WO2000022248A1

WO2000022248A1 - Method and apparatus for space frame construction

Info

Publication number: WO2000022248A1
Application number: PCT/GB1999/003190
Authority: WO
Inventors: Dennis Stubbs; Alan White; Nicholas Mark Middleton
Original assignee: Technitube Access Engineering Ltd.
Priority date: 1998-10-14
Filing date: 1999-10-13
Publication date: 2000-04-20
Also published as: AU6213599A; GB9822406D0

Abstract

The node described is provided with a channel or tubular section through which a longitudinal or transverse chord member can pass either continuously or can be connected in end-to-end relationship by means of being pinned therein and to another like member within said channel or section such that the structural continuity and therefore the load bearing capacity is drastically increased. The node is provided with a pair of angularly orientated flanges hich depend beneath said channel or section and allow for the connection of diagonal web members, also by means of pinning. Depending on the load which the space frame is to carry, and the desired depth to which the diagonal web members are to depend beneath the plane of the chord members, the pins between the nodes to said chord members can be removed and the nodes can be slid therealong without requiring to disconnect the diagonal web members, allowing for great flexibility and ease of construction.

Description

Method and Apparatus for Space Frame Construction

This invention relates to an improved method for space frame construction, and also to apparatus, in particular the components used in their construction.

Space frames are commonly used to allow human or robot access to typically inaccessible parts of structures by providing a platform which is suspended or otherwise attached to the said structure and which is capable of supporting the weight of the humans or robots working on the structure. These are only a few examples of the great number of uses to which space frames may be put, other examples including temporary scaffolding solutions , stage construction, roofing, provision of temporary and permanent bridges and buildings .

Such space frames when used as a temporary structure offer an alternative to conventional "tube and fitting" scaffolding techniques which suffer from the disadvantages that scaffolding is time- consuming to erect in comparative configurations, has only a limited load carrying capacity, and as a result of its usually "ground-up" erection, is often precluded from use where the foundations on which such scaffolding is to be erected are in themselves inaccessible, for example by being under water. Additionally the number of contact points required for secure and safe scaffolding can be excessive which is in many circumstances impractical and a potential liability.

Space frames in general have excellent strength-to-weight ratios which makes them ideally suited to such applications. Their ease of assembly and reconfigurability are further advantages over conventional scaffolding which has increased their popularity recently. A most common use for a space frame is to provide a working platform underneath a bridge in which case the space frame is generally suspended underneath the bridge either by cables which depend from underneath the arches of the bridge, or by a cantilever mechanism attached to the upper surface of said bridge. An alternate common application for space frames is in the structural alteration, repair or simple cleaning of skyscraper-type buildings in which case the space frame is usually bolted to a vertical structural member of said building or suspended by a cantilever mechanism attached to the roof of said building.

Although the following description of the invention relates almost exclusively to the use of space frames in connection with the provision of access to structures, it will be instantly appreciated from a consideration of the above and of the invention by those skilled in the art that the space frames described hereinafter have particularly wide application, and not merely in the field of providing human and robot access to otherwise inaccessible portions of existing structures, although the versatility of the space frames described below permit this with ease. Indeed it is the intention of the applicant that the space frame o f the invention may be used in the actual construction of structures where an aesthetic effect combined with structural strength is required.

The main design considerations in space frame construction are that the space frame should be able to carry typically a load many times its own weight, and as a whole must be capable of being moved simply and quickly, without a requirement for specialist knowledge. There is a further requirement that the space frame is versatile in that it must be capable of being constructed so as to provide a working platform of irregular shape such that the space frame can be positioned around or beneath a structure o f an accordingly irregular shape, and with discontinuities in the said platform to allow structural support members or platform supporting devices to pass through the said platform or simply to allow refuse created on the platform to be easily disposed of.

As a result of the above considerations, many different space frame constructions have been proposed, but in the interests of brevity, only two such constructions are discussed here, as these two are considered to be most relevant to the present invention and also typify the current state of the art most particularly. These are based on firstly a Modular system, and secondly a Continuous system.

US Patent No. 5214899 discloses a modular truss frame (or space frame) system which can be assembled in a variety of sizes and configurations and which is constructed from a number of chord members, node members, and diagonal web members. The space frame is constructed by first constructing a generally planar rectilinear lattice from the chord members by using the node members to connect said chord members in end-to-end and perpendicular relationship. The chord members are generally identical and in the same plane as one another such that a planar rectangular lattice results which is made up of a plurality square sections of four chord members, each chord member being connected at its ends by a node member. A second lattice is identically constructed from nodes and chord members but is of a dimension which is shorter and narrower than the first lattice by a single chord member length in both these directions. This facilitates the positioning of the second lattice above the first lattice and separated by a perpendicular distance determined by the particular configuration of the node, such that all the node connectors of the second lattice lie above the geometric centres of the square sections of the first lattice. In this condition, the diagonal web members can be connected to the nodes of the second lattice to depend therefrom at a predetermined angle depending on the distance between the said lattices and ultimately be connected to the nodes of the first lattice at the vertices of the square section above whose geometric centre the node of the second lattice lies. The construction of the truss is completed by connecting four diagonal web to every node of the second lattice and connecting the alternate ends of each of these web members to a respective node at a vertex of a square section in the first lattice. This system is hereinafter described as the Modular system, and is in current widespread use.

The Modular system has two important disadvantages. The structural response of the system under load is such that when the space frame is loaded to failure, "brittle collapse" can result. This is a catastrophic failure mechanism whereby a single member fails in compression and the load which it carried is immediately distributed to other members which are already carrying loads of a magnitude which is close to the ultimate compressive strength of those members. Thus the failure of a single member can have a knock-on effect such that the entire space frame collapses under the load it carries . It is obvious that such a failure can have catastrophic consequences where humans are supported on the platform provided by the space frame, and accordingly the Modular space frames are commonly designed with large factors of safety.

The second disadvantage of the Modular system is also connected to the overall strength and load carrying capacity of the space frame, and results from the fact that the entire space frame is comprised of square sections defined by chord members of a length which is usually much shorter than the overall length of the space frame. The discontinuities necessitated by the interconnecting nodes reduce the load distribution and ductility characteristics commonly associated with a Continuous space frame system and the members which constitute space frames of a Modular nature are generally more substantial to compensate for the reduced load carrying capacity.

It should be pointed out that the construction of the space frame using a plurality of identical chord members and the large factors of safety incorporated in the design of the Modular space frame does allow for one or other of the chord sections to be removed from the upper lattice during the use of said space frame, and accordingly the Modular system has some inherent versatility.

It will be appreciated that the nodes used in space frame construction often form the most significant cost element thereof, both in terms of manufacturing complexity of the nodes per se and in terms of the overall cost to the user of the space frame as taking into account the longevity and durability thereof. When it is also considered that the particular configuration of the node is vital in determining the strength and structural rigidity characteristics of the resulting space frame, it can be easily understood that the node is of crucial importance.

Continuous space frame systems attempt to overcome the disadvantages resulting from the use of discontinuous members as in the Modular system, and accordingly the lattice structures of the Continuous space frame are constructed from a plurality of longitudinal members and transverse members, the longitudinal members being of a length equal to the overall length of the space frame and the transverse members being equal in length to its overall width. The Continuous space frame is constructed by first laying a number of longitudinal members in parallel configuration and positioning the transverse members thereacross perpendicular to said longitudinal members and connecting the members at their points of intersection by a bolt which passes through each member. Diagonal web members are provided and the construction if the Continuous space frame is similar to that of the Modular space frame in that a second lattice of reduced overall dimensions compared to those of the first lattice is constructed in similar fashion to and positioned above the first lattice to allow the diagonal web members to connect the two said lattices as previously described. The fundamental constructional difference between the Continuous system and the Modular system is the use of continuous longitudinal and transverse members in the Continuous system. A degree of modularity in the Continuous system is provided only in that the diagonal web members are simply tubular sections with their ends flattened and bent such that the said ends lie in a plane parallel with the respective lattices to which either end is attached. The flattened ends of the diagonal members are provided with apertures to receive a bolt and in similar manner to the Modular system, four diagonal members attach every intersection point of the longitudinal and transverse members of the second smaller lattice to corresponding intersection points of the first lattice, the second lattice being positioned such that its intersection points lie geometrically centrally of the square or rectangular section of the first lattice defined by the intersection points thereof. The Continuous space frame is completed by securing the flattened, bent ends of the diagonal members to the respective lattices, the location of the said diagonal members optionally being facilitated by the bolts provided through the intersection points of the said lattices.

The above space frame which is visually similar to the of the Modular system results, but on closer inspection a skilled eye instantly notices the fact that the longitudinal members and transverse members are located in two separate parallel planes which can render decking of the space frame problematic. This is because in the Continuous system described above, the square decking sections are supported only along a pair of parallel edges as opposed to around their entire periphery as in the Modular system. Henceforth the bending stresses in the decking sections are greater when used to create a platform on a Continuous space frame.

Other but nonetheless important disadvantages associated with the Continuous system are the difficulty of providing suspension or attachment points from which or by which the space frame can be located proximate to a desired portion of a structure, and the difficulty of providing handrail attachments around the periphery of the platform provided by the space frame, all of which remain substantially intractable problems. These disadvantages result from the lack of connection means (which were provided by nodes in the Modular system) either on the platform or around its periphery

Furthermore, although the Continuous space frame possesses the strength and flexural rigidity advantages associated with continuous chord members, and when overstressed would fail in tension which is far more desirable than failure in compression as the space frame would audibly and visibly deteriorates before failure, the functionality and versatility associated with the Modular system is lost. Accordingly certain circumstances necessitate the use of a Modular space frame, and other circumstances allow a Continuous space frame to be used, and these circumstances are often mutually exclusive.

A yet further disadvantage of the Continuous space frame is the inherent weakness in the diagonal members caused during the plastic deformation and subsequent mechanical treatment of their ends.

A still further disadvantage of both the Modular and Continuous systems is the relative difficulty with which they are constructed. Both systems involve precise positioning of the first and second lattices before the diagonal members can be connected thereto, which is in itself a laborious task involving precision. Furthermore, in the case of the Continuous system, although the space frame is constructed at ground level, the frame undergoes a certain amount of relaxation when it first carries a load and as a result there is significant elongation and/or curvature of the various members as they settle under the load. Although relatively safe, this provides the space frame with an often irregular shape and the platform may be uneven which is undesirable from the point of view of humans working on and walking over said platform.

It is an object of this invention to provide a space frame which combines the durability, enhanced load distribution characteristics, and failure properties of the Continuous system with the versatility of the Modular system, but which mitigates against the disadvantages described above of both these systems.

It is a further object of the invention to provide an improved configuration of node which has greater versatility than the currently available prior art systems, and which provides additional functionality for attaching the space frame to structures , suspending the space frame, or providing a simple means of attachment for handrails and the like.

It is a further object of the invention to provide a space frame which is simple and extremely quick to construct as compared to those systems described.

It is further object of the invention to provide a space frame which can be suspended from or attached to a structure with a minimum number of contact points.

It is a further object of this invention to provide a node and method of constructing a space frame using said node which allows for incremental and decremental alterations in the depth of the space frame without requirement for complete reconstruction of said space frame.

According to the invention there is provided a node used in the construction of a space frame, said node capable of being used for the connection of longitudinal and transverse chord members and/or diagonal web members, said node being provided with a plurality of flanges and webs between or to which said chord members and diagonal web members may be connected, characterised in that the flanges and webs of the node are configured to permit: i. at least one of said chord or diagonal members to pass continuously through said node, and/or ii. contiguous interconnection of a pair of said chord or diagonal members to render the interconnected members substantially continuous through the said node.

It is preferable that the apertures are provided in the said webs and flanges of the node, and corresponding apertures are provided in the longitudinal and transverse chord members, and the diagonal web members permitting connection thereof to said node by means of bolts or pins or the like.

The meaning of "transverse" as used herein and applied to chord members is intended to cover the case where the said chord members subtend an angle with the longitudinal chord members which need not be 90°, although the most preferred configuration of the node is to ensure that the longitudinal chords and the transverse chords are perpendicular to one another. It is yet further preferable that the node allows connection of the chord members such that the longitudinal chord members and transverse chord members lie in substantially the same plane.

It is preferable that the flanges and webs of the node define a channel through which one of said chords and or diagonal web members may pass continuously, and most preferably define a channel of substantially the same width and depth as the longitudinal chord member thus allowed to pass therethrough or be contiguously, and yet further preferably matingly, connected to a further longitudinal chord member therein.

In an alternative aspect of the invention the web and flanges of the node define a section of substantially identical shape to that of the cross-section of one of said chords and or diagonal web members which pass continuously through the node.

Preferably the contiguous connection of the said longitudinal chord members is effected by providing said chord members with a pair of tongues in the length direction of the chord and at the ends of said chords, said tongues being are laterally offset in the width direction of the chord so as to allow interlock with a corresponding pair of tongues provided in a second chord member to which said chord member is to be contiguously connected. Such connection is known as a device connection and increases the overall continuity of a space frame so constructed in the longitudinal direction.

Preferably the chord members are capable of receiving a device connector in their ends of the type described above.

Preferably flanges of the channel of the node are each provided with three apertures in alignment such that a bolt or pin can be passed through aligned apertures in the respective flanges. It is yet further preferred that the connection of the device connectors within the ends of the chord members, the connection of one device member to another to provide the contiguous connection of the said chord members, and the connection of the node to said chord members in the vicinity of the contiguous connection is effected by passing pins or bolts through the three apertures of the said node, through apertures provided i. in the chord members and aligned with the apertures of the node, and ii. in the interlocking tongues of the device connectors between the chord members the device connectors further held within the ends of the chord members by means of the said pins or bolts passing through apertures on the alternate ends of the device connector to those at which the tongues are provided which are aligned with the apertures in the chord members.

In a most preferred embodiment of the invention, chord members, and preferably the longitudinal chord members, are provided with apertures along their length at locations such that a node can be slotted over the particular chord member at that position and connected to said chord by suitable means for example pins or bolts. It is to be pointed out that the means by which the node is connected to the chord members is not an essential requirement of this invention, and in certain configurations of space frame constructed according hereto, it is foreseeable that the node may be welded, bonded or otherwise securely affixed to the chord member, and in a most advantageous embodiment, certain flexibility as regards increments or decrements in the depth of the space frame may be provided by simply disconnecting and sliding same along particular chord members, and subsequently reconnecting said nodes. According to a second aspect of the invention there is provided a connector adapted for connection to a node of the present invention, characterised in that said connector has at least one channel section defined by a web and a pair of apertured flanges depending therefrom to allow the connector to be slotted over a chord member and connected to the node by means of the pin or like connector which connects that chord member to the node.

The invention stems from the realisation that chord continuity is more important, as regards the load carrying capacity and failure strength of space frames, in the longitudinal direction than in the transverse direction, and accordingly it is not necessary to provide continuous transverse chord members as in the Continuous system.

The longitudinal direction is commonly defined as the direction between the supporting sides of a rectangular space frame, and in this instance, it would be common to provide a number of continuous longitudinal chords to which nodes of the invention could be connected along their lengths without requirement for splicing. The channel of the node is simply slotted over the section of the longitudinal chord member at the desired position along its length whereat suitable apertures are provided in said section to allow a pin inserted both through apertures in the respective webs and/or flanges defining the channel of the node and the section of the chord to connect the node thereto.

It will be instantly appreciated that this method of connection applies equally in the case where a device connection between a pair of longitudinal chords is required, and provides the node of the invention with enhanced versatility without compromising the overall strength of space frames constructed in this manner. Furthermore, the assembly of space frames using the node of the invention is a simplified process which may increase the safety of space frames because the relatively complex assembly of both the Modular and Continuous space frames increases the likelihood of construction errors.

The further advantages of space frames constructed using the node of the present invention are many and various, and the most important are now described.

The planar orientation of the longitudinal and transverse chord members renders the decking procedure for the creation of a platform on the space frame simple, as in the Modular system.

The provision of handrails and additionally the lifting of the completed or partially completed space frame is easily effected by simply slotting a connector of the type described in the second aspect of the invention over a chord or pair of interconnected chords at a node location, or alternatively at a node which is provided at an intermediate point along the length of a chord member. Indeed this connector may have a variety of uses including the provision of an attachment point to the structure which the space frame surrounds, a connection point for conventional scaffolding, or for a direct physical connection to the space frame itself, which may be used for lifting same.

A further advantage of the simple connector is the facility for the provision of runners or guide rails on the surface of the platform to enable robots to guide themselves around said platform or to provide a support rail for the frame allowing translation thereof.

A yet further advantage of the simple connector is that it may provide an attachment means to external structures, for example another space frame. Henceforth a number of separate space frames may be easily and simply interconnected.

As mentioned above the node of the present invention has wider application than merely exclusively to flat plane space frame construction, and in particular it is considered that novel building structures may be simply and quickly erected using this concept of node connection.

The versatility of space frame construction provided by the node can be further appreciated when it is considered that the nodes can be positioned at any desired location along the length of the longitudinal chords. This alters the depth of the space frame and thus its load bearing capacity to weight ratio is accordingly amended giving greater flexibility in application. Also the inherent redundancy within the space frame permits the removal of a longitudinal member or transverse member while the space frame is in position or carrying a load.

Circular or partially curved space frames (wherein the platform is maintain substantially planar) can be constructed by cranking the ends of the transverse chord members and cambered space frames (wherein the platform is provided with camber) can be constructed by rotating either the longitudinal or transverse chord members about the pin by which they are interconnected or connected at to node. The provision of such a facility and the provision of a "hinged" space frame has heretofore been complex in practice, and this advantage further enhances the versatility of space frames constructed using the node as described.

A yet further advantage associated with the excellent load distribution characteristics of the novel node is the facility for designing particular space frames with platforms through which portions o f the structure being accessed pass . The built in redundancy renders it simple for a space frame designer to configure the shape of the platform according to the structure which is to be accessed. Almost any shape and configuration of platform is thus possible, and henceforth the said space frame is adaptable to provide a greater range of structures of greater value to structural and civil engineers.

The fabrication of the node is also simplified, and the node itself may be easily lengthened effectively itself performing the function of a chord, and these advantages and the others mentioned above will become evident from the specific description of the invention now provided by way of example only and with reference to the accompanying figures, wherein:

Figures l a, b, c show respectively a perspective view, an end elevation, and a side elevation of the node of the present invention,

Figure 2 shows an element used in the construction of the node of Figure l a,

Figures 3a, b, c show different views of a second element which in combination with elements of the type shown in Figure 2 form the node of Figure l a,

Figure 4 shows a yet further element used in the construction of the node of Figure l a,

Figures 5a, b and c show various views of the node of Figure l a as constructed using the elements shown in Figures 2, 3 and 4, Figures 6a and b show respectively elevation and/or plan views of the longitudinal cord members used in the construction of space frames according to the invention,

Figures 7a, b and c show various views of the device connector device used for connecting the longitudinal cord members shown in Figures 6,

Figures 8a and b shown respectively elevational and plan views of the transverse cord members used in the construction of space frames according to the invention,

Figures 9a and b show respectively elevational and plan views of the diagonal web members used in the construction of space frames according to the invention,

Figures 10a, b and c show the end connectors provided at the end of the diagonal web members shown in Figures 9,

Figures 1 1 a, b and c shown respectively a perspective view, a plan view, and a sectional view of a simple connector according to a second aspect of the invention,

Figure 12 shows a hand rail which can be connected to the space frame using the simple connector of Figures 11 ,

Figure 13 shows a partially constructed section of a space frame to indicate the overall construction.

Figures 14a, 14b, 14c show respectively a perspective view, a side elevation, and an end elevation of an alternate configuration of node according to the invention. Figures 15a, 15b show respectively a plan view and an end elevation of a pin connection across a channel of a node; and

Figures 16a and 16b, provide a diagrammatic illustration of the manner in which the depth of a space frame constructed according to the invention may be varied.

Referring firstly to Figures l a, b, c there is provided a node to for use in space frames construction which is provided with a central channel 4 defined on either side by flanges 6, 8 and an interconnecting web 10. Externally of the said channel 4 there are provided perpendicular side flanges 12, 14, 16, 18, and depending from the interconnecting web 10 there are further provided angled flanges 20, 24, 26, downwardly depending angled flange 22 being hidden from view. Apertures are provided in all the webs and flanges of the node and are denoted by the prime of the reference numeral indicating the particular web or flange in which said apertures are provided. Exceptions to this rule are given for those webs or flanges which are provided with more than a single aperture, and in these cases apertures are further denoted by reference letters x, y of z.

In Figures lb, and l c which provide different views of the node of figure l a, further apertures 15'and 25' provided in the flange portion 15 which interconnects side flanges 14 and 18, and in intermediate portion 25 which connects downwardly depending angle flanges 24 and 26. It should be noted that corresponding flange portions and apertures exist on the alternate sides of the node from that side which is shown in figures l b an l c.

Although it is possible from the node of figures l a, b, c to be cast as a single article, it is a much simpler and less expensive proposal to manufacture from a number of discrete elements as shown in figures 2, 3 and 4 which can be welded together quickly and effectively without significant degradation of the structural qualities of the node. In this regard, the node is constructed of a pair of side flange elements 30 provided with apertures 32, 34, 36 which correspond to apertures 14', 18', and 15' in Figure lb. The side flange element 30 is provided with angled slots 38, 40 which subtend an angle θ with a vertical line through the said element which corresponds to the angle of the downwardly depending flanges 20, 24, 26 as shown in Figure l a. These flanges and flanges 6, 8 are formed from sheet elements 42 also provided with apertures in the desired locations which are bent at a desired location along their length as is shown in Figures 3a, 3b and 3c. Once a pair of bent elements 42 have been inserted into the slots 38, 40 of a pair of side flange elements 30, and a base web element 50 can be inserted between the substantially vertical disposed elements 42 to form the channel 4 of the node. The resulting configuration is shown in Figures 5a, 5b, 5c which also indicate the relevant fillet welds which are required to complete the construction of a single node. As can be seen from figures 5a, 5b, 5c welds 52, 54, 56 are applied between the base web element 50, the bent sheet elements 42 and the side flange elements 30 on the underneath of the said base web element 50. In Figure 5b, welds 58, 60 are applied between the bent sheet elements 42 and the side flange elements 30 externally of the channel 4, and finally in Figure 5c, further welds 62, 64, 66 are provided between these two components and on either side of the channel 4. An extremely rigid and structurally strong node configuration results.

The interlocking construction provides a node of extreme strength and rigidity

Figures 6a and 6b show the typical configuration of a longitudinal cord 70 provided at an intermediate location with apertures 72, 74, 76 in a spaced relationship which corresponds to the spacing of the apertures 6X\ 6Y', 6Z', 8X', 8Y\ 8Z' provided in the vertical flanges 6, 8 which partially define the channel 4 of the node shown in Figure 1. The longitudinal cord member 70 is provided at either end with further apertures 78, 80 and are hollow such that a device connector 82 of the type shown more particularly in figures 7a, 7b, 7c can be received in the open ends of the said longitudinal cord members 70.

The device connector 82 as shown in said Figures 7 is provided with a pair of spaced tongues 84, 86 which are laterally off set in one direction from the centre of the said device connector so as to permit interengagement of a corresponding pair of tongues laterally off set in the alternate direction on a different device connector shown in dotted lines in Figure 7a at 88.

The respective tongues 84, 86 are radiused at their extremities as shown at 90 in Figure 7b, and are further provided with apertures 92, 94, and 96. The spacing of the said apertures 92, 94, 96 is important in that on complete insertion of the device connector 82 into the open end of the a longitudinal chord member 70, the aperture 96 will be in alignment with the aperture 78 of the cord member 70, the apertures 92, 94 will be in alignment with the apertures of the corresponding and inter engaged tongues of an adjacent device connector 88, and the spacing of the apertures 78 and 96, 92 and 94, and the aperture provided at the end of a chord member attached to the chord member 70 by means of said device connector 82 will be such as to correspond to the spacing of apertures of 6X'. 6Y', 6Z', 8X', 8Y', 8Z'. Such spacing ensures that adjacent chord members 70 which are interconnected using device members 82 can be successfully pinned within the channel 4 on the node which accordingly provides a rigid and secure connection between said cord members 70. Figures 8a and 8b shown a transverse chord member 100 which is also hollow and provided with apertures 102, 104 to facilitate pinning between the side flange members 12 and 14, and 16 and 18 of the node.

Figures 9a and 9b show a diagonal web member 110 which is provided at its ends with a double tongued connector 112 shown more clearly in Figures 10a, 10b, and 10c.

The said connector 112 is provided with a pair of tongues 114, 116 with apertures 118 and 120 provided therein and in spaced relationship but substantially centrally located of the cross section of the diagonal web member 1 10.

The spacing of the tongues 114, 1 16 allows for their disposition on either side of the downwardly depending angled flanges 20, 24, 26 of the node, and once the apertures 1 1 8, 120 are brought into alignment with the apertures provided in said downwardly depending angled flanges, the diagonal web members can be connected simply to the node by pinning or with a suitable bolt. It should be noted at this stage that the correction of the diagonal web members provides a rotational degree of freedom, and it is this feature which allows the depth of the space frame to be varied as desired.

Referring now to Figures 11 a, l ib, l i e a hand rail connector 130 is shown and is provided with a box section 132 and a channel 134 defined on either side by a downwardly depending flanges 136, 138 140, 142 which are provided with apertures 136', 138', 140', 142'. The spacing of said apertures corresponds to the spacing of the apertures 6X', 6Z', 8X', and 8Z' provided in the flanges 6, 8 which define the channel 4 of the node. Such spacing permits exceedingly simple connection of the connector 130 to the node 2 by simply removing any pins which currently connect longitudinal chord members within the channel 4 of the node, slotting the connector 130 over said node and longitudinal chord members seated therein ensuring that the downwardly depending flanges 136, 138, 140, 142 slot over and to the outside of the flanges 6, 8, which define the channel 4 whereafter the removed pins can simply be reinserted ensuring both secure connection of the chord members to the node and also of the connector 130 to said node. It is to be appreciated that the box section 132 shown in Figures 1 1 and which is adapted to receive square sectioned hand rail elements of the type shown in Figure 12 at 150 can easily be replaced with a hook or other connection means such that a number of connection points can be provided across the surface of the space frame for lifting or manoeuvring the completed space frame. Such connectors 130 increase the versatility of the invention and are considered as covered by this application.

Referring finally to figure 13, a partially completed space frame 160 is shown, and it will be instantly appreciated that the nodes 162, 164, 166, 168 which are used to connect the various chord members 170, 172, 174 and 176 together are identical to the node 178 to which the various diagonal web members 180, 182, 184, 186 are connected. The fact that only one particular type of node is required to complete any size and configuration of space frame is of great advantage, and drastically simplifies the construction process of space frames.

Simple connectors 188, 190, and 192 are shown connecting hand rail portions 194, 196 in Figure 13, but it is to be appreciated that the box section of said simple connectors may be replaced by simple hooks to facilitate the lifting of a space frame provided with such simple connectors, or to provide support locations for such a space frame.

It will also be seen from Figure 13 that the longitudinal chord members 170, 174 terminate flush with the end of the nodes 164, 166, but it is to be appreciated that this particular configuration is shown in the interests of clarity and that the cord members 170, 174 will typically extend continuously through the channel provided in said nodes 164, 166, and indeed may extend continuously through may similar nodes orientated identically to nodes 164, 166 or be terminated either in a device connection in the middle of the channel 4 of the node as previously described, or simply terminating at the end of the length of the particular space frame being constructed. It will be further appreciated that the space frames using the node of the present invention may be designed according to specific requirements, and in this regard the distant between respective nodes in the direction of the longitudinal cord members can be varied depending on the particular load which a space frame is to carry. Furthermore, the depth of the nodes 178 below the cord member 170, 172, 174, 176 can also be varied, and such variable parameters have a significant effect on both the overall weight of the space frame, and its strength and load carrying capacity. Where a space frame is required to carry a substantial load it is desirable that the distance between respective nodes in the direction of the cord members is reduced, and that the depth of the nodes 178 beneath said cord members is increased.

Regardless of the specific strength and weight considerations, the construction of space frames according to the invention is identical in all respects with the exception that an increase number of nodes will be required to be connected to the chord members in circumstances where a particularly strong space frame is required. Referring now to Figure 14a, there is shown an alternative configuration of node 200 provided with a pair of downwardly depending flanges 202, 204, 206, 208 with apertures provided therein and indicated by the prime of the reference numeral denoting the particular downwardly depending flange. These apertures allow for connection of diagonal web members as hereinbefore described with regard to Figures 9 and 10.

The node 200 is further provided with side flanges 210, 212, also provided with aperture therein to allow for connection of transverse members (not shown) to said node. It will be appreciated that a space frame constructed using the node of Figures 14a, 14b, 14c will require transverse members provided with double tongued connectors at their ends similar to those shown at the ends of the diagonal web member 1 10 shown in Figures 9.

The node of Figures 14 is further provided with a central circular channel 214 adapted to receive a longitudinal cord member which is of circular cross section. Although the said channel 214 is not shown with apertures for connection of the node to a cord member or suitable cross section, it will be appreciated that connection of the node can be accomplished in similar manner to that described above in relation to the node of Figures 1 if relevant apertures are provided.

The node 200 further comprises a perpendicular recessed protrusion 216 which may perform a variety of different functions including the provision of lifting points for a space frame constructed from such nodes, or for the provision of handrail attachment points.

Referring now to Figures 15a, 15b, the connection of a pair of longitudinal cord members 70 within the central channel 4 defined by flanges 6, 8 of a node of the type shown in Figure 1 is illustrated. Each of the cord members 70 is provided with a device connector 82 provided with tongues 84, 86 in interlocking configuration. From Figure 15a, the alignment of the various apertures 6Y', 92, 94', 94, 92', and 8Y' is immediately evident. A pin 220 is inserted through these various apertures until bores 222, 224 provided within the body of the pin 220 are disposed on either side of flange 6 and flange 8.

At this stage, cotta pins 226, 228 are inserted through the said bores until their travel is arrested by stop blocks 230, 232 provided at the ends of said cotta pins. The said stop blocks are provided with apertures 234, 236 which are adapted to receive circular springs clips 238, 240 whose diameter is less than the length of the cotta pins 226, 228 such that portions of the circular clips 238, 240 rest on one side of the cotta pin. The resultant combined width of the cotta pins and the circular clips is greater than the diameter of the bores 222, 224, and the cotta pins are therefore prevented from simply falling out of the bores as shown. Ideally, the pins are fabricated in grade VN16T with a bright zinc plating, and are 18mm in diameter.

Finally, referring to Figures 16a, 16b, a plurality of nodes 2 are shown in spaced relationship along a longitudinal cord member 70 and from each of said nodes 2 there depends diagonal web members 110 which are in turn connected to further nodes 2. An end elevation of a single section of a space frame 250 is shown in Figure 16b and it is to be assumed that for the purposes of explanation only that the transverse cord member 100 remains constant in length, and is ideally 1.2 metres.

Examining in detail the portion of the space frame of Figure 16a shown within dotted lines, it will be appreciated that if the node 2a is fixed, whereas for the purposes of explanation, the node 2b can translate along longitudinal cord member 70a, diagonal web member 110a, 110b, are free to rotate, and node 2c and longitudinal cord member 70b may be raised as a result of said rotation, then an increase in the distance between nodes 2a, 2b along cord 78 as shown at 260 will result in a decrease of the depth of the particular space frame portion as shown at 262, and vice versa.

Thus, if a predetermined distance between respective nodes along an upper longitudinal cord member is chosen, the depth of the space frame can be automatically determine, the ductility and load distribution characteristics of the resulting space frame can be simply changed to suit a particular set of circumstances, and an unprecedented level of flexibility is accordingly achieved. Furthermore, once a predetermined node separation distance has been chosen, and the cord members 70 have been provided with apertures in their sections separated by said pre-determined distance, said cord members can be used in either the upper section (70a) or lower section (70b) of the space frame, and there is no requirement to modify the diagonal web members.

From the forgoing, it will be immediately apparent to the skilled artisan that the node construction of the present invention provides both a radical departure from prior art systems, and may considerably enhance and improve the safety, reliability, structural strength and flexural rigidity characteristics which have heretofore been associated with space frames.

Claims

1. A node used in the construction of a space frame, said node capable of being used for the connection of longitudinal and transverse chord members and/or diagonal web members, said node being provided with a plurality of flanges and webs between or to which said chord members and diagonal web members may be connected, characterised in that the flanges and webs of the node are configured to permit: i. at least one of said chord or diagonal members to pass continuously through said node, and/or ii. substantially contiguous interconnection of a pair of said chord or diagonal members to render the interconnected members substantially continuous through the said node.

2. A node according to claim 1 characterised in that apertures are provided in the said webs and flanges of the node, and corresponding apertures are provided in the longitudinal and transverse chord members, and the diagonal web members permitting connection thereof to said node by means of bolts.

3. A node according to either of claim 1 or 2 characterised in that the node allows connection of the chord members such that the longitudinal chord members and transverse chord members lie in substantially the same plane.

4. A node according to any preceding claim characterised in that the flanges and webs of the node define a channel through which one of said chords or diagonal web members may pass continuously or a pair of said members may be substantially contiguously connected.

5. A node according to claim 4 characterised in that the channel is of substantially the same width and depth as the member passing therethrough or the members being contiguously connected therein.

6. A node according to either claim 4 or 5 characterised in that the said members are matingly connected therein.

7. A node according to any of claims 1 -4 characterised in that the web and flanges of the node define a tubular section of substantially identical shape to that of the cross-section of one of said chord and/or diagonal web members which pass continuously through the node.

8. A node according to any preceding claim characterised in that the connection of the said members to one another and to said node is effected by clevice-type connection means.

9. A node according to claim 8 characterised in that the clevice- type connection means is provided with apertures to allow the passing of a bolt or pin therethrough.

10. A node according to any of claims 4-9 characterised in that the flanges of the channel or closed section of the node are each provided with three apertures in alignment such that a bolt or pin can be passed through aligned apertures in the respective flanges.

11. A node according to claim 10 characterised in that the apertures proximate the ends of the channel or section length are the same distance away from the aperture disposed substantially at the mid-point of the channel or section length.

12. A node according to claim 1 1 characterised in that the clevice- type connection of the ends of said members with one another and with said node, is completed by passing pins or bolts through apertures provided in the clevice-type connection means and through apertures provided in the said node, said apertures being aligned.

13. A method of space frame construction comprising the steps of arranging a plurality of chord members in end to end and transverse relationship, said members being provided with clevice-type connection means, positioning nodes as described in claims 1 -12 over the said chord members at location where same are to be connected to one another or to the nodes, passing pins or bolts through the apertures in the nodes and through apertures in the clevice-type connection means to secure: i. the chord members to the node, ii. adjacent chord members to one another, and optionally iii. the clevice-type connection means to the chords, and connecting diagonal web members having clevice-type connection means to angularly orientated flanges of said nodes by passing pins or bolts through apertures provided in said means and in the flanges of said nodes such that diagonal web members from nodes disposed around the edges of an imaginary quadrangle defined by chord members are brought into proximate relationship for connection together at a single node.

14. A method according to claim 14 characterised in that that the connection of the clevice-type connection means to the ends of the chord members, the connection of adjacent clevice-type connection means to provide the contiguous connection of the said chord members, and the connection of the node to said chord members in the vicinity of the contiguous connection is effected by passing pins or bolts through the apertures of the said node, through apertures provided i. in the chord members and aligned with the apertures of the node, and ii. in interlocking tongues of the clevice-type connection means between the chord members, the clevice-type connection means further held within the ends of the chord members by means of the said pins or bolts passing through apertures on the alternate ends of the clevice-type connection means to those at which the tongues are provided which are aligned with the apertures in the chord members.

15. A method according to either of claims 13 or 14 characterised in that the chord members are provided with apertures along their length at locations such that a node can be slotted over the particular chord member at that position and connected to said chord by pins or bolts.

16. A connector adapted for connection to a node according to claims 1 -12, characterised in that said connector has at least one channel section defined by a web and a pair of apertured flanges depending therefrom to allow the connector to be slotted over a chord member and connected to the node by means of the pin or like connector which connects that chord member to the node.