The present invention relates to a triangular pyramidal supporting structure, a system including the supporting structure and a method for producing the same. The inven- tion is directed towards a triangular pyramidal supporting structure that is particularly for, but not restricted to, use as a supporting structure in a building structure where the supporting structure comprises at least one triangular pyramidal supporting struc ture, a so-called tetrahedron.

Supporting structures comprising triangular elements are well known from, among other things, the construction industry in which a plurality of triangular elements are arranged in series to form a so-called truss for use as so-called principals in buildings, bridges, towers, cranes, power pylons and other types of structures in which there is a need for relatively light structures that can transmit great forces to at least one foun dation and/or where there is a need to have a structure with a large span between supporting points. A truss structure comprises a so-called top chord and a bottom chord which are interconnected by slanted rods at joints or nodes. In some structures, such as a power pylon or a jib for a crane, the slanted rods may be connected to one or two top chords and two bottom chords to form a three-dimensional truss. Inde pendently of whether the truss is a two- or three-dimensional one, the top chord and the bottom chord are continuous structural elements in the position of application.

Building structures in which triangular, three-dimensional frames have been put to gether by means of nodes to form a so-called geodesic dome are known. A geodesic dome is a dome structure consisting of a space frame latticework of standardized ele ments such as short steel or aluminium pipes fitted together into a web-like system of tetrahedrons.

From the publication JP S5325589 U a structure for use as an artificial reef for fish is known, the reef being constructed by connecting skeletal structures into a triangular pyramid, each joint in the skeletal structure being connected by means of a spherical node. The skeletal structure consists of elements with a circular cross section.

From the publication FR 2639978 A1 a triangular pyramidal structure, a tetrahedron, is known, which has horizontal elements attached to the slanted elements of the structure and which is arranged between a ground plane and an apex of the slanted elements. The horizontal elements form an intermediate structure and are placed on an inside of the tetrahedron and parallel to an internal surface of the slanted ele ments.

The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art. The object is achieved through the features that are specified in the description below and in the claims that follow.

There is a need for a triangular pyramidal supporting structure, a tetrahedron, which is suitable for use as a single unit, but which is also suitable for positioning as a sys tem of tetrahedrons that are arranged to carry at least one further tetrahedron, wherein the external side faces of the system are in the same plane, independently of the shapes and sizes of the elements of the tetrahedron.

The invention is defined by the independent claims. The dependent claims define ad vantageous embodiments of the invention.

In what follows, the terms "imaginary line" and "imaginary plane" are used. These are to be understood in the sense of "auxiliary", that is to say an auxiliary line and an auxiliary plane for use when planning the triangular pyramidal supporting structure. The purpose of the imaginary lines is to form a three-dimensional and infinite crystal line structure of auxiliary lines, where the pyramidal supporting structures of the in vention can be placed inside each of the open spaces emerging between the lines and then be connected as in a three-dimensional building block system. The auxiliary lines of the crystalline structure may be made in various designs but are characterized by at least one of the joints in the supporting structure being connected to at least one joint in another supporting structure when several supporting structures have been put to gether into a system.

In a first aspect, the invention relates to a triangular pyramidal supporting structure comprising :

three primary elements that are joined together at three primary joints into an equi lateral triangle to form a primary plane; three sloping elements, equal in length, each of the three sloping elements having a first end portion and a second end portion in the position of application, the first end portions each being attached to a respective one of the primary joints, and the second end portions being connected to each other in a junction portion so that the primary elements and the sloping elements form a pyramidal shape. The sloping elements are arranged, in pairs, with an external portion that is parallel to and on an inside of a respective one of three imaginary planes defined by imaginary sloping lines which each extend from an intersection between two and two imaginary lines that are paral lel to and touch a portion of a respective primary element, and beyond an end portion of the junction portion, the imaginary lines being longer than the primary elements so that said intersection is on an outside of the first end portion of the sloping elements, the tree imaginary planes each touching a portion of a respective primary element so that at least a portion of the sloping elements is arranged within the imaginary planes.

In one embodiment, the first end portions of the sloping elements, which are each attached to a respective one of the primary joints, may have ends extending beyond the primary joints. An embodiment like that is particularly relevant if the triangular pyramidal supporting structure forms part of a system according to the second aspect of the invention.

The imaginary plane may thus be at a distance from the plane formed by the outer edge line of the primary elements, and the sloping elements. A distance is determined by the size and shape of the primary elements and the sloping elements. The imagi nary plane has a particularly important effect when several triangular pyramidal sup porting structures are used, assembled into a system according to the second aspect of the invention as described below. Thereby the triangular pyramidal supporting structure may be adapted for use either as an isolated supporting structure or in a system consisting of several triangular pyramidal supporting structures.

The primary plane which is defined by the primary elements has an outer end face facing away from the junction portion of the sloping elements. In this document, the term "top" is used in connection with the primary elements. By the term "top" will be understood the side or the portion of the primary elements that faces away from the outer end face of the primary plane, that is to say the side or the portion of the prima ry elements that is on the opposite side of the outer end face of the primary plane. By the term "outer" used in connection with the primary elements is meant, in this docu ment, the sides or the portions of the primary elements that define the maximum ex- tent of the primary plane. In one embodiment, the supporting structure may further include three secondary elements which are attached to a portion of the sloping elements between the primary joints and the junction portion to form a secondary plane, wherein each of the sec ondary elements may have at least three sides, at least one side of which is parallel to the primary plane and faces away from the primary plane, the at least one side being defined by an outer edge line and an inner edge line. At least the outer edge line of each of the secondary elements may be coaxial with the respective imaginary line ly ing in a respective one of the three imaginary planes.

The effect of at least one of the at least three sides being placed parallel to and facing away from the primary plane is that the secondary plane may form a flat foundation, for example for a floor in a building.

In an alternative embodiment to making the secondary elements with at least three sides, the supporting structure may include three secondary elements that are at tached to a portion of the sloping elements between the primary joints and the junc tion portion to form a secondary plane which is parallel to the primary plane, imagi nary lines touching a top portion of the secondary elements and extending beyond end portions of the secondary elements. Thereby the secondary elements may be made in any shape having a cross section that has an endless periphery, such as, but not lim ited to, a circular or oval cross section. It may be an advantage if, at a maximum, the secondary elements touch each of the respective imaginary planes of the supporting structure.

In one embodiment, the elements of the supporting structure may be produced from materials selected from the group of wood, metal, concrete and synthetic materials, or a mixture thereof. The wooden materials may be made from one piece of wood, or the wooden material may be glued laminated elements. The concrete may be an ordinary concrete with filler materials comprising sand and stones, or the concrete may be a lightweight concrete in which at least a portion of the filler material comprises materi als of low specific weight, such as light clinker, fractions of expanded polystyrene, so- called polymer concrete, and pumice. The synthetic material may typically be a suita ble plastic. Elements made of metal may have a cross section of any shape, such as: at least three sides; an endless periphery; or an I-shaped or H-shaped cross section.

In one embodiment, at least some of the elements of the supporting structure are joined by means of mountings. The mountings may be made of metal or som other suitable material, such as a plastic. One of the advantages of using mountings is that the end portions of the elements do not have to be cut to a very accurate angle. An- other advantage is that the joints and/or junction points may normally achieve a greater rigidity and strength. In one embodiment, the mountings may comprise a sleeve-shaped portion configured for at least partly enclosing an end portion of the element or each of the elements of the supporting structure. Such sleeve-shaped por tions may, similarly to other types of mountings, typically be made of metal, but other materials are also conceivable, such as a suitable plastic as mentioned above. When sleeve-shaped mountings are used, the end portions of the elements may be at right angles with respect to the longitudinal axis of the elements. In one embodiment, an external surface of the sleeve-shaped mountings are in the same plane as the element that is enclosed by the sleeve-shaped mounting. This may be achieved by a reduction in the cross-sectional area of the end portion which is at least partially enclosed by the mounting corresponding to the material thickness of the mounting. In such an embod iment, the part of the end portion that is enclosed by the sleeve-shaped mounting has a somewhat reduced cross-sectional area compared with the rest of the element. This has the advantage of the supporting structure having an even surface. An even sur face is particularly useful if the inside and/or outside of the supporting structure is to be covered with, for example, plate-shaped elements.

As an alternative to mountings formed by sleeve-shaped portions, the mountings may comprise plates arranged to be inserted into complementarily adapted recesses in an end portion of the element or each element in the supporting structure. This has the effect of the mountings becoming practically non-visible. In one embodiment, the mountings are provided with at least one bolt hole to be able to receive a bolt which is passed between two opposite sides of the element.

As a further alternative to said sleeve-shaped mounting and mountings comprising plates, at least the mountings for the primary joints may comprise at least one sleeve shaped portion, wherein the or each sleeve-shaped portion encloses one end portion of the elements of the supporting structure, and at least one plate that is fixed in a complementarily adapted recess in an end portion of another one of the elements of the supporting structure.

In an embodiment in which the elements of the supporting structure are made of con crete, the mountings may comprise metal plates embedded in a surface of end por tions of the elements of the supporting structure so that adjacent metal plates can be connected by means of welding.

The supporting structure may be formed as a regular tetrahedron in which the primary elements and the sloping elements are equal in length. In one embodiment, at least the sloping elements and the secondary elements may have a square cross section or a rectangular cross section. A square or a rectangular cross section is particularly useful if, for example, plates are to be attached to the ex ternal and/or internal surface(s) of the supporting structure. In an alternative embod iment, the sloping elements and/or the secondary elements may be of a design with a cross section with an endless surface. In one embodiment in which the sloping ele ments have a cross section with an endless surface, the surface may have a longitudi nal protrusion which is parallel to the imaginary lines of the sloping elements, wherein an outer portion of the protrusion touches the imaginary line.

In an embodiment in which the sloping elements have, for example, a triangular cross section, one of the edge lines of the sloping element may touch the imaginary line but, similarly to all the other cross-sectional shapes, not be on an outside of the imaginary line.

In yet another alternative embodiment, at least the secondary elements may have a cross section in the shape of a parallelogram, one side face of each of the secondary elements being positioned in the same plane as the respective outer edge lines of the secondary element which are coaxial with respective imaginary lines lying in the imag inary plane. This has the effect of allowing the secondary elements to have a relatively large surface that may be parallel to a respective one of said imaginary planes of the sloping elements. A large surface may be advantageous with respect to supporting a possible outer structure that might be placed against the tetrahedron.

Correspondingly, the primary elements may be formed with a square cross section or a rectangular cross section, or the primary elements may be formed with a cross sec tion selected from the group of triangular, polygonal, and a cross section with an end less surface, such as a circular or oval cross section.

To be able to absorb great loads, a cross-sectional area of the sloping elements may be larger at the first end portion than at the second end portion. In such an embodi ment, too, the portion of the sloping element that faces its respective imaginary plane is parallel to its respective imaginary plane.

In a second aspect, the invention relates to a system which comprises at least four triangular supporting structures according to the first aspect of the invention, in which:

the intersections of imaginary lines of the primary planes of at least three of the four triangular supporting structures are placed adjacent to each other in a first plane so that two of the intersections of the imaginary lines of each of the primary planes are adjacent to two of the intersections of the imaginary lines of the two other triangular supporting structures in order thereby to form an open, equilateral triangle defined between the intersections of the imaginary lines of the three triangular supporting structures; and

the intersections between two and two of the imaginary lines of the primary plane of the at least fourth triangular supporting structure each coincide with a respective one of the intersections of the sloping elements so that the primary plane of the at least fourth triangular supporting structure is carried in a second plane above said first plane, and the system defines a tetrahedron determined by the imaginary lines of the system.

Thus, several triangular supporting structures according to the first aspect of the in vention may be assembled into a system that has several triangular supporting struc tures wherein two and two of the joints of the primary planes face each other, and wherein a third one of the primary joints of the primary plane forms the outer bounda ry of the system, and in several planes. To form a tetrahedron in three planes, alto gether thirteen triangular supporting structures according to the first aspect of the invention may be assembled, wherein the thirteenth supporting structure is supported by four of a smallest embodiment of the system according to the second aspect of the invention.

In one embodiment, the triangular supporting structures are regular tetrahedrons, so that the system as a whole is a regular tetrahedron and may be built infinitely large.

In one embodiment, at least the at least three triangular pyramidal supporting struc tures in the first plane are provided with sloping elements that have a cross section which is larger at the first end portion than at the second end portion. The sloping el ements of at least the three lowermost tetrahedrons may thereby have a design with non-parallel outer and inner sides so that the sloping elements increase in thickness from the second end portion to the first end portion.

In one embodiment, the primary joints in the primary plane of the triangular support ing structure or structures that are placed against underlying triangular supporting structures may be formed with a cut-out that is complementarily adapted to the junc tion point of each of the three triangular pyramidal supporting structures that carry the triangular structure or structures, so that, in a position of application, the primary joints of the triangular structure or structures that are being carried enclose a portion of said junction point. This has the effect of substantially preventing sideways dis- placement of the triangular supporting structures relative to each other.

In a third aspect, the invention relates to a method for providing a triangular pyrami dal supporting structure according to the first aspect of the invention, the method comprising :

- connecting the primary elements at the primary joints to form an equilateral triangle in the primary plane;

- connecting the first end portions of the sloping elements to a respective primary joint each, and connecting the second end portions of the sloping elements in a junc tion portion; and

- arranging the external portions of the sloping elements parallel in pairs on an inside of a respective one of the three imaginary planes defined by the tangent lines that are parallel to longitudinal axes of the primary elements, and by the imaginary lines of the sloping elements, which each extend from an intersection between two and two of the imaginary lines that are parallel to the primary plane, and beyond an end portion of the junction portion.

The method may further comprise connecting the three secondary elements to a por tion of the sloping elements between the primary joints and the junction portion, as explained for the first aspect of the invention.

The method may further comprise assembling at least four triangular supporting struc tures into a system according to the second aspect of the invention, the method com prising :

placing at least three of the intersections of the imaginary lines of the primary planes of said at least three of the at least four triangular supporting structures adjacent to each other in a first plane, so that two of the intersections of the imaginary lines of each of the primary planes are adjacent to two of the intersections of the imaginary lines of the two other triangular supporting structures in order thereby to form an open, equilateral triangle defined between the intersections of the imaginary lines of the three triangular supporting structures; and

placing the intersections between two and two of the imaginary lines of the primary plane of the at least fourth triangular supporting structure in a manner making them each coincide with a respective one of the intersections of the sloping elements so that the primary plane of the at least fourth triangular supporting structure is carried in a second plane above said first plane, and the system defines a tetrahedron determined by the imaginary lines of the system.

As mentioned with reference to the second aspect of the invention, triangular support- ing structures may be placed in more than two planes, wherein each of the triangular supporting structures above the first plane is carried by the junction portions of three underlying triangular structures.

In what follows, examples of preferred embodiments are described, which are visual- ized in the accompanying drawings, in which:

Figure 1 shows a triangular supporting structure according to the invention, in which imaginary lines are shown on an outside of the supporting struc ture;

Figure 2 shows the imaginary lines of the supporting structure shown in figure 1; Figure 3 shows a system made up of four triangular supporting structures ac cording to figure 1, but in which only the imaginary lines of figure 2 are shown;

Figure 4 shows, on a larger scale, a detail A of figure 3, but in which the ele ments of the supporting structure are shown as well.

In the description, positional indications refer to the positions that are shown in the figures.

A reference numeral for an element that is generally indicated may also be used for a specific embodiment of the element generally indicated.

For illustrative reasons, the ratio between individual elements may be somewhat dis torted.

In the figures, the reference numeral 1 indicates a triangular supporting structure in accordance with the invention.

In what follows, the triangular supporting structure 1 will also be referred to as a tet rahedron 1. With reference to figure 1, the tetrahedron 1 comprises three primary elements 4a, 4b and 4c which are joined together at three primary joints 7. The joined primary ele ments 4a, 4b and 4c, shown here as elements with a quadrangular cross section, all equal in length, thus forming an equilateral triangle. The joined primary elements 4a, 4b, 4c form a primary plane. Three sloping elements 5a, 5b and 5c are supported by the primary elements 4a, 4b and 4c, a first end portion of the sloping elements 5a, 5b and 5c having been put to the primary joints 7, and a second end portion of each of the sloping elements 5a, 5b and 5c having been joined together into a junction portion 9. The sloping elements 5a, 5b and 5c are all equal in length. The primary elements 4a, 4b and 4c and the sloping elements 5a, 5b and 5c thus form the tetrahedron 1.

Each of the primary elements 4a, 4b and 4c has an outer edge line shown as, respec tively, 14a, 14b and 14c as an upper, outer boundary of the primary elements.

In the embodiment shown in figure 1, the tetrahedron 1 is further provided with three secondary elements 6a, 6b and 6c which are attached to side portions of the sloping elements 5a, 5b and 5c between the primary joints 7 and the junction portion 9 of the second end portions of the sloping elements 5a, 5b and 5c. The secondary elements 6a, 6b and 6c form a secondary plane which is parallel to the primary plane defined by the primary elements 4a, 4b, 4c. When the invention is used as, for example, a sup porting structure in a building structure, the secondary plane may, but does not have to, form a supporting structure for a floor. Even though one secondary plane is shown in figure 1, it will be understood that more than one secondary plane may be placed between the primary joints 7 and the junction portion 9 of the sloping elements 5a, 5b and 5c. It will further be understood that the tetrahedron 1 may be made without the secondary elements 6a, 6b and 6c so that the tetrahedron 1 does not include the sec ondary plane.

In the embodiment shown, the primary joints 7 and the junction portion 9 include sleeve-shaped mountings. The mountings are shown coloured in grey in figure 1. The sleeve-shaped mountings form part of the primary joints 7 and the junction portion 9 and are therefore indicated by the same reference numeral as the primary joint and the junction portion, that is to say 7 and 9. The sleeve-shaped portions 7, 9 are typi cally made of metal and are prefabricated. The centre axes of the sleeves of the mounting 7, which are to receive the primary elements 4a, 4b and 4c, have an angle of 60° between them. The angle of the centre axis of the part of the mounting 7 that is to receive the first end portion of the sloping elements 5a, 5b, 5c has an angle adapted to the length of the sloping elements 5a, 5b, 5c. Correspondingly, the angles between the centre axes of the sleeves of the mounting 9, which are to receive the second end portions of the sloping elements 5a, 5b, 5c, are adapted to the length of the sloping elements 5a, 5b, 5c.

In the embodiment shown, the secondary elements 6a, 6b and 6c are also attached by means of sleeve-shaped mountings 8 which each comprise fixing portions that are adapted for resting against one of the side faces of the sloping elements 5a, 5b, 5c.

In figure 1 there are several imaginary lines. The imaginary lines are shown in a thick stroke. In the primary plane, three imaginary lines la, lb and lc are shown, which are coaxial with the outer edge lines 14a, 14b and 14c, respectively, but which extend beyond each of the joints 7. The imaginary lines la, lb, lc are thus longer than the primary elements 4a, 4b, 4c. Two and two of the imaginary lines la, lb and lc thus form meeting points or intersections. From each intersection, imaginary lines 2a, 2b and 2c extend parallel along the sloping elements 5a, 5b and 5c, respectively. In the embodiment shown, the imaginary lines meet above the centre of the junction point and thereby the sleeve-shaped mounting 9.

In the secondary plane, three imaginary lines 3a, 3b and 3c are shown, which are co axial with upper, outer edge lines 36a, 36b and 36c of the secondary elements 6a, 6b and 6c, respectively, but which extend beyond the mountings 8 at each end portion of each of the secondary elements 6a, 6b and 6c until they meet or cross the imaginary lines 2a, 2b and 2c.

In the embodiment shown, having primary elements 4a, 4b and 4c of a quadrangular cross section, the imaginary lines la, 2a and 2b form a first imaginary plane. The im aginary lines lb, 2b and 2c form a second imaginary plane, and the imaginary lines lc, 2a and 2c form a third imaginary plane. The imaginary planes thus touch the up per, outer portions of the primary elements 4a, 4b, 4c.

In an embodiment (not shown) with primary elements having a cross section with an endless peripheral surface, such as a circular or oval one, imaginary lines correspond ing to la, lb and lc as shown in figure 1 will be parallel to axes extending along the uppermost portions of the primary elements, that is to say along the tops of the pri mary elements, whereas the imaginary planes touch the primary elements along lines that are below the imaginary lines.

In an embodiment (not shown) with secondary elements having a cross section with an endless surface, such as a circular or oval one, imaginary lines corresponding to 3a, 3b and 3c as shown in figure 1 will be parallel to axes extending along the upper most portions of the secondary elements, whereas the imaginary planes touch the secondary elements along lines that are below the imaginary lines.

The purpose of the imaginary lines will be explained with reference to figures 2 and 3, and in particular to figure 4. Reference is now made to figures 2 and 3 in which only the imaginary lines are shown. Figure 2 shows the imaginary lines shown in figure 1. It will thus be understood that figure 2 deals with the embodiment of figure 1.

Figure 3 shows the system S which is made up of four identical tetrahedrons which are shown in figures 2 and 3. For the sake of clarity, the four tetrahedrons are indicated by the reference numerals 1, 2, 3 and 4. Besides, the four tetrahedrons 1, 2, 3 and 4 are shown in different stroke thicknesses, this for the sake of clarity, too. However, it should be repeated that the tetrahedrons 1, 2, 3 and 4 are identical.

To facilitate the understanding, the reference numerals in figure 3 are indicated in such a way that the tetrahedron 1 as indicated by the reference numeral 1, has a first digit "1" in addition to the reference numerals in figure 1. The tetrahedron indicated by the reference numeral 2, has a first digit "2" in addition to the reference numerals in figure 1. Correspondingly for the tetrahedrons 3 and 4 which have first digits "3" and "4", respectively, in addition to the reference numerals in figure 1.

In figure 3, three tetrahedrons 1, 2, 3 are placed against each other in a first plane so that two of the intersections of the imaginary lines in the primary plane (see figure 1) of each of the primary planes coincide with two intersections of the imaginary lines of the two other tetrahedrons so as to form an open, equilateral triangle (shown hatched) defined between the imaginary lines 21c, 11a, 31b.

The intersection of the imaginary lines 11a, lib of the first tetrahedron 1 is placed in a position coinciding with the intersection of the imaginary lines 21b, 21c of the sec ond tetrahedron 2 and the intersection of the imaginary lines 11a, 11c of the first tet rahedron is placed in a position coinciding with the intersection of the imaginary lines 31b, 31c of the third tetrahedron 3. Correspondingly, the intersection of the imaginary lines 21a, 21c of the second tetrahedron 2 is placed in a position coinciding with the intersection of the imaginary lines 31a, 31b of the third tetrahedron 3.

Thus, it is the imaginary lines that decide the relative positioning of the tetrahedrons 1, 2, 3 and not the primary joints 7 formed by the end portions of the primary ele ments 4a, 4b, 4c as shown in figure 1.

In figure 3, a fourth tetrahedron 4 is placed against the meeting points or intersec tions of the sloping imaginary lines of the tetrahedrons 1, 2, 3 so that the intersection or meeting point of the imaginary lines 41b, 41c of the fourth tetrahedron 4 coincides with the intersection of the sloping imaginary lines 12a, 12b, 12c of the first tetrahe dron. The intersection or meeting point of the imaginary lines 41a, 41b of the fourth tetrahedron 4 coincides with the intersection of the sloping imaginary lines 22a, 22b, 22c of the second tetrahedron 2, and the intersection or meeting point of the imagi nary lines 41a, 41c of the fourth tetrahedron 4 coincides with the intersection of the sloping imaginary lines 32a, 32b, 32c of the third tetrahedron.

In the embodiment in figure 3, imaginary lines 13a, 13b, 13c; 23a, 23b, 23c; 33a,

33b, 33c; 43a, 43b, 43c of the secondary plane are also shown for each of the tetra hedrons 1, 2, 3, 4.

In figure 3, a fifth tetrahedron arranged laterally inversed to the primary plane 41a, 41b, 41c of the fourth tetrahedron 4 is also conceivable. A fifth tetrahedron like that will be defined by the imaginary line 12a of the first tetrahedron 1, the imaginary line 32c of the third tetrahedron 3, and the imaginary plane defined by the imaginary lines 22a and 22c of the second tetrahedron 2. Even though it does not appear clearly from figure 3, a lowermost portion of the imagined fifth tetrahedron will be at a centre of the open area that is shown hatched in figure 3.

In such an imagined embodiment with a fifth tetrahedron, the sloping imaginary lines extend downwards from the intersections of the imaginary lines 41c, 41b; 41c, 41a; and 41a, 41b. This means, with respect to the elements of the triangular supporting structure, that sloping elements corresponding to the sloping elements 5a, 5b, 5c (see figure 1) are connected to elements corresponding to the elements 4a, 4b, 4c (see figure 1 again) in the primary plane of the fourth tetrahedron 4, against which the imagined fifth tetrahedron abuts. Thus, the imagined fifth tetrahedron shares a prima ry plane with the fourth tetrahedron 4. In, for example, a building structure made up of several "storeys" of tetrahedrons, it will always be the case that the primary plane of an underlying tetrahedron is governed by an overlying tetrahedron.

The effect of the imaginary lines will be explained with reference to figure 4 which shows the detail A of figure 3 on a larger scale, but figure 4 additionally shows por tions of the elements 5a, 5b, 5c of the supporting structure and also the junction point 9 of the first, lower tetrahedron 1, and the joint 7 of the primary elements 4a, 4b and sloping element 5a of the upper tetrahedron 4. The reference numerals of said ele ments are the same as in figure 1 for each of the tetrahedrons 1, 4 in detail A.

The imaginary lines 12a, 12b and 12c which are parallel to the elements 5a, 5b and 5c, respectively, intersect in a point 14P above the top portion of the tetrahedron 1. A vertical imaginary line IV which extends through the point 14P hits a centre point of the junction point 9 which, in the embodiment shown, comprises a mounting. The fourth tetrahedron 4 is placed in such a manner that the intersection of the imagi nary lines 41b and 41c of, respectively, the elements 4b and 4c forming part of the primary plane of the fourth tetrahedron 4, and the imaginary line 42c of the sloping element 5c coincide with the point 14P as well. The imaginary lines 12c and 42c thereby form a straight line. By the very fact of the imaginary lines 12c, 42c being parallel to the sloping elements 5c of each of the tetrahedrons 1, 4, at least the out sides of the sloping elements 5c are arranged in line as well. In the embodiment shown, the outsides and the insides of the sloping elements 5 are parallel. Thereby, the insides of the sloping elements 5c are arranged in line as well.

From explanations above, it will be understood that it is the imaginary lines that de termine the relative positioning of the tetrahedrons, and not the dimensions and cross-sectional shapes of the elements of the tetrahedrons 1, 2, 3 4 forming part of the system S shown in figure 3. It is the top portions of the elements in the primary plane of the tetrahedrons, which, in the embodiments as shown in figures 1 and 4, coincide with the imaginary lines, that must have a particular elevation, while, at the same time, the outsides of the sloping elements are placed in such a way that the im aginary lines of the sloping elements form a straight line. Thereby the system S may be built practically infinitely large, the external sloping elements of the system forming straight lines from the uppermost one to the lowermost one of the tetrahedrons in the system.

Even though it is not shown in figure 4, the sloping element 5c (and, correspondingly, the two other sloping elements of each tetrahedron) may have an extent that pro trudes below the lower portion of the elements 4b, 4c, that is to say the primary plane has a somewhat higher elevation than the bottom sides of the sloping elements.

For a building structure that comprises one triangular pyramidal supporting structure as shown in figure 1, or several triangular supporting structures 1, 2, 3, 4 as shown in figure 3, the single supporting structure or those of the supporting structures in the system of supporting structures 1, 1, 3, 4 that abut against or are the nearest to a ground may be provided with sloping elements 5a, 5b, 5c that extend into the ground and/or carry the primary plane at a distance from the ground. Loads that are trans mitted to the ground via the sloping elements 5a, 5b, 5c may thereby be transmitted to the ground only as compressive forces. For a building structure that is placed against a sloping ground, the extents of the sloping elements 5a, 5b, 5c below the primary plane may be different in length.

From the description above, it will be understood that the triangular pyramidal sup- porting structure according to the first aspect of the invention may be used both iso- latedly, but also in a system which is well suited for use in a building structure as a substitute for or an addition to conventional structural principles using pillars and raft ers as load-carrying elements. The system according to the invention is well suited for absorbing vertical forces as well as horizontal forces caused by, for example, wind. Because of the tetrahedrons that form part of the system, the system may be pro duced with the tetrahedrons at any desired angle as long as the system is sufficiently supported.

According to the present invention, the imaginary lines form an imaginary tetrahe dron. Several imaginary tetrahedrons may be assembled into a system and form a three-dimensional, imaginary "diamond-like" structure which may be built infinitely.

An inside of each imaginary tetrahedron houses the pyramidal supporting structure. The system will therefore function like a "building-block system".

In one embodiment, the pyramidal supporting structures may be placed alternately with the junction point of the sloping elements pointing upwards, downwards and in each of the different directions that are possible inside each of the respective imagi nary tetrahedrons of the imaginary diamond-like structure. In another embodiment, the imaginary tetrahedrons are placed with the junction points of the sloping elements pointing upwards in order to form open spaces in the remaining spaces that emerge in the imaginary diamond-like structure.

It should be noted that all the above-mentioned embodiments illustrate the invention, but do not limit it, and persons skilled in the art may construct many alternative em bodiments without departing from the scope of the attached claims. In the claims, reference numbers in brackets are not to be regarded as restrictive.

The use of the verb "to comprise" and its different forms does not exclude the pres ence of elements or steps that are not mentioned in the claims. The indefinite article "a" or "an" before an element does not exclude the presence of several such elements.

The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.