EP2354355A1

EP2354355A1 - Load-bearing structure for the building industry having high thermal insulation

Info

Publication number: EP2354355A1
Application number: EP11153050A
Authority: EP
Inventors: Genesio Setten
Original assignee: Setten Genesio SpA
Current assignee: Setten Genesio SpA
Priority date: 2010-02-04
Filing date: 2011-02-02
Publication date: 2011-08-10
Anticipated expiration: 2031-02-02
Also published as: EP2354355B1; IT1398062B1; ITMI20100172A1

Abstract

A load-bearing structure for the building industry comprises at least three layers of conglomerate (1, 1') having a structural function, spaced apart by two layers of thermally-insulating material (2, 2'). A plurality of connections between said layers of conglomerate (1, 1', 1) is formed in correspondence of cavities (3, 3') provided in said layers of insulating material (2, 2'), the connections which engage with the opposite sides of a same layer of conglomerate (1') being mutually offset.

Description

FIELD OF THE INVENTION

The present invention refers to a load-bearing structure, such as a wall or a floor, having high thermal insulation, for the building industry. In particular, the invention refers to a structure of this type provided with very small thermal bridges compared to a conventional structure of the same thickness and material.

BACKGROUND OF THE PRIOR ART

It is well-known how in current manufacture of load-bearing structures for the building industry, and in particular of structures one side of which is exposed to the outside of the building, the insulation factor has become an essential design element. As a matter of fact, in order to curb energy consumption - both from the point of view of a reduction of the costs for the air-conditioning of buildings and of the reduction of the pollution caused by any energy consumption - various countries' legislation becomes increasingly stringent concerning the insulation features that building structures must have.
It is equally known that a key point in the accomplishment of the insulation of a building structure is the so-called "thermal bridge", i.e. those joint portions of building structures (intersections between pillars and floors, or between floors and perimeter walls), which connect the two opposite sides of the structure with no possibility of arranging a layer of insulating material in between.
For explanation clarity's sake, referring for example to the vertical bearing structures consisting of the perimeter walls of a building, it is well known that the adoption of a layer of insulating material inserted within the wall is not as effective as one might expect, if the insulating layer is necessarily interrupted where horizontal building structures (inner floors and outer shelves for coverings and balconies) cross the wall and are connected thereto to achieve the necessary resistance to mechanical stress. In such positions, devoid of insulation and hence with high thermal conductivity, a number of thermal bridges thus arises through which the heat flow between the warm side and the cold side of the wall concentrates, dramatically reducing the insulating effect of the layer of material inserted within the entire remaining part of wall.
More radical solutions to the problem have also been suggested, wherein the perimeter wall of the building consists of two fully independent elements between which a continuous layer (coating) of insulating material is arranged; the external wall element is structurally associated with the outer shelves, while the inner wall element is associated with the floors. In this case a building structure devoid of thermal bridges and hence characterised by a low coefficient of thermal conductivity is in fact obtained. However, since the two wall elements must be capable of independently supporting the loads weighing on them, the overall crosswise dimensions of the wall increase dramatically. The costs of a building structure of this type are hence such - also due to the fact that the two wall elements must of course be cast in subsequent times - as to make the adoption of this type of building on a general scale unviable.

PROBLEM AND SOLUTION

It is hence an object of the present invention to propose a load-bearing structure for the building industry which, at a similar cost to currently employed insulated structures, overcomes the drawbacks mentioned above and allows in particular to fully remove direct thermal bridges in junction areas between vertical and horizontal structures. This object is achieved by means of a load-bearing structure for the building industry having the features defined in claim 1. In the dependent claims additional preferred features of said structure are defined.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will in any case be more evident from the following detailed description of a preferred embodiment, given purely by way of a non-limiting example and illustrated in the attached drawings, wherein:

fig. 1 is a front view of the structure of the present invention, wherein the parts of conglomerate are not shown in order to highlight the configuration and the mutual position of the two sheets of insulating material incorporated in said structure;
fig. 2A is a cross-section view of the structure of the invention according to the line A-A of fig. 1;
fig. 2B is a cross-section view of the structure of the invention according to the line B-B of fig. 1;
fig. 3 is a perspective view of a portion of a unitary area of the two sheets of insulating material of fig. 1, which schematically shows the reinforcement grids in the crosswise connection areas of the structure of the invention; and
fig. 4 is a schematic, perspective view similar to fig. 3, which schematically also shows the reinforcement grids in the layers of conglomerate of the structure of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The structure of the present invention, as shown in fig. 2, consists of 5 alternated layers of conglomerate and of insulating material, respectively. The three layers of conglomerate 1, 1', 1 accomplish the load-bearing and covering functions of the structure, while the two layers of insulating material 2, 2' arranged between the same meet solely insulating requirements. As a conglomerate, concrete or any other conglomerate known in the building industry may be used, as long as the latter one is in a fluid condition and has load-bearing functions suited to the load the structure must bear after consolidation. As an insulating material, foamed synthetic materials, such as polystyrene, mineral fibres such as glass fibres, biologic materials such as wood and cork, or coupled versions of these materials may be used. However, the load-bearing structure of the invention is not limited in any way by the type of material used for forming the layers of conglomerate and the insulating layers. As a matter of fact, for the purpose of the invention, it is merely sufficient that the conglomerate, upon casting, has a fluidity sufficient for filling the gaps around the layers of insulating material, as will be better explained in the following, and that the layers of insulating material be in the form of rigid, planar sheets, which can be processed with cutting tools and are substantially impervious to the conglomerate used.
In order to reach the desired object it is necessary that the structure of the invention has the minimum number of layers indicated above and that the layers 1, 1', 1 of conglomerate and the layers 2, 2' of insulating material be mutually alternated; however, the same object of the invention can be reached by means of structures having a number of alternated layers in excess of 5.
The structure of the invention can be accomplished indifferently by means of in-site or out-of-site castings (hence following a prefabrication logic) and the finished structure may have thicknesses varying according to the load it is intended to bear and of the required insulation performance. However, the structure of the invention is preferably crosswise symmetrical, i.e. the thicknesses of insulating layers 2, 2' and of the outer layers of conglomerate 1 are mutually equal, respectively; as a matter of fact, an arrangement of this type allows greater regularity in casting operations.
According to an essential feature of the present invention, the layers of insulating material 2, 2' are not continuous, but have a series of through cavities 3, 3' cut out in the insulating material. Cavities 3, 3' are filled by the fluid conglomerate during casting operations, hence forming a plurality of point-by-point connections between the outer layers of conglomerate 1 and the inner layer of conglomerate 1'. As clearly illustrated in fig. 1, cavities 3 preferably have the same geometric arrangement on each of the layers 2 and 2' of insulating material, but are mutually offset between said layers, so that the cavities 3' of layer 2' are found in correspondence of an area devoid of cavities 3 of layer 2. In fig. 1 the arrangement of cavities 3 and 3' in layers 2 and 2' follows a regular square pattern, and hence each of cavities 3' is positioned in the middle of four cavities 3; however, it must be clear that this is only a schematic indication of a generic way of arrangement of cavities 3, which arrangement may vary according to the specific load-bearing requirements of the structure, both in the distribution geometry and in the density per surface unit, as well as in the shape of each individual cavity which, as an example, in addition to being square-section, may also be circular, elliptical, rectangular-section and many other section shapes.
The function of through cavities 3, 3' formed in layers 2, 2', as stated above, is to mutually connect the layers of conglomerate 1, 1', 1 guaranteeing a connection between the layers having a suitable resistance to shear stresses. Such connections considerably increase flexural rigidity, for stresses beyond the plane, of the structure, and improve the structural behaviour of the wall even in the presence of eccentric loads in respect of the average layer, allowing a redistribution of inner tensions and an evenness thereof in the wall thickness (hence also on non directly loaded layers). In order to achieve a more effective distribution of stresses, it is of course possible to arrange cavities 3, 3' with varying pitch (a, b, and a1, b1, respectively, in fig. 1) and density according to the structural requirements arising in the individual applications of the load-bearing structure of the invention.
For the construction of such structure, be it in-site cast or prefabricated, initially the two layers of insulating material 2, 2' are arranged, with metal reinforcement grids 5 arranged in between the central layer 1' and in the two side layers 1. The reinforcement grids found in the layers are mutually connected by means of through reinforcement grids 4, intended to transmit the shear stresses between one layer and the next, and to impart the necessary rigidity and stability to the system thus assembled. The shape and the arrangement of reinforcement grids 4 is preferably designed so that reinforcement grids 4 also make up elements of mutual positioning and spacing of layers 2, 2' and of reinforcement grids 5. The position and the shape of reinforcement grids 4 is clearly visible in figs. 3 and 4, wherein a portion of unitary area of layers 2, 2' is shown, where by the term "portion of unitary area", a portion corresponding to a quadrilateral having as vertexes the centre of four cavities 3' of layer 2' is intended.
The assembly thus formed is fastened to the floor, preferably using the bars of already arranged reinforcement grids and such as to impart the necessary structural continuity between one casting and the next. Preparation operations are completed with the application of outer formworks, positioned at a preset distance from layers 2 and 2' corresponding to the desired thickness of outer layers 1 of conglomerate, and it is hence ready for casting.
The conglomerate is cast within the formwork in correspondence of the central gap formed between the two layers 2 and 2', so firstly forming inner layer 1' of conglomerate, and then from here flowing through cavities 3, 3' to form the outer layers of conglomerate 1. Formwork filling exclusively through the central gap which will form central layer 1' is advantageous, due to the fact that the filling of outer layers 1 thus occurs in a symmetrical way and, consequently, the side load on layers 2, 2' of insulating material is always well balanced and no uncontrollable movements of the same arise in a crosswise direction during casting operations.
Through the above-described structure it is possible to fully achieve the object of the invention. As a matter of fact, assuming to use the structure of the invention as perimeter wall element, it is possible to create the connections with the horizontal structures without said structures affecting the entire length of the wall, as occurs in the known art, but only the portion thereof which is found on the side of the horizontal structure, i.e. the outer layer for supporting the outer horizontal structures of the building (shelves for coverings and balconies) and the inner layer for the support of the horizontal inner structures of the building (floors), thus fully avoiding the forming of direct thermal bridges between warm side and cold side of the above-said perimeter wall, while the loads transmitted by said horizontal structures are in any case gradually distributed also on the layers not directly loaded through the connection elements formed in cavities 3 and 3', between one layer and the next of conglomerate.
As a matter of fact, since the conglomerate connections formed in cavities 3, 3' are mutually offset in correspondence of the two insulating layers 2, 2', in order to cross the structure, the heat flow coming from one of outer layers 1 is forced to cross insulating layers 2 and 2' or to follow a zigzag path through the connections formed in cavities 3 and 3' along the central layer 1' of conglomerate, thus remarkably reducing the thermal conductivity coefficient of the wall.
The load-bearing structure of the invention furthermore offers the advantage of having already finished outer walls or alternatively outer walls which are ready to receive any type of finish.
As an example, the load-bearing structure has been illustrated with reference to the application thereof as perimeter wall, but it is clear that it can be advantageously used also for the forming of floors, whenever the two opposite surfaces of the structure are habitually found (floors under roofs or above cellars) or may be found (buildings with independent heating systems) at different temperatures. It can also be used in prefabrication as horizontal or vertical filling-in panel.
However, it is understood that the invention must not be considered limited to the particular arrangement illustrated above, which makes up only an exemplifying embodiment thereof, but that a number of variants are possible, all within the reach of a person skilled in the field, without departing from the scope of protection of the invention as defined by the following claims.

Claims

Load-bearing structure for the building industry of the type comprising layers of conglomerate (1) having a structural function, and layers of thermally insulating material (2), characterized in that it comprises at least three of said layers of conglomerate (1, 1', 1) alternated with two of said layers of thermally insulating material (2, 2'), as well as a plurality of connections of conglomerate between said layers of conglomerate, formed in respective cavities (3) provided in said layers of insulating material, and in that the connections which engage with opposite sides of a same layer of conglomerate (1') are in mutually offset positions.
Load-bearing structure as claimed in claim 1), wherein the connections of conglomerate which engage with opposite sides of a same layer of conglomerate (1') are offset so as to maximize the distance thereof.
Load-bearing structure as claimed in claim 2), further comprising metal reinforcement grids (4) incorporated in said conglomerate connections and metal reinforcement grids (5) incorporated in said layers of conglomerate.
Load-bearing structure as claimed in any one of the preceding claims, wherein said connections of conglomerate have a square, rectangular, circular, or elliptical section.
Casting mould for a load-bearing structure as claimed in any one of the preceding claims, comprising said layers of insulating material (2), said reinforcement grids (4) of the connections and said reinforcement grids (5) of the layers of conglomerate (1, 1', 1), all inserted between two outer formworks for casting containment, wherein said reinforcement grids (4) of the connections are members for the mutual positioning and spacing of the layers of thermally insulating material (2, 2').