AU2010202033B2 - Clip assembly - Google Patents

Abstract

Abstract A clip assembly, for concealed securing of metal profiled sheets, has a base by which the assembly is mountable on a support structure, and two elongate 5 clip members separately secured in relation to and projecting from the base. Each clip member, at an end remote from the base, has an end portion adapted for locating over and bearing against a re-entrant ledge defined by the inner face of a rib of the sheet. The end portion of the two clip members is turned oppositely with respect to each other. 88851 .do C)C0 CNo 0) 0) C C) co CC')

Description

P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: CLIP ASSEMBLY Applicant: Stramit Corporation Pty Limited The following statement is a full description of this invention, including the best method of performing it known to me: 1 6067 SD 2 CLIP ASSEMBLY This invention relates to a clip assembly for securing sheet metal profiled roofing sheets. 5 One method of fixing sheet metal profiled roofing sheets to a roof structure provides concealed fixing. In this method roof clips, of which there is a wide variety of types, are secured to purlins. The roofing sheets then are laid on top of the clips and pressed down to engage a channel defined by each of 10 respective ribs of the sheets down over a roof clip. One such fixing arrangement is used with the profiled roofing sheets available under the trade mark SPEED DECK ULTRA. One form of SPEED DECK ULTRA roofing sheet and of that one fixing arrangement is disclosed in Australian patent specification AU-685102 and its counterparts in other countries. As in 15 specification AU-685102, a number of clips may be mounted along a common strap to form a series of clips, with the spacing between centres for the clips corresponding so that for successive ribs of the profiled roofing sheet. Thus, a number of clips can be positioned simultaneously on a purlin and then individually secured to the purlin. The length of a strap may correspond 20 substantially to the width of the roofing sheets in a direction laterally of the ribs, with successive straps able to be inter-connected end to end. The clips typically are integrally formed and have a base by which they may be secured directly on an upper surface of the purlins, such as by use of suitable 25 screw fasteners comprising a Tek screw or the like. From the base, the clips have a pair of upstanding legs down over which the channel defined by a rib is able to be received. The legs may have a width which extends transversely or longitudinally with respect to the channel but, with either arrangement, the legs define or are bent to provide abutments for locating against an upwardly facing 30 surface of a re-entrant ledge defined by the inner face of opposite side walls of the rib. On a roof that requires a layer of insulation material, a spacer is provided between each purlin and the clips secured thereon. One method is to provide a foam plastics spacer, such as of polystyrene foam, with a steel 888851.doc 3 channel section above the spacer, and to use fasteners which accommodate the thickness of the spacer and steel section. The method of concealed fixing of profiled roofing sheets enables very good 5 securement of the sheets. However, roof failure can occur under very high wind conditions, such as in cyclonic conditions. During high wind conditions, wind gusts that strike the side of a building are forced upwards and over the building, creating a partial vacuum immediately above the roofing. The wind gusts and resulting variation in the magnitude of the partial vacuum enables 10 the atmospheric pressure prevailing at the underside of the roofing to give rise to a pulsed force effect on the roofing. The pulses can vary in amplitude, and may have a frequency of many cycles per minute. With a roofing of profiled roofing sheets, the pressure at the underside of the 15 roofing sheets causes them to distort and bow upwardly, between the ribs by which they are held down by the clips. Roof failure occurs when a roofing sheet bows up to an extent that the side walls of a rib are pulled outwardly away from each other so that the rib opens out to disengage the rib from a clip. Typically, each rib is engaged on a respective clip on each purlin traversed by 20 the rib. The engagement is by the downwardly facing abutment surface defined by each of opposite sides of each clip locating against the upwardly facing surface of a re-entrant ledge defined by the inner face of each of opposite side walls of each rib. Disengagement occurs when the rib opens sufficiently, as this pulls the re-entrant ledge of at least one side wall of the rib 25 from below the respective abutment surface of the clip. The present invention provides an alternative clip assembly for concealed securing of sheet metal profiled roofing sheets. At least in preferred forms of the invention, the clip assembly enables securement of roofing sheets which 30 provides improved resistance to roof failure in high wind conditions, such as to enable improved resistance to cyclonic conditions. 88851.doc 4 Accordingly, the present invention provides a clip assembly for concealed securing of sheet metal profiled roofing sheets, wherein the assembly has a base by which the assembly is mountable on a purlin or other support structure, and two elongate clip members separately secured in relation to and 5 projecting from the base; each clip member, at an end remote from the base, has an end portion (hereinafter referred to as a turned portion) adapted for locating over and bearing against an upwardly facing surface of a re-entrant ledge defined by the inner face of a side wall of a rib of a roofing sheet; and the turned portion of the two clip members is turned oppositely with respect to 10 each other; wherein the two elongate clip members are oppositely inclined and an end of each clip member adjacent to the base is secured in relation to the base by a hinged, flexible or pivot connection between its lower end and a respective end of a locating member mounted within the base enabling the clip member to pivot arcuately so the turned portion is able to move with, and 15 retain its location against, a re-entrant ledge of the rib as the rib opens under wind loadings on the roofing sheet. According to embodiments, the clip assembly has a base having a basal surface by which the assembly is mountable on a purlin or other support 20 structure, and two elongate clip members separately secured in relation to and projecting from the base. Each clip member, at an end remote from the base, has an end portion which defines an abutment surface which faces towards the base or towards a plane containing the basal surface. By the abutment surface, the end portion is adapted for locating over and bearing against an 25 upwardly facing surface of a re-entrant ledge defined by the inner face of a side wall of a rib of a roofing sheet. The end portion of the two clip members is to opposite sides with respect to each other. Thus, each end portion is to the side of its clip member which faces the other clip member, or each is to the side of its clip member which faces away from the other clip member. The end 30 portion may be provided by an end part of the clip member which is bent, turned or otherwise shaped or formed to provide an abutment surface to one side of the main extent of the clip member which faces back towards the base or the plane containing the basal surface. The most convenient form of end NZ1718 10oce 4a portion is provided by bending or turning the end of the clip member remote from the base and, while the end portion could be provided by attachment of a component to that end of the clip member, the term "turned portion" is used in the following but is to be understood as encompassing any suitable 5 arrangement for providing the abutment surface. A number of arrangements are possible for the clip assembly of the invention. In a first arrangement, the two clip members are closely adjacent such that the turned portion of each clip member is adapted for locating over and bearing 10 against a respective one of the re-entrant ledges defined by the opposing side wall inner faces of the same rib of a profiled roofing sheet. In that first arrangement, the clip members extend from the base and mutually towards each other so that the spacing between them is a minimum at the turned portions. In that one form, when each turned portion is located over and bears 15 against a respective re-entrant ledge, its clip member may extend adjacent to the respective side wall inner faces in which that re-entrant ledge is defined, NqZ1 7181/110.doc 5 with the turned portion of each clip member turned away from the turned position of the other clip member. In a second arrangement, the two clip members are spaced apart by a 5 distance which is considerably greater than in the first arrangement and short of the spacing between centres for successive ribs of a profiled roofing sheet. The clip members project from the base with each clip member inclined away from the other. The magnitude of the inclination of the clip members may be similar to that of the first arrangement. Thus, the turned portion of each clip 10 member is able to locate over and bear against a re-entrant ledge defined by the inner face of one of the side walls of its one of the successive ribs which is nearer to the other rib, but with the turned portion of each clip member turned towards the other clip member. 15 In a third arrangement, the base is of an elongate form enabling the clip assembly to provide securement of a roofing sheet or at least two adjacent roofing sheets at each of a series of more than two successive ribs. In the case of adjacent roofing sheets, one rib of the series may be defined by overlapping side margins of the sheets. 20 In one form of the third arrangement, each of the two clip members may extend from the base at or adjacent to a respective end of the base, in a manner similar to the second arrangement. However, the base has at least one further location intermediate of its ends from which a further two clip 25 members project, in a manner similar to the first arrangement. Thus, the turned portion of each clip member at or adjacent to an end of the base may be able to locate over and bear against a re-entrant ledge defined by the inner face of one of the side walls of its one of the first and last of the series of ribs, while each of the two clip members at an intermediate location is able to locate 30 over and bear against a respective re-entrant ledge of an intermediate rib of the series. 888851Sdoc 6 In the third arrangement, there may be provided a clip assembly according to the invention, wherein the base is of an elongate form enabling the assembly to provide securement of a roofing sheet at each of more than two successive ribs, each clip member projects from the base at or adjacent to a respective 5 end of the base, and each clip member is inclined away from the other clip member; the turned portion is able to locate over and bear against a re-entrant ledge defined by the one of the side walls of a respective one of the first and last ribs of the series which is nearer to the other of the first and last ribs, with the turned portion of each clip member turned towards the other turned 10 portion; and wherein the base has at least one further location intermediate of its end from which a further two clip members project, with each of the clip members at a further intermediate location able to locate over and bear against a re-entrant ledge defined by each of the opposed side walls of an intermediate rib of the series. 15 In each of the arrangements described, a plurality of the clip assemblies may be inter-connectable to provide a series, at a required spacing between successive assemblies, able to be secured along a purlin or other support structure. Thus, in the case of the assembly of the first arrangement, a 20 plurality of the assemblies may be mounted along a common strap in a manner similar to that disclosed for the clips disclosed in the above-mentioned specification AU-685102. A plurality of assemblies of the second or third arrangement also can be mounted on a common strap. In each case, successive series can be inter-connected end to end. However, with each 25 arrangement, it is preferred that the assemblies are able to be inter-connected in a series by the bases being inter-connectable end to end. With a series of assemblies of the second or third arrangement, the clip member at each of adjacent ends of successive bases most preferably form two clip members which are able to engage in a common rib of a roofing sheet. That is, those 30 end clip members are able to engage in a common rib in a manner similar to that for the clip members of an assembly of the first arrangement or similar to two clip members at an intermediate location on the base of an assembly of the third form. 888851.doc 7 The base of each clip assembly may define at least one basal surface by which the assembly is mountable on a purlin. At least one basal surface of a base may have an aperture through which a retaining fastener, such as a Tek 5 screw can be applied to secure the assembly in position on the purlin. Successive clip assemblies to be connected end to end in a series may have a basal surface at each end, with an end portion at one end of the base of one assembly able to extend over an end portion at the other end of the base of the next assembly to enable each assembly to be secured on the purlin by use 10 of a common fastener which secures the successive assemblies of the series. Alternatively, each assembly may have an upstanding tang at one end of its base and a slot at its other end, with successive assemblies able to be secured in end to end relation either by the slot of one received down over the tang of the other or the tang of one received into the slot of the other. 15 Relative to an in-use orientation of the clip assembly as mounted on a purlin, the base forms a support or anchor from which the clip members extend upwardly. Thus, in that orientation, it is by a lower end portion that each clip member is secured in relation to the base. 20 The base may be formed from a wide variety of metals, ceramics or synthetic plastics materials, on a combination of two or more of these materials. The base most preferably is made of an engineering plastics material. Polyamides, such as Nylon 66, are highly suitable materials for the base, with Nylon 66 25 having a glass filling being a preferred material. The clip members also may be formed from a wide variety of materials. However, high tensile steel or spring steel are most suitable, particularly for clip assemblies for providing a maximum performance under high wind 30 conditions. The clip members preferably have a thickness in the direction of spacing between clip members which is substantially less than the width of the clip 880851.doc 8 members laterally of the direction of that spacing. This enables important characteristics of the clip members. The width dimension increases the distance longitudinally of a rib over which the turned portion of a clip member is able to locate over and bear against a re-entrant ledge of the rib. This 5 increases the spread, or area, of surface to surface contact between the turned portion and re-entrant ledge, assisting in maintaining that contact. The width dimension also increases the resistance of the clip members to lateral bending. However, despite the clip members being sufficiently stiff as a result of that resistance, their thickness enables the clip members to flex to move the 10 turned portion arcuately, such as to bend on a lateral axis, at least when subjected to a sufficient force. Thus, in use, the clip members are able to flex in response to a lifting force which acts on a roof panel and is sufficiently strong as to cause a rib to open out to enable the turned portion of each clip member to follow movement of and continue to bear against the respective re 15 entrant ledge. The flexing may result from engagement between the turned portion and the ledge, or by recovery of the clip member from a position to which it has been flexed on installation of the roofing sheet, or a combination of the engagement and recovery. 20 Each clip member of the clip assembly may be shaped to favour a particular flexing geometry such as, for example, flexing principally at a part of the length of the clip member which is closely adjacent to the base. To achieve a chosen flexing geometry, the clip member may be shaped by means of holes, stiffening ribs, thickness or width variation, or the like. 25 While the clip member may be able to flex in response to a lifting force acting to cause a rib to open out, it is preferred that the clip member pivots in response to the force. In pivoting, the clip member also may flex to a degree, particularly towards the end of pivoting before the rib opens to an extent 30 resulting in the turned portion of the clip ceasing to retain its location over and against the re-entrant ledge. 8885I .doc 9 Each clip member of the clip assembly may be adapted to enable its turned portion to locate over and bear against the re-entrant ledge of a side wall of a rib of a roofing sheet so that a resultant line of force at the contact location between the abutment surface and the ledge is outside a position at which the 5 clip member flexes, pivots or is hinged. In each case, the arrangement may be such that the angle between a line providing a continuation of the ledge and the line of force through that location and position is substantially less than a right angle. This enables contact between the abutment surface and the ledge to be maintained up until a point is reached, with progressive opening of the rib 10 under increasing wind loadings, at which that angle reaches and the exceeds 90 degrees and the ledge is able to pull free from the abutment surface and failure of the roofing occurs. However, arcuate movement of the turned portion of the clip member as it flexes, hinges or pivots in response to opening of the rib enables the turned portion to follow movement of the ledge to a significant 15 extent and thereby maintain the contact with the ledge even under very high wind loadings, even up to cyclonic wind loadings. The clip members may comprise elongate straps of high tensile steel or spring steel. The straps may have a width which is about 7 to 14 times the thickness 20 of the straps, while the thickness may be from about 2 to 3 mm. However, as an alternative to comprising elongate straps, the clip members may be formed of high tensile steel or spring steel wire. In that alternative, the clip may have two legs extending from respective ends of a web portion, with the legs turned adjacent to the web portion to define the turned portion of the clip member. 25 The wire of which the clip members are formed may be from about 2 to 4 mm in diameter. The legs may be secured in relation to the base at their ends remote from the web portion, while the turned portion of a clip member may be shaped such that it is by the web portion that the clip member is adapted for locating over and bearing against a re-entrant ledge of a web. Thus, the legs 30 may be spaced laterally of the direction of spacing between clip members. The pivoting or flexing of a clip member enables its turned portion to move with, and retain its location against, a re-entrant ledge as the rib opens out. 886851.doc 10 Under extreme conditions, a rib can be caused to open out to an extent causing its permanent deformation. The turned portion of the respective clip member is likely to have ceased to retain its location over and against the re entrant ledge before permanent deformation, resulting in failure of the roof 5 where this occurs. However, throughout a substantial part of opening out of the rib before its elastic limit is reached, the clip member is able to pivot or flex and follow the rib to retain its turned portion against the re-entrant ledge. The clip member is able to pivot or flex by the movement of the re-entrant ledge as the rib opens out in response to a pulsed force caused by wind conditions. 10 The re-entrant ledge lifts, as the rib opens out, and thereby increases frictional engagement between that surface and the turned portion of the clip. As the re entrant ledge also is drawn laterally with opening of the rib, the increase in frictional engagement results in the turned portion being drawn laterally and upwardly with the re-entrant ledge, and resultant pivoting or flexing of the clip 15 member. The clip members may be secured in relation to the base in a number of different ways. Each clip member may have a portion, remote from the turned portion, around which the base is formed, such as by casting or moulding, to 20 secure the clip member to the base. Alternatively, each clip member may have a portion which is a firm frictional fit in a recess defined by the base. Each of these alternatives provides securement of the clip in a manner such that the clip is able to flex in response to a lifting force acting on a roof panel. However, as indicated herein, the clip member preferably is able to respond by 25 pivoting and to enable this, a locating member with which the clip member is pivotably engaged may be defined by, or be fixed in relation to, the base. An end portion of the clip member remote from its turned portion may, for example, be bent to a J-configuration so that it is able to hook around or through the locating member. Alternatively, the clip member may be pivotable 30 by the locating member hooking through or around an end portion of the clip member. In each case, the arrangement is such that the clip members are unable to pull free of the base under the action of a pulling force acting on the 11 clip member as roofing sheets are caused to bow upwardly as a partial vacuum is created above the sheets. Where the clip member is able to pivot by being pivotably engaged with a 5 locating member fixed in relation to the base, the locating member may be fixed by having a portion around which the base is formed. The base may be formed around the portion of a locating member by being cast or moulded around that portion. Alternatively, the portion of the locating member may be inter-engaged or inter-fitted with formations of the base so as to be fixed in 10 relation to the base. In one suitable form, the base may have parts which are secured together by inter-engagement, such as snap-fitting, or by fasteners or bonding, with the portion of the locating member held between the parts of the body when the parts of the body are secured together. Thus, the body may comprise two laterally adjacent, longitudinal parts which are secured together 15 such as at a plane parallel with the longitudinal extent of the body. For example, the body may comprise two halves, such as of complementary form, which are secured together at a plane which, relative to an in-use orientation for the clip assembly, is vertical and parallel with the longitudinal extent of the body. 20 One form of clip assembly according to the first, second and third arrangements, is formed from metal strip material, such as from a strip of suitable steel. Where so formed, the base may be formed by part of the length of the strip, with a plurality of longitudinally spaced tongues formed from the 25 strip and folded or bent so as to project at an acute angle from the base. Each tongue preferably projects from a central part of the width of the base and may comprise a respective clip member, or a part of a respective clip member. Thus, where each tongue comprises a clip member, an end portion remote from the base comprises a turned portion which defines an abutment surface. 30 Where each tongue is part of a clip member, an extension member is secured to the end of the tongue remote from the base, with the tongue and the extension member comprising a clip member and an end of the extension 688851.dc 12 member remote from the base has an end portion which comprises a turned portion which defines an abutment surface. In a second form, a plurality of longitudinally spaced tongues are formed from 5 the strip but remain substantially parallel to the base. In this arrangement, each tongue forms part of a clip member, with the remainder of the clip member provided by an extension member which is secured to a free end of the tongue and projects therefrom at an acute angle to the base. An end of the extension member remote from the tongue has a turned portion which 10 defines an abutment surface. Each form of clip assembly formed from metal strip material may have only one pair of clip members, with these inclined towards each other and each having its turned portion extending away from the other clip member and its 15 turned portion. However, each form of assembly preferably has a plurality of such pairs of clip members spaced along its length, with the spacing between centres for successive pairs corresponding to that between ribs of a profiled roofing sheet. 20 Where the assembly is formed from a metal strip material, each tongue to comprise, or form part of, a clip member, may be formed by a metal stamping or cutting operation to form a blank from the strip material. In the first form, but not in the second, each tongue is bent to a position in which it projects from the base. However, with each form the metal stamping or cutting operation 25 results in the tongue being separated from the base around the periphery of the tongue. That periphery may be, and preferably is, somewhat U-shaped in form. Where, as in the first form, the tongue is bent, the bend may be across the free-end of the arms of the U-shaped periphery, but preferably is at a transverse line spaced from the free-ends. Thus, after bending, each tongue 30 may be joined to the base by a relative short end portion of the tongue which is substantially parallel to the base, or inclined slightly to the base at a much smaller angle, such as up to about 50, than the acute angle through which a main part of the length of the tongue extends after it is bent from the base. 886851.doc 13 With two successive clip members which each have their turned portion able to locate over and bear against a re-entrant ledge defined by a side wall of a respective one of successive ribs, the two successive clip members may be 5 able to pivot by being pivotably engaged with a respective end of a common locating member fixed in relation to the base. Thus, the common locating member may be of elongate form and at each of opposite ends adapted for engagement by a respective clip member. The common locating member may, for example, comprise an elongate strap, such as of steel, which has 10 respective end formations to which each of a respective clip member is secured. Each formation may, for example, comprise a transverse slot which a respective clip member is able to hook through. Each clip member, along its length from securement to the base to the turned 15 portion, extends along the base and, relative to an in-use orientation for the clip assembly, upwardly to space the turned portion above the base. At an intermediate location along that length the clip member may be bent to provide a first portion from the securement to the base, to that intermediate location, which extends upwardly at a lesser angle than a second portion from the 20 intermediate location, to the turned portion, with the portions being inclined to each other at an obtuse angle. The first portion may be supported by an inclined upper surface of the base, with the second portion projecting away from the base such that, in the in-use orientation, the turned portion is spaced above the base. The second portion of the clip member may be inclined 25 upwardly so that the second portion of the clip member is at an angle to the horizontal relative to the in-use orientation of, for example, from about 650 to 850, such as from about 420 to 800. However, the first portion of the clip member may be inclined at a lesser angle than the second portion, such as an angle to the horizontal of from about 200 to 30*. Between the mutually inclined 30 first and second portion of the clip member there may be a short connecting part which, in the in-use orientation, may be supported on a surface of the base and substantially horizontally disposed. 88851.doc 14 The clip assembly may include a mechanical fuse for each clip member which resists pivoting or flexing of its clip member in response to modest lifting forces acting on roofing sheets. This is important with pivoting clip members, particularly if they are relatively freely hinged for pivoting, since clip members 5 which are unconstrained can allow an entire roofing sheet to lift, even under most wind induced pressure. This would limit the serviceability capacity of the sheets to which an arbitrary deflection limit can be imposed. Each mechanical fuse may be a tab, abutment or wall which restricts free movement of the clip member in response to lifting forces up to a predetermined valve. In response 10 to lifting forces in excess of that value, the fuses are adapted to release the clip members for greater pivoting or flexing, by the fuses deflecting from a clip member blocking condition or position, or by breaking. That is, the fuses restrict pivoting or flexing movement of the clip members up to a serviceability limit-state loading or action, but then deflects, fails or shears at a higher load. 15 This then allows the clip members to pivot or flex freely up to a full strength limit state. The fuses may be of a plastics material, in which case they may be formed integrally with the base. Alternatively, the fuses may be attachable to the 20 base, each adjacent to a clip member, and they again can be of a plastics material. In one convenient arrangement, each fuse is a strap or tab which extends part-way or fully across a clip member. The fuses may extend between opposite sides of the base, while their failure may be visually apparent. The fuses may be replaceable, to enable "re-setting" of a roofing 25 system. In order that the invention may more readily be understood, reference now is directed to the accompanying drawings, in which: 30 Figure 1 is a perspective view of a section of roofing showing a roofing sheet retained by a first prior art arrangement according to the above mentioned specification AU-685102; 888851.doc 15 Figure 2 is similar to Figure 1, but shows a second prior art arrangement according to AU-685102; Figure 3 is an end elevation of a roofing sheet secured on a purlin by a 5 plurality of clip assemblies according to a first embodiment of the present invention, under low wind conditions; Figure 4 corresponds to the arrangement of Figure 3, but under high wind conditions; 10 Figure 5 shows an enlarged part of the arrangement of Figure 3 under the low wind conditions; Figure 6 is an enlarged view of part of the arrangement of Figure 4, 15 under the high wind conditions; Figure 7 is a perspective view of one end of a clip assembly of Figure 3; Figure 8 is similar to Figure 6 but shows detail of a junction between clip 20 assemblies of the first embodiment of Figure 3, on an enlarged scale; Figure 9 is a perspective view corresponding to Figure 7, but with a component removed; 25 Figure 10 is similar to Figure 8, but at an overlap between successive roofing sheets; Figure 11 is a perspective view of an assembly of a second embodiment; 30 Figure 12 is a perspective view of a first alternative form of clip member embodiment; 888851 do 16 Figure 13 is a perspective view of a clip member for the assemblies of the first or second embodiments; Figure 14 is a view similar to Figure 3 showing end to end connection 5 between clip assemblies of the first embodiment; Figure 15 is an exploded perspective view of an assembly of Figure 14; Figure 16 is a perspective view of an assembly according to a third 10 embodiment of the invention; Figure 17 corresponds to Figure 16, but shows a variant of the third embodiment; 15 Figure 18 is a plan view of a blank from which the assembly of Figure 16 is able to be formed; Figure 19 is a plan view of a blank from which the assembly of Figure 17 is formed; 20 Figure 20 is a perspective view of an assembly according to a fourth embodiment of the invention; and Figure 21 is a plan view of a blank from which the assembly of Figure 25 20 is able to be formed. In Figure 1, the section of roofing 10 is illustrated by a sheet metal profiled roofing sheet 12 which is secured on at least two purlins 14 (of which only one is shown) by a respective series of clips 16. The clip series 16 has a strap 17 30 and, spaced along strap 17, a plurality of clips 18. The spacing between clips 18 corresponds to the spacing between ribs 20 of sheet 12. The complete roofing has end to end rows of sheets 12, with the successive rows having overlapping edges which form a composite rib 20. The complete roofing also 8888i AM 17 includes laterally spaced purlins, each extending under successive rows. Each sheet 12 is secured on two or more purlins by clip series 16, in a manner fully described in specification AU-685102, the disclosure of which is incorporated herein by reference and to be read as part of this disclosure to 5 enable a full appreciation of the differences introduced by the clip assembly of the present invention. The arrangement of Figure 2 differs from that of Figure 1 in that the strap 17 of the clip series 16 is spaced from each purlin 14 by a strip 22 of foamed plastics 10 material and by a cap 24 of channel section steel provided over strip 22. In each of Figures 1 and 2, the clip series 16 is secured on the purlins 14 by a respective fastener (not shown) applied through each clip 18 into the purlin 14. The clip assemblies 16 of Figures 1 and 2 secure the sheet metal roofing sheets 12 against rattling or lifting up until a predetermined serviceability force 15 is applied by prevailing wind conditions. The serviceability force is an industry standard that all roofing sheet must withstand without lifting up more than a determined amount. Indeed, the assemblies 16 of Figures 1 and 2 provide securement of the roofing sheets 12 well in excess of that serviceability force and prevent roofing failure in very strong wind conditions short of cyclonic 20 conditions. The clips have some ability to flex so as to adjust with movement of the re-entrant ledges of the ribs of the sheets 12 as the sheets 12 bow up under prevailing strong wind gusts. However, the scope for flexing is limited and, particularly with strong wind gusts of high frequency, the clips are relatively static and unable to adjust to any substantial extent. In contrast, the 25 clip assembly of the present invention provides less static, relatively dynamic securement of sheets 12 and, hence, has a greater capacity to adjust for securing the sheets under very strong wind conditions, ranging up to high, or even to a level of cyclonic, wind conditions. 30 Figures 3 and 4 show a sheet metal profiled roofing sheet 28 which is secured in relation to an end to end series of three clip assemblies 32. The sheet 28 has uniformly spaced longitudinal ribs 29 and a pan 27 between each successive pair of ribs 29 which is relatively flat under low wind conditions. 888851.doc 18 The sheet 28 and assemblies 32 are shown in an in-use orientation and secured on a purlin (shown only by an upper surface depicted by line P). However, the bolts, screws or other fasteners, by which overlapping ends of assemblies 32 would be secured on the purlin P, are not shown. 5 With reference to Figures 3 to 10, the sheet 28 has, in addition to the uniformly spaced ribs 29, respective side margin formations 30, 31. The underlapping formation 30 of one sheet 28 is able to be received in the overlapping formation 31 of a laterally adjacent sheet 28, to form a composite rib, as shown 10 in Figures 10 by composite rib 29a. As can be appreciated most clearly in Figures 5 and 6, the ribs 29 have side walls 33 which taper to top wall 34 of the ribs 28. However, below the junction of side walls 33 and top wall 34, each side wall 33 is stepped inwardly such that a re-entrant ledge 35 is defined within rib 29 and the rib 29 has an internal channel 36 which is somewhat 15 mushroom shaped. The clip assemblies 32 have an elongate base 38 of which only one half is shown in Figures 3 to 6, and 8 and 10. At each end of the base 38, each assembly 32 has a clip member 40. Each clip member 40 is connected to the 20 other in that each of them has one part 41 of its length engaged in and retained in relation to base 38 by a locating member 42,while the other part 43 of its length projects from base 38 to space turned part 39 from the base 38. As seen in Figures 7 and 15, the base 38 in the in-use orientation in which assemblies 32 are shown, includes two longitudinally separate laterally open 25 half shells 44 and 45 of complementary form. Each of shells 44 and 45 has a wall 46 which defines one side of base 38. The shells 44 and 45 are able to be joined along a central longitudinal plane through base 38, with the plane vertical in an in use orientation for the assembly 32. At two longitudinally spaced locations, shell 44 has a respective sleeve 47 which projects at right 30 angles to its wall 46 towards shell 45. At each of corresponding locations, shell 45 has a stud 48 which projects towards shell 44 and is a tight friction-fit in a respective sleeve 47; each stud having a three-arm star shape in end elevation in the form shown. Above one sleeve 47 and the corresponding stud 88MtWdC 19 48, each of sheets 44 and 45 has a top wall 49 over only part of the length of the base 38. With each stud 48 received into the corresponding sleeve 47, the opposed top walls 49 of sheets 44 and 45 abut edge to edge along a longitudinal centreline for base 38. In the in-use orientation for assembly 32, 5 the abutting top walls 49 are substantially horizontal. In side elevation, the base 38 has an asymmetrical form. Towards one end, the left hand end in Figures 3 to 10, the body has a first basal surface 50 which is substantially parallel to top wall 49 and by which assembly 32 is able to 10 stand on purlin P. From basal surface 50 towards the other end of base 38, the underside of base 38 defines a longitudinal arch 51. Beyond arch 51, base 38 has a thin terminal strip 52 which defines a second basal surface 53 which is substantially parallel to top wall 49 and by which assembly 32 is able to stand on purlin P. At a transverse end margin, strip 52 increases in thickness 15 to the free end, above surface 53, to define a retaining wedge 54. Along the length of each of shells 44 and 45, a respective bottom wall 56 defines arch 51 and continues to provide one half of strip 52 and wedge 54. With each stud 48 received in the corresponding sleeve 47, walls 56 and the 20 parts of strip 52 and wedge 54 abut edge to edge on the longitudinal centreline for base 38. Extending below the top wall 49 of each of shells 44 and 45, there is a respective longitudinally extending support wall 58. From the end of base 38 25 remote from strip 52, the support wall 58 has longitudinally successive parts 60, 61, 62, 63, 64, 65, 66 and 67. The first part 60 extends from the free end of its one of shells 44 and 45 and is substantially co-planar with the lower surface of top wall 49 and substantially parallel to basal surfaces 50 and 53. From part 60, part 61 is inclined downwardly at a relatively shallow angle such 30 as of about 20* to 30* from the plane of part 60. From part 61, the part 62 is inclined down more shapely, such as at an angle of about 600 to 420 from that plane. From part 62, part 63 extends substantially parallel to part 60, and to basal surfaces 50 and 53. Part 63 extends towards one end of surface 50, but 888851.dc 20 is spaced above surface 50 by an amount corresponding substantially to the thickness of strip 52. From part 63, part 64 is inclined upwardly over surface 50 and below top wall 49, at a slightly more shallow and opposite angle to part 61. From part 64, part 65 is more sharply inclined upwardly over a short 5 distance, at a similar but opposite angle to part 62. From part 65, part 66 is inclined upwardly at an angle similar, but opposite, to the angle of part 61, to pass longitudinally beyond the end of top wall 49, and to the plane of top wall 49. From part 66, part 67 extends in the same plane as part 60, while part 66 terminates over the respective one of the sleeve 47 and stud 48 remote from 10 wall 49. Each of the clip members 40 extends upwardly, from below top walls 49. One member 40 passes through an opening between walls 49 and parts 60 of the support wall 58, beyond the end of base 38. The other member 40 passes 15 through an opening between walls 49 and parts 67 of walls 58, but is spaced from the other end of base 38. The parts 41 of clip members 40 are supported on parts 61 and 66, of support walls 58, respectively. The part 43 of members 40 extend beyond parts 60 and 67 of wall 58, respectively, to locate the turned part 39 at a required spacing above base 38. Intermediate of the parts 41 and 20 43, each member 40 has a connecting part 42 which is supported on parts 10 and 67 of walls 58, respectively. To secure clip members 40 in relation to base 38, assembly 32 includes a locating member 42 fixed in relation to the base 38. The locating member 42 25 is a length of a steel strap which is supported on support wall 58. The member 42 is bent to a form corresponding to part of wall 58, and has longitudinally successive parts 71, 72, 73, 74 and 75. The parts 72, 73 and 74 are supported by parts 62, 63 and 64 of walls 58, respectively. The part 71 extends over an end of parts 62 of walls 58, but at an angle providing a slight 30 spacing from parts 62. Similarly, part 74 is inclined from part 73 so as to be spaced from parts 65 of walls 58 to provide a slight spacing between parts 74 and parts 66 of walls 58. 888851.doc 21 Each of parts 71 and 74 of locating member 42 defines a transverse slot 76 adjacent to a respective free end of member 42. Also, the end of the part 41 of each clip member 40 remote from its part 43 is bent to a J-configuration and the resultant bent end 70 is looped through a respective slot 76 of locating 5 member 42. Thus, with member 42 secured in relation to base 38, each clip member 40 is able to pivot at its engagement with member 42 so as to move away from and return to, support walls 58. However, as seen most clearly in Figure 7, the extent of pivoting away from walls 58 is limited by mechanical fuses in the form of shear bars 78 which project from the wall 46 of each shell 10 44. A respective shear bar 70 from each wall 46 projects adjacent to the bent end 70 of a respective clip member 40, such as to limit pivoting of members 40 to a range of about 40 to 60 while bars 78 are intact. As shown most clearly in Figure 13, each clip member 40 has a turned part 39 15 at the free-end margin of its part 43. The turned part 39 is turned from part 43 through a little less than 1800 so as to be almost semi-circular. At the free end of part 39, the member has laterally spaced teeth formations 79 which point towards part 41 of their member 40. 20 With shells 44 and 45 abutting, with each stud 48 received fully into a respective sleeve 47 to secure clip members 40 and locating member 42 in base 38, the assembly 32 is able to be secured on purlin P in an end to end series of inter-fitting like assemblies 32. With the shells abutting, the respective top walls 49 abut edge to end, the respective bottom walls 56, the 25 respective strips 52 and wedges 54 and the respective support walls 58 also abut edge to edge. The locating member 42 then may be gripped along its side edges between the walls 46 of the shells so as to be held in its supported position on the support walls 58, or member 42 may be held in that position by dimples or projections on the support walls 58 or by a groove in each wall 58. 30 To secure a number of assemblies 32 on a purlin P in an end to end inter fitting series, a first assembly is placed along a centre line of the upper surface of the purlin P at a required location. That first assembly 32 is positioned with 888851.doc 22 its left hand end as viewed in the drawings at the start for the required series and with first and second basal surfaces 50 and 53 contacting the purlin. The first assembly then is secured on the purlin. For this purpose a hole 80 is pre formed in part 73 of locating member 42, and a fastener such as a self-tapping 5 screw is applied through hole 80 and into purlin P. This holds the member 42 firmly on the support wall 59, while the first basal surfaces 50 are pressed firmly against the purlin P. A next assembly 32 in the same orientation then is presented endwise to the 10 first assembly, to seat the underside of parts 63 of the support walls 59 of the second assembly on the strips 52 of the first assembly. To enable this, part of the underside of base 38 of each assembly 32 is complementary to the top side of the assembly 32. Thus, at one end, the underside of base 38 through to first basal surface 50, defined by parts 60, 61, 62 and 63 of walls 59, and an 15 initial section of part 64 of wall 59, is complementary in form to the upperside of the other end of base 38 from the end of parts 67 of walls 59 through to the end of wedges 54. Thus, one end of one assembly 32 interfits with the other end of another like assembly 32. Again, a fastener is inserted through the hole 80 in the part 73 of the locating member 42 of the second assembly 32. The 20 fastener serves the same function as for the first assembly, while it also holds the parts 54 of the supporting walls of the second assembly 32 firmly down on the strips 52 of the first assembly 32. Also, the wedges 54 are secured within a complementary shaped recess defined adjacent to first basal surfaces of the second assembly 32, below the parts 64 of the support wall 59 of the second 25 assembly. With the second assembly 32 secured, the same procedure is repeated for each successive assembly 32 of the series. In the series of like assemblies 32, each oppositely extending clip member 40 extends towards and is closely adjacent a respective clip member 40 of the 30 next adjacent assembly 32. Thus, along the series, there are successive pairs of closely adjacent, oppositely extending clip members 40. These pairs have a spacing between centres which is substantially the same as the spacing between centres for successive ribs of sheet metal profiled roofing sheets 28. 886851.doc 23 Each pair of clip members 40 are able to function in a similar manner to the known type of integrally formed clip in engaging with the roofing sheets. Thus, as shown in Figures 3 and 5, the sheet 28 is able to be received down over laterally spaced parallel purlins P to receive a respective pair of clip members 5 40 on each purlin P into each channel 36 defined within each rib 29. The sheet 28 may be so received by being rolled down from a trailing edge to present each channel 36 in turn to a respective pair of clip members 40 on each of successive purlins P traversed by sheet 28. Each rib 29 can be forced down firmly, such as by an installer applying foot pressure down on the top of 10 the rib 29. The upwardly converging side walls 33 defining the channel 36 ride down over the turned parts 39, thereby causing the parts 43 of the clip member 40 to flex closer together until parts 39 are able to pass beyond the re-entrant ledge 35 defined in each side wall 33 of the rib 29. The parts 43 then are able to resiliently recover to that the turned portion of each locates 15 over and, through the formations 79, bears against the respective ledge 35. Figures 3 and 5 show sheet 28 as fully installed, and under mild wind conditions. Figures 4 and 6 correspond to Figures 3 and 5, but under strong wind conditions causing the pan 27 between successive ribs 29 to bow 20 upwardly. As bowing of pans 27 progresses, each rib 29 opens laterally by its side walls 33 moving outwardly away from each other. As this occurs, re entrant ledges 35 move laterally outwardly, while they also are lifted away from base 38 and purlin P with sheet 28 as a whole. However, the clip members 40 of each pair are able to pivot oppositely so each member 40 lifts away from its 25 support wall 59 and thereby follows the respective wall 33 of the rib 29, as seen in Figure 6. The pivot axis for each clip member 40 is substantially co-incident with the upper one of the two longitudinal side edges of slot 76 in the respective 30 locating member 42. The length of the pivot arm between that axis and teeth formations 79 is such that formations 79 traverse a pronounced arc which not only allows formations 79 to move laterally with widening of the rib 29 and its channel 36, but also to move away from base 38 with lifting of sheet 28. 88O851.dDC 24 Within limits, the length of the pivot arm can be chosen to give a selected curvature of the arc and, hence, the extent of lateral movement of teeth formations 79, relative to the extent of movement of formations 79 away from base 38, for a given angle of pivoting. 5 In Figure 6, the clip members 40 are shown at about the full extent through which they can pivot without breaking the shear bars 70. On breaking of the bars 70, further pivoting of members 40 becomes possible, up to a limit set by each re-entrant ledge 35 pulling free of engagement by teeth formations 79. In 10 general, the angle e made between an outward continuation C of the upper surface of ledge 35 and a line L between the tips of teeth formations 79 and the pivot axis for clip members 40 needs to be less than 90* in order for that limit not to be reached. However, the inclination imparted to ledge 35 when it is formed can be increased to increase the extent of widening of the channel 15 36 before that limit is reached. That is, as formed the re-entrant ledge 35 can be beyond the substantially horizontal disposition shown in Figure 5 so that the ledge 35 slopes outwardly and downwardly relative to the top wall 34 of the rib 29. 20 Thus, the pivot or hinge axis for each clip member 40 is positioned so that the turned part 39 of each member is retained over and bears against the ledge 35 as the angle of ledge 35 changes as the sheet 28 bows up between successive ribs in response to wind loadings. The shear bars 70 stop members 40 from pivoting beyond a range allowing for wind conditions up to a 25 serviceability wind loading force set by an industrial standard that all roofing sheets must be able to withstand without lifting up more than a predetermined amount. The shear bars 70 are designed to shear off at a wind loading force above serviceability, allowing the clip members to rotate further and maintain the desired geometrical relationship with re-entrant ledge 35 at values of e 30 below 90*. 88851.doc 25 The perspective view of Figure 7 shows the shear bars 70 and clip member 40 positioned for zero load. Figure 8 shows the shear bars 70 at the point of shearing under a load just in excess of the serviceability wind loading force. 5 In the perspective view of Figure 9, the clip assembly 32 shown generally corresponds to the assemblies 32 of Figures 3 to 8, again with shell 45 removed for the purpose of illustration. However, the one of the clip members 40 at the left hand end and distinguished as clip 40a, is of a modified form enabling better securement at the composite rib 29a shown in Figure 10. As 10 can be seen most clearly in Figure 10 by comparing that member 40a with the adjacent clip member 40 of an end to end adjacent assembly 32, part 43a and turned part 39a of member 40a are modified in that part 43a is of greater length than part 43 of other clip members 40 and, while bent mid-way along its length in the direction in which part 39a is turned, part 43 extends to a greater 15 spacing above base 38 than for other members 40. Also to allow for that greater length, the length of turned part 39a also is increased to that its teeth formations 79a are at the same spacing above base 38 as the formations 79 of the adjacent clip member 40. 20 As shown in Figure 10, rib 29a is formed from an underlapping formation 30 of the left hand roofing sheet 28 which is engaged within an overlapping formation 31 of the right hand roofing sheet 28. Figure 10 shows sheets 28 as lifted under a wind loading in excess of the serviceability wind loading force which as resulted in rib 29a opening out by its side walls 33a being pulled 25 outwardly away from each other. The movement of the wall 33a which includes the underlapping formation 30 has caused that wall to rotate away from its engagement against the overlapping formation 31. This rotation, which is along the junction between formation 30 and the adjacent pan 27, would continue with an increase in loading force to cause the roofing to fail by 30 formation 30 pulling-out of overlapping engagement with formation 31. However, the greater length of part 43a of the modified clip member 40a results in the pivoting of formation 30 being arrested by it abutting against member 40a adjacent turned part 39a. This presses the re-entrant ledge of 88Mmi dc 26 the underlap 30 into firm contact with the re-entrant ledge of the overlap 31, thereby resisting separation of the underlap formation 30 from the overlap formation 31. 5 Figure 11 shows a clip assembly 132 according to a second embodiment of the invention. In this, parts corresponding to parts of assembly 32 of Figures 3 to 10 have the same reference numeral, plus 100. As detail of the assembly 132 will be understood from the description of assembly 32, the following description focuses principally on differences. 10 A principal difference in assembly 132 is that it corresponds to a series of three assemblies 32 in end to end relationship. Like a series of three assemblies 32, the assembly 132 has a width corresponding to the width of a roofing sheet. 15 The base 138 of assembly 132 comprises two full-length half shells 144 and 145 which are of complementary form and inter-fit to provide base 138. At one end, body 138 has a clip member 140, while at its other end it has a clip member 140a. Each of those members 140 and 140a extends oppositely away from the other. Each of those members 140 and 140a is engaged with 20 one end of a respective locating member 142. A second clip member 140 from each end is engaged with the other end of that member 140, and extends away from the respective one of the clip members 140 and 140a at or adjacent to its end of base 138. Intermediate the second clip members 140, there are two further oppositely extending clip members 140. Each of the two further 25 members 140 extends towards a respective one of the second clip members 140, while each of the two further members 140 is engaged with a respective end of a third locating member 142 positioned between them. The arrangement is such that there are two intermediate pairs of clip members 140 which have their oppositely turned portions 139 mutually spaced but closely 30 adjacent. The five clip members 140 and member 149a, as well as the three locating members 142 are supported in base 138 to enable all five clip members 140 to 888851.doc 27 function in the same way as members 14 of Figures 3 to 10, and to enable clip member 140a to function in the same way as member 40a of Figures 3 to 10. Thus, members 140, 14a and 142 may be positioned on a suitably profiled support wall, to enable members 140 and 140a to pivot. 5 The undersurface of base 138 below clip member 140a is of a complementary form to the top surface of base 138 beyond the first clip member 140 at the other end. Thus, the assemblies 132 are able to inter-fit end to end to provide a series of assemblies 132. Figure 12 shows the end of a first assembly 132 10 having a clip 140a being presented downwardly onto the opposite end of a second assembly 132. As can be appreciated from Figure 12, the inter-fitting results in a clip member pair, comprising a respective clip member 140a and a member 140, for engaging in and securing a roofing sheet at a rib (as with rib 29a in Figure 10) between co-operating underlapping and overlapping profiled 15 side margins of two laterally adjacent roofing sheets. The intermediate pairs of clip members 140 of the assembly similarly engage in and secure the roofing sheet at a respective intermediate rib. In the case of assemblies 132, the undersurface below clip member 140a is 20 provided with a fin 90 which is inclined downwardly and beyond the adjacent end of base 138. The fin 90 is centrally positioned and parallel to a vertical central plane through base 138. As one assembly 132 is presented to a like assembly, the fin 90 is able to be received into a corresponding slot (not shown) extending down from the complementary upper surface at the other 25 end of another assembly 132. The fin 90, and the slot into which it is received, assist and enhance inter-fitting of successive end to end assemblies 132. However, the fin and slot arrangement also assists in ensuring that the correct pitch is maintained for 30 roofing sheets. The fin aids the end to end joining of assemblies in the presence of a layer of insulating material provided over a purlin, and it also prevents an assembly 132 which is to be joined to an installed assembly 132 866851.doc 28 from toppling over as foot pressure is applied to force a rib down onto a pair of clip members. The clip member 40 shown in Figure 13 readily will be understood from 5 description in relation to Figures 3 to 10. As indicated previously, turned portion 39 is provided along its free edge with teeth formations 79. As can be seen, these terminate at a contact point which is able to indent into the re entrant ledge within a rib of a roofing sheet, to further prevent shippage under high wind loads. 10 As highlighted in Figure 14, the base 38 of a clip assembly 32 spaces the roofing sheet 28 at a height H above the purlins P. When the base 38 is made of a plastics material, the height H ensures a thermal break between the roofing sheets 28 and the purlin P or other support structure. As detailed 15 earlier herein, the base 38 can be made of a variety of materials, such as plastics materials. Nylon 66 with glass fibre filling is one highly suitable material. Similar considerations apply to the base 138 shown in Figures 11 and 12. 20 The clip members 40, 40a, 140 and 140a also may be made of a range of materials. However high tensile and spring steel are highly suitable. The same applies to locating members 42 and 142, with high tensile steel being preferred. 25 Figure 16 shows a clip assembly 211, while Figure 17 shows a clip assembly 311 which is a variant of assembly 211. As the assemblies 211 and 311 are similar in many respects, the components of assembly 311 have the same reference numeral as for assembly 211, plus 100. 30 Each of assemblies 211 and 311 has an elongate base 213, 313 having a flat central region 213a, 313a and a down turned side 213b, 313b. Projecting upwardly from the base 213, 313 there is a pair of clip members 215, 315 which are inclined towards each other but are spaced at their ends remote 886851doc 29 from the base 213, 313. At those remote ends, each of members 215, 315 has a turned portion 217, 317 which is turned away from the portion 217, 317 respectively of the other member 215, 315. Each portion 217, 317 has a free end which forms an abutment surface 217a, 317a. 5 Clip assemblies 211 and 311 are formed from a blank 221, 321 shown in Figures 18 and 19, respectively. In the case of blank 221, the assembly 211 is formed from an elongate strip of steel in which adjacent pairs of U-shaped cut outs 225 are formed at longitudinally spaced intervals along the length of the 10 strip 223. The cut-outs 225 have their webs 225a spaced from each other and extending across a central part of the width of strip 223, and with legs 225b of the cut-outs extending longitudinally of strip 223, away from the other cut-out 225 of the pair. Between the legs 225b, each cut-out 225 results in a tongue 227. The end section of each leg 225b is shaped such that tongue 227 has a 15 rectangular free end section 227a beyond which it defines a narrower waist section 227b at its end joined to a central region of strip 223. Also, as shown, strip 223 has a margin 223a along each side which is able to be turned through 900 to provide central region 213a and side walls 213b of base 213 shown in Figure 16. 20 To form an assembly 211, a length of steel strip is cut to dimensions required for a blank 221, the cut-outs 225 are formed, and margins 223a are turned from the sides of blank 221, to produce base 213 with tongues 227. A respective extension member 229 then is connected to each tongue 227. 25 Each member 229 is bent on line A-A to form a turned end 229a which extends under end section 227a of a respective tongue 227, and is secured to end section 227a by spot welds or rivets 231. From end 227a, each extension member 229 extends at an acute angle away from base 213, with tongue 227 and its extension member 229 comprising a respective clip member 215, with 30 its turned portion 217 and abutment surface 217a. The blank 321 of Figure 19, for forming a clip assembly 311 of Figure 17, differs from the arrangement of blank 221, essentially only in that each tongue 888851.doc 30 327 is bent on line B-B to provide an upturned free end section 327a. To form a clip member 315, a respective extension member 329 is secured to end section 327a of each tongue 327, again by spot welds or rivets 331. Each tongue 327 and its extension member 329 comprise a respective clip member 5 315, with a turned portion 317 and abutment surface 317a. The extent of extension member 329 between its turned portion 317 and tongue section 327a is substantially planar, as shown. The clip assembly 411 of Figure 20, and the blank 421 of Figure 21, readily will 10 be understood from the description of Figures 16 to 19. The principal differences are the longitudinal length of each cut-out 425 and, hence, the length of tongues 427. Each clip member 415 is formed solely from a tongue 427. Thus, with a blank 421, the tongues 427 of blank 421 are bent on lines C-C, and adjacent to their free ends, to form clip members 429 with turned 15 portions 417 having an abutment surface 417a. Each of clip assemblies 211, 311, 411 of Figures 16, 17 and 20 show only a single pair of clip members 215, 315, 415 which engage a respective one of opposed side walls of the one rib of a profiled roofing sheet. However, the 20 assemblies may be of greater length than that illustrated and have a plurality of pairs of members 215, 315, 415 at a spacing between centres corresponding to the spacing between centres for successive ribs of the roofing sheets. This is indicated in Figure 16 by the broken end shown to the left, and in Figure 20 by the partial showing of a further cut-out 425. 25 As shown in Figures 16, 17 and 20, each of the respective assemblies may have one or more holes 231, 331, 431 formed through its base 213, 313, 413 to enable insertion of a fastener (not shown) for securing the assembly 211, 311, 411 on a purlin. The holes may be provided centrally, between the or 30 each pair of clip members 215, 315, 415 as shown, or in some other convenient position. Also, at one end of base 213, 313, 413, there preferably is a formation (not shown) which co-operates with complementary formation at the other end, to enable a plurality of assemblies 211, 311, 411 to be 885 oc 31 connected in an end-to-end series, such as described in Australian patent specification AU-685102 for the common strap for a series of clips. With each embodiment of the invention, each clip member is adapted to 5 enable its turned position to locate over and bear against the re-entrant ledge of a respective side wall of a rib of profiled roofing sheet. In each case the arrangement is such that a line of force, generated at a location at which the abutment surface of the turned portion contacts the ledge, is outside a position or line at which the clip member flexes, pivots or is hinged. The arrangement 10 preferably is such that the angle between (a) a line or plane providing a lateral continuation of the ledge and (b) a line or plane through the contact location between the abutment surface and ledge and the position or line at which the clip member flexes, pivots or is hinged, is substantially less than a right angle. As that angle increases, due to the rib opening under increasing wind loadings, 15 the contact is able to be maintained until the angle reaches and exceeds 900, at which point contact is lost and failure of the roofing occurs. In the case of clip assemblies as in Figures 3 to 15, performance with increasing wind loads is described above with reference to Figure 6. In the 20 case of each of Figures 16, 17 and 20, the situation is similar. With each of clip assemblies 211, 311 and 411, the respective turned portions 217, 317, 417 are able to be received within a rib of a profiled roofing sheet to locate over and bear against a re-entrant ledge of a respective side wall of that rib. When so received, the abutment surface 217a, 317a, 417a contact the ledge 25 at a location such that a resultant line of force is outside the position or line at which the clip member 215, 315, 415 flexes, pivots or is hinged, with that position or line being on or along the respective line A-A, B-B, C-C. As with other embodiments, "outside" in this context denotes a direction in which a clip member extends longitudinally from the base, beyond the location at which the 30 clip member flexes, pivots or is hinged. As a consequence an angle, corresponding to angle 0 in Figure 6, is able to be substantially less than 900, even with significant wind loadings. The angle increases with wind loading until, ultimately, at quite high loadings such as under cyclonic conditions, the 888851.doc 32 angle exceeds 90*, causing a roofing failure. However, the magnitude of the wind loading necessary to cause roofing failure is increased as a consequence of flexing, pivoting or hinging at lines A-A, B-B, C-C. Also, before the angle approaches 90*, the magnitude of forces able to result in roofing failure can be 5 further increased by lines A-A, B-B, C-C moving arcuately away from base 213, 313, 413 by flexing of the length of the clip member or tongue between base 213, 313, 413 and the line A-A, B-B, C-C, as this enables turned portion 217, 317, 417 of the clip members 215, 315, 415 to follow widening side walls of a rib further. That is, the abutment surface 217a, 317a, 417a are able to 10 continue to bear against the re-entrant side wall ledge through a greater extent of rib widening. To assist with engagement of surfaces 217a, 317a, 417a with a re-entrant ledge of a rib side wall, those surfaces may have teeth, similar to teeth formulations 79 shown in Figure 13. 15 The clip assemblies 211, 311, 411 may incorporate a mechanical "fuse" for the purpose described above in relation to Figures 3 to 15. Thus, the cut-outs 225, 325, 425 may leave a thin bridge of connecting metal between each tongue 227, 327, 427 and a laterally adjacent part of base 213, 313, 413. The or each bridge may be between the line A-A, B-B, C-C and the end of the 20 tongue 227, 327, 427 at which it is joined to base 213, 313, 413. Alternatively, there may be a bridge member which is similarly located and extends laterally across tongue 227, 327, 427 to locate an end of the bridge member under base 213, 313, 413 to restrain arcuate lifting of line A-A, B-B, C-C at wind loadings below a predetermined level. At higher wind loadings, the bridges or 25 bridge members break, to enable the lines A-A, B-B, C-C to lift and the clip members to flex, pivot or hinge to accommodate the higher wind loading. The clip assemblies of the invention, in using pairs of complementary clip members which co-operate to engage and hold a roofing sheet at successive 30 ribs differs significantly from the use of a respective integral clip for achieving this. The clip members are able to respond independently in the event that they are subjected to respective wind loadings. The integral clips are designed to hold a rib in place by holding each side of the rib, with negligible ability to lift 888851.doc 33 with lifting of the rib. In contrast, the clip members of the assemblies of the invention holds a continuation of a rib half and the adjacent pan of the roofing sheet. This is achieved by enabling the resultant line of action between a re entrant ledge of the rib and corresponding clip member to be outside of the 5 pivot position for each clip member. The effect of this is that when the pan bulges under pressure and opposing walls of the rib separate, the clip members tend to grip more tightly. The teeth formations able to be provided on the turned portion of each clip 10 member preferably are close to but not at the edge of the clip member. This has the effect of at least increasing the friction between the clip member and the re-entrant ledge and, particularly under repeat loadings, also developing a partial mechanical lock by indenting the metal of the re-entrant ledge. Testing has shown that teeth formations at the edges of the arms tend to bend under 15 the considerable forces they encounter. Insetting the teeth formations slightly from the edges reduces the stress concentration on the teeth formations. Another benefit of the clip assemblies of the present invention is the ability to incorporate a mechanical "fuse". A consequence of having relatively freely 20 moveable clip members is that the entire roofing sheet tends to lift under even modest wind pressure. This limits the serviceability capacity of the roofing sheets which has an arbitrary deflection limit imposed. The mechanical fuse enables the movement of the clip members to be restricted uniformly up to a serviceability limit-state load or action, but then fails, shears or is deflected at a 25 slightly higher load. When this occurs, the clip members are free to move up to the full strength limit-state. Finally, it is to be understood that various alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts 30 previously described without departing from the spirit or ambit of the invention. 886851.doc

Claims (17)

1. A clip assembly for concealed securing of sheet metal profiled roofing sheets, wherein the assembly has a base by which the assembly is mountable 5 on a purlin or other support structure, and two elongate clip members separately secured in relation to and projecting from the base; each clip member, at an end remote from the base, has an end portion (hereinafter referred to as a turned portion) adapted for locating over and bearing against an upwardly facing surface of a re-entrant ledge defined by the inner face of a 10 side wall of a rib of a roofing sheet; and the turned portion of the two clip members is turned oppositely with respect to each other; wherein the two elongate clip members are oppositely inclined and an end of each clip member adjacent to the base is secured in relation to the base by a hinged, flexible or pivot connection between its lower end and a respective end of a locating 15 member mounted within the base enabling the clip member to pivot arcuately so the turned portion is able to move with, and retain its location against, a re entrant ledge of the rib as the rib opens under wind loadings on the roofing sheet. 20

2. The clip assembly of claim 1, wherein an end of each clip member adjacent to the base is secured in relation to the base to enable the clip member to pivot or flex arcuately to enable the turned portion to move with, and continue to bear against, a re-entrant ledge of the rib as the rib opens out under wind loadings on the roofing sheet. 25

3. The clip assembly of any one of the preceding claims, wherein the base defines a support wall on which each of the oppositely inclined clip members and the locating member to which they are connected are supportable and from which the clip members are pivotable in response to a wind loading. 30

4. The clip assembly of claim 3, wherein a first portion of each clip member is supported on the support wall at an acute angle to the longitudinal extent of NZ1718 10oce 35 the base, and a second portion of the clip member extends from the base at an obtuse angle to the first portion.

5. The clip assembly of any one of the preceding claims, further including 5 a respective mechanical fuse engageable by each clip member on pivoting or flexing of the clip member under a serviceability wind loading force, with the mechanical fuses adapted to fail and thereby allow further pivoting or flexing of the clip members in response to a wind loading force in excess of serviceability. 10

6. The clip assembly of claim 5, wherein the mechanical fuses comprise shear bars which shear off or deform at a wind loading force above serviceability. 15

7. The clip assembly of any one of the preceding claims, wherein the two clip members are closely adjacent such that the turned portion of each clip member is adapted for locating over and bearing against a respective one of re-entrant ledges defined by opposing side walls of the same rib of the roofing sheet. 20

8. The clip assembly of any one of claims 1 to 6, wherein the two clip members are inclined from the base and away from each other but with the turned portion of each turned towards the other of the two clip members, and wherein the two clip members are spaced apart from each other by a distance 25 which is short of the spacing between centres for successive ribs of the roofing sheet but sufficient to enable the turned portion of each clip member to locate over and bear against a re-entrant ledge defined by an inner face of one side wall of a respective one of successive ribs of the roofing sheet. 30

9. The clip assembly of any one of claims 1 to 6, wherein the base is of elongate form and enables securement of a roofing sheet or at least two adjacent roofing sheets at each of a series of more than two successive ribs; each of the two clip members extends from the base and is inclined from the NZ1718 1/10.oc 36 base and away from each other but with the turned portion turned towards the other of the two clip members, and wherein the two clip members are spaced apart from each other by a distance enabling the turned portion of each clip member to locate over and bear against a re-entrant ledge defined by the inner 5 face of one side wall of respective ribs; and wherein the base has at least one location intermediate of its ends from which two further clips project, the two further clips are closely adjacent such that the turned portion of each is adapted for locating over and bearing against a respective one of re-entrant ledges defined by opposing side walls of the one rib of the roofing sheet, and 10 the one rib is intermediate of the respective ribs.

10. The clip assembly of any one of the preceding claims, wherein the base of the clip assembly is inter-connectable with similar clip assemblies to provide an end to end series of clip assemblies. 15

11. The clip assembly of any one of the preceding claims, wherein relative to an in-use orientation for the clip assembly, the clip members extend upwardly with each clip member having a lower end by which it is secured in relation to the base. 20

12. The clip assembly of any one of the preceding claims, wherein each clip member is formed from a length of high tensile steel or spring steel strap.

13. The clip assembly of any one of the preceding claims, wherein the base 25 is formed from an engineering plastics material, such as Nylon 66 having glass filling.

14. The clip assembly of claim 13, wherein the base comprises two laterally connected shells within which the clip members are secured in relation to the 30 base.

15. The clip assembly of any one of claims 1 to 12, wherein the base and clip members are formed from steel sheet. NZ1718 1/10.oc 37

16. The clip assembly of claim 15, wherein each of the oppositely inclined clip members includes or comprises a tongue which projects from an edge of a respective one of two cut-outs formed in the base, with the edge of each cut 5 out remote from the other cut-out, and the clip member is inclined from a part of the tongue which is substantially parallel with, or at an angle of not more than 5c to, an upper surface of the base.

17. The clip assembly of claim 15, wherein each of the oppositely inclined 10 clip members includes or comprises a tongue which projects from an edge of a respective one of two cut-outs formed in the base, with the edge of each cut out adjacent to the other cut-out, and the clip member is inclined from a part of the tongue which is substantially parallel with, or at an angle of not more than 57 to, an upper surface of the base. 15 NZ1718 1/10.oc