 associated in an upper region with the vertical wall 2 of the last level.

The further ridge 61 is such as to rest upon and be fixed to the first horizontal element l ib of the end vertical wall and define an inclined surface 62 for the resting and fixing of the roof 8a.

The further ridge 61 also comprises at least one metallic longitudinal member the transverse cross-section of which is substantially Ω-shaped.

The further ridge 61 , specifically, comprises a plurality of longitudinal members connected to each other at their ends and is fixed, by means of threaded elements of the type of self-tapping screws and/or bolts, to the first horizontal element l ib of the end vertical wall adapted to support the roof 8a.

In particular, the two horizontal base portions of the Ω-shape rest on the first horizontal element, and the central portion directed upward, which is inclined with respect to the horizontal at an angle that can vary according to the preset pitch of the roof 8a, defines the inclined surface 62 and acts as a resting element for the roof,

Each vertical wall of the structure 1 is provided according to what is described for the vertical walls 2 and each horizontal wall of the structure is provided according to what is described for the covering wall 8, be they balconies and associated connecting perimeter balconies, the rises and treads of steps, fence walls, and the like.

Advantageously, the vertical walls 2 can comprise one or more doors and windows.

The doors and windows are delimited by a plurality of metallic containment elements, which are C-shaped and mutually connected so as to define a closed profile. The accommodation seat defined by each containment element is directed toward the outside of the corresponding door or window and is fitted on the border of the corresponding panel which is conveniently contoured in order to define the window.

Each containment element is integrally associated, for example by electrowelding or by means of threaded elements, with the first metallic nets 9, conveniently cut at the border of the corresponding door or window, of the vertical wall 2 in which the window is defined.

The fixtures of the doors and windows are anchored integrally to the corresponding containment elements.

Furthermore, in order to increase the thermal insulation of the structure, it is possible to provide insulating means, such as for example layers of thermally insulating material like rubber, polystyrene or the like, that wrap part of the metallic structure directly facing the outside of the building structure or at the points of greatest thermal criticality.

The method of providing a building structure according to the invention is described below.

First of all a plurality of substantially continuous first panels 3 of a thermoplastic polymer are obtained, and also a plurality of first vertical elements 11a, each defining a corresponding accommodation seat for a lateral end of one of the first panels 3.

The method according to the invention then involves the alignment of the first vertical elements 11a, two by two, with the corresponding accommodation seats facing each other for the containment of a corresponding first panel 3 and optional angular columns 56 arranged at the peripheral corners of the building structure 1.

Subsequently, the first vertical elements 11a thus arranged are fixed to the reference plane 5, by means of the threaded elements 6.

Once the first vertical elements 1 1 a are fixed, a corresponding first panel 3 is positioned between each pair of first vertical elements 11 a which are mutually aligned and facing.

Conveniently, the first vertical elements 11 a are mutually arranged so that the corresponding first panels 3 define at least one substantially closed perimeter. More specifically, the first vertical elements 11a corresponding to the first panels 3, which are designed to define two vertical walls 2 that are mutually connected, are positioned in contact and are mutually fixed together.

Optionally, where required, it is possible with the vertical elements

11 a to encircle the anti-seismic rods 51 that protrude from the reference plane and, once the vertical elements and the reference plane 5 are fixed to each other, pour a quantity of cement plaster into the cavity defined by the vertical elements 11a and such as to envelop the rod.

Advantageously, after the positioning of each first panel 3, on the corresponding upper edge a first horizontal element 1 lb, which is also C- shaped and substantially without discontinuities, is applied and is fixed to the first metallic nets 9 of the corresponding first panel 3.

Then a pair of first metallic nets 9 are positioned at the opposite sides of each first panel and these first metallic nets are fixed to the first vertical elements 11 a of the corresponding first panel 3.

Before positioning and fixing the first metallic nets 9 it is possible to cut the corresponding first panel 3 in order to define one or more windows

32.

The method according to the invention further involves the application of at least one layer 4 of cement plaster on each side of the first panels 3, at the corresponding first metallic nets 9, in order to define the faces of the vertical walls 2 of the building structure 1.

Specifically, for a building structure with multiple levels, after positioning and fixing the first metallic nets 9 of the vertical walls of the lowest level of the building structure 1, the ridge 52, which is constituted by the plurality of longitudinal members 54 associated at their ends by means of the angular elements 55, is positioned over the corresponding first horizontal elements 11 b.

The longitudinal members 54 and the angular elements 55 are resting on, and fixed to by means of threaded elements, the first horizontal elements l ib.

On the resting surface defined by the ridge 52 (or specifically by the longitudinal members that define it) the covering wall 8 is arranged to rest, defining the ceiling of the first level and, in the upper part, the reference plane for the upper level of the building structure.

In practice the layer of polystyrene 13 encircled by the intermediate beams 60 that are fixed at the ends to the ridge 52 is positioned so as to rest on the resting surface 53 thereof and anchored by means of threaded elements.

Work proceeds by fixing the metallic net 9 arranged substantially horizontally above and below the layer of polystyrene 13 to the metallic structure 50, for example to the ridge 52, fixing it by means of threaded elements and mutually by means of the connectors 10.

Finally, the above mentioned metallic nets 9 are surrounded with corresponding layers 4 of cement plaster defining, once hardened, respectively the ceiling of the lower level and the floor or the reference plane of the upper level.

Then the second horizontal elements 12 are arranged, and in practice they are rotated through 90° with respect to the first horizontal elements l i b, resting on the ridge 52 (on the horizontal surface defined by the central horizontal portion thereof) so as to define a closed profile and a seat for the containment of the first panel 3 defining the vertical wall 2 of the second level or plane of the building structure.

Then follows the erection of a further vertical wall 2 corresponding to the upper level as described previously for the vertical wall 2 of the first level. Advantageously, the next step is to integrally mutually associate the first metallic nets 9 directed toward the faces of the vertical walls 2 of the various levels that externally delimit the building structure 1 and which are mutually overlapped.

With the positioning and fixing of the first metallic nets 9 of the vertical walls 2 of the various levels of the building structure 1 finished, work proceeds with the application of the layer 4 of plaster on the faces of the vertical walls 2 that externally delimit the building structure.

With the vertical walls 2 of the upper level of the building structure 1 provided, work proceeds by positioning and fixing the roof 8a.

In particular, a further ridge 61 is positioned to rest on the first horizontal element l ib, the further ridge 61 having its central portion inclined and defining the inclined surface 62 that exhibits the inclination set for the pitch to be attained for the roof which is rested thereupon and fixed by means of threaded elements.

In practice it has been found that the invention as described achieves the intended aim and objects and, in particular, attention is drawn to the fact that the building structure, provided with reinforcement elements, that is to say the ridges, makes it possible to provide structures for habitation and other uses with multiple levels, ensuring a high mechanical strength and notable anti-seismic characteristics.

Furthermore the building structure according to the foregoing description enables the provision of structures for habitation and other uses by means of elements that can be standardized and also easily and rapidly assembled, thus enabling considerable savings of time, labor and cost for the provision thereof, as well as savings of discarded materials and site waste and facilitating transport of the materials.

All this makes possible, at the same time, the provision of dwellings with a high capacity for saving energy, and resistance to atmospheric agents and to the mechanical stresses deriving from natural calamities. The invention, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

Furthermore, all the details may be substituted by other, technically equivalent elements.

In practice the materials employed, as well as the contingent dimensions and shapes, may be any according to requirements.

The disclosures in Italian Patent Application No. MO2010A000233 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.