GB2495734A - Roof with multiple domes - Google Patents

Abstract

A building system has a roof structure (2) comprising a skeletal framework (1) of struts (3) connected at joint nodes (4) to form a triangular lattice. The framework defines a plurality of interconnected domes (5,6) of two types, the first type of dome comprising a primary dome (5) and the second type of dome comprising a secondary dome (6) smaller than each primary dome. Each of the primary domes has the same configuration of struts as the others and is supported at support nodes where struts are connected to supporting columns (10) located at apices of a respective regular hexagon (7) as seen in plan view. Each of the secondary domes has the same configuration of struts as the others and is supported at support nodes where struts are connected to supporting columns located at apexes of a respective equilateral triangle as seen in plan view. The support nodes (13) of adjacent domes are shared so that supporting columns mutually support adjacent domes. The arrangement of domes in the complete framework corresponds to a geometrical figure formed of tessellating or interlocking hexagons (7) and triangles (8) with apices (12) corresponding to the positions of the support nodes supporting the primary domes and secondary domes respectively. The framework is assembled from a set of replicated modular units of four types, each modular unit of a given type comprising a respective configuration of struts.

Description

A BUILDING SYSTEM

The present invention relates to a building system and in particular to a building system having a roof structure supported by columns and is particularly suited to buildings in which a combination of large open plan areas and smaller scale compartmentalised area are required, for example supermarkets and other retail outlets, industrial buildings and commercial buildings.

BACKGROUND

Roof structures required for large scale areas such as supermarkets and warehouses have traditionally utilised portal frame systems in which horizontal roof panels supported by horizontal beams extend between support columns in a rectangular pattern with columns typically spaced apart to define a span between support columns of 12 metres. In order to withstand the bending moments applied to such beams, steel girders have typically been used More recently, attempts have been made to use materials that are more ecologically friendly, and which should be less expensive, such as timber. Timber however in its natural state is not suitable for withstanding large bending moments, being better suited to withstanding loads in compression. Laminated timber beams have provided a partial solution to the problem in that they are more capable of withstanding bending moments but the cost of such materials is greater than that of natural timber and therefore there is a need to provide a building system in which a significant portion of the structure could be constructed using natural timber.

Roof domes have also been proposed in which in which a framework of struts is used following the principals of geodesic design first proposed for building construction in US 2682235 by Richard Buckminster-Fuller, the framework of struts essentially being associated with panels distributed over part of the surface of a sphere so that the struts are stressed mainly in axial compression and with minimal bending moments. Such arrangements would therefore be suitable for constructions using natural timber for the struts.

US 4833843 proposes a vaulted dome structure in which a single dome covering a large span is constructed from an assembly of dome modules, a plurality of major dome modules having a diamond shape plan and minor modules having a generally triangular shape in plan view, together forming a composite dome of which the exterior surface is locally dimpled convex outwardly, the curvature of each dimple being greater than the overall curvature of the dome. such a large scale dome is however unsuitable for many retail and industrial applications where it would desirable to have some areas where the root structure provided a large span and high roof and other areas where a shorter span and lower roof construction would be desirable, for example compartmentalised areas including back office facilities and storage areas requiring lower ceiling and closer partitioning than the main working space of the retail outlet.

Us 3974600 proposes a building system in which self supporting domes are constructed from a limited inventory of framework elements which in combination with a limited number of exterior and interior panels can be utilised to erect a variety of integral structures in which the framework elements bear substantially all loads. Although this results in potentially infinite variation in construction, it is targeted at the mass housing market that requires flexibility and is thus designed to be a dernountable system which facilitates both erection and change.

Because of this emphasis on flexibility, this disclosure fails to suggest a systematic approach to providing a roof structure to meet the above mentioned requirements of commercial and industrial buildings-

DISCLOSURE OF THE INVENTION

According to the present invention there is disclosed a building system having a roof structure comprising a skeletal framework of struts connected at joint nodes to form a triangular lattice; the framework defining a plurality of interconnected domes of two types, the first type of dome comprising a primary dome; each of the primary domes having mutually the same configuration of struts and each primary dome being supported at support nodes where struts are connected to supporting columns located at apeces of a respective regular hexagon as seen in plan view; the second type of dome comprising a secondary dome smaller than each primary dome, each of the secondary domes having mutually the same configuration of struts and each secondary dome being supported at support nodes where struts are connected to supporting columns located at apeces of a respective equilateral triangle as seen in plan view; the support nodes of adjacent domes being shared so that supporting columns mutually support adjacent domes; and wherein the arrangement of domes in the complete framework corresponds to a geometrical figure formed of interlocking hexagons and triangles with apeces corresponding to the positions of the support nodes supporting the primary domes and secondary domes respectively.

Preferably the framework is assembled from a set of replicated modular units of a number of types, each modular unit of a given type comprising a respective configuration of struts.

In an embodiment, the modular units comprise four types; a column unit comprising six struts joined in splayed relationship to a respective one of the supporting columns with outer ends of the struts at apeces of a hexagonal configuration of transverse struts; an apex unit comprising an assembly of struts of hexagonal outline and defining an apex of one of the primary domes; a ring unit comprising an assembly of struts with edge struts defining a hexagonal outline, a group of six ring units co-operating in annular formation with abutting edge struts to define a hexagonal aperture receiving one of the apex units; and a link unit in which the struts define a rectangular portion with end struts adapted to fit to abut the transverse struts of adjacent column units and side struts from which triangular portions extend at an inclined angle relative to the plane of the rectangular portion and adapted to abut the edge struts of adjacent ring units when the supporting columns to which the link unit is connected are peripheral to a primary dome.

Preferably each secondary dome is formed by three link units extending in triangular formation between three supporting columns in an equilateral triangular arrangement and wherein abutting triangular portions of the link units define an apex of the secondary dome.

Preferably at least the apex units, ring units and link units comprise struts formed of natural timber.

Preferably the modular units further comprise roof elements assembled with the respective configuration of struts, the roof elements being selected from a group comprising; insulating panels; transparent panels; and ventilation structures.

S

Preferably at least one of the primary domes includes an apex unit having a ventilation structure and at least one of the domes is supported by at least one column unit having a ventilation structure.

Preferably the support nodes are arranged such that a locus of a first group of the support nodes defines a first planar surface which is inclined at a first angle relative to the horizontal whereby the roof structure is correspondingly inclined-A locus of a second group of the support nodes defines a second planar surface included at a second angle relative to the horizontal, the first and second planes intersecting at a ridge line, wherein the roof structure is correspondingly inclined at different angles on either side of the ridge line.

Preferably the configuration of struts of each of the primary domes comprises joint nodes which lie on a spherical surface.

Preferably the building system comprises a tie structure arranged to restrain outwardly radial movement of the support nodes with respect to each dome.

A method of constructing a building using the above building system is also disclosed.

Embodiments of the present invention will now be described by way of example and with reference to the accompany drawings of which; Figure 1 is a schematic plan view illustrating a skeletal framework of struts in a roof structure in accordance with an embodiment of the present invention, together with a geometrical figure with interlocking hexagons and triangles corresponding to positions of primary and secondary domes; Figure 2 is a schematic drawing in plan view showing the geometric figure of Figure 1; Figure 3 is a side elevation of the root structure of Figure 1 together with supporting columns; Figure 4 is a front elevation of the roof structure and supporting columns of Figure 3; Figure 5 is a perspective view from below and to one side of a portion of the roof structure of preceding figures in which the framework has adjacent primary and secondary domes; Figure 6 is plan view with selected elevation views of the portion of root structure of Figure 5; Figure 7 is a perspective view from above and to one side of the portion of roof structure of Figures 5 and 6; Figure 8 illustrates schematically in a number of different views of each of four types of modular unit after being assembled on-site ready for installation into the root structure of preceding figures; Figure 9 is a schematic plan view showing the relative positions of the four types of modular units of Figure 8 when used in the portion of the roof structure of Figure 5; Figure 10 is schematic perspective view from above and one side of the portion of the roof structure of Figure 6 revealing the location of annular ties; Figure ilA is a schematic perspective view of part of the roof structure of Figure 1 illustrating an alternative tie structure comprising a network of linear beams Figure 113 illustrates the network of beams of Figure llA as it extends over the entire roof structure; Figure 12 is a schematic illustration of façade units; Figure 13A and 138 is schematic illustration of off-site modular construction and transportation of S sub-assenthiles which are assembled on-site to form the modular units of Figure 8; Figure 14A and 148 illustrate column units in timber and steel construction respectively; Figure 15 is a schematic perspective view of part of the roof structure in which transparent panels are included; Figure 16 is a schematic perspective view and sectional elevation of part of the roof structure illustrating the provision of ventilation; Figure 17 illustrates on-site assembly of an apex unit; Figure 18 illustrates on-site assembly of column and link units; Figure 19 illustrates examples of different shapes which can be formed using the above building system; and Figure 20 illustrates examples of insulation layers for panels and details of the joint construction between panels.

Figure 1 illustrates the way in which a skeletal framework 1 is configured in a roof structure 2 of a large scale building which in the present example is a supermarket with a retail floor area of the order of 60,000 square feet (5,574 square metres) and a total floor area of 91,400 square feet (8,500 square metres) The framework 1 is formed from an assembly of struts 3 connected to one another at their free ends at joint nodes 4, the overall configuration of struts being organised into an assembly of primary domes 5 and secondary domes 6 so that, as seen in elevation view in Figure 3, the profile of the roof structure 2 undulates in a manner which resembles an array of intersecting bubbles. In the following description, the term dome' is applied to a portion of the framework 1 itself, unless otherwise stated.

Each of the primary domes 5 has the same configuration of struts as other primary domes, thereby allowing for modular construction as described in greater detail below, and is bounded in plan view by a regular hexagonal figure 7 as seen in Figure 2. Each of the secondary domes 6 has the same configuration of struts as other secondary domes, thereby allowing for modular construction as described in greater detail below, and exhibits a triangular outline when viewed plan view, as represented by triangular figure 8 as shown in Figure 2 which is in the form of an equilateral triangle of which the length of each side is identical to the length of each side of the hexagonal figure 7.

The apeces 9 of each hexagonal figure 7 in Figure 2 correspond to the location of supporting columns 10 as seen in Figure 1 which maintain the roof structure 2 at an elevated position above ground level 11.

similarly, apeces 12 of triangular figures 8 in Figure 2 correspond to supporting columns 10.

As seen in Figures 3 and 4, struts 3 of the framework 2 are joined to the supporting columns 10 at support nodes 13 which, when seen in plan view, coincide with the location of the supporting columns 10.

The support nodes 13 of adjacent domes are shared so that supporting columns 10 mutually support adjacent domes such as primary and secondary domes 7 and 8.

Figures 5 and 6 illustrate in greater detail the construction of the primary dome 5 and secondary dome 6 and, for the purpose of illustration, each of these Figures shows how a single primary dome 7 connects to a single adjacent secondary dome 6.

The primary dome 5 is larger in terms of height and span than the secondary dome 6 and the configuration of struts 3 in the primary dome 5 is that of a triangular lattice in which joint nodes 4 between connected struts lie on a spherical surface, or more precisely lie on a surface which forms part of a sphere having a radius which is greater than the height of an apex 14 of the primary dome above the ground level 11. In this embodiment, the span of the primary dome S defined by the distance between opposite sides of the hexagonal figure 7 is 24 metres.

The corresponding span of the secondary dome 6, defined by the distance from one apex of the triangular figure 8 to the mid point of the opposite side of the triangle, is 12 metres.

The configuration of struts 3 in the primary dome 5 is therefore similar to the arrangement of a geodesic dome, a known property of which is that of providing a self supporting structure in which the individual struts are stressed predominately in axial longitudinal compression with minimal bending forces.

Figure 7 illustrates that the roof structure 2 is clad with roof elements which for the most part are triangular panels 15 so as to span the triangular lattice defined by the struts 2, with the exception of a number of rectangular panels 16, as seen in Figure 5, located peripherally of the primary dome 5 so as to provide a flat drainage surface between adjacent domes, the rectangular panels 16 also being used to overlay the base of each secondary dome 6. The panels and 16 combine to form a roof surface 70 which generally follows the configuration of the framework 1, with the exception of the struts 50 which are connected to the support nodes 13 and which project beneath the roof surface. This is evident from the view of Figure 5 in which the struts 50 are exposed beneath the surface 70.

In order to provide drainage of rainwater from the root surface 70, the roof structure 2 is tilted as shown in Figure 4. The support nodes 13 on one side of a ridge 17 in this example are arranged to lie in a plane which is inclined relative to the horizontal at a gradient of 1 in 40, and to the other side of the ridge 17 the support nodes lie in a plane which is inclined at a similar angle in the opposite direction to provide run off of rainwater in the opposite direction. Multiple ridges may be provided in more complex structures.

The shape of the roof structure 70 in areas where it covers secondary domes 6 has a configuration in the form of a three sided pyramid rising to an apex 60, the remaining struts 50 of the secondary dome being beneath the roof surface and extending in splayed relationship from a triangular array of support nodes 13.

Figure 8 illustrates four modular units A,R,C,L used in the assembly of the framework 1, the modular units also including panels 15 and 16. Each of the modular units is typically of a size which is too big to conveniently transport to the assembly site by road or rail and therefore consists of sub-assemblies prefabricated off-site and assembled to form the modular units on-site before assembly of the framework 1.

Modular unit A will be referred to as an apex unit and is designed to be positioned at the top of a primary dome 5 and therefore includes the apex 14 as shown in plan view 80 and perspective view 81 from above. The apex unit A is formed by a triangular network of struts 3, each triangle in this example supporting a roof element comprising an insulating panel 15 consisting of inner and outer cladding layers, between which an insulating layer is located.

The perspective view 82 from below shows that the struts 3 are also visible from beneath. The apex unit A may be fitted with other roof elements where required, including a transparent panel or a ventilation structure f or example, as described in greater detail below.

Modular unit R will be referred to a ring unit because a ring of these units is formed around the apex unit A as shown in Figure 9 when assembling the primary dome 5.

As seen in plan view 83, the ring unit R closely resembles the apex unit A but is formed of heavier gauge timber in the formation of the struts 3. Root elements comprising insulating panels 15 are supported within each triangle of the lattice of struts 3, as seen further in the perspective view 84 from above and perspective view from below 85. A hexagonal configuration of edge struts 800 provides a hexagonal outline such that a ring of abutting ring units R defines a central aperture in which an apex unit A will fit.

Nodular unit C will be referred to as a column unit since it includes a supporting column 10, the upper end of which defines the support node 13 to which six struts 89. The struts 89 are connected in splayed arrangement such that their outer ends are connected to apeces of a hexagonal configuration of transverse struts 87 which supports an area of rood surface comprising a flat hexagonal portion 86, consisting of six triangular panels 15. A central support strut 87 extends from the support node 13 to the centre of the hexagonal portion 86.

In the example of Figure 8, hexagonal portion 86 is planar and positioned at right angles to the axial extent of the supporting column 10. This configuration would be suitable where the support nodes 13 are all in a horizontal plane. In a preferred embodiment however the support nodes 13 are in an inclined plane, typically sloping at a gradient of 1 in 40, to allow drainage from the root, and this requires the hexagonal portion 86 to be corresponding inclined. This is accommodated by use of connector fittings at the support node 13 adapted to achieve the required inclination.

As seen in Figure 9, each primary dome 5 relies upon six of these column units C to provide the connection to support nodes 13.

Modular unit L will be referred to as a link unit which, as indicated in Figure 9, is inserted between adjacent column units C throughout the root structure 2. Each link unit L, as shown in plan view 88, includes a rectangular portion with end struts 801 which in the assembled framework abut transverse struts 88 of column units C. The link unit L also has side struts 802 from which struts defining triangular wing portions 803 extend at angles inclined relative to the plane of the rectangular portion. The struts of wing portions 803 are arranged to abut edge struts 800 of adjacent ring units P. The rectangular portion supports a roof element in the form of a flat rectangular panel 16 which, when assembled between adjacent column units 6, is co-planar with the flat hexagonal portions 86 of the column units. The struts of triangular wing portions 803 support roof elements in the form of triangular insulating panels 89 which are inclined relative to the plane of the rectangular panels 16 at an angle selected to achieve interlock with an adjacent one of the ring units R as shown in Figure 9.

As shown in Figure 9, the secondary dome 6 is formed entirely from the struts 3 within a group of modular units comprising three column units C arranged in interlocking arrangement with three link units L. The roof surface 70 overlaying the secondary dome 6 of framework 1 therefore includes a pyramid shaped projection 91 rising above the flat surface of hexagonal portions 86 and the rectangular panels 16.

The pyramid shaped projection 91 is formed of the triangular elements 89 which together rise to an apex 90. By choosing to form the secondary dome 6 in this way, a highly convenient level of modularity is achieved in the pre-assembly of the framework 1 and roof elements such as panels 15 and 16.

Figure 10 illustrates a tie structure 100 arranged to restrain movement of the support nodes 13 in order to resist outwardly radial deformation of each of the primary domes 5 and secondary domes 6. For each of the primary domes 5, an annular tie 101 is attached to the framework of struts at the level of the flat hexagonal portions 86 and panels 16. similarly, at the same level, a triangular steel tie 102 is attached to the framework around the base of each of the secondary domes 6. The annular ties 101 and triangular ties 102 may be formed of timber or steel.

It is a characteristic of dome structures, and in particular geodesic domes, that the base perimeter of the dome needs to be reinforced to resist such outward deformation. Including such a tie structure 100 allows each dome to be inherently stable when considered in isolation, i.e. without the support of surrounding domes, and allows much of the framework to consist of struts 3 which are only stressed in axial compression.

This facilitates the use of natural timber for the struts.

Figure 11 shows an alternative tie structure 110 in which a network of ties ill is interconnected across the full extent of the building, leaving hexagonal openings corresponding to the hexagonal shape of each primary dome 5. The ties lii are connected to the framework 1 at the level of the rectangular panels 16 and flat hexagonal portions 86 of the column units C. The ties 111 in this tie structure 110 are preferably formed of steel.

Figure 12 illustrates the way in which the side walls of the building are constructed using façade units 120. The façade is formed of large panels 121 which extend vertically from ground level 11 to the level of the rectangular panels 16 and flat hexagonal portions 86 of the column units C, which form the lower surface 122 of the roof surface 70. As seen in the side elevation in Figure 12, where the façade panels meet a horizontal edge of the lower surface 122, the façade panels are rectangular and with a width X/6 where X is the horizontal span between opposing side of the hexagonal figure 7.

For the front elevation of the building as shown in Figure 12, the lower surface 122 of the roof structure 2 is inclined relative to the horizontal so that each of the façade panels 121 is formed of two parts, a lower part which is trapezoidal so as to have an upper edge which is inclined to the horizontal and is parallel to the surface 122, and a second portion 124 which is rectangular which abuts between the surface 122 and the upper edge of the lower portion.

The width of each of the portions 123 is selected to match the location of joint nodes 4 when projected horizontally onto the façade units 120, thereby facilitating ease of connection between the façade units and the framework 1 and creating an aesthetically pleasing design. As shown in Figure 12, for each length of façade corresponding to one of the sides of the hexagonal figure 7, there are four corresponding façade panels 121.

The above arrangement of façade panels readily integrates with the modular approach to the implementation of the framework 1 and roof structure 2 allowing a systematic approach to overall design.

Figure 13 illustrates various aspects of sub-assembly and assembly. A triangular element 130 is shown at the stage of being constructed off-site (meaning away from the site at which the building is to be erected, and for example in a factory) and consists of an equilateral triangle formed of three struts 3, with three reinforcing struts 131 in triangular formation.

Between the reinforcing struts and the struts 3, triangular panels 132 of insulating material are inserted before adding outer cladding in order to complete assembly of the triangular element 130 when a roof element in the form of a panel 15 is required.

Figure 13 also illustrates an alternative configuration of a triangular element 134 which again consists of a triangle of struts 3 but with reinforcing struts 135 arranged in parallel array to allow the insulating material to be parallel sided when inserted as strips 135. This arrangement allows more efficient cutting of the insulating material.

A subsequent stage of sub-assembly takes a number of triangular elements 130 and joins them in the required configuration to form a sub-assembly 137 which in the example shown is one half of an apex unit A. In the present embodiment, the distance between opposite sides of the hexagonal figure 7 is seven metres so that the sub-assembly 137 may be readily transported since it presents a height of less than 3.5 metres when loaded as shown in Figure 13.

When delivered to the on-site location, two sub-assemblies 137 are presented to each other and connected together to form the completed apex unit A which can then be hoisted into position to be integrated with the framework 1 as shown in Figure 17.

Similar sub-assemblies are envisaged in respect of the ring unit R, column unit C and link unit L enabling manageable loads to be transported to the building site for subsequent assembly into modular units for use in constructing the framework 1 Figure 18 shows on-site assembly at the stage of connecting column units C and link units L. Alternative embodiments are envisaged, some of which are described below.

The column unit C as described above comprises a supporting column 10 to which timber struts 3 are connected in splayed formation, as illustrated in Figure l4A, together with a centre strut 87, also of timber, connected between the top of the support column and the centre of the hexagonal portion 86.

Figure 14A shows in greater details the way in which the struts are connected and pre-formed using triangular sub-assemblies 140.

In this arrangement, support column 10 may be of natural timber or of a composite timber construction in which laminated sections are glued together to impart greater strength and rigidity. Support column may alternatively be formed of other materials such as steel and having a configuration as shown in Figure l4S.

The annular tie 101 described above with reference to Figure 10 may be connected to the framework 1 at the level of the flat hexagonal portion 86 or alternatively at the level of the support node 13, although potentially this suffers the disadvantage of making the annular tie structure visible below the roof surface as viewed from below.

In embodiments where the alternative tie structure 110 of Figure 11 is used, the column unit C may preferably be formed using steel components as shown in Figure 14E such that the supporting column 10 is formed of steel and is connected at its upper end (the support node 13) to struts 141 formed of steel. Centre strut 142 may similarly be formed of steel.

Figure 15 illustrates how natural lighting can be introduced into the roof structure 2 by replacing panels 15 with roof elements in the form of transparent panels 150 in selected modular units.

Figure 15 shows a number of column units C in which the flat hexagonal portion 86 of Figure 8 is constituted by transparent panels 150, thereby providing natural light to areas covered by the secondary dome 6. Additional natural light is provided beneath the primary dome 5 by additionally including transparent panels 150 in the central portion of each of the ring units R. Ventilation is provided by modifying the apex unit A to include a roof element in the form of a louvered ventilation structure 151 to allow venting of air from within the primary dome 5.

As shown in Figure 16, air fans 152 may be located at or adjacent to the support nodes 13 of support columns supporting the primary dome 5, the air fans 152 acting to create an airflow, or enhance natural air convection, from a low level peripheral to the dome, upwardly to the apex unit A, whereby air may be vented through the louvered ventilation structure. This is a particularly efficient arrange because the vaulted nature of the roof structure comprising the primary dome 5 is such that it provides a natural collecting volume for warm air which will naturally rise by stack effect from the low level to be replaced by fresh air drawn in at ground level either by natural convection or by forced ventilation.

As also shown in Figure 16, some of the column units C may be configured to allow ingress of air, either through a louvered ventilation structure 153 or some other ventilation structure suitable for convective or forced air flow. This is particularly useful for large scale buildings to allow central areas to achieve adequate mixed mode or fully natural ventilation without extensive air ducting being provided. Such embodiments of the invention have the advantage of reduced energy consumption.

The column unit C in this instance has a flat hexagonal portion 86 which is modified to include an upwardly projecting louvered ventilation structure 153, the louvered ventilation structure being sufficiently upstanding to avoid ingress of rain water which collects in the channels defined between primary and secondary domes and flows along the flat surface including the hexagonal portions 86.

In an alternative embodiment, the height of the support columns 10 may be sufficient to allow one or more additional floors to extend beneath the roof structure 2. For example, one of the levels may be used for a car park facility beneath or above the area used commercially, for retail or other purposes. In such an embodiment, it may be desirable to use primary domes 5 with a span of 32 metres, measured between parallel sides of the octagonal figure 7, with the span of the secondary domes 6 being correspondingly changed to 16 metres, measured from the apex of triangular figure 8 to the middle of the opposing side of the triangular figure. Such dimensions have been found to integrate conveniently with the preferred layout for car parking.

The construction of the roof structure 2 on-site will typically start by erecting column units C. including temporary ties to provide stability until the loading on each supporting column 10 is balanced. Link units L between column units C are then installed, followed by ring units R of the primary domes 5. Finally the apex unit A of each primary dome S is lowered into place.

The above described embodiments allow the roof structure 2 to be designed such that forces are well distributed, allowing natural timber to be used.

The above described embodiments allow flexibility in the way in which buildings are designed and constructed, it being evident that the layout of primary domes 5 and secondary domes 6 corresponding to the hexagonal figures 7 and triangular figures 8 in Figures 1 and 2 could be varied to include greater or smaller numbers of each type of dome and to vary the way in which hexagonal and triangular figures are interconnected. Examples of different variants are shown in Figure 19. A particular advantage of interconnecting hexagonal and triangular figures may be illustrated by looking at the right hand side of Figure 1 and 2 where the roof structure corresponding to the assembly of a number of hexagonal figures 7 is provided with a planar storefront simply by using the triangular figures 8 to mt ill the gaps between hexagonal figures at the edge of the building. As described above, a further advantage of having the flexibility of using both the hexagonal large span primary domes 5 and triangular small span secondary domes 6 is to readily accommodate both large scale open plan areas and smaller scale, lower roofed areas within a building. In the case of a supermarket for exawtple, checkout areas and retail areas need to have preferably large span high roof workspaces whereas storage and office space requires preferably smaller span areas with a low roof to allow easy compartmentalisation of these areas.

The particular configuration of the column unit C and link unit L has the advantage of providing good drainage channels by virtue of the flat surfaces between the raised portions of each adjacent dome and the entire structure is readily tilted relative to the horizontal by a small amount to promote natural run off of rain water. Thermal insulation and waterproof layers 200, 201 are readily added to the overall structure once completed, or preferably added to the modular units during sub-assembly off-site. The roof surface may have an insulation layer within the construct of each panel 15, 16 or affixed to an inner or outer surface of each panel. Examples are shown in Figure 20 together with details of the joint arrangement between panels.

Further embodiments are envisaged within the scope of the invention which is defined by the scope of the appended claims.

Claims (1)

1. <claim-text>CLAIMS: 1. A building system having a roof structure comprising a skeletal framework of struts connected at joint nodes to form a triangular lattice; the framework defining a plurality of interconnected domes of two types, the first type of dome comprising a primary dome; each of the primary domes having mutually the same configuration of struts and each primary dome being supported at support nodes where struts are connected to supporting columns located at apeces of a respective regular hexagon as seen in plan view; the second type of dome comprising a secondary dome smaller than each primary dome, each of the secondary domes having mutually the same configuration of struts and each secondary dome being supported at support nodes where struts are connected to supporting columns located at apeces of a respective equilateral triangle as seen in plan view; the support nodes of adjacent domes being shared so that supporting columns mutually support adjacent domes; and wherein the arrangement of domes in the complete framework corresponds to a geometrical figure formed of interlocking hexagons and triangles with apeces corresponding to the positions of the support nodes supporting the primary domes and secondary domes respectively.</claim-text> <claim-text>2. A building system as claimed in claim 1, wherein the framework is assembled from a set of replicated modular units of a number of types, each modular unit of a given type comprising a respective configuration of struts.</claim-text> <claim-text>3. A building system as claimed in claim 2 wherein the modular units comprise four types; a column unit comprising six struts joined in splayed relationship to a respective one of the supporting columns with outer ends of the struts at apeces of a hexagonal configuration of transverse struts; an apex unit comprising an assembly of struts of hexagonal outline and defining an apex of one of the primary domes; a ring unit comprising an assembly of struts with edge struts defining a hexagonal outline, a group of six ring units co-operating in annular formation with abutting edge struts to define a hexagonal aperture receiving one of the apex units,-and a link unit in which the struts define a rectangular portion with end struts adapted to fit to abut the transverse struts of adjacent column units and side struts from which triangular portions extend at an inclined angle relative to the plane of the rectangular portion and adapted to abut the edge struts of adjacent ring units when the supporting columns to which the link unit is connected are peripheral to a primary dome.</claim-text> <claim-text>4. A building system as claimed in claim 3 wherein each secondary dome is formed by three link units extending in triangular formation between three supporting columns in an equilateral triangular arrangement and wherein abutting triangular portions of the link units define an apex of the secondary dome.</claim-text> <claim-text>5. A building system as claimed in any of claims 3 and 4 wherein at least the apex units, ring units and link units comprise struts formed of natural timber.</claim-text> <claim-text>6. A building system as claimed in any of claims 2 to 5 wherein the modular units further comprise roof elements assembled with the respective configuration of struts, the roof elements being selected from a group Comprislngy insulating panels; transparent panels; and ventilation structures.</claim-text> <claim-text>7. A building system as claimed in claim 6 wherein at least one of the primary domes includes an apex unit having a ventilation structure.</claim-text> <claim-text>8. A building system as claimed in any of claims 6 and 7 wherein at least one of the domes is supported by at least one column unit having a ventilation structure.</claim-text> <claim-text>9. A building system as claimed in any preceding claim wherein the support nodes are arranged such that a locus of a first group of the support nodes defines a first planar surface which is inclined at a first angle relative to the horizontal whereby the roof structure is correspondingly inclined.</claim-text> <claim-text>10. A building system as claimed in claim 9 wherein a locus of a second group of the support nodes defines a second planar surface included at a second angle relative to the horizontal, the first and second planes intersectinq at a ridge line, wherein the roof structure is correspondingly inclined at different angles on either side of the ridge line.</claim-text> <claim-text>11. A building system as claimed in any preceding claim wherein the configuration of struts of each of the primary domes comprises joint nodes which lie on a spherical surface.</claim-text> <claim-text>12. A building system as claimed in any preceding claim comprising a tie structure arranged to restrain outwardly radial movement of the support nodes with respect to each dome.</claim-text> <claim-text>13. A method of constructing a building comprising the steps of; constructing a roof structure comprising a skeletal framework of struts connected at joint nodes to form a triangular lattice; assembling the framework to define a plurality of interconnected domes of two types, the first type of dome comprising a primary dome; each of the primary domes having mutually the same configuration of struts and each primary dome being supported at support nodes where struts are connected to supporting columns located at apeces of a respective regular hexagon as seen in plan view; the second type of dome comprising a secondary dome smaller than each primary dome, each of the secondary domes having mutually the same configuration of struts and each secondary dome being supported at support nodes where struts are connected to supporting columns located at apeces of a respective equilateral triangle as seen in plan view; erecting supporting columns whereby the support nodes of adjacent domes are shared so that supporting columns mutually support adjacent domes; and io wherein the arrangement of domes in the complete framework corresponds to a geometrical figure toned of interlocking hexagons and triangles with apeces corresponding to the positions of the support nodes supporting the primary domes and secondary domes respectively.</claim-text> <claim-text>14. A method as claimed in claim 13, comprising assembling the framework from a set of replicated modular units of a number of types, each modular unit of a given type comprising a respective configuration of struts.is. A method as claimed in claim 14 comprising of f site assembly of modular units comprising four types; a column unit comprising six struts joined in splayed relationship to a respective one of the supporting columns with outer ends of the struts at apeces of a hexagonal configuration of transverse struts; an apex unit comprising an assembly of struts of hexagonal outline and defining an apex of one of the primary domes; a ring unit comprising an assembly of struts with edge struts defining a hexagonal outline, a group of six ring units co-operating in annular formation with abutting edge struts to define a hexagonal aperture receiving one of the apex units; and a link unit in which the struts define a rectangular portion with end struts adapted to fit to abut the transverse struts of adjacent column units and side struts from which triangular portions extend at an inclined angle relative to the plane of the rectangular portion and adapted to abut the edge struts of adjacent ring units when the supporting columns to which the link unit is connected are peripheral to a primary dome.16. A method as claimed in claim 15 comprising forming each secondary dome from three link units extending in triangular formation between three supporting columns in an equilateral triangular arrangement and wherein abutting triangular portions of the link units define an apex of the secondary dome.17. A method as claimed in any of claims 14 to 16 comprising assembling the modular units to further comprise roof elements assembled with the respective configuration of struts, the roof elements being selected from a group comprising; insulating panels; io transparent panels; and ventilation structures.18. A method as claimed in any of claims 13 to 17 comprising assembling the framework such that a locus of a first group of the support nodes defines a first planar surface which is inclined at a first angle relative to the horizontal whereby the roof structure is correspondingly inclined.19. A method as claimed in claim 18 wherein a locus of a second group of the support nodes defines a second planar surface included at a second angle relative to the horizontal, the first and second planes intersecting at a ridge line, wherein the roof structure is correspondingly inclined at different angles on either side of the ridge line.20. A method as claimed in any of claims 13 to 19 comprising connecting to the roof structure a tie structure arranged to restrain outwardly radial movement of the support nodes with respect to each dome.21. A building comprising a building system as claimed in any one of claims 1 to 12.22. A building system substantially as hereinbefore described with reference to and as shown in any of the accompanying drawings.</claim-text>