Background Art Currently, horizontal structures, particularly floors, are made of heavy materials, mostly reinforced concrete, with optional lightening bodies made of hollow tiles, polystyrene foam or other materials.

More frequently, these kinds of structure are partially or fully provided by means of prefabricated concrete components in specific factories and are assembled on-site in order to obtain the finished horizontal structure, which is completed, also on-site, by additional castings with optional additional reinforcements.

Normally, these horizontal structures have an intrinsic final weight on the order of 2.50-4.00 kN/m2, depending on the spans and load-bearing capacities.

Development in the field of building and of steel supporting structures has raised considerable interest in the search for lightweight products that can be transported easily and can be manufactured in-factory as much as possible.

Furthermore, prefabricated components having the above described characteristics might be used in the case of renovation of old buildings owing to the difficulty, in this case, of working with cranes and bulky vehicle and owing to the need to bear as little as possible on existing structures that have a limited load-bearing capacity.

It is of course evident that structural components, in order to allow their easy installation, must have features such as the ability to support themselves in addition to lightness and ease of handling during transport and

installation.

The need to lighten prefabricated elements and provide a better finish thereof has led, for some years, to use formwork elements made of GFRC (Glass Fiber Reinforced Concrete), hereinafter also referenced as GRC, on which the concrete casting is to be performed, with the optional reinforcement, which constitutes the load-bearing structure (reference should be made, in this regard, to EPA-0183526-A1 by Permanent Formwork Limited).

GRC is a composite material, constituted mainly by concrete, selected sands (generally sands having a high quartz content), and glass fibers that are normally resistant to alkali : sometimes it is reinforced with stainless steel net, lattice girders, conventional steel frames, fibers or nets of carbon and/or glass.

By using GRC, in practice the characteristics of compressive strength of concrete and quartz have been combined with the tensile strength of glass fibers.

The use of GRC has allowed to solve some problems, such as durable surface finish and light weight and therefore transportability, of finishing and face elements of buildings, utilizing the great lightness of this material with respect to conventional concrete, owing to the low thicknesses that are typical of GRC and to its high strength characteristics.

Up to now, however, this use has been limited to architectural cladding and/or to the subsequent casting of reinforced structural concrete; therefore, in economical and practical terms, this solution does not solve all the problems related to the production of horizontal structures and floors.

A first limitation consists in that the GRC structure is used exclusively as a finishing and supporting surface and therefore it is still necessary to produce reinforced concrete castings and the supporting slab.

Furthermore, the floor, after pouring the concrete, loses most of its lightness determined by the use of GRC.

Disclosure of the invention The aim of the present invention is to provide a structural component for a self-supporting floor, which is capable of eliminating the above mentioned drawbacks.

Within this aim, an object of the invention is to provide a floor structure that is pre-finished, self-supporting, lightweight and easy to transport and assemble.

Another object of the invention is to provide structural components that constitute unidirectional or bidirectional parts of horizontal structures, acting also as continuous or partition elements, and optionally usable in a seismic area without the need for a load distribution slab made of reinforced concrete.

Another object of the invention is to provide a floor structure that is able to support the load of its own weight, the sealing castings, the finishing elements provided on-site, the design overloads and the optional reinforced structural concrete flooring, when prescribed for distributing concentrated loads.

Another object of the invention is to allow to accommodate, inside the floor structures, channels for technology networks.

This aim and these and other objects that will become better apparent hereinafter are achieved by a self-supporting structural component, characterized in that it comprises an elongated self-supporting shell-like element made of cement mortar reinforced with glass fibers, provided with a base and two longitudinal sides which have an edge that is substantially parallel to said base, said shell-like element comprising a connecting reinforcement frame.

Advantageously, said structural component has a closure element for said shell-like element made of cement mortar reinforced with glass fibers, adapted to rest on said edge of said shell-like element and be fixed thereto by way of said connecting reinforcement frame.

Conveniently, the present invention relates to a floor structure, characterized in that it comprises a plurality of elongated shell-like elements arranged side by side and/or end to end.

Advantageously, the structure comprises a closure element adapted to rest on said edge of said shell-like element and to be fixed thereto by means of said connecting reinforcement frame, in order to obtain a self-supporting final structure.

According to a second aspect, the present invention provides a method for obtaining floor structures, comprising the steps of: -- producing, by means of a mold or by using a form as a supporting base, an elongated shell-like element made of cement mortar reinforced with glass fibers and with a connecting reinforcement frame, said elongated shell-like element having a base and two longitudinal sides which have an edge that is substantially parallel to said base; -- arranging side by side and/or end to end a plurality of shell-like elements until a length equal to the span of the floor is reached.

Advantageously, said method comprises the steps of: -- connecting each edge of said plurality of shell-like elements to a closure element made of cement mortar reinforced with glass fibers, which is adapted to rest on each edge of said plurality of box-like elements and be fixed thereto by means of said connecting reinforcement frame; and -- performing joining castings between shoulders of said side-by-side elements and/or heads of said end-to-end elements, in order to obtain a structural element that is adapted to provide a horizontal structure or floor with an underside and/or top face that is flat and/or ribbed or divided into compartments.

Brief description of the drawings Further characteristics and advantages of the present invention will become better apparent from the following detailed description of some currently preferred examples of embodiment thereof, given merely by way

of non-limitative example with reference to the accompanying drawings, wherein: Figure 1 is a perspective view of a floor structure according to the invention, rested at its ends on steel beams; Figure 2 is a perspective view of a shell-like element or profiled element made of GRC; Figure 3 is a perspective view of an elongated box-shaped shell-like element made of GRC ; Figure 4 is a sectional view of a floor structure, taken along the line IV- IV of Figure 1; Figure 5 is a sectional view of a floor structure, taken along the line V-V of Figure 1; Figure 6 is an enlarged-scale sectional view of a type of resting contact between a floor structure and a steel beam; Figure 7 is a sectional view, similar to Figure 6, of a resting contact between a floor structure and the lower wing of a steel beam ; Figure 8 is a perspective view of a floor structure made of GRC and rested on an underlying steel beam; Figure 9 is a sectional view of a floor structure rested on an underlying concrete beam; Figure 10 is a perspective view of a finishing element made of GRC for underlying steel beams; Figure 11 is a view of a floor structure with stiffening ribs at the top face; and Figure 12 is a perspective view of a structure of elongated shell-like profiled elements rested on a steel beam.

Ways of carrying out the Invention An aspect of the present invention entails, for the execution of structural components and generally of floor structures, a method as described hereinafter.

EXAMPLE 1 A form was taken and, by way of a technology known as spray casting, GRC was used to produce an elongated shell-like element, in this case a box- like element 2, which has a base 2a, two longitudinal sides 2b, and two end closure walls 2c; the longitudinal sides and the closure walls have an edge 6 that is substantially parallel to the base 2a.

In spray-casting technology, mortar, constituted by cement, sand, water and additives, is prepared in mixers and pumped to a gun which at the same time sprays said mortar as well as glass fiber of a preset length (which, in the example being considered, is between 15 and 40 mm).

The connecting reinforcement frame used was a distributed reinforcement 5, in this case a stainless steel net, which protruded from the edge 6 of the box-like element.

After obtaining the structural component, a filler material, polystyrene in the particular case, was inserted therein in order to produce, again by using spray-casting technology followed by a roll forming process, the closure element 7, using a stainless steel net as distributed reinforcement also for said closure element.

EXAMPLE 2 The structural component 2 was produced by proceeding as in example 1, replacing the stainless steel net with an alkali-resistant glass fiber net larger than the surface of the form, so that the structural component had, once produced, a portion of glass fiber net that protruded from the edge 6.

During the production of the base 2a, a longitudinal stiffening ridge 21 parallel to the longitudinal sides was produced in order to ensure greater rigidity of the component and accordingly of the structure.

A non-prestressed steel bar was inserted in this stiffening ridge.

Furthermore, plastic tubes were inserted parallel to the base and to the longitudinal sides in order to allow, after completion of the component, the passage of technology networks, such as for example the electrical system,

inside said tubes.

The closure element was produced by spreading the mix with the so- called premix technology; in the premix technology, the glass fiber (with a length variable between 10 and 40 mm) is embedded already during the preparation of the mortar and is sprayed or spread only after said embedding and after mixing.

In the particular case, the mixture was spread onto a flat form and packed by vibration.

A glass fiber net was inserted in said closure element, and the edge 6 of the structural component obtained with the spray method was rested on said element.

The distributed reinforcement that protruded from the structural component was embedded in the closure element, thus ensuring adequate mutual fixing of the two elements.

In this case, filling material between the shell-like element and the closure element was not used, since the shell-like element was already in the solid state.

EXAMPLE 3 The premix method was used to produce six box-like elements made of GRC and provided with a distributed reinforcement constituted by a net of carbon fibers; said elements were left to harden within the formwork.

During the production of these elements, plastic tubes, arranged substantially parallel to the end closure walls, for the passage of the technology networks, as well as removable plastic elements, were positioned at the bases in order to allow access, after laying the floor, from the underside or the top face, to the inside of said box-like elements.

By using the spray-casting method, a closure element 7 was produced, and the edges 6 of the six box-like elements, arranged along two rows of three elements each in order to obtain a floor structure whose length is equal to the span of the floor, were fixed onto the closure element.

Then the ends of the floor structure were rested on two steel beams 4, after producing longitudinal and transverse joining castings at the side-by- side and end-to-end mating regions.

The transverse castings were reinforced with normal steel bars, while the longitudinal joining castings were reinforced with prestressed steel cables.

Finally, a self-supporting floor was obtained whose weight was equal to 0.95 kN/m2.

An aspect of the present invention relates, with reference to the above cited figures, to a self-supporting floor structure, generally designated by the reference numeral 1, constituted by a plurality of elongated shell-like elements, arranged side by side or end to end and connected to a closure element 7, said floor structure being adapted to be supported by a structure constituted for example by steel beams 4 or reinforced concrete beams.

Said-like shell element 2 can be a profiled element 3, for example a U- shaped profiled element as shown in Figure 2, or, as shown more clearly in Figure 3, can be constituted by a box-like element 2 that has a base 2a, two longitudinal sides or shoulders 2b and two end closure walls 2c.

The elongated shell-like element is constituted by GRC (Glass Reinforced Concrete), a composite material with a cement matrix, with the addition of alkali-resistant glass fibers.

By way of the premix method, the GRC can be equally spread, cast or injected between a form and a complementary form.

In particular, a typical composition for this material is given in the following table: Cement Ordinary Portland White cement 52.5 R Aggregates Silica sand with a diameter of 0.6-0.7 mm Fibers Alkali-resistant glass fibers (3-5%) Length : 12-40 mm Water Potable A/C Ratio = 0.35-0.38) AdditivesSuperplasticizers Polymers Acrylic resins

Said element 2 furthermore has a connecting reinforcement frame, particularly, as shown in the figures, a distributed reinforcement 5 which protrudes from an edge 6 that is substantially parallel to the base 2a.

The distributed reinforcement 5 can be constituted by a net made of normal, galvanized or stainless steel, glass fibers or carbon fibers.

The shell-like element is meant to be mated, at its edge 6, with a closure element 7, also constituted by a composite material having a cement matrix, reinforced with glass fibers, in order to obtain a structural component.

Advantageously, the closure element 7 also has a distributed reinforcement, for example a glass fiber net, and during the mating between the element 2 and the closure element 7, the distributed reinforcement 5 that protrudes from the edge of said element 2 is"embedded"in the closure element when it is still in the liquid or semiliquid phase.

Conveniently, the shell-like element, both in the case of a box-like element and in the case of a profiled element, has longitudinal and/or transverse stiffening ridges 8 that protrude from the base 2a of the shell-like element 2.

Inside said stiffening ridges, in particular, it is possible to insert steel reinforcement cables.

By arranging side by side and end to end a plurality of box-like elements 2, one obtains a floor structure whose length is equal to the span of the floor and whose width is modular.

As in the case of the production of a structural component, each edge 6 of the plurality of side-by-side and end-to-end elements is coupled to a single closure element 7, embedding the distributed reinforcement 5 inside said closure element.

At the side-by-side and end-to-end mating regions of the box-like

elements, the structure has longitudinal and transverse joining castings, designated by the reference numerals 9 and 10 respectively, made of conventional concrete or GRC.

Said joining castings can of course be reinforced with concrete, structural or wild steel reinforcements 11.

Advantageously, the longitudinal joining castings 9 can also have additional reinforcements made of prestressed steel 12.

During use, the inside of the box-like element can be empty or can have a filling material, which acts as a lightening and/or soundproofing and/or thermal element, such as for example a foam, polystyrene, rock wool, or other materials.

In particular, as regards the box-like elements and the profiled elements, it is possible to provide, during in-factory production, a plurality of interconnected cavities orientated in various directions in order to allow to accommodate in the floor, during on-site assembly, the channels for technology networks such as for example electrical, electronic and telecommunications networks but also hydraulic channels and optionally channels for providing the air circulation required for conditioning of the enclosed spaces of the building.

Figure 8 illustrates a constructive detail of a resting contact between a floor structure and a lower steel beam 4: in this solution, said resting occurs at the upper surface of the beam.

Advantageously, in this type of embodiment, at the steel beam and at the underside there is a protection with a separate box-like element 14, also made of GRC, as shown more clearly in the perspective view of Figure 10.

Figure 7 illustrates a resting contact between a floor structure and a steel beam 4 in the case in which one wishes to provide resting contact on the lower wing 4a of the beam.

Conveniently, the floor structure can have one or more metallic connections 15, which protrude from the shell-like elements made of GRC,

for fixing the GRC finishing element to the underside of the beams.

Figure 11 illustrates a particular type of floor structure, in which the top face has transverse stiffening ridges 22 and longitudinal stiffening ridges 21 made of GRC.

The cross-section of these stiffening ridges can be equally triangular or rectangular and can optionally have rounded corners.

The function of said stiffening ridges is indeed to stiffen and reinforce the slab at the top face with respect to actions and stresses that act at the top face (vertical loads and punch-through loads) and to internal compression stresses, with consequent pressure-related and flexural instability effects.

The dimensions of the stiffening ridges 21 and 22 and their mutual distance are of course selected in each instance according to the span, the overload of the floor, and the thickness of the structural components and of any joining castings.

In practice it has been found that the component and the structure according to the invention fully achieve the intended aim and objects, providing structural components and floor structures that are pre-finished, self-supporting, lightweight and easy to transport.

Furthermore, said structural components have an adequate durability by virtue of the use of alkali-resistant glass and optionally low-alkalinity cements.

In particular, it has been found that the weight of the GRC floor structures according to the invention is between 0.60 and 1.30 kN/m 2.

Another advantage of the invention is to provide a method for manufacturing and laying a self-supporting horizontal structure that is reliable and has low manufacturing and labor costs.

The structural component and the floor structure according to the invention described above are susceptible of numerous modifications and variations within the scope of the protection defined by the content of the appended claims.

The materials and the dimensions may be various according to requirements.

The disclosures in Italian Patent Application No. VR2001A000024 from which this application claims priority are incorporated herein by reference.