CANTILEVER SUPPORT AND ERECTABLE STRUCTURES

Abstract: The invention relates to a support (12) for an erectable structure (10), in particular a canopy for a grandstand seating platform (98). The support (12) includes a pliable elongate main member in the form of a frame (26); a plurality of compression legs in the form of A-frames (28) mounted to the frame (26); restraint means in the form of tension wires (30) connected between the A-frames (28) and the frame (26); and an elongate tensionable element in the form of a cable (32). The support (12) is movable between a collapsed and an erect position by pivoting the support (12) about a pin joint (100), through which it is coupled to the seating platform. In a preferred embodiment, a structure (10r) comprises three such supports (12r) coupled by purlins (16r) and including membranes (14r) to define a grandstand canopy.

Description: CANTILEVER SUPPORT AND ERECTABLE STRUCTURES The present invention relates to supports including cantilever supports . The present invention also relates to erectable structures. In particular, but not exclusively, the present invention relates to a cantilever support, an ■ erectable structure, and an erectable grandstand canopy moveable between a substantially collapsed position and a substantially erect position. Erectable structures which are movable between collapsed and erect positions are known, such as tents and the like, and often comprise a substantially rigid frame and a stressed membrane material. Also, permanent fixed structures such as canopies having large, cumbersome frameworks are known. However, such fixed structures suffer from disadvantages including excessive weight, particularly in the case of cantilever canopies, which require excessive supporting framework for a relatively lightweight roof membrane. In the case of erectable structures, these often ..comprise many interconnecting parts, and are often complex and difficult to erect, store and transport. Furthermore, known erectable structures often have internal supporting framework which is disposed coupled to or arranged around an inner surface of the structure. This can reduce inner clearance within the structure beneath the framework, and may require the dimensions of the framework and a stressed membrane of the structure to be increased to provide a predetermined inner clearance. Also, the erectable structure may define a roof for an internal structure, and it may be desired to couple the roof to the internal structure; such internal framework may hamper coupling of the roof to the internal structure, and may be unsightly. One such erectable structure is disclosed in US Patent Number 4,325,207. An embodiment of US' 207 comprises a substantially flat flexible member for bending to the shape of a curved arch. Tension line guides are attached to a side of the flexible member, and first and second tension lines are attached to the side of the flexible member at the tension line guides. The first and second tension lines are attached to respective alternate tension line guides. The tension lines are then tensioned by a motor/pulley arrangement to pull the flexible member into the arch shape, where the tension lines are disposed on the inside of the arch. In another embodiment of US' 207, the tension lines are tensioned by inserting spreader bars extending inwardly of the arch. A further such erectable structure is disclosed in International Patent Publication Number O9708411. An embodiment of GB WO9708411 discloses a tent having fabric sections supported and interconnected by trusses. Each truss has a flexible rib which is elastically deformed into a curved shape. This is achieved by securing a web having a number of support panels on the inside of the rib via connecting elements disposed between adjacent panels and slidably coupled to the rib, and subsequently tensioning the web. It is amongst the objects of the present invention to obviate or mitigate at least one of the foregoing disadvantages. According to a first aspect of the present invention, there is provided a support capable of being reversibly moved between a substantially collapsed position and a substantially erect position, the support comprising: a pliable elongate main member capable of being bent into a curved shape; a plurality of compression legs extending above an upper surface of the main member; restraint means effectively connected between the compression legs and the main member; and an elongate tensionable element coupled between the compression legs; wherein in use, the tensionable element and the restraint means are tensioned as the pliable elongate main member is bent and the support is moved to the substantially erect position. According to a second aspect of the present invention, there is provided a cantilever support capable of being reversibly moved between a substantially collapsed position and a substantially erect position, the cantilever support comprising : a pliable elongate main member for coupling to a rigid support, the main member being constructed and arranged so as to be deformable between the substantially collapsed and substantially erect positions of the cantilever support, wherein in the substantially erect position, the main member is in an elongate curved configuration; a plurality of compression legs mounted at intervals along the length of the main member; respective restraint means effectively connected between each compression leg and a location spaced longitudinally along the main member from the pertaining leg; and an elongate tensionable element coupled between the compression legs; wherein in use, the cantilever support is moved to the substantially erect position by pivoting the main member about the rigid support, to tension the elongate tensionable element and the restraint means and move the main member to the elongate curved configuration. It will be appreciated that the elongate main member is pliable in that it is easily bent, as it has a low bending strength, such that it may be elastically curved into the elongate curved configuration. Furthermore, in the elongate curved configuration, the main member may adopt an arch-like profile. Preferably, the compression legs are mounted along the length of an upper surface of the main member. In a preferred embodiment of the present invention, the compression legs are each pivotally coupled to the main member, and are movable between substantially collapsed and substantially erect positions when the elongate tensionable element is 1 tensioned, by pivoting the main member about the rigid support. When the compression legs are moved to the substantially erect position, they are generally restrained from further movement beyond the substantially erect position. For example, the compression legs may be restrained by the restraint means, which may comprise a plurality of tension members such as tension wires . In alternative embodiments, the compression legs may be restrained by a sheet of a flexible material, which may define the restraint means and the elongate tensionable element. In further alternative embodiments, the compression legs may be rigidly coupled to the main member and disposed in a substantially erect position. It will further be appreciated that the restraint means are effectively connected between each compression leg and the spaced location in that the restraint means may be directly or indirectly connected therebetween. Preferably, the erectable structure is pivotally coupled to the rigid support, which may be a member of a grandstand seating platform. Each cantilever support may be pivotally coupled to the member of the grandstand seating platform at a location intermediate the ends thereof. Conveniently, each cantilever support is pivotally mounted to the member of the grandstand seating platform by a pin joint. The main member may be pivoted about the rigid support, to move the cantilever support to the substantially erect position, by pulling the end of the main member disposed' adjacent the grandstand seating platform towards the platform. The end may be pulled towards the platform by, for example, a winch. Conveniently, the winch includes means for retaining the end of the main member adjacent the platform, such as a clamp. This may allow the winch to be deactivated when the canopy has been moved to the substantially erect position. According to a third aspect of the present invention, there is provided a cantilever support capable of being reversibly moved between a substantially collapsed position and a substantially erect position, the cantilever support comprising.: a pliable elongate main member for coupling part way along the length thereof to a rigid support, the main member being constructed and arranged so as to be deformable between the substantially collapsed and substantially erect positions of the cantilever support, wherein in the substantially erect position, the main member is in an elongate curved configuration; a plurality of compression legs pivotally mounted at intervals along the length, and extending above an upper surface, of the main member, each capable of being reversibly folded away from and towards the upper surface when the cantilever support is moved between the substantially collapsed and substantially erect positions; respective restraint means effectively connected between each compression^ leg and a location spaced longitudinally along the main member from the pertaining leg, to limit the extent of folding movement of the compression legs; and an elongate tensionable element coupled between the compression legs; wherein in use, the cantilever support is moved to the substantially erect position by pivoting the main member about the rigid support, to tension the elongate tensionable element and the restraint means, to fold the compression legs away from the upper surface of the main member and move the main member to the elongate curved configuration . According to a fourth aspect of the present invention, there is provided an erectable structure moveable between a substantially collapsed position and a substantially erect position, the erectable structure comprising at least two spaced supports as previously described herein and a membrane coupled between the supports, whereby movement of the supports to the substantially erect position moves the erectable structure to the substantially erect position. Preferably, the supports comprise the cantilever supports previously described herein. Thus the present invention may provide a cantilever support which is moveable between a substantially collapsed position and a substantially erect position, by pivoting a main member of the cantilever support about a rigid support. The cantilever support may be moved from the substantially erect position to the substantially collapsed position by pivoting the main member about the rigid support in an opposite direction, reducing tension in the elongate tensionable element and the restraint means. This may allow the compression legs to fold towards the upper surface of the main member. Similarly, the present invention may allow erection of an erectable structure to a substantially erect position by pivoting the main members of at least two such cantilever supports, having a membrane coupled thereto, about their respective rigid supports. The erectable structure may similarly be collapsed to a substantially collapsed position by pivoting the main members of the cantilever supports about their respective rigid supports in an opposite direction. This may allow the/each cantilever support and/or the erectable structure to be transported in a substantially collapsed position, erected to a substantially erect position, and collapsed to the substantially collapsed position for storage and/or transportation. Alternatively, the/each cantilever support and/or the erectable structure may be adapted to be permanently or semi-permanently retained in the substantially erect position. The/each cantilever support may have an end which, in use, is adapted to overhang, for example, a grandstand seating platform, and an opposite end which, in use, is adapted to be disposed adjacent to or coupled to the grandstand seating platform. Conveniently, the/each rigid support of the/each cantilever support comprises a member of the grandstand seating platform. The erectable structure is conveniently in the form of a canopy for a grandstand wherein the membrane defines a roof which, in the substantially erect position, overhangs the grandstand seating platform. Alternatively, the/each support may have opposite ends which, in use, are adapted to be coupled to a rigid support, or to respective rigid supports. The erectable structure may take the form of a tent, arch or the like, the ends of the supports of which are adapted to be coupled to or disposed on or adjacent -to the rigid support or to the respective rigid supports. In a further alternative, the erectable structure may take the form of a vaulted structure having at least two cantilever supports disposed, in use, back-to-back, each cantilever support having an end adapted to overhang the/each rigid support and an end adapted to be coupled thereto. The rigid support may be a substantially # flat planar surface, a wall, column, platform, stage or the like. The/each pliable elongate main member may comprise a lath-like member, for example. Preferably, the/each main member comprises an elongate frame. This may allow the weight of the/each main member to be minimised. The frame may comprise a ladder truss structure, having two spaced elongate arms coupled together at points along the length thereof by spacing struts. Clear, flexible panels may be provided in spaces defined by th,e arms and the struts . This may both increase the strength of the main member, and allow visibility and/or light therethrough without substantially increasing the weight of the main member. Alternatively, the/each main member comprises a substantially solid rib, of a material such as a composite ■glass fibre/resin material. The substantially solid rib may define the membrane of the erectable structure and may extend between the at least two cantilever supports of the erectable structure. Alternatively, a single cantilever support may define an erectable structure, with the substantially solid rib defining ' the membrane. Conveniently, the/each main member tapers towards the overhanging end thereof when viewed in plan. The compression legs may progressively shorten in height towards the overhanging end of the/each cantilever support. This may allow the/each main member to be moved to the desired elongate curved configuration, to reflect a progressive * reduction in the bending forces in the main member in the tapered portion towards the overhanging end of the/each cantilever support. Additionally or alternatively, the compression legs may progressively shorten in height towards the end adapted to be disposed adjacent to or coupled to the grandstand seating platform. The main member may further comprise a plurality of rungs or spacers. The rungs or spacers may be integral with the main member. Where the main member comprises a frame, the rungs or spacers may comprise part of the frame. In particular, the rungs or spacers may comprise or be coupled to spacing struts of the frame . Alternatively, the main member may comprise outriggers, and the outriggers may be bars or struts coupled to the main member. The outriggers may be coupled to the main member using, for example, nut and bolt assemblies, screws and/or adhesive. The compression legs may be pivotally coupled to the main member. Preferably, two compression legs are coupled together to define an A-frame. This may brace the cantilever support under lateral loading, transverse to a longitudinal axis of the cantilever support. Preferably, the A-frames comprise two hollow compression legs, each pivotally coupled at a lower end to the main member via hinges. Each compression leg of an A-frame may alternatively be coupled at a respective lower end to opposite ends of an outrigger. The A-frames may each have an upper end adapted to engage the elongate tensionable element. .Preferably, the A-frames include a coupling at the upper end thereof defining a channel for receiving the elongate tensionable element. The elongate tensionable element may carry a plurality of ferrules . Each ferrule may be adapted to engage in a respective channel of an A- frame. Each A-frame channel may comprise a shoulder for engaging a corresponding shoulder of a ferrule. This may allow the elongate tensionable element to be removed from engagement with the A-frames for transport and/or storage of the/each cantilever support, by disengaging the ferrules from the coupling channels. The shoulders of the A-frames and the elongate tensionable element may co-operate to transmit a force to the A-frames when the elongate tensionable element is tensioned by pivoting the main member about the rigid support. Alternatively, each coupling may include a bore extending therethrough and adapted to receive the elongate tensionable element, and each ferrule of the elongate tensionable element may comprise a shoulder adapted to engage an external corresponding shoulder of the coupling. The shoulder may be an outer surface of each ferrule surrounding an opening of the bore adjacent to the ferrule. The restraint means may comprise a plurality of tension members, such as wires. Alternatively, the tension members may be cables, chains or the like. Each tension member may be coupled at a first end to an upper portion of a first compression leg and may be coupled indirectly to the main member at a second end. Each tension member may be coupled at the second end to a lower portion of a second compression leg spaced longitudinally along the main member from the first leg. Alternatively, each tension member may be coupled at the second end to a rung, spacer, spacing strut or outrigger of the main member. Conveniently, there are two tension members for each A-frame. Each tension member of an A-frame may be coupled at the first end to the upper end of the A-frame. Conveniently the tension members are coupled to the coupling at the upper end of the A- frame . Furthermore, each tension member may be coupled at respective second opposite ends to opposite ends of a rung, spacing strut, spacer or outrigger. In a preferred embodiment, the/each cantilever support includes one tension member for each A-frame, coupled at one end to a leg of the second A-frame, extending through the coupling at the upper end of the A-frame, and coupled at the other end to the other leg of the second A-frame. Alternatively, the tension member may be coupled at the ends thereof to opposite ends of a rung, spacer, spacing strut or outrigger . Preferably, the elongate tensionable element is a cable. Alternatively, the elongate tensionable element may be a wire, chain, or the like. In a particular alternative embodiment, the elongate tensionable element comprises a sheet of a flexible material. The sheet of flexible material' may also define the restraint means of the/each cantilever support. The/each cantilever support may comprise two sheets coupled to compression legs of the A- frames. Each sheet may be coupled to the compression legs extending from common respective sides of the main member, such that the sheets together define a tent-like structure. Conveniently, the sheet of flexible material comprises a web-like material. The sheet may comprise a fabric material, for example, a material such as a bias cut woven material. The bias cut woven material may be sail cloth, and warp and weft fibres of the material may both be disposed diagonally to the extent of the main member. Most preferably, the warp and weft fibres are disposed at angles of approximately 45° to the main member when the material is under load. The/each sheet of flexible material may comprise a plurality of fabric panels, each panel extending between the compression legs of adjacent A-frames. Preferably, each fabric panel comprises webbing stitched or otherwise secured to the periphery of the panel, to strengthen each panel under load. The webbing may comprise a Kevlar (TM) material. Each panel may be adapted, under load, to assume a support position. In the support position, the upper and lower edges of each panel may curve inwardly to uniformly tension each panel. In an alternative embodiment, the sheet of flexible material may be coupled to the compression legs, and may extend between struts of the support member frame and be coupled to a tie cable coupled at one end to the cantilever support adjacent the overhanging end thereof, and at an opposite end to the cantilever support adjacent the end adapted to be disposed adjacent to or coupled to the grandstand seating platform. Thus, there may be a single sheet of flexible material extending along the length of the/each cantilever support. The erectable structure may further comprise stabilising means for stabilising the erectable structure in use.- The stabilising means may, in particular, stabilise the erectable structure under external loading, for example, wind loading. The .stabilising means may comprise a tie-down cable, coupled at one end to the erectable structure in a location adjacent the overhanging end of each cantilever support, and at an opposite end to the ground. Conveniently, the tie-down cable is coupled at the first end to the membrane. Alternatively, the tie-down cable may be coupled at the first end- to a cantilever support . There may be a tie-down cable for each cantilever support, or for each membrane or membrane portion disposed between adjacent cantilever supports. Alternatively, the tie-down cable may be coupled at the opposite end to the grandstand seating platform. In a further alternative, the stabilising means may comprise the tie cable. The tie cable may also be coupled to the cantilever support at one or more locations intermediate said ends thereof via tension elements. The tension elements are preferably wire ropes, but may be cables, chains, bars or the like. Preferably, the erectable structure further comprises two or more coupling members for coupling the cantilever supports together. The coupling members may include purlins and/or cross-bracing members, able to resist one or both of compression and tension loading. The cross bracing- members may particularly provide support under wind loading. Preferably, the end of .the/each cantilever support adapted to be coupled to the grandstand seating platform is anchored to the platform after having been moved to the substantially erect position. The end of the cantilever support may be anchored to a frame member of the platform. According to a fifth aspect of the present invention, there is provided an erectable grandstand canopy for a grandstand seating platform, the canopy being moveable between a substantially collapsed position and a substantially erect position, the canopy comprising at least two spaced cantilever supports as previously described herein, and one or more membranes, the/each membrane being coupled between two of the cantilever supports, the one or more membranes, in use, defining a roof of the canopy, whereby movement of the cantilever supports to the substantially erect position moves the erectable grandstand canopy to the substantially erect position. It will be appreciated that a membrane may be coupled between two ' adjacent cantilever supports, and that a membrane may be provided coupled between each adjacent pair of cantilever supports. It will also be appreciated that ■ a membrane may be coupled between two non-adjacent supports . Accordingly, a membrane may be coupled to a first cantilever support, and extend to and be coupled to a second, non-adjacent cantilever support. In such a structure, the membrane may extend over or through, but not coupled to, one or more cantilever supports intermediate said first and second supports . According to a sixth aspect of the present invention, there is provided a method of erecting an erectable canopy, the method comprising the steps of: providing two or more cantilever supports, the supports being adapted to be moved between a substantially collapsed, slack position, and a substantially erect, taut position in which each cantilever support is in an elongate curved configuration, each cantilever support being initially disposed in the substantially collapsed, slack position; pivotally coupling each cantilever support to a rigid support; coupling one or more membranes between two of the cantilever supports; and pivoting each cantilever support about its respective rigid support, to move them to the substantially erect, taut position, whereby the one or more membranes define a roof of the canopy. Preferably, the method comprises a method of erecting a grandstand canopy. Each cantilever support may be pivotally coupled to a member such as a frame member of a grandstand seating platform. Preferably also, the canopy is collapsible to be movable between the substantially erect, taut position and the substantially collapsed, slack position. The method may further comprise the step of providing a cantilever support as previously described herein . Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figures 1A to 1C are schematic perspective illustrations of an erectable structure in accordance with an embodiment of the present invention, in -the form of an erectable grandstand canopy having two cantilever supports, the cantilever supports and the erectable structure being moveable between a substantially collapsed position and a substantially erect position, and being shown in Figures 1A to 1C in the substantially erect position; Figures 2A to 2C are front, plan and side views respectively of the erectable structure of Figures 1A to 1C; Figure 3 is an enlarged, perspective view of part of one of the cantilever supports of Figures 1A to 1C; Figure 4 is an enlarged, perspective view of an embodiment of a coupling forming part of the cantilever support of Figures 1A to 1C; Figures 5A and 5B are enlarged cross-sectional views of a frame forming part of the cantilever support of Figures 1A to 1C; Figures 6A and 6B are front and rear shaded perspective illustrations of the erectable grandstand canopy of Figures 1A to 1C, drawn to a smaller scale; Figures 7A to 7D are schematic side views of the erectable structure of Figures 1A to 1C showing various stages during movement of the erectable structure from the substantially collapsed position shown in Figure 7A, to the substantially erect position shown in Figure 7D; Figure 8A is a schematic side view of an erectable grandstand canopy in accordance with an alternative embodiment of the present invention, similar to the canopy of Figures 1A to 1C, and illustrating the forces in the canopy; Figure 8B is an end view of an A-frame and part of the structural support of Figure 8A; Figures 8C, 8E, 8H and 8J are views of grandstand canopies in accordance with further alternative embodiments of the present invention, similar to the view of the canopy of Figure 8A; Figures 8D, 8F, 81 and 8K are end views of A-frames and part of the structural supports of Figures 8C, 8E, 8H and 8J, respectively, similar to the view of Figure 8B; Figure 8G is an enlarged view of a panel forming part of the grandstand canopy of Figure 8E; Figures 9A to 9E are schematic side views of erectable structures . in accordance with further alternative embodiments of the present invention; Figures 10A to 10D are schematic side views of erectable structures in accordance with still further alternative embodiments of the present invention; Figure 10E is a schematic side and plan illustration of an arrangement of erectable structures comprising a plurality of one of the structures of Figures 10A to 10D; Figure 10F is a schematic plan, enlarged plan and perspective illustration of an arrangement of erectable structures comprising a plurality of one of the structures of Figures 10A to 10D; Figures 10G and 10H are schematic side views of an erectable structure in accordance with a yet further alternative embodiment of the present invention, shown in collapsed and erect positions, respectively; Figure 11 is a view of an erectable grandstand canopy in accordance with a preferred embodiment of the present invention, shown in a substantially erect position; Figures 12A and 12B are a side view and cross- sectional view of part of a support of the structure shown in Figure 11; Figures 13A - 13C are plan and cross-sectional views, respectively, of a bracket forming part of a support of the structure shown in Figure 11; Figures 14A - 14C and Figures 15A - 15C are perspective and cross-sectional views, respectively, of female and male connectors forming part of a support of the structure shown in Figure 11; and Figures 16A - 16C are front, plan and side views respectively, of an alternative coupling forming part of a support of the structure shown in Figure 11. Referring firstly to Figures 1A to 1C, there are shown perspective views of an erectable structure indicated generally by reference numeral. 10, in the form of an erectable grandstand canopy for a grandstand seating platform (shown in Figures 7A-7D and described below) . The Figures 2A-2C are also referred to, which are front, plan and side views respectively of the erectable structure 10 of Figures 1A to 1C. The structure 10 generally comprises at least two cantilever supports 12 with a membrane 14, for example a PVC coated fabric or a sheet material such as plywood, coupled between the two cantilever supports 12. Coupling members in the form ' of purlins 16 are coupled between the cantilever supports 12 to strengthen the structure 10, whilst diagonal cross-members 18, extending between the supports 12, provide bracing for the structure 10 to resist independent movement of the supports 12 under, for example, wind-loading. The erectable structure 10 and each of the supports 12 are moveable between a substantially collapsed position (shown in Figure 7A and described below) and a substantially erect position shown in Figures 1A to 1C. It will be noted that in Figures 1A to 1C, the structure 10 adopts, in this substantially erect position, an elongate curved configuration, to define a roof for the grandstand seating platform. This provides shelter for occupiers of the grandstand seating platform during adverse weather conditions . The structure 10 further comprises a tie down cable 20 which is coupled to the membrane 14, and tethers an overhanging end 22 of each support 12 of the structure 10 in the substantially erect position. This applies a pretension to the structure 10, to brace it under, for example, wind loading, and also prevents the membrane 14 from "flapping" in the wind. As will be described in more detail below, an end 24 of each support 12 of the structure 10 is anchored to a frame of the grandstand seating platform when the structure 10 is moved to the erect position. Each cantilever support 12 comprises a lath-like pliable elongate main member in the form of an elastically deformable main rib or frame 26, a • plurality of equidistantly spaced compression legs in the form of A- frames 28, restraint means comprising a plurality of tension members which- are tension wires 30, and an elongate tensionable element in the form of a cable 32. The structure 10 is pivotably coupled to a rigid support of the grandstand seating platform by a pin joint 100 (see Figures 7A-7D) , as will be described below. As shown in Figures 1A and 2C, the tension wires 30 to the left of pin joint 100 extend in a direction towards the ends 24 of each support 12. Conversely, the tension wires 30 to the right of pin joint 100 extend in a direction towards ends 22 of each support 12. This balances the forces in the structure 10, 5 which pivots about pin joint 100, as will be described below. It will be noted that an A-frame 28 is provided at the location of the pin joint 100, which is braced by tension wires 30 extending in both directions. Figure 3 is an enlarged view of part of one of the 10 cantilever supports 12 of the structure 10 shown in Figures 1A to 1C, and more clearly shows the component parts of the structural support 12. The frame 26 is generally elongate and comprises two flexible arms 34 coupled together by ■ ■ struts 36 at various points along the lengths of the arms 15 34. The frame 26 is pliable, having a low bending strength, such that the frame 26 is easily bent and elastically deformed into an elongate curved configuration, when the cantilever support 12 is moved to the erect position. Also, the structure of the frame comprising the 20 arms 34 and struts 36 is such that the frame is relatively light, but sufficiently pliable to deform to the desired elongate curved configuration. As will .be noted particularly in Figures 1A, 2A and 2B, the frame 26 of each support 12 tapers towards the end 25 22 of the supports 12 of structure .10. This is achieved by progressively shortening the struts 36 towards the ends 22. This allows the height of the A-frames 28 to be reduced towards the ends 22 of the supports 12, whilst maintaining > the same angle between the legs 38 of each A-frame 28. The 30 height of these A-frames towards the ends 22 can be reduced as the bending moment about the hinges 42 of these A-frames 28 is lower. This is desired in order to deform the frames 26 into a shallower curve at the ends 22, as shown particularly in Figure 2C, as where the bending moment 35 about the hinges 42 is lower (due to the shorter A-frames 28), the resultant deformation of the frame 26 is less. A further advantage of tapering the arms 34 of frame 26 towards the ends 22 is the reduction in material (and thus weight) obtained as the struts 36 are shortened. Each A-frame 28 comprises two hollow compression legs 38 pivotally coupled to a rung or spacer 40 (shown only as a line in Figure 3) via hinges 42 on the lower end of each leg 38. The legs 38 are coupled at an upper end to a coupling 44 (shown in Figure 4) through which the ' cable 32 passes. The tension wires 30 are coupled to a coupling 44 of a respective A-frame 28 and to the rung or spacer 40 of an adjacent A-frame 28. The hinges 42 allow each A-frame p 28 to pivot and fold between a collapsed position, where the A-frames 28 are "folded" and lie substantially parallel to the frame 26, to an erect position, where the A-frames are disposed substantially perpendicular to the frame 26. In this erect position shown in Figure 3, the tension wires 30 are taut and restrain the A-frames 28 from further rotation about the hinges 42. The cable 32 is coupled at one' end to the A-frame 28 adjacent end 22, and at the other end to the A-frame 28 adjacent end 24, as well as to each A-frame between the ends 22 and 24, as will be described belo . Referring now to Figure 4, an embodiment of a coupling 44 of each A-frame 28 is shown in more detail. The coupling 44 comprises a generally cylindrical cast body, and has a recess at either end thereof, one of which is shown and given the reference numeral 46. The ' recesses are adapted to receive an end 48 of a hollow compression leg 38 of each A-frame 28, which has been flattened as shown in Figure 4. The end 48 includes an aperture 50 through which a threaded retaining bolt 52 passes and engages with a corresponding threaded bore 54 of the coupling 44. Thus each hollow leg 38 is coupled to the coupling 44. The change in height of the A-frames 28 towards the end 22 of supports 12 allows a standard coupling 44 to be provided for, each of the A-frames 28, as the angle between the legs 38 of each A-frame 28 is the same. This also allows a single hinge 42 to be manufactured. Each coupling 44 also includes a passage 56 which extends through the coupling 44 and which, in the erect position of Figure 3, is substantially parallel to- the frame 26 of the structural support 12. The passage 56 receives the cable 32, and it will be appreciated that the cable 32 extends between each A-frame 28 and through each passage 56 of the couplings 44. The tensioning cable 32 includes a plurality of ferrules in the form of collars 33 fixed to the cable 32 spaced appropriately along the length thereof. A portion of the cable 32 carrying a collar 33 is shown in Figure 4. The collars 33 each have a shoulder 35 which engages an outer surface of a respective coupling 44 when the tensioning cable 32 is tensioned, to raise the A- frames 28 to the erect position shown in Figures 1A-3. The coupling 44 also includes a passage 58, having wire inlets 60. The passage 58 is in the shape of a generally inverted V, and is angled downwardly in use, towards the hinges 42 of an adjacent A-frame 28. The tension wire 30 is received in the passage 58, passing through the passage 58 from one of the inlets 60 to the other inlet 60, and coupled to the opposite ends of an rung 40 of an adjacent A-frame as shown in Figure 3. The tension wires 30 carry ferrules (not shown) such as collars similar to the collars 33, which are fixed to the wires 30 following location in passage 58. This provides bracing to the A-frames 28, and thus the frame 26, to lateral loading. Figures 5A and 5B, which are enlarged cross-sectional views of the frame 26 of each support 12 illustrate the frame 26 in more detail. As shown in Figure 5A, the arms 34 are hollow and generally box-shaped in cross-section, and include a channel 62 defined by lips 63, in which an edge 64 of the membrane 14 is received. The edge 64 comprises a bolt rope 66 extending along the length of the membrane 14 from the end 24 of each support 12. towards the end 22. The material of the membrane 14 surrounds the bolt rope 66 and an edge 68 of the material folds over the bolt rope 66 and is stitched or otherwise secured to the membrane 14, to retain bolt rope 66 in a pocket. This enables the edge 64 to be threaded along the length of the arms 34 to form the canopy roof. The arms 34 also include an inner channel 70 defined by fingers 72, and the channel 70 is profiled to receive and engage a glazing gasket 74 of a resilient material, typically of a rubber material, therein. Gasket 74 includes a channel 76 with resilient engaging fingers 78 extending into the channel 76. Panels 80 of a clear plastics material (typically a polycarbonate material) having an edge 82 are coupled to each arm 34 with the edge 82 engaged within the channel 76 of each gasket -74, and retained by the resilient fingers 78. It will be appreciated by persons skilled in the art that a single panel 80 and gasket 74 is shown in Figure 5A, but that a plurality of panels 80 are provided, and coupled to the frame 26 as ' shown in Figures 5A and 5B. Furthermore, Figure 5A only shows one edge 82 and one gasket 74 of the support 12. However, it will be appreciated that each arm 34 includes a gasket 74 for engaging opposite side edges 82 of each panel 80. The arms 34 also include upper and lower lips 84 and 86 respectively in the regions of each hinge 42 of the A- frames 28. The hinge 42 includes a generally inverted T- shaped plate 88 and a casting 90 pivotally coupled to a portion 92 of plates 88. The plate 88 includes a base 94 which is engaged by the upper lips 84 of each arm 34. A hollow leg 38 (not shown in Figure 5A) of an A-frame 28 is coupled to the casting 90, allowing the A-frame 28 to move between the collapsed and erect positions. A support plate 96 is coupled to the arm 34 and retained by the lower lips 86 in the region of the hinge 42 to provide support for forces exerted on the frame 26 through hinge 42. There follows a description of the method of moving the cantilever supports 12, and thus the erectable structure 10, between the substantially collapsed position and the substantially erect position. Referring to Figures 6A and 6B, which are front and rear shaded perspective illustrations of the erectable structure 10 of Figures 1A to IC, it will be appreciated that the canopy defines a roof for sheltering a grandstand seating platform (not shown in Figures 6A and 6B) beneath the canopy. Figures 7A to 7D are schematic side views of the erectable structure 10 of Figures 1A to IC showing the various stages during movement of the erectable structure 10 from the substantially collapsed position, shown in Figure 7A, to the substantially erect position shown in Figure 7D. For clarity, only one of the cantilever supports 12 is shown in Figures 7A to 7D. However, it will be appreciated by persons skilled in the art that the structure 10 comprises at least two such supports 12, as shown in Figure 1A, and that each support 12 is assembled and moved to the substantially erect position as will be described below. Referring initially to Figure 7A, the erectable structure 10 is assembled in sections a,b,c by interconnecting a series of frame portions to form the •frame 26, each frame portion having a number of A-frames 28. The assembled frame 26 initially rests on a grandstand seating platform 98. In the collapsed position, the A- frames 28 lie at an angle to, and are typically substantially parallel to, the frame 26. The tensioning cable 32 is then coupled to the couplings 44 of the A- frames 28. For ease of transport it will be understood that the tensioning cable 32 is released from the structural support 12 and that each of the tension wires 30 is, in the collapsed position, slack, with the A-frames 28 lying in a flat position. The structure 10 is then moved to the position shown in Figure 7B, and is pivotally coupled to a structural member of the grandstand seating platform 98 by the pin joint 100, which allows the frame 26 of the cantilever support 12 to pivot thereabout. In this position, the weight of the structure 10 causes it to bend elastically to some degree about both sides of the pin joint 100. A winch (not shown) is connected to an end 27 of the frame 26 at the end 24 of each support 12 by a winch cable 29. The winch cable 29 is then tensioned by the winch, which pivots the frame about the pin joint 100, and pulls the end 27 of the frame 26 (and thus support 12) towards the seating platform 98. Co-operation between the ferrules 33 of the cable 32 and the couplings 44 of each A-frame 28 causes • each A-frame 28 to be progressively rotated to the erect position of Figure 3, the progressive rotation of the A- frames 28 occurring in a direction outwardly from the - pin joint 100. Thus, initially, the A-frames 28 towards the end 22 of the support 12 remain in a collapsed position until the cable 32 has become taut, as will be described with reference to Figures 7C and 7D. Thus initially the front sections b and c of the structure 10 remain substantially flat and supported by the seating platform 98. Referring now to Figure 7C, progressive reduction in the distance between the end 27 and the seating platform 98 results in progressive rotation of the A-frames 28 until all of the A-frames 28 have been moved to the substantially erect position. The free upper end 22 of the structure 10 then "lifts off" the seating platform 98, and in this position, the cable 32 and all of the tension wires 30 are under tension. This causes the frame 26 of the structural support 12 to begin to deform and assume the elongate curved configuration which is assumed in the substantially erect position shown in Figure 7D. In Figure 7D, the lower fixed end 24 of the structure 10 has been anchored to a frame member (not shown) at the rear 102 of the seating platform 98. The erectable structure 10 is now in the erect position, with the end 22 disposed above and overhanging the seating platform 98 to define the roof, and with the cable 32 and tension wires 30 taut. The tie-down cable 20 is then attached to the membrane 14 of the structure 10 in the region of the end 22, and to the seating platform 98, to brace the structure 10 under wind-loading, by introducing a pre-tension into the structural support 12. It will be understood that the pliable elongate main member (frame 26) is easily bent into the elongate curved configuration of Figure 7D. The A- frames 28, and the cable 32 and tension wires 30 (when taut) .are flexible, but are substantially undeformed when the frame 26 is bent into the elongate curved configuration. Furthermore, it will be understood that the elongate curved configuration adopted by the frame 26 when the support 12 is in the erect position is determined by the dimensions of the A-frames 28 (and their relative spacing) , the cable 32 and the tension wires 30; these are all of predetermined lengths, to cause the frame 26 .to adopt the desired arc or curve, when the cable 32 and tension wires 30 are taut, as shown in Figure 7D. It will be noted that, in use, each of the A-frames 28 extends above an upper surface of the frame 26. It will be understood by persons skilled in the art that references to the A-frames 28 extending above the upper surface of the structure 10 are to the A-frames 28 extending above the upper surface of the structure 10 when in use. It will be further noted that the structure 10 only assumes the erect position with the frame 26 in the desired elongate curved configuration when the cable 32 and the wires -30 have been tensioned. When it is desired to collapse the erectable structure 10 to the substantially collapsed position of Figure 7A for storage and/or transportation, the steps of moving the structure 10 to the substantially erect position of Figure 7D are reversed, as will be appreciated by persons skilled in the art. This allows the structure 10 to be readily used temporarily in various different locations, and to be quickly and easily transported between these locations and subsequently erected. However, it will be understood that the erectable structure 10 may also be a permanent or semipermanent structure. Figures 8A to 10H illustrate alternative embodiments of the present invention. Like components with the structure 10 of Figures 1 to 7D share the same reference numerals with the addition of the letters a to q respectively. Turning firstly to Figures 8A to 8K, figures 8B, 8D, 8F, 81 and 8K are end views of A-frames and part of structural supports of the structures of Figures 8A, 8C, 8E, 8H and 81 respectively. Referring now to Figures 8A and 8B, there is shown a schematic side view of an erectable structure indicated generally by reference numeral 10a, which is similar to the structure 10 of Figures 1A to IC, and illustrates the forces in the structure 10, with tension forces indicated by an arrow and the letter T, and compression forces by an arrow and the letter C. The erectable structure 10a comprises two cantilever supports 12a, one of which is shown in Figure 8A. The structure 10a is shown in the substantially erect position, where the frame 26a of each support 12a has been pivoted about pin joint 100a, tensioning cable 32a and the tension wires 30a to rotate the A-frames 28a to the erect position. Also the frame 26a of support 12a experiences compression in a lower surface 27a due to the bending stresses experienced by the frame 26a. A tie-down cable 20a is under tension to provide a pre-tension in the structure 10a. Figures 8C and 8D show an alternative embodiment of an erectable structure, indicated generally by reference numeral 10b, similar to structure 10a of Figure 8A. A tie cable 20b is coupled via tension elements in the form of wires or struts 31 to a frame 26b and to an end 24b. This provides a tie cable 20b which does not cause a viewing obstruction. Figures 8E and 8F show a further alternative embodiment of an erectable structure, indicated generally by reference numeral 10c, similar to 'the structure 10a of , Figure 8A. In the structure 10c, flexible webbing panels 104 are provided between legs 38 of adjacent A-frames 28c, in place of cable 32 and tension wires 30, as shown in Figure 8E in particular. Thus panels 104 are provided coupled between both legs 38c of adjacent A-frames 28c, forming a tent-like structure above ■ frame 26c. These panels 104 move the frame 26c to .the elongate curved configuration when the frame 26c is pivoted about pin joint 100 and an end 27c of frame 26c pulled towards a grandstand seating platform (not shown) , in 1 a similar fashion to the structure 10 of Figure 1A. Referring now to Figure 8G , which is an enlarged view of a panel 10-4 of Figure 8E, each panel is made from a bias cut woven fabric material.. An inelastic material of good shear strength, such as a tightly woven and heat-shrunk polyester sail cloth, is suitable. The panel 104 includes webbing, typically a narrow strip 105 of Kevlar (TM) stitched to its upper and lower edges, to strengthen the edges of the panel 104. Edge stitching 109 couples the panel 104 between the A-frames 28c. The panels 104 are formed such that, in the erect position of the structure 10c, the threads of the panels 104 in the warp and weft directions (shown at 107) are neither parallel nor perpendicular to the axis of the frame 26c, but are at an angle in the region of 45°. In certain circumstances, such as for larger structures, a higher strength fabric such as Kevlar (TM) or Dyneema (TM) may be utilised. Figures 8H and 81 show a yet further alternative embodiment of an erectable structure indicated generally by reference numeral lOd, similar to the structure 10a of Figure 8A. Structure lOd is essentially a combination of the features of the structures 10b and 10c, and thus comprises flexible webbing panels 104d disposed between adjacent A-frames 28d, and a tie cable 20d coupled to a fixed lower end 24d of structure lOd and with tension wires 31d coupling the cable 20d to frame 26d. Figures 8J and 8K show a still further alternative embodiment of an erectable structure, indicated generally by reference numeral lOe. The structure lOe is similar to the structure lOd of Figure 8H, and- includes flexible webbing panels 104e. The panels 104e, instead of being coupled between legs 38e of adjacent A-frames 28e, extend substantially perpendicularly through a frame 26e and are coupled to tie cable 20e. The frame 26e of the structure lOe does not have any glazing panels such as the clear panels 80 of the structure 10 of Figure 1A. Thus 'the panels 104e extend "through spaces in frame 26e between struts 36e. Figure 9A shows a still further alternative embodiment of an erectable structure, indicated generally by reference numeral lOf . The structure lOf is ..formed into an arch, rather than a canopy, and has two fixed ends 106, and includes a support 12f. The support 12f is similar in structure to the support 12 of Figure 1A, and tapers from a midpoint '108 towards the fixed ends 106. The structure lOf is moved to the substantially erect position shown in Figure 9A by pulling ends 106 inwardly in the direction of the arrows A, to tension cable 32f and tension wires 30f, moving the frame 26f to the desired elongate curved configuration. This also applies a pre-tension to stabilise the structure under, for example, wind-loading. It will be noted that each adjacent pair of A-frames 28f of structure lOf are cross-braced by tension wires 30f extending in both directions. This cross-bracing braces the structure lOf under wind-loading in the direction of the arrows B and C. Figure 9B shows a still * further alternative embodiment of an erectable structure, indicated generally by reference numeral lOg. The structure lOg is similar to the structure lOf of Figure 9A, and to the structure 10b of Figure 8C, and includes a tie cable 20g for applying a tension to move the structure lOg to the erect position and to provide additional bracing. Figure 9C shows a still further alternative embodiment of an erectable structure, indicated generally by reference numeral lOh. The structure lOh is similar to the structure lOf of Figure 9A and the structure 10c of Figure 8E, and includes webbing panels 104h disposed between adjacent A- frames 28h. Figure 9D shows a still further alternative embodiment of an erectable structure, indicated generally by reference numeral lOi. The structure lOi is similar to the structure lOf of Figure 9A and the structure lOd of Figure 8H, and includes flexible webbing panels 104i, and a tie cable 20i. Figure 9E shows a still further alternative embodiment of an erectable structure, indicated generally by reference numeral 10J . The structure 10J is similar to the structure lOf of Figure 9A and the structure lOe of Figure 8J, and includes flexible webbing panels 104e which extend to a tie cable 20j . Figures 10A to 10C show still further alternative embodiments of the present invention, indicated generally by reference numerals 10k, 101 and 10m respectively. Each of the structures 10k, 101 and 10m define vaulted structures having supports with overhanging ends 110 and ends 112 at ground level, and define roof portions 114. The structure ' 10k essentially comprises two cantilever supports 12k similar to the supports 12 of structure 10 shown in Figure 1A, which are provided back-to-back. Each of the supports 12k comprises a frame 26k, with A-frames 28k, tension wires 30k and cables 32k. The cables 32k are coupled together at a joint 116, and a secondary cable 118 which extends from joint 116 to ends 112 is tensioned to move the structure 10k to the substantially erect position shown in Figure 10A. Struts 120 couple the frames 26k of the supports 12k together in a lower region of the structure 10k, and provide support when the structure 10k is moved to the substantially erect position. It will be noted that the tension wires 30k extend inwardly from the ends 110 towards the ends 112. Tie-down cables 20k are coupled to the ends 110 to pre-tension the structure 10k and provide support under, for example, wind loading. Structure 101 is similar to structure 10k and to structure 10b of Figure 8C, structural supports 121' of the structure 101 having tie-cables 201 rather than tie-down cables . Structure 10m is similar to structure 10k of Figure 10A and to structure' lOe of Figure 8J, with flexible webbing panels 104m coupled to A-frames 28m and to tie cables 20m of each structural support 12m of the structure 10m. Figure 10D is a view of a still further alternative embodiment of the present invention, indicated generally by reference numeral lOo, and which is substantially similar to the structure 101 of Figure 10B. However, the structure lOo has tension wires 30o which extend from free ends 22o of cantilever supports 12o of the structure lOo, but which do not extend to lower restrained ends 24o of the supports 12o. Instead, the tension wires 30o extend to a joint 1160 between the two supports 12o. From the joint II60 to the ends 24o, the supports 12o are coupled together by restraining wires 121. Figure 10E is a schematic side and plan illustration of an arrangement of erectable structures indicated generally by reference numeral 122, which comprises a plurality of one of the erectable structures of Figures 10A to 10D, which in Figure 10E are denoted by reference numeral lOp. In the arrangement 122 shown in the side view, three structures lOp of the type shown ' in Figure 10D are connected together, to define the width of the arrangement 122, and two or more. further sets of structures lOp are connected as shown in the plan view of Figure 10E, to define the length of the arrangement 122. It will be understood that membranes 14p extend between adjacent structures lOp to define a roof. Figure 10F is a schematic plan, enlarged plan and perspective illustration of an arrangement of erectable structures indicated generally by reference numeral 124, which comprises a plurality of one of the structures 10k to lOf of Figures 10A to 10D, in a similar fashion to the arrangement 122 of Figure 10E. The structures are cross- linked to provide the structure shown in the plan views . Figures 10G and 10H are schematic side views of an erectable structure in accordance with a yet further alternative embodiment of the present invention, indicated generally by reference numeral lOq, shown in collapsed and erect positions, respectively. The structure lOq is similar to the structure 10 of Figures 1A to 7D, and includes cantilever supports 12q (one of which is shown) . Each support 12q is pivotally coupled to a grandstand seating platform 98q by a pin joint lOOq. However, each support 12q is coupled at an end 24q to the pin joint lOOq on a frame member (not shown) of the platform 98q, rather than at a point between the end 24q and an end 22q which overhangs platform 98q when the structure lOq is erect. The support 12q includes A-frames 28q, each restrained by a tension wire 30q when structure lOq is erect. The tension wires 30q are directed towards the end 24q of the support 12q, and a lever plate 126 is coupled to the frame 26q of the support 12q at an end 27q thereof. The structure lOq is moved to the erect position of Figure 10H by simply pivoting the lever plate 126 about joint lOOq, to in-turn pivot frame 26q of support 12q about the joint lOOq, in the direction of the arrow A. This tensions cable 32q, raising A-frames 28q to the erect position, and tensions the tension wires 30q. When the lever plate 126 has been pivoted sufficiently about joint lOOq, the cable 32q and tension wires 30q are taut, all the A-frames 28q are erect, and the frame 26q is brought to the desired elongate curved configuration. Turning now to Figure 11, there is shown a cross- sectional side view of an erectable grandstand canopy in accordance with a preferred embodiment of the present invention, similar to the canopy 10 of Figures 1A-7D. Like components with the structure 10 of Figures 1-7D and with the embodiments of Figures 8A to 10H share the same reference numerals with the addition of the letter "r" . The canopy lOr includes three supports 12r defining a canopy for the seating platform 98r; only one of the supports 12r is shown in Figure 11. It will be noted that the seating platform 98r is of a type known in the art including a base 134 supported at an inclined angle by framework 136, with a number of rows of seats 138 on the base 134. Each support 12r of the canopy lOr is coupled by a pin joint lOOr to a frame member 140 of the base 134. This allows the canopy lOr to pivot to the erected position shown in Figure 11, in a fashion described above. The support 12r is thus similar, to the supports 12 described above. However, the structure of the component parts of the support 12r will be described in more detail below. Generally speaking, it will be noted that there is a shorter distance between the lower end 24r of the support 12r and the pin joint lOOr. Furthermore, it will be noted that several A-frames 28r are provided on the part of the support 12r between the pin joint lOOr and the free-end 22r of the support 12r, with a single support A-frame 28 'r provided on the part between the joint lOOr and the end 24r. Turning now to Figures 12A and 12B, there is shown an enlarged view of part of the support 12r of Figure 11 and a schematic, partial cross-section view of a middle support 12r forming part of the canopy lOr, respectively. Hollow legs 38r of each A-frame 28r are coupled at a lower end to a frame 26r of the support by brackets 142 and pivoting connectors 144, which allow the A-frames 28r to pivot between the folded and erect positions . At an upper end of the A-frame 28r, a coupling 44r is provided which includes a plate 146 defining a shaped channel 148 for receiving the tensioning cable 32r. A threaded bolt 150 is mounted in the channel 148 and abuts a ferrule or stop 152 on the cable 32r. Rotating the bolt 150 provides fine adjustment of the spacing between the tops of adjacent A- frames 28r. Two hollow bolts 154 are also coupled to the plate 146 for receiving the tension wires 30r and, in a similar fashion, provide for fine adjustment. A shackle 156 coupled to the bracket 142 receives a lower end of the tension wire 30r from an adjacent A-frame 28r (not shown) by a pressed. eye 158. Considering in particular Figure 12B, each of the arms 34r are of extruded, hollow aluminium and receive a PVC coated polyester fabric membrane 14r, in a similar fashion to the structure 10. However, in addition, a similar panel 160 is provided between the adjacent arms 34r. The brackets 142 will be described in more detail with reference to Figures 13A to C below. However, it will be noted that the assembly shown in Figure 12B includes a spacing structure located between the arms 34r in the form of a tube 162, secured to the bracket 142 by a bar 164, threaded at the ends thereof. This bar is secured in the bracket 142 and engages both the tube 162, and a purlin 16r through a purlin coupling assembly 166. This assembly 166 allows the support 12r to be adaptable for coupling to, for example, purlins of different lengths for use in appropriate situations such as where structures lOr of different dimensions are required. Assembly 166 includes a female connector 168 shown in the perspective and cross-sectional views of Figures 14A-14C, and a male connector 170 shown in the perspective and cross-sectional views of 15A-15C. The female connector 168 is coupled to the purlin 16r whilst the male connector 170 is coupled to the bracket 142 by the bar 164. The bracket 142 is shown in more detail in the plan view of Figure 13A, the sectional view of Figure 13B (sectioned on B-B of Figure 13A) and the cross-sectional view of Figure 13C sectioned on A-A. It will be seen that the bracket 142 includes a base 172 which is coupled to an arm 34r of the support 12r by bolts located in holes 174, provided in the base 172. Shoulders 176 extend from the base 172, and define a passage 178 for receiving the bar 164, as shown in Figure 12B. A cut-out portion (Figure 13B) 180 is provided, which allows the bar 164 to be securely located in the passage 178 when retaining bolts in threaded holes 182 are tightened. Turning again to Figures 14A to 15C, it will be noted that the female connector 168 shown in Figure 14A, and in the cross-sectional view of Figure 14B (sectioned on A-A of Figure 14C) and the cross-sectional view of Figure 14C (sectioned on B-B of Figure 14B) includes a slot 184 shaped to receive a key 186 on the male connector 170. When the connectors 168 and 170 are coupled, they are secured by a bolt located through respective holes 188 and 190. It will also be noted that the connector 170 includes a threaded hole 192 for receiving an end of the bar 164. Turning now to Figures 16A-16C, there is shown a view of an alternative coupling 44s for an A-frame 28s. Like components with the A-frame 28 of the structure 10 shown in Figures 1A-7D share the same reference numerals with the addition of the letter "s". Upper ends of hollow legs 38s of the A-frame 28s are coupled to a plate 194 which carries two spaced brackets 196. A tube 198 is secured between the brackets 196 by bolts 200 and the tube 198 includes a passage 202 for receiving a threaded bolt 204, similar to the bolt 150 of the coupling 44r shown in Figures 12A and 12B. This hollow threaded bolt receives a tensioning cable (not shown) . In a similar fashion, the tube 198 includes two passages 206, for receiving hollow threaded bolts 208, each of which receives and engages tension wires (not shown) of the A- frames 28s. In a further alternative (not shown) a coupling may be provided including a plate similar to the plate 146 of the coupling 44r, but with a straight sided channel 148. Various modifications may be made to the foregoing within the scope of the present invention. For example, the cantilever support or the support may include a pliable elongate main member comprising a flexible rib, which may be a single rigid sheet. The rib may extend between two supports and may thus define a roof of an erectable structure. Alternatively, a single cantilever support may define an erectable structure with the flexible rib extending laterally from the support to define the roof. The ribs may be tethered at its edges for stability. The compression members (A-frames 28) of structure 10 may shorten in height towards the end 24 adapted to be disposed adjacent to or to be coupled to the grandstand seating platform, or towards both the overhanging end 22 and the end 24. The coupling 44 of each A-frame 28 of structure 10 may include an open channel in which the cable 32 may be received. The channel may define a shoulder for engaging a shoulder of a ferrule on the cable 32, thus allowing the cable to be removed from engagement with the A-frames 28. The main member may comprise outriggers coupled to the top or bottom surface thereof, to which the A-frames 28 may be coupled. The A-frames may be welded or otherwise permanently secured to the frame in the erect position. Alternatively, the A-frames may be disconnected from the frame when the cantilever support is moved to the collapsed position. The tension wire 30 passing through coupling 44 may be otherwise secured to the coupling than by ferrules; for example, the tension wire 30 may be glued, or a notch may be provided in the back of the coupling passage 58, for locating a clip or the like on the wire 30, to restrain it from moving within passage 58. The elongate tensionable element may comprise a series of rigid members for coupling between adjacent A-frames 28. Alternatively, the cable 32 may comprise a series of short cables, each coupled between adjacent A-frames 28. There may be a single compression leg, rather than two compression legs coupled together to form the A-frames .

Claims: CLAIMS ' 1. A support capable of being reversibly moved between a substantially collapsed position and a substantially erect position, the support comprising: a pliable elongate main member capable of being bent into a curved shape; a plurality of compression legs extending above an upper surface of the main member; restraint means effectively connected between the compression legs and the main member; and an elongate tensionable element coupled between the compression legs; wherein in use, the tensionable element and the restraint means are tensioned as the pliable elongate main member 1 is bent and the support is moved to the ' substantially erect position. 2. A support as claimed in claim 1, wherein the compression legs are mounted along the length of an upper surface of the main member. 3. A support as claimed in either of claims 1 or 2 , wherein the main member is for coupling to a rigid support and wherein, in use, the main member is pivoted about the rigid support, to tension the tensionable element and the restaint means and move the main member to an elongate curved configuration. 4. A support as claimed in claim 3, wherein the rigid support is a member of a grandstand seating platform. 5. A support as -claimed in either of claims 3 or 4, wherein the compression legs are each pivotally coupled to the main member, and are movable between substantially collapsed and substantially erect positions when the elongate tensionable element is tensioned, by pivoting the main member about the rigid support. 6. A support as claimed in claim 5, wherein when the compression legs are moved to the substantially erect position, they are generally restrained from . further movement beyond the substantially erect position. 7. A support as claimed in claim 6, wherein the compression legs are restrained by the restraint means, which comprises a plurality of tension members. 8. A support as claimed in claim 6, wherein the compression legs are restrained by a sheet of a flexible material, which defines both the restraint means and the elongate tensionable element. 9. A support as claimed in any preceding claim, wherein the main member comprises an elongate frame. 10. A support as claimed in claim 9, wherein the frame comprises a ladder truss structure, having two spaced elongate arms coupled together at points along the length thereof by spacing struts. ■ 11. A support as claimed in any preceding claim, wherein the main member tapers in width towards an overhanging end thereof when viewed in plan. 12. A support as claimed in any preceding claim, wherein the compression legs progressively shorten in height from a point along the length of the main member towards an overhanging end of the support. 13. A support as claimed in claim 12, wherein the compression legs progressively shorten in height from the point along the length of the main member towards the end opposite the overhanging ' end. 14. A support as claimed in either of claims 12 or 13, wherein the point along the length of the main member is a pivot point, about which the main member is pivoted in use. 15. A support as claimed in any preceding claim, wherein two compression legs are coupled together to define an A- frame . 16. A support as claimed in claim 15, wherein the compression legs are each pivotally coupled at a lower end to the main member via hinges. 17. A support as claimed in either of claims 15 or 16, wherein the A-frames each have an upper end adapted to engage the elongate tensionable element. 18. A support as claimed in claim 17, wherein the A-frames include a coupling at the upper end thereof defining a channel for receiving the elongate tensionable element. 19. A support as claimed in claim 18, wherein the elongate tensionable element carries a plurality of ferrules, each adapted to engage in a respective channel of an A-frame. ' 20. A support as claimed in claim 19, wherein each A-frame channel includes a shoulder for engaging a corresponding shoulder of a ferrule. 21. A support as claimed in any one of claims 18 to 20, wherein the A-frames and the elongate tensionable element co-operate to transmit a force to the A-frames when the elongate tensionable element is tensioned by pivoting the main member about a rigid support. 22. A support as claimed -in any one of claims 15 to 21, wherein the restraint means comprises a plurality of tension members, each tension member coupled at a first end to an upper portion of a first compression leg and at a second end to the main member. 23. A support as claimed in claim 22, wherein there are two tension members for each A-frame. 24. A support as claimed in claim 23, wherein each tension member of an A-frame is coupled at the first end to the coupling at the upper end of the A-frame. 25. A support as claimed in any one of claims 15 to 21, wherein the restraint means comprises one tension member for each A-frame, coupled at one end to the main member, extending through the coupling at the upper endi of the A- frame, and coupled also at the other end to the main member . 26. A support as claimed in any preceding claim, wherein the elongate tensionable element is a cable. 27. A support as claimed in any one of claims 15 to 25, wherein the elongate tensionable element comprises a sheet of a flexible material which also defines the restraint means of the support, the support including two sheets coupled to compression legs of the A-frames, each sheet being coupled to the compression legs extending from common respective sides of the main member. 28. A support as claimed in claim 27, wherein each sheet of flexible material comprises a plurality of fabric panels, each panel extending between the compression legs of adjacent A-frames. 29. A support as claimed in claim 28, wherein each fabric panel includes webbing secured to the periphery of the panel, to strengthen each panel under load. 30. A support as claimed in either of claims 28 . or 29, wherein each panel is adapted, under load, to assume a support position in which the upper and lower edges of each panel curve inwardly to uniformly tension each panel . 31. A support as claimed in any one of claims 8 to 30, wherein the/each sheet of flexible material comprises a bias cut woven material, where warp and weft fibres of the material are disposed diagonally to the extent of the main member . 32. A support as claimed in claim 31, wherein the warp and weft fibres are disposed at angles of approximately 45° to the main member when the material is under load. 33. A support as claimed in either of claims 31 or 32, wherein the sheet of flexible material is coupled to the compression legs, and extends between struts of the support member frame and is coupled to a tie cable, the tie cable coupled at one end to the support adjacent an overhanging end thereof, and at the other end to an end of the support opposite the overhanging end. 34. A cantilever support capable of being reversibly moved between a substantially collapsed position and a substantially erect position, the cantilever support comprising : a pliable elongate main member for coupling to a rigid support, the main member being constructed and arranged so as to be deformable between the substantially collapsed and substantially erect positions of the cantilever support, wherein in the substantially erect position, the main member is in an elongate curved configuration; a plurality of compression legs mounted at intervals along the length of the main member; respective restraint means effectively connected between each compression leg and a location spaced longitudinally along the main member from the pertaining leg; and an elongate tensionable element coupled between the compression legs; wherein in use, the cantilever support is moved to the substantially erect position by pivoting the main member about the rigid support, to tension the elongate tensionable element and the restraint means and move the main member to the elongate curved configuration. 35. A cantilever support capable of being reversibly moved between a substantially collapsed position and a substantially erect position, the cantilever support comprising: a pliable elongate main member for coupling part way along the length thereof to a rigid support, the main member being constructed and arranged so as to be deformable between the substantially collapsed and substantially erect positions of the cantilever support, wherein in the substantially erect position, the main member is in an elongate curved configuration; a plurality of compression legs pivotally mounted at intervals along the length, and extending above an upper surface, of the main member, each capable of being reversibly folded away from and towards the upper surface when the cantilever support is moved between the substantially collapsed and substantially erect positions; respective restraint means effectively connected between each compression leg and a location spaced longitudinally along the main member from the pertaining leg, to limit the extent of folding movement of the compression legs; and an elongate tensionable element coupled between the compression legs; wherein in use, the cantilever support is moved to the substantially erect position by pivoting the main member about the rigid support, to tension the elongate tensionable element and the restraint means, to fold the compression legs away from the upper surface of the main member • and move the main member to the elongate curved configuration. 36. An erectable structure moveable between a substantially collapsed position and a substantially erect position, the erectable structure comprising at least two spaced supports as defined in any one of claims 1 to 35, and a membrane coupled between the supports, whereby movement of the supports to the substantially erect position moves the erectable structure to the substantially erect position. 37. A structure as claimed in claim 36, wherein the main member of each support is pivotally coupled to a rigid support, which is a member of a grandstand seating platform. 38. A structure as claimed in claim 37, wherein each support is pivotally coupled to the member of the grandstand seating platform at a location intermediate the ends thereof. 39. A structure as claimed in either of claims 37 or 38, wherein each support is pivotally mounted to the member of the grandstand seating platform by a pin joint. 40. A structure as claimed in any one of claims 37 to 39, wherein each main member is adapted to be pivoted about the rigid support, to move each support to the substantially erect position, by locating an end of the main member adjacent the grandstand seating platform. 41. A structure as claimed in any one of claims 36 to 40, wherein the erectable structure is in the form of a canopy for a grandstand wherein the membrane defines a roof which, in the substantially erect position, overhangs the grandstand seating platform. 42. A structure as claimed in claim 36, wherein each support has opposite ends which, in use, are adapted to be coupled to respective rigid supports . 43. A structure as claimed in claim 42, wherein the structure takes the form of one of a tent and an arch, the ends of the supports of which are adapted to be coupled to the respective rigid supports . 44. A structure as claimed in claim 36, wherein the structure takes the form of a vaulted structure having at least two supports disposed, in use, back-to-back, each support having an end adapted to overhang the rigid supports and an end adapted to be coupled thereto. 45. A structure as claimed in claim 44, wherein the rigid support comprises one of a substantially flat planar surface, a wall, column, platform and a stage. 46. A structure as claimed in any one of claims 36 to 45, wherein the structure further comprises stabilising means for stabilising the structure ' in use. 47. A structure as claimed in claim 46, wherein the stabilising means includes a tie-down cable, coupled at one end to the structure in a location adjacent an overhanging end of each support, and at an opposite end to the ground. 48. A structure as claimed in claim 47, wherein the tie- down cable is coupled to the membrane disposed between adjacent supports. 49. A structure as claimed in either of claims 47 or 48, wherein the tie-down cable is coupled at the opposite end to the grandstand seating platform. 50. A structure as claimed in any one of claims 47 to 49, wherein the tie cable is coupled also to the support at least at one Location intermediate said ends thereof via tension elements . 51. A structure as claimed in any one of .claims 36 to 50, wherein the structure further comprises two or more coupling members for 'coupling the supports together. 52. A structure as claimed in claim 51, wherein the coupling members comprise purlins and cross-bracing members, able to resist compression and tension loading. 53. A grandstand canopy for a grandstand seating platform, the canopy being moveable between a substantially collapsed position and a substantially erect position, the canopy comprising at least two spaced supports as defined in any one of claims 1 to 35, and one or more membranes, the/each membrane being coupled between two of the supports, the one or more membranes, in use, defining a roof of the canopy, whereby movement of the supports to the substantially erect position moves the erectable grandstand canopy to the substantially erect position. 54. A canopy as claimed in claim 53, wherein a membrane is coupled between each adjacent pair of supports. 55. A canopy as claimed in claim 53, wherein a membrane is coupled between two non-adjacent supports. 56. A method of erecting an erectable canopy, the method comprising the steps of: providing two or more cantilever supports, the supports being adapted to be moved between a substantially collapsed, slack position, and a substantially erect, taut position in which each cantilever support is in an elongate curved configuration, each cantilever support being initially disposed in the substantially collapsed, slack position; pivotally coupling each cantilever support to a rigid support- coupling one or more membranes between two of the cantilever supports; and pivoting each cantilever support about its respective rigid support, to move them to the substantially erect, taut position, whereby the one or more membranes define a roof of the canopy. 57. A method as claimed in claim 56, wherein the method comprises a method of erecting a grandstand canopy, and wherein the step of pivotally coupling each cantilever support to a rigid support comprises the step of coupling each cantilever support to a frame member of a ' grandstand seating platform. 58. A method as claimed in either of claims 56 or 57,. further comprising the % step of providing a support as defined in any one of claims 1 to 35.

Inventors: BURFORD NEIL KEITH, SMITH FRASER WILLIAM, BURFORD, NEIL, KEITH, SMITH, FRASER, WILLIAM
Applicants: BURFORD NEIL KEITH, SMITH FRASER WILLIAM, UNIV DUNDEE, BURFORD, NEIL, KEITH, SMITH, FRASER, WILLIAM, UNIVERSITY OF DUNDEE
Application year: 2001
Main classification: E04H3
IPC codes: E04B1, E04B7, E04C3, E04H3