Residential building structure, and method for dimensioning thereof

Abstract

A method for dimensioning structures for residential buildings comprises the steps of providing a metal framework, comprising a plurality of pillars (10) positioned vertically and parallel to each other, and determining the dimensions of at least one self-supporting panel (12), that is, determining a dimension thereof such that horizontally it substantially extends to cover the entire span (L) or distance between two pillars (10), and determining a thickness (SP) thereof as a function of the characteristic elastic modulus of the material of the panel (12).

Description

Technical field

[0001] The present invention generally relates to the field of residential building construction; in particular, the invention refers to a residential building structure, and to a method for dimensioning thereof.Prior art

[0002] In order to address the issues related to the high degree of craftsmanship required by a traditional approach in construction techniques, in the prior art it is provided to replace significant work steps from the identified construction site, in favour of a location designated for the production of structural elements, suitably industrialised.

[0003] These methods are referred to as "off-site", and generally employ materials whose use is also defined as "dry", in that they employ materials that substantially do not require water.

[0004] In known construction methods of the aforementioned type, the materials used to implement the structures with an "off-site" approach are mainly wood, steel, and concrete.

[0005] In particular, the technologies employing wood or steel, as described for example in documents IT AN 20 100 029 A1 and US 2012 / 137610 A1, mainly have the following features.

[0006] The former employ structural elements made of engineered wood, such as CLT (Cross-Laminated Timber), and Timber-Frame (commonly called frame structure). Both structural solutions provide a wide possibility for an "off-site" approach, and the structure is made with wooden elements that structurally function as load-bearing walls. It follows that they must have spans which, although varying based on the loads expected in relation to the settlement area, are around 4.5 / 5 m at most. Another common aspect is the insulation of the walls, which is placed on the outside of the infill walls, which also perform a structural function. In some cases, the insulation is placed both outside and inside the infill wall, thus creating stratigraphies designed to integrate with the installation steps on the job site.

[0007] Steel construction types instead provide for the insertion of heavy steel elements (point structure), arranged following a dedicated engineering process, and assisted by light steel frames which perform the function of infill. Sometimes they also play a structural role comparable to that of "load-bearing walls".

[0008] Wood, where used in such solutions, plays the simple role of supporting the various stratigraphy layers of the infill walls.

[0009] However, engineered stratigraphies are complex, and include a considerable number of alternating layers, which in turn make the product placed on the market difficult to adapt, while a lot of on-site labour is required.

[0010] In general, therefore, the prior art to date aims to size the panels, which have a load-bearing and structural function, according to a stress / deformation principle, determining the ultimate collapse stress of the panel or the connection.

[0011] This is valid as long as the panels indeed have a structural value, and one wishes to verify that the corresponding collapse resistances are not exceeded.Summary of the invention

[0012] One object of the present invention is to overcome the aforementioned limitations.

[0013] To achieve this result, a method for dimensioning structures for residential buildings, and a residential building structure according to the present invention, provide to arrange a metal framework having a structural function, and at least one self-supporting panel (conveniently non-structural, that is, not intended to perform a load-bearing function with respect to the vertical loads of the building), configured to extend substantially to cover the entire span or distance between two pillars, and having a thickness that is preferably a function of the characteristic elastic modulus of the panel material.

[0014] Differently from what is contemplated in the prior art, such dimensioning aims to avoid second-order effects, and not to define a collapse stress.

[0015] In fact, known methods use loads as input, to verify the resistance of the panel and determine its thickness. A panel according to the present invention, not being structural, is dimensioned according to geometric criteria.

[0016] In particular, the adoption of Young's modulus as a sizing parameter for such non-structural panels is not applicable to the known solutions, since the calculation bases on which the respective approaches are founded would substantially change (as they contemplate very different failure criteria between wood and concrete, for example).

[0017] A methodology according to the present invention is therefore distinguished from the prior art in that, since the panel does not have a structural function, it does not aim to define its collapse stress.

[0018] Preferably, the panel and the framework are mutually coupled in a labile manner, i.e., in such a way that the panel can move with respect to the pillar, accommodating for example expansions or deformations of the structure.

[0019] According to one embodiment of the present invention, it is provided to use a point steel structure, dimensioned in a modular and standardised manner, according to a structurally "hangar-like" approach. This is made possible by the fact that the structural module can be implemented with very wide spans (for example, 8 m). It is thus possible to obtain a heavy steel structure, hot-dip galvanised, which can be assembled in a few days on the intervention site.

[0020] The infill walls can instead be made at least in part of wood, in order to take maximum advantage of the ductility of this material, which also boasts excellent hygroscopic properties, is quick to install, and lends itself well to "off-site" prefabrication. The external infill of the perimeter walls can for example be made using CLT panels. This technical choice provides to use this material mainly to perform a function of resistance to horizontal thrust loads and not vertical loads, thereby substantially relieving the infill walls from any structural burden.

[0021] This allows for a product that is very quick to assemble on site, and also results in a wide possibility to customise the infill from the point of view of the insulating composition.

[0022] Such combined use of two structural technologies, which to date are instead employed exclusively, is particularly facilitated by the possible use of structural joining elements, which allow for the stable connection of the two materials, while enabling them to move independently, following the natural expansions that the two materials may undergo.

[0023] The result is a modular solution, suitable for broad-spectrum use in engineering architectural solutions of various kinds.

[0024] The structural modules thus obtained embrace architectural forms of greater complexity compared to solutions employing only steel or only wood, thanks to the greater spans (and the consequent internal architectural freedom in the partitions).

[0025] Thanks also to the fastening system, which may use sliding skids and slotted plates, it is possible to decouple the thermal expansion of the steel from that of the wood, thereby eliminating the stresses generated by the different coefficients of thermal expansion.

[0026] This makes it possible to achieve greater flexibility in the application of the insulating materials, without impairing the design and / or construction capacity.

[0027] Moreover, site times are reduced compared to the current ones, when only steel or only wood are used.

[0028] Among the advantages, one may include the simplification of the structural plan, which allows for greater architectural freedom in the geometries (in terms of external forms and internal subdivisions), and the fact that the insulating material may, for example, be inserted internally and not as external cladding, also allows unskilled personnel to perform the installation operations.

[0029] The operations may be performed "off-site", without the large investment currently required to implement production lines that then prove to be scarcely updatable.

[0030] The advantage of being able to use CLT-structured panels as infill walls, avoiding the external cladding and placing the insulating material inside the wall (within the thickness occupied by the steel structure), allows for the application of the same insulating material in a faster manner and with less skilled labour, while ensuring better performance in relation to thermal bridges and airtightness, with costs comparable to the cases wherein traditional structural technologies in wood or steel are used.

[0031] The system with labile fastenings, which makes it possible to structurally decouple the steel structure from the wooden one, finally allows for no limitation on the height of the building, net of the structural limits of the steel.

[0032] The above and other objects and advantages are achieved, according to one aspect of the invention, by a residential building structure, and a method for dimensioning thereof, having the characteristics defined in the appended claims. Preferred embodiments of the invention are defined in the dependent claims.Brief description of the drawings

[0033] The functional and structural characteristics of some preferred embodiments of a structure and a method according to the invention will now be described. Reference is made to the accompanying drawings, wherein: Figure 1 is a schematic view of a portion of a vertical wall, comprising part of a supporting framework and a plurality of self-supporting panels, coupled to each other and / or to the framework by means of coupling elements, according to an embodiment of the present invention; Figures 2 and 3 are two graphs showing the values of the thickness of the self-supporting panel (in cm) as a function of a dimension of the section of the pillars and of the span or distance between the pillars to which the panel is to be coupled, according to an embodiment of the present invention; Figures 4 and 5 are two tables reporting the values of the thickness of the self-supporting panel (in cm) as a function of the elastic modulus of the material and of the span or distance between the pillars to which the panel is to be coupled, according to an embodiment of the present invention; and Figures 6 to 8 are schematic views of coupling elements, according to respective embodiments of the present invention. Detailed description

[0034] Before explaining in detail a plurality of embodiments of the invention, it should be clarified that the invention is not limited in its application to the construction details and the configuration of the components presented in the following description or illustrated in the drawings. The invention is capable of assuming other embodiments and of being implemented or practically realised in different ways. It should also be understood that the phraseology and terminology are intended for descriptive purposes and are not to be regarded as limiting.

[0035] With exemplary reference to the figures, a method for dimensioning structures for residential buildings comprises the steps of providing a metal framework, comprising a plurality of pillars 10 positioned vertically and parallel to each other, said framework having a structural function and being adapted to support the vertical loads of the building, and determining the dimensions of at least one self-supporting panel 12, that is, determining a dimension of said panel 12 such that horizontally it substantially extends to cover the entire span L or distance between two pillars 10.

[0036] The panels 12 are self-supporting in the sense that, in addition to performing their own function (of infill, covering, partition, etc.), they also perform that of supporting themselves (and, preferably, also any additional load).

[0037] Preferably, the panels 12 are configured to perform mainly a function of resistance to horizontal thrust loads and not vertical ones, thereby substantially relieving the infill walls of any structural burden. The panels 12 are therefore preferably configured not to perform a structural or load-bearing function with respect to the vertical loads of the building, that is, they are not adapted to perform such a structural or load-bearing function.

[0038] The method preferably further comprises the step of determining a thickness SP of the panel 12 as a function of the characteristic elastic modulus of the material of the panel 12, or of the elastic modulus resulting from the average of the characteristic elastic moduli of the materials of which said panel 12 is composed.

[0039] Thus dimensioned, the self-supporting panel 12 may be arranged and coupled to a pair of pillars 10.

[0040] The framework may comprise, in addition to the vertical pillars 10, also horizontal beams 11 and / or reinforcements or bracings 13, for example in the form of wooden slats or battens, which connect several vertically adjacent panels 12, thereby stiffening them.

[0041] Preferably, the span L between the two pillars 10 wherein the self-supporting panel 12 is to be inserted is between 3000 mm and 12000 mm.

[0042] According to a preferred embodiment, the thickness SP of the self-supporting panel 12 is determined by the formula SP = a / (b - c ·ME), wherein parameter a is a function of the length of one side of the pillar 10, parameters b and c are two constants, and parameter ME is the characteristic elastic modulus of the material of the panel 12, or the elastic modulus resulting from the average of the characteristic elastic moduli of the materials of which said panel 12 is composed.

[0043] Preferably, parameter a corresponds to the length DP of the larger side of a section of the pillar 10. According to a preferred embodiment, parameter DP is equal to the ratio between the span L and an integer value CF between 15 and 50, hereinafter also referred to as "splitting coefficient". Parameter CF may be selected within the aforementioned range according to the structural dimensions foreseen or desired at the design stage, and is mainly relevant for defining the limits within which the thickness of the panel fully satisfies the dimensional conditions provided by the present invention, according to an embodiment thereof.

[0044] Preferably, b = 4 (more preferably, b = 4.079), c = 0.05 (more preferably, c = 0.0526), and ME is between 1 GPa and 70 GPa (more preferably, ME is between 10 GPa and 14 GPa).

[0045] Figures 2 and 3 show two graphs reporting the values of the thickness SP of the self-supporting panel as a function of a dimension DP of the section of the pillars and of the span or distance between the pillars to which the panel is to be coupled, obtained using the formula and parameters described above, adopting ME = 11.6 GPa. The values of SP are here expressed rounded up to the nearest integer.

[0046] The tables of Figures 4 and 5 instead report the values of the thickness SP of the self-supporting panel as a function of the elastic modulus ME of the material and of the span L between the pillars to which the panel is to be coupled, obtained using the formula and parameters described above, adopting respectively a parameter CF = 50 and CF = 15, according to an embodiment of the present invention. The values of SP are here expressed rounded up to the nearest integer.

[0047] Below is a table showing the ranges of values for DP (pillar dimension) and SP (panel thickness) as the span L varies, assuming the Elastic Modulus of laminated timber (11.6 GPa), according to an embodiment of the invention.

[0048] Such values were calculated assuming DP = L / CF (with CF between 15 and 50), and SP = DP / (4.079 - 0.0526xME). NE 11 600 STANDARD FRAME STANDARD PANEL LIGHT Pillar Dimension Range (interval including thickness in cm) Panel Thickness Range (interval including thickness in cm) 3 6 - 20 2 - 6 4 8 - 27 4 - 8 5 10 - 34 4 - 10 6 12 - 40 4 - 12 7 14 - 47 6 - 14 8 16 - 54 6 - 16 9 18 - 60 6 - 18 10 20 - 67 6 - 20 11 22 - 74 6 - 22 12 24 - 80 6 - 24

[0049] As an alternative or in combination with the embodiments described and illustrated above, there may be the step of placing between at least two pillars 10 of the metal framework at least one self-supporting panel 12, coupled in a labile manner to said pillars 10, in such a way as to substantially prevent the transmission of vertical loads from the pillars 10 to the panel 12.

[0050] According to a further aspect of the invention, a residential building structure comprises a metal framework, which includes a plurality of pillars 10 positioned vertically and parallel to each other, said framework having a structural function and being adapted to support the vertical loads of the building, and at least one self-supporting panel 12, positioned between at least two pillars 10 of the metal framework and dimensioned according to any of the embodiments described and illustrated above.

[0051] Preferably, the panel 12 is made at least in part of engineered wood, for example laminated timber or CLT (or XLam).

[0052] At least one coupling element 14, 16, 18 may be present, suitable for coupling the panel 12 to a respective pillar 10, said coupling element 14, 16, 18 being configured to be fixed to one between the panel 12 and the pillar 10, and to engage the other between the panel 12 and the pillar 10 in such a way that a degree of freedom is allowed between the latter and the coupling element 14, 16, 18 (preferably with respect to the vertical axis), so that the panel 12 is movably secured to the pillar 10, that is, the panel 12 is allowed to slide with respect to the other element to which it is coupled (or vice versa), due for example to expansions and / or settlements of the respective materials.

[0053] As schematically illustrated in Figure 6, the coupling element 14 may be substantially shaped as a brace, and have a central hole, through which a retaining means 15 (for example, a screw) passes, adapted to fix the coupling element 14 to the panel 12, said coupling element 14 being positioned so that one end thereof engages the pillar 10, so as to slidably secure the coupling element 14 to said pillar 10.

[0054] As schematically illustrated in Figure 7, the coupling element 16 may be L-shaped, and comprise two perpendicular plates respectively coupled to the pillar 10 and to the panel 12, wherein one or both plates have through slots 17, adapted to slidably receive the retaining means designated to engage said plates to the respective pillar 10 or panel 12, so that the latter is coupled to the former in a mobile manner. Conveniently, the slots 17 are vertically oriented, when the coupling element 16 is coupled to the panel 12, so that the latter can slide vertically with respect to the pillar 10.

[0055] As schematically illustrated in Figure 8, the coupling element 18 may be shaped as a flat plate having a plurality of holes and / or slots 17, suitable for coupling two adjacent panels 12 to each other or a panel 12 to a pillar 10 or to a beam 11, also possibly in a labile manner, that is, allowing the panel 12 to slide with respect to the other element to which it is coupled (or vice versa), due for example to expansions and / or settlements of the respective materials.

[0056] Preferably, between the pillar 10 and the panel 12 and / or between the pillar 10 and the coupling element 14, 16, 18, at least one Teflon skid 20 is interposed, adapted to facilitate mutual sliding between said pillar 10 and said panel 12.

[0057] Throughout the present description and in the claims, the terms and expressions indicating positions and orientations, such as "vertical" or "horizontal", shall be referred to the orientation of the axes of the pillars 10, when erected to support the structure.

[0058] Several aspects and embodiments of a method and a structure according to the invention have been described. It is understood that each embodiment may be combined with any other embodiment. Furthermore, the invention is not limited to the described embodiments, but may be modified within the scope defined by the appended claims.

Claims

1. A method for dimensioning structures for residential buildings, comprising the steps of: a) providing a metal framework, comprising a plurality of pillars (10) arranged vertically and parallel to each other, said framework having a structural function and being adapted to support the vertical loads of the building; and b) determining the dimensions of at least one self-supporting panel (12), i.e. determining a dimension of said panel (12) such that horizontally it substantially extends to cover the entire span (L) or distance between two pillars (10), and determining a thickness (SP) of said panel (12) as a function of the characteristic elastic modulus of the material of said panel (12), or of the elastic modulus resulting from the average of the characteristic elastic moduli of the materials of which said panel (12) is composed.

2. A method according to claim 1, comprising the step of arranging at least one self-supporting panel (12) dimensioned according to step (b), and coupling it to a pair of pillars (10).

3. A method according to claim 1 or 2, wherein the span (L) between the two pillars (10) wherein the self-supporting panel (12) is to be inserted is be-tween 3000 mm and 12000 mm.

4. A method according to claim 3, wherein the thickness (SP) of the self-supporting panel (12) is determined by the formula SP = a / (b - c ·ME), wherein: the parameter a is a function of the length of the side of the pillar (10); parameters b and c are two constants; and parameter ME is the characteristic elastic mod-ulus of the panel material (12), or the elastic mod-ulus resulting from the average of the characteristic elastic moduli of the materials of which said panel is composed (12).

5. A method according to claim 4, wherein the parameter a corresponds to the dimension DP of the largest side of a section of the pillar (10).

6. A method according to claim 5, wherein the parameter DP is equal to the ratio of span (L) to an integer value CF between 15 and 50.

7. A method according to any one of claims 4 to 6, wherein: b=4; c = 0,05; ME is between 1 GPa and 70 Gpa.

8. A method according to claim 7, wherein ME is between 10 GPa and 14 Gpa.

9. A method according to any one of the preceding claims, comprising the step of placing between at least two pillars (10) of the metal framework at least one self-supporting panel (12) coupled in a labile manner to said pillars (10).

10. A residential building structure, comprising: - a metal framework, which includes a plurality of pillars (10) arranged vertically and parallel to each other, said framework having a structural function and being capable of supporting the vertical loads of the building; and - at least one self-supporting panel (12), arranged between at least two pillars (10) of the metal framework and dimensioned according to any of the preceding claims.

11. A structure according to claim 10, wherein the panel (12) is made at least in part of laminated timber or CLT.

12. A structure according to claim 10 or 11, comprising at least one coupling element (14, 16, 18), suitable for coupling the panel (12) to a respective abutment (10), said coupling element (14, 16, 18) being configured to be fixed to one between the panel (12) and the pillar (10) and to engage the other between the panel (12) and the pillar (10) in such a way that a degree of freedom is allowed between the latter and the coupling element (14, 16, 18), so that the panel (12) is movably secured to the pillar (10).

13. A structure according to claim 12, wherein the coupling element (14) is substantially shaped in the form of a brace, and has a central hole, within which a retaining means (15) passes for securing the coupling element (14) to the panel (12), said coupling element (14) being arranged so that one end thereof engages the pillar (10), so as to slidably secure the coupling element (14) to said pillar (10).

14. A structure according to claim 12, wherein the coupling element (16) is L-shaped, and comprises two perpendicular plates coupled respectively to the pillar (10) and to the panel (12), wherein one or both plates have through slots (17), adapted to slidably receive the retaining means for coupling said plates to the respective pillar (10) or panel (12), so that the latter is coupled to the former in a mobile manner.

15. A structure according to any one of claims 10 to 14, wherein between the pillar (10) and the panel (12) and / or between the pillar (10) and the coupling element (14, 16, 18) there is interposed at least one Teflon skid (20), adapted to facilitate mutual sliding between said pillar (10) and said panel (12).

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