WO2022185154A1

WO2022185154A1 - System and method for improving the anti-seismic and energetic performances of existing buildings with a frame structure of reinforced concrete

Info

Publication number: WO2022185154A1
Application number: PCT/IB2022/051621
Authority: WO
Inventors: Alessandro BORNETO; Alberto BORNETO; Stefano FOGLIETTA; Andrea BORNETO
Original assignee: Antisismicam Società A Responsabilità Limitata
Priority date: 2021-03-03
Filing date: 2022-02-24
Publication date: 2022-09-09
Also published as: EP4301949A1; CN116981820A; IT202100004928A1

Abstract

A system is described for improving the anti-seismic and energetic performances of an existing building having a frame structure (10) made of reinforced concrete with a plurality of perimetral columns (12) and a plurality of perimetral beams (14) intersecting each other in perimetral node regions (16), the system comprising: a reinforcing structure (24, 26) having steel reinforcing plates (24) arranged to be secured onto the outer face of the perimetral node zones (16), and reinforcing elements (26) made as steel truss beam elements, arranged to be secured onto the outer face of the perimetral columns (12) and the perimetral beams (14); and an outer insulation and finishing system having a supporting frame (52, 54), carried by the reinforcing structure (24, 26) and formed by a plurality of vertical posts (52) and a plurality of horizontal profiles (54), and a plurality of insulating panels (22) mounted on the supporting frame.

Description

SYSTEM AND METHOD FOR IMPROVING THE ANTI-SEISMIC AND ENERGETIC PERFORMANCES OF EXISTING BUILDINGS WITH A FRAME STRUCTURE OF REINFORCED CONCRETE

Technical field of the invention

The present invention relates generally to the field of "retrofitting" of existing buildings, i.e. buildings that are not new. More specifically, the present invention relates to a method aimed at combining the reduction of seismic risk with the improvement of energetic performances of existing buildings.

In particular, the invention is addressed to buildings with a frame structure of reinforced concrete, designed without considering anti-seismic criteria or on the basis of anti- seismic regulations less strict than the current ones, and built before the recent regulations on the containment of energy consumption in buildings.

State of the art

The type of building to which the present invention is mainly, though not exclusively, directed is that of residential buildings with a frame structure of reinforced concrete.

This type of building is generally characterized both by vulnerability to seismic action and by a lack of energy containment requirements for the outer shell. This type of building is therefore a building stock which needs general upgrading in terms of seismic protection and energy, both to improve safety and to reduce maintenance costs.

Many old reinforced concrete buildings, designed as framed structures for bearing vertical loads only, and therefore without considering anti-seismic criteria, have a recurring series of vulnerabilities to the effects of horizontal forces of the earthquake. Among other things, these buildings are often characterized by planimetric schemes with evident eccentricities which determine, in case of an earthquake, a torsional-type behaviour of the building and consequent considerable increase in stresses, especially on the structural elements on the perimeter of the building.

In general, the nodes of the frame structure (i.e. the areas of intersection between columns and beams of the frame) are vulnerable because, due to previous design rules, they were not provided with brackets and are therefore subject to brittle crises due to shear stresses in case of an earthquake. This vulnerability is particularly evident, as well as particularly critical, for the perimetral nodes (i.e. the nodes placed on the perimeter of the building structure), since on the one hand they cannot benefit on the outer side of the confinement effect offered by the beams and on the other hand they are subject to greater loads due to the torsional behaviour of the building. In addition, perimetral nodes are often the most degraded ones due to exposure to weather agents.

In order of vulnerability, after the nodes, in particular the perimeter ones, come the columns, since the shear effects induced by the earthquake on the ends of the columns are often not adequately counteracted by the brackets, which are generally thin or at least very thinned out (at least compared to the standards of a proper anti-seismic design). Also in this case the perimetral elements are among the most vulnerable ones for the same reasons as above.

Next, in order of vulnerability, are the beams, whose ends have similar vulnerabilities to the shear stresses produced by the earthquake as the columns.

Since these crises result in brittle failure of the elements, their consequences adversely affect the functionality of the frame structure, leading to collapse. This prevents the elements of the frame structure from developing ductile damage mechanisms which would help to damp the seismic actions (the so-called plastic hinges at the ends of the beams).

There is therefore a need to provide reinforcements on the aforementioned vulnerable elements of the frame structure of a building in order to exclude brittle failure due to shear stresses at the nodes and/or at the ends of beams and columns, thus leading to a significant improvement in the behaviour of the building with respect to seismic actions. However, the solutions currently envisaged to increase the resistance of these old structural types to the shear stresses typical of seismic events are penalised by the fact that they involve invasive activities inside the buildings, which are often inhabited or in operation, and/or by the fact that they are particularly costly.

Well-known examples of solutions for increasing the seismic resistance of a building are the reinforcement of the structure of the building by means of cortical coatings in high- resistance structural mortars with the integration of frames ("jacketing") or by using composite materials (commonly known by the acronym FRP, from the English "Fiber Reinforced Polymers") consisting of tapes or fibre fabrics solidified with epoxy resins. However, both these solutions, even though they operate on the perimeter of the building, often lead to invasive operations because they also involve the interior spaces. In the first case, there are costly operations for preparing the reinforced concrete surface, laying supplementary irons, setting up formworks and casting mortar, as well as waiting times for curing before removing the formworks. Moreover, the operational commitment of the construction site where mortar mixing and the preparation of strictly tailored formwork are carried out is also to be taken into account.

Even in the second case, which requires specialised labour, customised work is required depending on the elements to be reinforced. In addition, such work is invasive to the interior spaces of the building and involves problems connected with the use of resins with toxic components as well as limitations in terms of durability and temperature of use. The use of more technologically advanced materials to reinforce the critical elements of the building structure, such as fibres immersed in an inorganic matrix (commonly known by the acronym FRCM, from the English "Fiber Reinforced Cementitious Matrix") or high- strength fibre-reinforced mortars (commonly known by the acronym HPFRC, from the English "High Performance Fiber Reinforced Concrete"), while improving some critical aspects of the aforementioned known solutions, has not eliminated the costly and invasive work required to increase the anti-seismic resistance of old buildings either.

On the other hand, as far as the reduction in the energy consumption is concerned, older buildings are built with criteria and materials that are far from those currently required, in terms of thermal transmittance, for example. In particular, the outer shell of buildings with a frame structure of reinforced concrete is made up of infill walls which, depending on the decade in which they were built, may be solid masonry (made of stones and/or bricks) or a double wall with a cavity. Initially, the wall cavity was left empty (and therefore the thermal insulation relied only on air), while in the decades following the 70s and '80s, thermal insulation such as vermiculite or fibrous materials began to be inserted into the cavity. In any case, various problems remain, which are connected with the numerous thermal bridges that characterize this type of building, both due to the presence of elements of the reinforced concrete structure in the wall, or in any case almost surfacing the cladding, when not deliberately left exposed to give the building an aesthetic connotation, and due to the presence of projecting structural elements such as balconies, cornices, and lower floors of bay windows. These types of shell, even if equipped with the thermal insulation used at the time, do not reach levels of energy containment comparable to the performance required today. There is therefore considerable economic and environmental interest in implementing measures to improve the energetic performance of these buildings.

At present, the methods of intervention on the outer shell of a building consist essentially in the application of outer layers (the so-called "sheathing") and/or the insertion of insulating materials into the wall cavities (if any). The insertion of insulating materials into the wall cavity, besides requiring the presence of the cavities and a minimum width to be carried out with the so-called "blowing" technique, does not solve the issue of thermal bridges and its effectiveness is also limited by the thickness of the insulating material that can be obtained (equal to the width of the cavity space). In addition, there is often a local worsening of thermal bridges due to the increase in the temperature differential between the infill walls and the structures, which results in the formation of real condensation stains in the region of beams and columns, even more so when the blowing process is accompanied by other energy efficiency measures such as the replacement of the original windows with new insulated ones. Sheathing (which does not, however, exclude the simultaneous blowing of insulating material into the cavities) is therefore generally the most applicable and effective approach, since it is possible to vary the type of material used and the thickness of the sheathing to achieve the desired energy efficiency objectives. Cladding can also generally solve thermal bridges due to outcropping structures. In addition, this solution, if carried out only on the outer side of the building, does not take away any useful space inside the building and does not cause any inconvenience due to internal work.

Summary of the invention

It is an object of the present invention to provide a system and a method for improving the anti-seismic and energetic performances of existing buildings having a frame structure of reinforced concrete by means of less burdensome and invasive interventions than the prior art.

This object is fully achieved, according to a first aspect of the present invention, by a system having the features defined in the appended independent claim 1 , and, according to a further aspect of the present invention, by a method as defined in the appended independent claim 9.

Further advantageous aspects of the system according to the invention and advantageous modes for carrying out the method according to the invention are defined in the dependent claims, whose subject-matter is to be intended as forming an integral part of the present description.

In summary, the invention is based on the idea of applying to the perimetral frame structure of the building, made of reinforced concrete, a reinforcing structure comprising a metal carpentry truss, for the purpose of anti-seismic protection of the building, and an outer insulation and finishing system integrated with the reinforcing structure, for the purpose of reducing the energy consumption of the building, so as to require exclusively an intervention from outside the building.

The reinforcing structure basically comprises reinforcing elements of the following two types:

- a first type of reinforcing elements formed by steel plates, intended to be applied on the outer face of the node regions of the existing structure of the building; and

- a second type of reinforcing elements formed by steel truss beam elements, intended to be applied to the outer face of the beams and/or columns of the existing structure of the building.

The use of such reinforcing elements makes it possible to reinforce different building structures with a limited set of standardised pieces that can be manufactured industrially with low production costs and high quality standards and that can be suitably combined to form a modular reinforcing system adapted each time to the specific application, with a reduction in construction time and better guarantees of correct execution of the intervention.

These reinforcing elements are applied to the existing reinforced concrete structure of the building, on the outer face of a node region, of a beam or of a column depending on the type of reinforcing element, by means of chemical or mechanical anchor-type fixing members, i.e. by inserting a steel bar into a respective hole made in the concrete volume and subsequent securing of the steel bar inside the hole with chemical resins and/or mechanical expansion devices.

The use of chemical or mechanical anchor-type fixing members for the application of the reinforcing elements to the existing structure of reinforced concrete of the building allows for an installation that does not require specialised labour, can be carried out quickly, and does not require preparatory work on the surfaces of the structure or mixing or blending on site, thereby being cleaner and reducing the production of waste. Preferably, the plates forming the aforementioned first type of reinforcing elements (hereinafter referred to as reinforcing plates) have holes suitably distributed on the surface of the plate, for example according to an arrangement symmetrical with respect to at least one axis, preferably according to an arrangement symmetrical with respect to a pair of orthogonal axes, so as to ensure adequate fixing of the plate to the respective node region of the reinforced concrete structure.

Preferably, the truss beam elements forming the aforementioned second type of reinforcing elements comprise a first longitudinal element, extending along a substantially straight direction, a second longitudinal element, extending along a substantially straight direction parallel to the first longitudinal element, and a pair of shaped bars which extend along a substantially sinusoidal, or generally wave-shaped, path, offset relative from one another, and are each connected to both the first longitudinal element and the second longitudinal element at respective opposite peak points.

The truss beam elements forming the aforementioned second type of reinforcing elements may further comprise, on at least one of their opposite longitudinal ends, an end plate having holes for allowing connection of said elements to the reinforced concrete structure by means of anchor-type fixing members. Preferably, these holes are arranged with a spacing corresponding to that of the holes of the reinforcing plates, so as to allow the end plates of the truss beam elements to be attached to the reinforced concrete structure by means of anchor-type fixing members at the reinforcing plates, so as to create a continuous reinforcing structure extending horizontally from a node region along one or both the beams joining at that node region and/or vertically along the columns joining at that node region.

In addition, in the node regions of the reinforced concrete structure to be strengthened, steel connection elements may be provided to which the opposite ends of bracing elements may be connected. In particular, the connection elements may be connected to the node regions at the aforementioned reinforcing plates, preferably using part of the same anchor-type fixing members used for connection of the respective reinforcing plates to the reinforced concrete structure, in such a way as to be oriented at a certain angle both relative to the beams and relative to the columns joining in said node region, therefore both to the horizontal and to the vertical.

Preferably, dissipation devices, of per-se-known type, may be associated with the bracing elements and are positioned preferably aligned with these elements. In this way, a damping function of the earthquake by means of energy dissipation is added to the reinforcing function of the reinforcing structure.

Thanks to the application of an outer insulation and finishing system, the improvement of the anti-seismic resistance of the building is combined with an improvement in the energetic performance of the same building.

For this purpose, support elements for the support of the insulation panels are connected to the reinforcing elements of the reinforcing structure. More particularly, a plurality of vertical struts carrying in turn a plurality of horizontal profiles acting as supporting elements for support of the insulation panels are connected to the steel truss beam elements applied onto the outer face of the beams of the existing structure of the building, preferably by means of the same anchor-type fixing members used for mounting the steel truss beam elements on the outer face of the beams of the existing structure of the building.

The aforementioned vertical struts and horizontal profiles thus form a supporting frame for the sheathing which can be easily adapted to the geometry of the building fagades, in particular to take account of the presence of openings such as windows. This supporting frame can be easily dismantled, in whole or in part, if access to the building structure is required, for example to check the state of the building structure following a major earthquake.

The vertical struts and the horizontal profiles are advantageously made of non- degradable materials such as aluminium, PVC, etc.

Depending on the condition of the surfaces of the building fagades, the outer insulation and finishing system and the associated supporting frame may be installed either close to the fagade or at a distance from the fagade, e.g. a few centimetres, in order to compensate for any unevenness of the surfaces or to create an air space between the fagade and the insulation layer (i.e. a so-called "ventilated fagade").

The supporting frame for the insulating layer, and in particular the vertical struts of this frame, also acts as a means of preventing the outer infill walls of the building from tipping over, since in case of a seismic event it constrains any movement of the masonry, which would tend to tip outwards.

In this way, the reinforcing structure to be joined to the existing structure of the building and the outer insulation and finishing system, with the associated supporting frame, are integrated to form a single retrofitting system applicable to the outer shell of existing buildings in order to improve their anti-seismic and energetic performances.

Brief description of the drawings

Further features and advantages of the present invention will become clearer from the following description, given purely by way of non-limiting example with reference to the appended drawings, wherein:

- Figure 1 is a front view of a portion of the reinforcing structure and the supporting frame for an outer insulation and finishing system forming part of a system for improving the anti-seismic and energetic performances of a building with a frame structure of reinforced concrete;

- Figures 2 and 3 are a frontal view and a side view in section, respectively, of a perimetral node region of the frame structure of the building, on which a steel reinforcing plate is applied as part of the reinforcing structure of Figure 1 ;

- Figure 4 is a front view showing in detail a steel truss beam element forming part of the reinforcing structure of Figure 1 ;

- Figure 5 is a front view of a node region to which connection elements for connection of bracing elements are applied, in addition to the reinforcing elements shown in Figure 1 ;

- Figure 6 is a front view showing a beam portion of the building of Figure 1 between two columns, to which the reinforcing elements of Figure 1 are applied;

- Figures 7 and 8 are a front view and a side view in section, respectively, showing in detail the connection between a steel truss beam element forming part of the reinforcing structure of Figure 1 and the ends of two vertical struts forming part of the supporting frame for the outer insulation and finishing system of Figure 1 ;

- Figures 9, 10 and 11 are a front view, a side view and a plan view, respectively, of the connection area between a vertical strut and a pair of horizontal profiles of the supporting frame of Figure 1 ; and

- Figures 12 and 13 are schematic side views showing in sequence the mounting of the insulating panels on the supporting frame of Figure 1.

Detailed description

Figure 1 shows a portion of the perimeter of a frame structure 10 made of reinforced concrete of an existing building to which a system for improving the anti-seismic and energetic performances according to an embodiment of the present invention is applied. For the purposes of the present invention, what is relevant is only the perimetral portion of the entire frame structure of the building, and therefore the term "frame structure" hereinafter used is to be understood as referring to the perimetral portion of the entire frame structure, comprising, in a per-se-known manner, a plurality of perimetral columns 12 and perimetral beams 14 which intersect each other in perimetral node regions 16. On the inner side of the frame structure 10 there is generally present (as partially shown in Figure 3) a floor 18, which is outerly connected to the perimetral beams 14 and is internally supported by internal beams 20 (only one of which is shown in Figure 3). The system for improving the anti-seismic and energetic performance of the building according to the present invention basically comprises a reinforcing structure applied to the outer faces of the frame structure 10, i.e. to the outer faces of the perimetral columns 12, of the perimetral beams 14 and of the perimetral node regions 16, to increase the anti-seismic resistance of the building, and an outer insulation and finishing system comprising a plurality of insulating panels 22 (shown in Figures 12 and 13) supported by a supporting frame attached to the aforementioned reinforcing structure.

The reinforcing structure basically comprises steel reinforcing plates 24, applied onto the outer face of the perimetral node regions 16, and reinforcing elements 26 made as steel truss beam elements, applied onto the outer face of the perimetral beams 14 and, preferably (as in the example of Figure 1 ), also of the perimetral columns 12.

With reference to Figures 2 and 3, each reinforcing plate 24 is fixed to the outer face of the respective perimetral node region 16 by means of fixing members 28 which are preferably formed as chemical or mechanical anchor-type fixing members. An example of a fixing member 28 is shown in Figure 8 (where it is used for fixing a truss beam element 26 to a perimetral beam 14) and comprises, in a per-se-known manner, a steel bar 30 intended to be inserted into a respective hole 32 made in the concrete volume and subsequently secured within the hole 32 with chemical resins and/or mechanical expansion devices (not shown).

The reinforcing plates 24 are preferably of rectangular shape. Furthermore, in the example of Figures 1 and 2 the reinforcing plates 24 are mounted with their long side oriented vertically and preferably having a length greater than the thickness of the perimetral beams 14. Alternatively, the reinforcing plates 24 might be, in whole or in part, mounted with their long side oriented horizontally and preferably having a length greater than the width of the perimetral columns 12. The reinforcing plates 24 might also have a cross-like shape or a T-like shape, so as to be applied not only onto part of the two perimetral columns 12, but also onto part of one or both of the perimetral beams 14 joining into the perimetral node region 16, so as to be applied not only onto part of the perimetral beams 14, but also onto part of one or both of the perimetral columns 12.

In order to allow the insertion of the fixing members 28, the reinforcing plates 24 each have a plurality of holes suitably distributed on the surface of the plate, preferably according to an arrangement symmetrical with respect to at least one axis, in particular an axis parallel to one of the two sides of the plate, more preferably according to an arrangement symmetrical with respect to a pair of orthogonal axes. As mentioned above, in addition to the reinforcing plates 24 the reinforcing structure comprises reinforcing elements 26 made as truss beam elements (hereinafter referred to, for convenience, simply as "reinforcing elements 26"), which in the example of Figure 1 are applied onto the outer face of both the perimetral columns 12 and the perimetral beams 14 and are connected to the reinforcing plates 24 in the perimetral node regions 16.

With reference to Figure 4, each reinforcing element 26 comprises a first end plate 34 having holes 34a, a first longitudinal element 36 (upper longitudinal element, according to the orientation of the reinforcing element 26 in Figure 4) extending in a substantially straight direction (horizontal direction, with respect to the viewpoint of a person looking at Figure 4), a second longitudinal element 38 (lower longitudinal element, according to the orientation of the reinforcing element 26 in Figure 4) extending in a substantially straight direction, parallel to the first longitudinal element 36, a pair of shaped bars 40 which extend along a substantially sinusoidal, or more generally wave-like, path, offset relative to one another, and are each connected to both the first longitudinal element 36 and the second longitudinal element 38 at respective opposite peak points, and a second end plate 42 having holes 42a.

The holes 34a in the first end plate 34 and the holes 42a in the second end plate 42 allow connection of the reinforcing member 26 to the reinforced concrete structure by means of the same fixing members 28 used for connection of the reinforcing plates 24. Preferably, the holes 34a in the first end plate 34 are arranged with a mutual spacing corresponding to the spacing of the holes in the reinforcing plates 24, so as to allow the reinforcing elements 26 to be applied onto the reinforced concrete structure at the reinforcing plates 24 by means of the fixing members 28 of the first end plates 34, so as to create a continuous reinforcing structure which extends from a perimetral node region 16 horizontally along one or both of the perimetral beams 14 joining at said node region and/or vertically along the perimetral columns 12 joining at said perimetral node region. Preferably, the reinforcing element 26 further comprises a plurality of bushes 44 arranged in the joining regions between the first longitudinal element 36 and the shaped bars 40 and/or in the joining regions between the second longitudinal element 38 and the shaped bars 40 to allow the insertion of fixing members, for example of the same type as the fixing members 28 used for fixing the reinforcing plate 24 as well as for fixing the end plates 34 and 42 of the reinforcing element 26.

Figure 5 shows a perimetral node region 16 to which a reinforcing plate 24 is applied. To the reinforcing plate 24 are connected the end plates 34 of four reinforcing elements 26, two for the perimetral columns 12 joining into the perimetral node region 16 and two for the perimetral beams 14 joining into the perimetral node region 16. Furthermore, in the example of Figure 5 to the reinforcing plate 24 are applied, preferably using the holes provided in the plate and the same fixing members 28 used for fixing the plate to the underlying reinforced concrete structure, steel connecting elements 46 for connecting the opposite ends of bracing elements 48 (only partially shown in Figure 5, where they are depicted in dashed line). These connecting elements 46 are oriented by a certain angle (which in Figure 5 is an angle of about 45°, but which might be greater or less than 45° depending on the specific application) with respect to both the perimetral columns 12 and the perimetral beams 14, thus with respect to both the horizontal and the vertical direction.

Preferably, dissipation devices (not shown in the drawings, but in any case of a type known per se) may be associated with the bracing elements 48 and are preferably arranged in alignment with said elements. In this way, the reinforcing function performed by the reinforcing structure described above may also be accompanied by an earthquake damping function by energy dissipation.

Figure 6 shows in front view a portion of the reinforcing structure described above, applied to a perimetral beam 14 between two perimetral columns 12. In addition to the reinforcing plates 24 applied to both perimetral node regions 16 between which the perimetral beam 14 extends, there are two reinforcing elements 26 applied along the entire length of the perimetral beam 14. The end plates 42 of the reinforcing elements 26 are for this purpose juxtaposed to each other and connected to each other, as well as to the perimetral beam 14, by means of a connection plate 50.

Referring again to Figure 1 , the supporting frame for supporting the insulating panels 22 forming the outer insulation and finishing system comprises a plurality of vertical struts 52 and a plurality of horizontal profiles 54.

Each vertical strut 52 is fixed at its upper and lower ends to a respective reinforcing element 26, advantageously by means of the same fixing member 28 with which the reinforcing element 26 is fixed, in the region of the bushes 44, to the respective perimetral beam 14 (Figures 7 and 8). As can be observed in Figure 11 , each vertical strut 52 preferably has a U-shaped cross-section and is mounted with its end wall 52a arranged parallel to the fagade of the building.

With reference to Figures 9 to 11 , each horizontal profile 54 is fixed at its opposite ends to respective vertical struts 52, for example by means of angle brackets 56 and bolts 58. Each horizontal profile 54 preferably has a double T cross-section, with a pair of side walls 54a and a connecting wall 54b connecting the side walls 54a to each other, and is mounted such that the side walls 54a are oriented vertically and therefore the connecting wall is oriented horizontally.

The vertical struts 52 and the horizontal profiles 54 are advantageously made of non- degradable material, such as aluminium, PVC, etc.

The spacing between the vertical struts 52, as well as the spacing between the horizontal profiles 54, can be easily adapted to the geometry of the fagade of the building, in particular to take into account the presence of openings such as windows F, as shown for example in Figure 1 .

Finally, with reference to Figures 12 and 13, the outer side walls 54a of the horizontal profiles 54, i.e. the side walls 54a facing away from the building fagade, are inserted into special slits 60 provided on the upper and lower sides of the insulating panels 22, thereby binding the insulating panels 22 to the supporting frame and thus to the building. Figures 12 and 13 also show how the insulating panels 22 are installed by first mounting a row of panels on top of the previous one, then mounting a horizontal profile 54 so as to firmly bind the row of panels just mounted, and so on.

The insulating panels 12 and the supporting frame formed by the vertical struts 52 and the horizontal profiles 54 may be mounted adherent to the fagade, as in the example of Figures 12 and 13, or at a certain distance from the fagade, for example at a few centimetres, in order to compensate for any non-planarity of the surfaces or to create an air space between the fagade and the insulating layer.

The present invention has been described so far with reference to preferred embodiments thereof. It is to be understood that other embodiments sharing the same inventive core may be envisaged, all falling within the scope of protection of the following claims.

Claims

1. System for improving the anti-seismic and energetic performances of an existing building, having a frame structure (10) of reinforced concrete with a plurality of perimetral columns (12) and a plurality of perimetral beams (14) intersecting each other in perimetral node regions (16), the system comprising

- a reinforcing structure (24, 26) having steel reinforcing plates (24), arranged to be secured onto the outer face of said perimetral node regions (16), and reinforcing elements (26) made as steel truss beam elements, arranged to be secured onto the outer face of said perimetral columns (12) and of said perimetral beams (14), and

- an outer insulation and finishing system, having a supporting frame (52, 54), carried by said reinforcing structure (24, 26) and formed by a plurality of vertical struts (52) and a plurality of horizontal profiles (54), and a plurality of insulating panels (22) mounted on said supporting frame (52, 54).

2. System according to claim 1 , wherein each of said reinforcing plates (24) has holes

(24a) distributed all over its surface, preferably according to an arrangement symmetrical with respect to at least one axis, more preferably according to an arrangement symmetrical with respect to a pair of orthogonal axes, to allow insertion of anchor-type fixing members (28) for fixing the reinforcing plate (24) to a respective perimetral node region (16).

3. System according to claim 1 or claim 2, wherein said reinforcing plates (24) have a rectangular shape and/or a cross-like shape and/or a T-like shape.

4. System according to any one of the preceding claims, wherein each of said reinforcing elements (26) comprises a first longitudinal element (36) extending along a substantially straight direction, a second longitudinal element (38) extending along a substantially straight direction parallel to said first longitudinal element (36), and a pair of shaped bars (40) which extend along a wave-like path, in particular a substantially sinusoidal path, offset relative to one another, and are each connected both to said first longitudinal element (36) and to said second longitudinal element (38) at respective opposite peak points.

5. System according to claim 4, wherein each of said reinforcing elements (26) further comprises, on at least one of its opposite longitudinal ends, an end plate (34, 42) having holes (34a, 42a) for insertion of anchor-type fixing members (28) for fixing the end plate (34, 42) to one of said perimetral columns (12) or one of said perimetral beams (14).

6. System according to claim 4 or claim 5, wherein each of said reinforcing elements (26) further comprises a plurality of bush-like members (44) arranged in joining regions between said first longitudinal element (36) and said shaped bars (40) and/or in joining regions between said second longitudinal element (38) and said shaped bars (40) for insertion of anchor-type fixing members (28) for fixing the reinforcing element (26) to one of said perimetral columns (12) or one of said perimetral beams (14).

7. System according to any one of the preceding claims, wherein the vertical struts (52) of said supporting frame (52, 54) are connected to the reinforcing elements (26) of said reinforcing structure (24, 26) and wherein the horizontal profiles (54) of said supporting frame (52, 54) are connected to said vertical struts (52).

8. System according to any one of the preceding claims, wherein each of the horizontal profiles (54) of said supporting frame (52, 54) has a side vertical wall (54a) and wherein the insulating panels (22) have slits (60) on respective upper and lower sides thereof for insertion of said side vertical walls (54a) of the horizontal profiles (54).

9. Method for improving the anti-seismic and energetic performances of an existing building having a frame structure (10) of reinforced concrete with a plurality of perimetral columns (12) and a plurality of perimetral beams (14) intersecting each other in perimetral node regions (16), the method comprising the steps of: a) applying steel reinforcing plates (24) onto the outer faces of the perimetral node regions (16) of said frame structure (10) and applying reinforcing elements (26) made as steel truss beams onto the outer faces of the perimetral columns (12) and of the perimetral beams (14) of said frame structure (10), said reinforcing plates (24) and said reinforcing elements (26) forming a reinforcing structure (24, 26) arranged to increase the anti-seismic resistance of said frame structure (10), b) mounting on said reinforcing structure (24, 26) a supporting frame (52, 54) formed by a plurality of vertical struts (52) and a plurality of horizontal profiles (54), and c) mounting on said supporting frame (52, 54) a plurality of insulating panels (22) to form an outer insulation and finishing system.

10. Method according to claim 9, wherein the reinforcing plates (24) and the reinforcing elements (26) of said reinforcing structure (24, 26) are secured onto the outer faces of the perimetral node regions (16) of said frame structure (10) and onto the outer faces of the perimetral columns (12) and of the perimetral beams (14) of said frame structure (10), respectively, by means of chemical or mechanical anchor-type fixing members (28).

11. Method according to claim 10, wherein the vertical struts (52) of said supporting frame (52, 54) are connected to the reinforcing elements (26) of said reinforcing structure (24, 26) by means of the same anchor-type fixing members (28) used for fixing said reinforcing elements (26) to the perimetral beams (24) of said frame structure (10).

12. Method according to claim 10 or claim 11 , wherein the insulating panels (22) are mounted between pairs of vertically adjacent horizontal profiles (54) of said supporting frame (52, 54) and are connected to said horizontal profiles (54) by insertion of side vertical walls (54a) of said horizontal profiles (54) into slits (60) provided on upper and lower sides of the insulating panels (22).