EP3047078B1

EP3047078B1 - A construction system of wooden load-bearing structures for buildings and a structure thus obtained

Info

Publication number: EP3047078B1
Application number: EP14806064.3A
Authority: EP
Inventors: Giuseppe Ricci
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-09-18
Filing date: 2014-09-15
Publication date: 2017-11-08
Anticipated expiration: 2034-09-15
Also published as: EP3047078A1; WO2015040534A1; ITPR20130070A1

Description

FIELD OF APPLICATION OF THE INVENTION

The present finding is inserted in the building field and regards a construction system with a particular load-bearing wooden structure.
This system uses prefabricated structural elements such as beams, sawn wood and panels arranged according to a precise and effective arrangement, described and claimed hereinbelow. The structure thus obtained is fixed to a system of support beams integral with the foundations so as to create, together with other analogous structures, the load-bearing skeleton of the building. As an example, DE-375-240-C is mentioned, which discloses a construction system of wooden load-bearing structures that comprises: short uprights, with height equal to one floor; long uprights, extending from the foundation level up to the roof structure; and horizontal and tilted structures constituted by the double beams of the various floors, which clamp in a jaw-like manner the long uprights that are arranged on the sides perpendicular to the double beams. In other words, the finding regards a construction system using structural elements (beams, uprights, etc...) that can be fixed together directly at work sites or that can be partially prefabricated.

STATE OF THE ART

Building construction is represented by the assembly of different materials, such by the joining thereof they generate a new object, which comes to achieve - joined to other objects - the constructed environment.
In the field of architecture and civil engineering, construction is a process that consists of building a set of structures connected on the basis of a design or in any case some level of planning. It is not a single activity but rather a system of components, plants, finishing. For large-scale constructions, the work is organized by a project manager and supervised by engineers, architects, construction companies and contractors.
In order to successfully attain a building operation, the general plan of the intervention is essential. This binds the architectural design with the construction and must consider various correlated factors: impact and environmental sustainability, work times, work site safety, availability of resources and materials, and logistics.
A construction can be represented by simple masonry (wall etc.), by a structure (staircase etc.), by a building (homes, offices, stores), and by public works (bridge, stadium etc.).
A structure can be classified:

by different types: structure made of wood, stone, brick, reinforced concrete, mixed
by different strength and environmental relationship characteristics: light (tensile structures), anti-seismic, bio-architecture etc.

STATE OF THE ART OF WOOD STRUCTURES

Over time, various techniques have been developed that use wood for obtaining building elements capable of carrying out different functions inside a building. The geographical diffusion and the time continuity of wood use have made possible the improvement of a considerable amount of structural techniques, whose differences depend substantially on environmental, climactic, social, cultural and production factors, as well as of course by the availability of the raw material.
Indeed, in areas and times characterized by a large availability of wood, the technique of solid constructions with overlapped wood logs, otherwise termed "log house", has prevailed, still in use today with various adaptations. Otherwise, in conditions with little material availability, techniques have developed such as "fachwerk" or "colombage", which combine a wood frame with brick walls. Even if excellent structures built with this technique are still present, it is currently not employed in a wide scale due to the achievement complexities involved.
Currently, the construction systems in use can be grouped into two large categories (each of which comprises different techniques):

Solid constructions, constituted by:
- overlapped logs
- multilayer structural panels
Light constructions, constituted by:
- systems with load-bearing frame
- load-bearing panels with wooden framework
- frame with load-bearing cage

The most widespread techniques today are:

advanced overlapped log systems;
structural panels with crossed boards joined with various systems (glues, pins, nails);
platform frame, which belongs to the systems with "load-bearing frame", used considerably in the United States but widespread through the world;
systems with load-bearing panels with wooden framework, an advancement of the aforesaid platform frame, which allow high prefabrication.

Each of the aforesaid techniques has specific characteristics, described briefly hereinbelow:

overlapped log system: involves the use of great quantities of wood (which confers optimal mass characteristics to the building thus achieved) but is subjected to considerable vertical expansion; in addition, due to the energy efficiency needs required today, a further insulation is necessary.
system with structural panels with crossed boards: those joined with wood pins or nails represent a market niche; glued boards prevail. This system allows the prefabrication of entire wall sections but is limited by a great use of glue.
platform frame system: it is not a prefabricated system but rather a construction system formulated in detail. It can be adapted aesthetically and/or architecturally, and is characterized by panels constituted by a "two by four" wooden framework of uprights and stringers, i.e. 2 by 4 inches. Such framework is covered, on both sides, by structural plywood panels or O.S.B. Analogous to the above-described systems, it requires additional thermal insulation and uses a great amount of glue (present in the panels).
system with load-bearing panels with wooden framework, an advancement of the aforesaid platform frame: it allows a high prefabrication but has the same drawbacks of the platform frame (presence of glues).

EXPOSITION OF THE ADVANTAGES OF THE FINDING

Object of the present finding is to provide a new structural technique with load-bearing structure, obtained entirely with natural materials, which is characterized for the aspects described hereinbelow:

A. Structural: the perimeter walls, the structure of the floors and roof, suitably positioned, form a "box-like" structure where the structural wood elements are mainly stressed with compression or traction perpendicular to the grain, exploiting the physical-mechanical characteristics as much as possible. The fixing is carried out with cylindrical shank connectors on elements placed orthogonally with respect to each other; given that they are numerous and uniformly distributed, they carry out the function of force dissipation in the best possible manner. This, together with the structure type that also exploits favorable compression and friction actions between the structural elements and low specific weight of the materials used, confers optimal mechanical characteristics to the building and excellent behavior with regard to seismic actions.
B. Ecological: all the materials used are of natural origin, widely available and renewable. The working required consumes little energy, and produce little processing waste, moreover reusable. With regard to the life cycle, all is fully reusable and/or recyclable. The entire process is therefore characterized by high sustainability.
C. Energy: the structure, the stratigraphy and the arrangement for the plants was conceived as an organic whole, easy to achieve, which allows obtaining energy performances on the passive house level in the most diverse environmental settings, both in winter and summer conditions, also through the size optimization and the selection of the most appropriate insulating materials.
D. Fire protection: the fire protection, notwithstanding the biases regarding wood, is good and can be further improved by protecting the wooden structural elements with fireproof material finishing layers. The internal dividing walls are covered on both sides by drywall and/or fiber gypsum, hence they are protected.
E. Comfort: in addition to the typical comfort of the passive houses, due to the high insulation, which causes a uniform and constant temperature on all surfaces, with the presence of the controlled ventilation plant, which ensures a constant change of air, this system also benefits from the optimal mass properties of the materials provided for the interior of the enclosure. The structure, entirely executed with materials of natural origin and without glues, ensures good health conditions, with no harmful emissions. The acoustic performances are high and greater than those prescribed by law, due to the good characteristics of the materials employed and to the provided stratigraphy, which in every structural part achieves a mass-spring-mass system.
F. Aesthetics: the flexibility of the system is such to not place great limits on the designer, apart from that of an accurate detail design, which is always desired and necessary for reaching the stated results. For the exterior of the structure, a wide selection of materials and finishing is possible; for the interiors, the uprights being made of wood, the support beams and the beams of the floors can remain in view or be covered, allow the designer maximum possible expression.
G. Economical: the mounting system is quick and precise and, with the use of standard production materials, allows obtaining the exact results provided by the design specifications. This reflects positively on the costs, which are not changed with respect to the estimate and remain competitive with those of other lower-performance systems.
H. Flexibility: the system is adapted to achieve many different structure types: houses with one or more floors, villas, town houses, industrial buildings, artisanal buildings, commercial buildings and schools. It is particularly well-suited for renovations with an additional storey and, finally, it can be self-built.

With regard to the materials, these are the following:

A) Beams of wood which can be made of solid wood, KVH, or bilam/duo (no formaldehyde) with variable sections, according to the construction types and based on structural calculations: 50,60,80,100,120 or more mm for the smaller side (b) while the other side can be equal to the smaller side or longer; such beams are all of standard production and easy to find.
In the following embodiments, reference will be conventionally made to uprights with base width of 80 mm and to insulating panels with width of 600 mm (the resulting interaxis is therefore equal to 680 mm).
The size of the interaxis of the uprights is in fact given by the width of the uprights themselves plus the width of the insulating panels inserted between them.
B) Other wood-based materials such as: panels of glued boards (no formaldehyde), panels of plywood (no formaldehyde), rough, sawn wood boards, wood fiber, mineralized wood wool.
C) Other products made with widely-available and renewable materials such as: fiber gypsum panels, drywall panels, fiber-reinforced concrete panels.
D) Insulating panels made of mineral fibers, cellular glass insulators in gravel and panels.
E) Cellulose-based insulators (recycled paper) in panels or flakes.
F) Hemp-based insulators.
G) Bales of hay.

The above-described objects and advantages are all achieved by the construction method and system that are the object of the present finding, which is characterized for that provided in the below-reported claims.

BRIEF DESCRIPTION OF THE FIGURES

The figures illustrate and show, as a merely non-limiting example, the most important characteristics of the finding.

Figure 1: illustrates the portal structure, part of the invention, with which the present construction system is obtained;
Figure 2: illustrates the joining of multiple portals;
Figure 3: illustrates the joining of the uprights with the beams;
Figure 4: illustrates an overall construction embodiment obtained with the present system;
Figure 5: illustrates the anchorages to the bed;
Figure 6A: illustrates the joining of the plank of the ground floor to the foundation bed and to the external uprights;
Figure 6B: illustrates that described in figure 6A plus the panel/board of the ground floor;
Figures 7A, 7B: illustrate the fixing of the external uprights of the various sides with the beams;
Figure 8: illustrates the vertical bracing/joining layer with crossed boards seen from inside;
Figure 9: illustrates the vertical bracing/joining layer with crossed boards seen from outside;
Figure 10: illustrates the internal uprights, the support beams, the beams of the floor, the main beam and the respective columns;
Figures 11A, 11B: illustrate, in plan and in section view, the joining of the beams with the relative uprights and the bracing layer;
Figure 12: illustrates a truss of the portal structure.

DESCRIPTION OF THE FINDING

With reference to the abovementioned figures, reference number 11 indicates overall the load-bearing structure, object of the invention, that uses structural elements such as:

A) vertical structures (load-bearing walls) composed of:
- Internal uprights 2, with height equal to one floor, on which the support beams 3 rest,
- Bracing/joining layer 4,
- External uprights 5, which are vertically extended from the foundation to the roof.
B) Horizontal and/or tilted structures (specifically those of the floors and roof) constituted by double beams 6 which rest on the support beams 3 and clamp in a jaw-like manner the external uprights of the walls.

The assembly of these elements forms "portal" 10, as illustrated in figure 1, which, when arranged at regular intervals, are joined together by means of the vertical bracing/joining layer 4 (in the walls) and by the horizontal or tilted panels/boards 7 of the floors and roof, as Figure 2 indicates.
The portal structure 10 thus obtained can be repeated in order to form the construction system 11 that is the object of the finding.
The system can be assembled starting from elements prefabricated at the plant, in the form of panels constituted by the frame, formed by the external uprights 5 or by the internal uprights 2 plus the bracing/joining layer 4; in such a manner, semi-closed panels are obtained that are already arranged with the openings for doors, windows, holes for the passage of the beams of the floor and sealing sheath which are positioned in place with the aid of mechanical means; bolted together, they act as a support for the subsequent installations, facilitating a quick, accurate and precise installation.
It is also possible to mount in place starting from wood beams, sawn wood, panels and boards, all of standard production, sized on the basis of calculations (in the following embodiments, for the sake of simplicity, reference will be made to structures with section beams with 80 mm base). The single parts of the system are prepared with simple cutting operations (previously executed at the plant or also at the work sites itself), simply assembled with brackets, nails and screws, with a procedure that ensures a precise error-proof result. Figure 4 shows an embodiment thereof, generically illustrated an overall construction.
The structure thus obtained has spaces already sized and arranged for receiving the insulating materials of standard size, the window/door frames and the subsequent finishings, facilitating and accelerating the subsequent working steps.
The structural elements are described in detail below.

PLANKING OF THE GROUND FLOOR

Above a suitable ground support system, for example a reinforced concrete foundation bed 8, the following are set in place:

a waterproofing sheath (not shown)
support beams 3 along the perimeter of the building and other beams at their interior and at a suitable distance as cross-pieces;
the beams 6 of the foundation plank which, in pairs, clamp "in a jaw-like manner" the external uprights of the perimeter walls perpendicular to the beams themselves. The joints will be obtained with L-shaped brackets 9 anchored to the foundation plate with anchor rods (figure 5 illustrates said anchorages to the bed).
the wood panel/board 7 fixed with screws (detail in figure 6B) which is set above the beams of the plank after having filled the empty spaces with loose insulation.

STRUCTURE OF THE LOAD-BEARING EXTERNAL WALLS

The structure of the perimeter walls, starting from the outside, is constituted by:

A) External uprights 5: they rest on the support beams 3 of the foundation with their greater axis perpendicular to the latter and extend upward to the beams of the roof structure.
With reference to figures 7A and 7B, it is observed that the uprights 5 placed on the sides perpendicular to the beams are clamped "in a jaw-like manner" by double beams 6 of the various floors, including the beams of the roof level; they are also fixed to the internal uprights 2, to the support beams 3 and to the bracing/joining layer 4.
It is instead observed, still in figures 7A and 7B, that the external uprights 5 arranged on the other perimeter sides of the building are fixed to the internal uprights, to the support beams and to the lateral beams of the plank of each floor and of the roof and with possible spine walls and/or main beams, with screws which cross through the vertical bracing/joining layer.
B) Bracing/joining layer 4: fixed on the internal side of the external uprights are fixed structural panels or two rough board layers with 25 mm thickness, rotated 45° with respect to the uprights and 90° with respect to each other. See in this regard figure 8 (vertical bracing/joining layer seen from inside) and figure 9 (vertical bracing/joining layer seen from outside).
C) Internal uprights 2: with reference to figure 10, it is observed that within the vertical bracing/joining layer, the internal uprights are set in place with an interaxis of 1.360 mm (hence two of every three external uprights); such internal uprights generally have size of 80 x 160 millimeters and a height that extends from the panel/board of the underlying floor to the support beams of the subsequent floor placed at the top thereof.

The internal uprights 2 are placed orthogonally to the external uprights 5 and fixed thereto with screws, by clamping the bracing layer (which is therefore situated arranged between the internal uprights) and forming an assembly with high strength and ductility.
Figures 11A and 11B illustrate, in vertical and horizontal section, the connection system of the beams 2, 5, 6, 13. Such system provides for arranging the internal uprights 2 orthogonally with respect to the external uprights 5 and fixing them together by interposing the bracing/joining layer 4; above the internal uprights 2, the support beams 3 are set, these too fixed to the external uprights 5. In addition, the double beams 6 and 13 of all the floors rest on the support beams 3 and, passing through holes in the bracing/joining layer 4, come to clamp the external uprights 5 in a jaw-like manner.

STRUCTURE OF THE FLOORS (FLOOR SLABS)

The structure of the floors (floor slabs) is obtained with double beams, spaced from each other, with 80 mm base and with suitable height which rest on the support beams; passing through holes in the vertical bracing/joining layer, such beams come to tighten, in a jaw-like manner, the external uprights to which they are fixed with screws.
Above these beams, wooden panels or boards are fixed with the function of distributing the static and dynamic loads.
In order to attain floor surfaces with wide openings, it is necessary to arrange load-bearing spine walls or main crosspiece beams 16. These are composed of the joining of two lateral beams of equal height with a beam of lesser height interposed; the whole set forms an overturned U-shaped section. These beams are fixed (in a manner analogous to the secondary beams-figure 7A) to the external uprights 5 of the walls perpendicular thereto and are supported by suitable columns 17; see figure 10.

STRUCTURE OF THE ROOF

The structure of the roof, figure 12, can be constituted by trusses 12 composed of tilted double beams 13 (struts), which are spaced from each other, are fixed, and clamp both the external uprights 5 and a horizontal beam 14 with tie rod function and a vertical beam segment at the top (king post 15).
Or, in a manner analogous to the floors, the structure of the roof is attained with main beams 16 supported by columns 17 which bear the double beams connected to the external uprights 5.
At the extrados of the tilted beams 13, a panel/board is fixed, together with a vapor blockage sheath, hence a first layer of insulating material panels, alternated with rafters set orthogonally to the beams of the roof and fixed thereto with screws; above this, there is a further insulating layer set with continuity.
The gutter projections are attained with struts oriented according to the pitch - incorporated in the second insulating layer and fixed to the underlying rafters; in this manner, they remain separated by a suitable insulating layer from the internal environment, in order to prevent thermal bridges.
Still for this reason, possible verandahs or balconies require their own structure that does not interfere with the insulated enclosure; these are anchored to the structure with suitable fixing.

Claims

A construction system of wooden load-bearing structures, for buildings, said structures being extended from a foundation level (8) to a roof structure, comprising:
a. internal uprights (2), with height equal to one floor, on which support beams (3) rest,

b. external uprights (5), extending from the foundation level up to the roof structure,

c. vertical bracing/joining layer (4), clamped between the internal uprights (2) and the support beams (3) on one side and the external uprights (5) on the other,

d. horizontal and/or tilted structures constituted by the double beams (6, 13) of the various floors which rest on the support beams (3) and, by crossing through the bracing/joining layer (4), clamp in a jaw-like manner the external uprights (5) that are arranged on the structure sides perpendicular to the beams (6, 13) themselves,

e. a layer of wooden panels or boards (7), with the function of distribution of the static and dynamic loads, fixed above the double beams (6, 13).
System according to claim 1, characterized in that the bracing/joining layer (4) is inserted and fixed between the internal side of the external uprights (5) and the external side both of the internal uprights (2) and of the support beams (3).
System according to claim 1, characterized in that the bracing/joining layer (4) is constituted by structural panels or by two board layers rotated 45° with respect to the uprights (2, 5) and 90° with respect to each other.
System according to claim 1, characterized in that the external uprights (5), placed on the perimeter sides perpendicular to the beams of the floors, are clamped in a jaw-like manner by the double beams themselves, and are also fixed with screws that cross through the bracing/joining layer to the internal uprights and the support beams.
System according to claim 1, characterized in that the external uprights (5), placed on the perimeter sides parallel to the beams of the floors, are fixed with screws that cross through the bracing/joining layer to the internal uprights and to the lateral beams of the plank of each floor and of the roof, as well as to possible spine walls and/or main beams.
System according to claim 1, characterized in that the fixing to the ground support system, such as a foundation bed (8), provides for: a waterproofing sheath; the support beams (3) along the perimeter of the building on which the external uprights (5) rest; in the perimeter walls perpendicular to the beams (3), the uprights (5) are clamped in a jaw-like manner by the double beams (6) of the foundation plank; the joints are obtained with L-shaped brackets (9) anchored to the foundation plate with anchor rods.
System according to claim 6, characterized in that the fixing to the ground of the external uprights (5), placed on the sides parallel to the beams, is obtained with L-shaped brackets (9), anchored to the foundation plate with anchor rods.
System according to claim 1, characterized in that the internal uprights (2) are placed orthogonally to the external uprights (5) and fixed thereto with screws, by clamping the bracing layer (4).
Structure according to claim 1, characterized in that the external uprights (5) are placed on the support beams of the ground floor orthogonally to the perimeter of the structure; they are fixed to the ground, to the internal uprights (2), to the support beams (3) of the various floors, to the double beams (6) of all the floors and to the beams (13) of the roof level.
A structure or a building comprising a wooden structure obtained according to claim 1.