AU738555B2

AU738555B2 - Joining steel framing

Info

Publication number: AU738555B2
Application number: AU37995/99A
Authority: AU
Inventors: Lionel Desmond Hill
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-01-20
Filing date: 1999-07-05
Publication date: 2001-09-20
Anticipated expiration: 2016-01-22
Also published as: AU3799599A

Description

'V

1 JOINING STEEL FRAMING This invention relates to improvements to joining steel sections in the formation of framing.

This invention has particular application to joining rolled hollow section steel in the formation of roof trusses for pitched roofs, but is not limited to such application.

For example, it may be utilised for wall joining, other framing or for other structural and non-structural applications, or non-truss roofing and frames or the like for supporting structures other than roofs. For illustrative purposes however the present invention will be described in relation to its application to roof trusses and pitched roofs.

This invention also concerns forming joints on site and reference is made to such application. However, such joins may also be formed in factories, workshops or such like, or mass produced products.

BACKGROUND OF INVENTION S' Structural beams and trusses formed of metal sections are usually factory formed with welded joints to ensure trueness of the frame. Factory jigs and fixtures are used for maintaining accuracy in forming joints which would otherwise tend to warp during welding, as well as for the accurate and precise alignment of the joined sections.

25 For dwellings in particular, timber framing is frequently used, including timber roof trusses for supporting the structure upon which the roofing material is fixed. Because of the limited strength of timber, roof trusses constructed from timber are required to be spaced relatively close together, adding to the cost of materials and time required for construction. Steel trusses have been proposed, however, the cost of such trusses have traditionally exceeded that of timber trusses even though a smaller number of steel trusses have been required.

Additionally, lightweight metal frame trusses formed of open roll formed sections may fail under load due to eccentric loading or damage of a member. When such frames are prefabricated, they are prone to damage during transport or additional transport costs due to the nature of the 6- 8-01;12:43 ;PIZZEYS 3/ 8 2 article being transported may be incurred- Also welded steel frames for buildings are prone to corrosion near weld joints.

SUMMARY OF THE INVENTION According to the first aspect of the invention there is provided a method for obliquely joining a hollow, substantially rectangular member to a second rectangular member, wherein the rectangular members are of the same dimension normal to the respective longitudinal axes parallel to the line of intersection, wherein said method comprises the steps of: forming a pair of opposed flanges from the proximal surface of the hollow substantially rectangular member; and opening said pair of opposed flanges, whereby the second rectangular member abuts the end of the proximal surface; and engaging said opposed flanges over the corresponding side walls of the second rectangular member.

According to a second aspect of the invention there is provided a joint for obliquely 15 joining a hollow substantially rectangular member to a second rectangular member wherein the rectangular members are of the same dimension normal to the respective longitudinal 9 axes parallel to the line of intersection wherein said joint is formed from said hollow rectangular member and comprises a pair of opposed flanges formed from the proximal surface of the hollow substantially rectangular member said flanges being disposed parallel to the side walls of the hollow rectangular member where the second rectangular member may be received there between.

The present invention aims to alleviate one or more of the above disadvantages and to provide improved steel framing and a method of forming joints for steel framing which will be reliable and efficient in use.

With the foregoing in view, this invention in one aspect resides broadly in a joint for joining metal sections, each section including a pair of spaced apart wall portions and an interconnecting wall portion extending between said spaced wall portions, said joint including:on one of said sections, end portions of one or both said spaced wall portions projecting longitudinally beyond the end of said interconnecting wall portion; said end portions forming overlap portions which overlap at least some of said other section, and 06/08 '01 MON 12:52 [TX/RX NO 5481] 2a fixing means fixing said overlap portions to said other section.

The overlap portions may be made separate by removing a portion of the interconnecting wall portions or by cutting into or slitting the interconnecting wall portions. The end portions may be formed from all or a portion of the available material in the respective spaced wall portions, however, it is preferred that the end portions include additional material from at least some of an adjoining interconnecting wall portion.

It is also preferred that the end portions be shaped to lie substantially against one or more surfaces of the other section. Where the end portions are to lie against a substantially planar surface of the other section, and the additional material is S.originally substantially at right angles to the spaced wall portions, the additional material is preferably made to be substantially planar with the respective spaced wall portions by folding or unfolding.

15Hereinafter, the term fold includes within its meaning unfold where the context "15 requires, such as, for example, oo *o *o° •ooo ooo* where an initially bent or folded component is substantially straightened out or unfolded.

Preferably the sections have similar widths and the end portions are offset whereby the inside dimensions of the offset overlap portions are compatible with the outside dimensions of the corresponding section or sections.

Where there are more than two sections to be joined by the joint of this invention, it is also preferred that the overlap portions are so formed and arranged that the centrelines of all three sections converge substantially to a single point.

The fastening means may be by rivet or welding or bolting, but preferably, the fastening means is in the form of a screwed joint. Preferably, self drilling and self 15 tapping screws are utilized for this purpose. It is also preferred that the sections are hollow metal sections and more preferably rolled hollow box sections having a square or rectangular cross-section. Preferably the sections are formed from steel but if desired they may be formed from 20 other materials such as a suitable aluminium. However, it will be appreciated that other sections may be used, including pipe or channel. The hollow sections are also S.suitably formed of high tensile steel and the offset end portions are opened to a substantially planar configuration 25 in such manner that the minimum bending radii between the adjoining wall portions is maintained.

Furthermore where an interconnecting wall portion is offset with the adjoining wall portion it is preferred that the work hardened corner joint originally formed therebetween not be fractured by subsequent cold working such as by endeavouring to flatten the fold line. For example, a cold worked corner between adjoining wall portions of a rolled hollow section may be folded to be substantially flat, but the -roll-formed bend left substantially undisturbed or substantially intact.

Preferably, this is achieved by using a simple bending process as opposed to a hammering or beating process Thus, the overlap portion formed by folding flat a rollformed bend would include bends in the reverse direction of the roll-formed bend alongside each peripheral edge of the roll-formed bend.

The join between two metal sections may be, for example, formed between the top and bottom chords of a truss.

Moreover, for the provision of a veranda rafter extending from the truss, the overlap portions of the joint of this invention may be modified to permit attachment of a third section, such as a veranda rafter to a truss. Preferably, the modified overlap portion permits the veranda rafter to be attached at its end and extend from the truss at any desired angle. For this purpose, the overlap portions include pivot means to permit a pivotal connection between the two joined sections (being rigidly joined) and the third section.

15 Thus, a triangular roof supporting frame may be formed having an apex and two bottom corners, two top chords connected to one another at said apex and a bottom chord extending between and connected to each said top chord at said respective bottom corners to form a bottom corner 20 joint, and wherein said bottom corner joint is a joint as hereinbefore described.

This invention in another aspect resides broadly in steel framing including interconnected hollow section framing members extending angularly to one another with the 25 connected end of one member nesting within a portion of the bore of another member and the one member having a terminal lateral wall portion angled to lie flush against a side wall portion of the other frame member whereby the interconnection may be formed by a mechanical fastener or fasteners passing through the terminal lateral wall portion and the side wall portion.

It will be seen that the formation of a joint between interconnected frame members may be readily made on site to suit the particular application and may be done in a manner which is common to tradesmen with metalworking skills. It is believed that the simple bending process is suitable for on-site construction and formation of joints in accordance with this invention.

A frame having such joints may be laid out on a concrete slab forming the floor of a structure in conventional manner with the interconnection being performed with the aid of a screw gun through the readily accessible overlap portion of the hollow section top and bottom plates. That is, in a manner similar as that used for timber frames which are currently assembled on-site with nailing guns.

Both sides of the frame may have fasteners operatively placed by first completing the placement of fasteners on one side of the frame, then inverting the frame to place the fasteners on the other side of the frame. Thus a hollow section frame member with a lateral end wall or an .intermediate portion formed in accordance with the present invention provides a building element which may be utilised 15 in a building structure in the manner of a corresponding timber building element.

Moreover, the hollow metal sections may be pre-cut off site and delivered to the building site for assembly by the builder. It will be appreciated that a similar method may 20 be used for forming a roof truss using the joint of this invention. It is preferred that a roof truss be formed by .first fastening the top chords to the bottom chord and then fastening the two top chords together at the apex. The truss is preferably laid out on a floor and the king post, queen posts and struts are placed in alignment and fastened in place.

In another aspect, this invention resides broadly in a method of forming a joint between two metal sections, said method including:providing two metal sections, each section including a pair of spaced apart wall portions and an interconnecting wall portion extending between said spaced wall portions; removing an end portion of said interconnecting wall portion on one of said sections, whereby respective projecting end portions are provided said spaced wall portions; aligning the other of said sections against said projecting end portions, and fixing said projecting end portions to said other section. The method may also include removing part of one of the spaced wall portions whereby only one projecting end portion is formed, however, it is preferred that both projecting end portions are provided and that at least some of the removed end portion of the interconnecting wall portion is retained to form an extended end portion by bending the retained portion into alignment with the remainder of the projecting end portion.

Suitably, the extended or projected end portions form overlap portions as hereinbefore described.

Where two sections are to be joined with their longitudinal axes substantially in alignment, or only slightly out of alignment, the overlap portions may provided 15 on both sections, and the respective overlap portions of each section fastened to the side of the faces the other section at right angles thereto.

The overlap portions may be formed by standard metal :working techniques, such as by cutting the respective 20 sections to a pattern and folding the metal to the required shape. Preferably, a tool set is provided including a .section insert tool, a primary folder and a secondary folder.

The section insert tool suitably includes an oversize 25 portion having a dimension larger than the bore of the section. The oversize portion permits the offset fold to be formed by folding an overlap portion with the primary folder and subsequently folding the overlap portion against the oversize portion of the section insert tool with the secondary folder.

Where two overlap portion are to be formed on the end of a hollow section, the included oversize portion is preferably constituted by a shoulder formed around a portion of the periphery of a tongue portion adapted to provide a clearance fit internally of the hollow metal section upon which the offset overlap portions are to be formed.

Alternatively, the section insert tool may be constituted by a solid body portion having locating means for locating the body portion internally of a hollow section after the primary fold has been made and against which the overlap portion or portions are folded to form the offset fold.

The second fold may complete the formation of the overlap portion ready for fastening to the corresponding section, but preferably, the section having the overlap portions is pressed over a die to accurately form the overlap portions to the appropriate configuration.

BRIEF DESCRIPTION OF THE DRAWINGS In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein: Figure 1 is a schematic diagram for the layout of a truss; Figures 2 and 3 respectively show a plan and an elevation of a top king post joint shown at 1 in Figure 1; Figures 4 to 7 show a bottom king post joint shown at 2 in Figure 1'; Figures 8 to 11 show a top strut joint shown at 3 in ~Figure 1; Figures 12 to 14 show a bottom strut joint shown at 4 in Figure 1; Figures 15 to 17 show a chord joint shown at 5 in Figure 1; Figure 18 is a schematic diagram showing a screw fixing pattern for the truss shown in Figures 1 to 17; Figure 19 is a schematic diagram showing an alternative screw fixing pattern for the truss shown in Figures 1 to 17; Figures 20 and 21 show the layout and screw fixing pattern for a 7.5 metre truss; Figures 22 and 23 show the layout and screw fixing pattern for a nine metre truss; Figures 24 and 25 show a screw fixing pattern for joining a truss to a column; Figure 26 shows an alternative arrangement for connecting a top chord to a bottom chord; 8 Figures 27 and 28 show a sectional view and partial sectional view of a low pitch angle roof using the alternative arrangement of Figure 26; Figures 29 to 33 show diagrammatically the arrangements for a pivotal rafter connection for the trusses of Figures 1 to Figure 34 is a diagrammatic plane view of a hip roof arrangement for the trusses of Figures 1 to 25 (with only some of the roof forming members shown); Figure 35 is a plan view of detail B of Figure 34; Figure 36 is a sectional view on A-A on Figure Figure 37 is a pictorial view of the hip roof detail shown in Figures 35 and 36; Figure 38 is a sectional view of detail A of Figure 34; Figure 39 is an elevation view of a folded connector; Figures 40, 41 and 42 are respective pattern 0-.-:developments of brackets for connecting rafters to top plates, trusses and/or fascias; Figure 43 shows the connection of a rafter to a top plate and a fascia section using the brackets of Figures and 42; Figure 44 shows the connection of a rafter to a top plate and a fascia section using the brackets of Figures 41 and 42; 25 Figures 45 and 46 respectively show a pattern development for and the connection using a bracket for connecting a creeper, cripple, valley jack or hip jack to a hip rafter.

Figures 47 and 48 show part formation of the overlap portions of a hollow metal section; Figures 49 to 53 show the formation of the overlap portions, and Figures 54 to 57 show four tools or jigs for forming offset overlap portions.

In the Figures relating to the truss assembly, the structural members are rolled hollow sections each having four walls. For clarity, walls parallel to the plane truss are generally referred to as facing walls.

9 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Figure 1, a truss 10 is comprised of two top cords 11, a bottom cord 12, a king post 13, two queen posts 14 and two struts 15. The truss 10 includes a bottom king post joint 2, a top strut joint 3, a bottom strut joint 4 and a chord joint Referring to Figures 2 and 3, the two top cords 11 are connected together by a connecting plate 16 across the top surfaces of the respective top chords 11. Additionally, the two top cords 11 are also connected by the arrangement of connecting the king post 13 at the top king post Joint 1.

Referring to Figure 4, the bottom king post Joint 2 is made by connecting the lower ends of two respective struts and the lower end of the king post 13 to a central 15 portion of the bottom cord 12. In order to facilitate the oining of the struts 15 to the bottom cord 12, the strut lower wall 17 is shortened and the strut upper wall 18 is left intact with a strut wall extension 20 to provide two strut lower overlap portions 19 as shown in particular in Figure 7. The strut lower overlap portions 19 are offset outwardly at a strut lower offset 34 to permit the lower *overlap portions 19 to be overlapped over the bottom chord 12.

Referring in particular to Figures 5 and 6, the king 25 post 13 at its lower end has its respective king post side walls 22 shortened to provide two respective king post lower wall extensions 21. The king post facing walls 25 are offset outwardly at a king post lower offset 32 to permit the king post lower wall extensions 21 to overlap the bottom chord 12.

Referring to Figure 8, the top strut joint 3 is made by connecting the queen post 14 to the top chord 11 and attaching the strut 15 at its upper end to the queen post 14 adjacent the joint between the queen post 14 and the top chord 11.

Referring to Figures 9 and 10, the queen post 14 has its queen post side walls 23 shortened to provide queen post upper wall extensions 24 from the respective queen post facing walls 26. Each queen post upper wall extension 24 is offset from its alignment with the respective queen post facing wall 26 at a queen post upper offset 33 to permit the queen post upper wall extensions 24 to overlap the top chord 11.

Referring to Figure 11, the strut 15 has two strut facing walls 27 and a strut lower wall 17 and strut upper wall 18. The strut lower wall 17 and strut upper wall 18 are shortened to provide a strut upper overlap portion 28.

The strut upper overlap portion 28 is offset at a strut upper offset 35 to permit the strut upper overlap portion 28 to overlap the queen post 14.

In a similar fashion, as shown in Figures 12, 13 and 14, the queen post 14 is connected to the bottom chord 12 at the bottom strut joint 4 by providing two respective queen post 15 wall extensions 31 of the queen post facing walls 30 by shortening each queen post side wall 29 and further ee providing a queen post lower offset 36 to permit the queen post lower wall extensions 31 to overlap the bottom chord 12.

Referring to Figures 15, 16 and 17, the chord joint between the top chord 11 and bottom chord 12 is formed by .slitting the bottom chord upper wall 43 as shown in detail in Figure 17 by providing a longitudinal slit 37 and a cross slit 38 and a V-cut-out 39. The distal portion of the bottom chord upper wall 43 is straightened out to substantially align with respective bottom chord facing walls 42 to provide two respective bottom chord overlap portions Additionally, the bottom chord facing walls 42 are shortened to provide a bottom chord wall extension 41.

Additionally, the end portions of the bottom chord facing walls 42 are offset at respective bottom chord offsets 45 to provide respective bottom chord wall distal portions 46 such that the bottom chord wall distal portions 46 and bottom chord overlap portions 40 substantially align and overlap the top chord 11 as shown in Figure Because the bottom chord wall distal portions 46 including the bottom chord overlap portions 40 are formed from high tensile grade steel, the original rolled edge of the bottom chord 12 is left intact as a retained crease 47 to avoid overworking the material in the region of the retained crease 47.

Referring to Figure 18, the top king post joint 1 is formed by providing four bolts or screws as shown, the bottom king post joint 2 is formed by providing four screws in the king post and three screws in each strut for fastening the respective members to the bottom chord 12.

The top strut joint 3 is formed by providing four screw fasteners in the top chord 11 and three screw fasteners through the strut and screwed into the queen post 14. The bottom strut joint 4 is formed by providing four fasteners through the bottom of the queen post 14 and screwed into the bottom chord 12 and the chord joint 5 is formed by providing S 15 six screw fasteners through the bottom chord 12 and screwed into the top chord 11.

Referring to Figures 19, 21 and 23 in an alternative screw fixing pattern to that shown in Figure 18, the top king post joint 1 is formed by providing eight screws as S 20 shown, the bottom king post joint 2 is formed by providing six screws in the king post and four screws in each strut for fastening the respective members to the bottom chord 12.

The top strut joint. 3 is formed with the centrelines of the queen post 14 and strut 15 intersecting substantially at 25 their respective intersections with the centreline of the top chord 11. This is achieved by having the strut connected to the top chord 11 rather than the queen post 14 (as shown in Figure 18). The overlap portions of the strut are shown being so formed that they abut the overlap portions of the queen post 14, however, it will be appreciated that the overlap portions of both the strut and the queen post 14 may be arranged to overly one another for fastening to the top chord 11. The top strut joint 3 has four screw fasteners screwed into the top chord 11 through the queen post 14 and three screw fasteners screwed into the top chord 11 through the strut The bottom strut joint 4 is formed by providing five fasteners through the bottom of the queen post 14 and screwed into the bottom chord 12. The chord joint 5 is 12 formed by providing seven fasteners through the bottom chord 12 into the top chord 11 in the cases of the six metre truss of Figure 19 and the 7.5 metre truss of Figure 21.

In the nine metre truss, where the bottom chord facing walls 42 are wider, there are sixteen screw joining the top chord 11 to the bottom chord 12. The facing walls of the top chord 11 are also wider than for the six metre and metre trusses.

An extra strut joint 6 is required for the nine metre truss shown in Figures 22 and 23. The extra strut joint 6 is arranged with the centrelines of the queen post 14 and strut 15 intersecting substantially at their respective intersections with the centreline of the bottom chord 11.

The extra strut joint 6 has eight screw fasteners screwed into the bottom chord 12 through the queen post 14 and six screw fasteners screwed into the bottom chord 12 through the strut 15. The centrelines of the strut 15 and the queen 14 converge at the centreline of the bottom chord 12 in the same manner as described in relation to the connection 20 between the strut 15 and the queen post 14 attached to the top chord 11 described in relation to Figure 19.

Referring to Figures 24 and 25, the truss 10 may be fastened to the top of a column 80 by a bracket 81 having a fastening bolt 82 penetrating the truss 10 at the chord 25 joint 5 and the bracket 81.

Referring to Figure 26, an alternative form of chord joint 5 is provided by slitting the top chord 11 instead of the bottom chord 12, and providing a top chord overlap portion 40a and a top chord offset 45a on the top chord, and also including the retained crease 47 as described in respect of Figures 15 to 17.

Referring to Figure 27, a low pitch angle truss 85 is shown having roofing iron 86 supported on roof battens shown typically at 87. The bottom chord 12 is connected to the top chord 11 and the king post 13 is also provided to separate the top and bottom chords 11 and 12 and form a triangular truss frame. The top king post joint 1 and the bottom king post joint 2 are provided as previously described and the chord Joint 5 is provided as shown in detail in Figure 26.

The low pitch angle truss 85 may be supported on a rolled hollow section (RHS) column 88 or a block wall 89.

When supported on the RHS column 88, an overlap portion 84 is provided on the top end of the RHS column 80 for connection to the low pitch angle truss 85. For the block wall 89, a J-bolt 90 is provided for connection to block reinforcing 91.

A fascia purlin 92 is connected to the distal end of the bottom chord 12, and guttering 93 may be attached thereto as shown.

The roofing iron 86 is also attached to the end portion of the bottom chord 12 such that the low pitch angle truss S 15 85 provides its own eaves through an overhang portion 94, the roofing iron 86 thus tapering from the top of the lowermost roofing batten 87 to the distal end of the bottom chord 12 to provide an overhang portion 94.

Referring to Figures 29 to 33, in a slight modification 00 S 20 of the alternative form of the chord joint 5, a veranda connection assembly 100 has a veranda rafter 104 attached to 0the top chord 11 which is joined to the bottom chord 12 in the manner previously described, but the top chord 11 has a modified end portion 103 including a pivot connection 101 and angle fixing connections 102.

The pivot connection 103 connects with the corresponding pivot connection 105 on the veranda rafter 104 and the angle fixing connections on the top chord 11 are aligned with corresponding apertures 106 on the veranda rafter 104.

The veranda rafter 104 is a rolled hollow section of similar dimensions to that of the rolled hollow section forming the truss and may be disposed at any desired angle such as the examples shown in Figure 33 where, for a 200 pitch on the truss, the veranda rafter 104 is shown at 15, 10 and 50 from the horizontal.

Referring to Figures 34 to 39, two hip rafters 111 and an end jack 110 are connected to a truss 10 at the top chord 11 by a conical support 121 to form a jack and rafter connection 120. The conical support 121 is attached to the underside of the respective top chords 11 and the respective hip rafters 111 and end jack 120 are also attached by fasteners fitted through respective bolting apertures shown typically at 122.

Referring in particular to Figure 38, a rafter to batten connection 125 is made to connect a rafter (whether a common rafter 116, hip Jack 112 or valley Jack 114, end jack 110, hip rafter 111 or valley rafter 115) to respective battens.

A batten 127 is connected to each side of the rafter 110, etc on a support angle section 129. A flashing angle section 128 is supported on each respective batten 127, and a flashing 126 is attached to the flashing angle section 128 to cover the join.

Referring to Figure 39 in particular, a folded

RHS

15 section 130 is formed in the end portion of a rolled hollow section to form a sealing joist and connector to a common rafter or the like. The folded RHS section 130 may also be used in connecting a collar-tie to a rafter, with struts or the like able to be connected to the collar-tie or an under- 20 purlin provided beneath the intersection of the collar-tie with the rafter 110, etc and the top wall of a supporting wall, or a strutting beam or binder.

0 Referring to Figures 40 to 44, the rafter 110, etc may be connected to a top plate 150 of a wall frame as shown in particular in Figures 43 and 44.

,A rafter bracket 141 which fits under the rafter 110, etc, or an alternative rafter bracket 142 which fits over the rafter 110, etc are shown in Figures 43 and 44 respectively. Additionally, a sloping end bracket 143 may be used to attach a rafter 110 etc to a fascia section 151.

It will also be appreciated that the sloping end bracket 143 may be used to connect the rafter to the ridge member 113.

Referring to Figures 40 and 43 in particular, the rafter bracket 141 is fastened to the top plate 150 by passing a bolt through a bolting aperture 155. The head of the bolt may be accommodated in a wedge-shaped gap 147 between the top plate 150 and the rafter 110 etc. Additionally, fasteners such as self-drilling and taping screws may be used to attach the rafter bracket 141 to the top plate 150 through respective fixing screw apertures shown typically at 53.

The rafter bracket 141 also includes two side panels 146 which may be fastened to the rafter through respective fastener apertures 154.

Referring in particular to Figures 41 and 44, the alternative rafter bracket may be fastened to the top plate 150 and rafter by placing it over the top of the rafter and fixing thereto, and to the top plate 150 by fasteners through respective fixing screw apertures shown typically at 153.

Referring in particular to Figures 42, 43 and 44, the rafter is operatively fastened to the fascia section 151 using the sloping end bracket 143 and using self-drilling S 15 and taping fasteners the sloping end bracket 143 is attached to the underside of the rafter 110 etc by fastening a centre panel 152 thereto, and respective side panels 146 are attached to the sides of the rafter whilst the fascia section 151 is fixed to respective lap panels 149 using the 20 abovementioned fasteners through the respective fixing screw apertures shown typically at 153.

Referring to Figures 45 and 46, a hip rafter connector 144 is used to connect the hip rafter 111 to the hip jack "oo 112. The hip rafter connection 144 comprises a lapped side panel 160 adjoining a lapped edge panel 161, which further 0 adjoins a short side panel 162 and a short edge panel 163.

A further edge panel 165 is provided on the other side of the lapped side panel 160 from the lapped edge panel 161.

The further edge panel 165 is folded across one corner to form a triangular lap panel 168. The lapped side panel 160 and lapped edge panel 160 and 161 also include respective lap panels 169.

The hip rafter connector is attached to the end of the hip jack 112 and to a side face of the hip rafter 111 by respective fasteners being passed through respective fixing screw apertures shown typically at 167.

It will be appreciated that the hip rafter connector may be folded in the opposite direction to that shown in Figure 46 to provide a connection at the complementary opposite angle. Additionally, the hip rafter connector may be used to connect a valley rafter 115 to a valley jack 114, or a cripple-jack (not shown) to a broken hip (not shown) or to a valley rafter 115, or a hip rafter 111 to a ridge member 113.

It will also be appreciated that the brackets 141, 142, 143 and 144 may be used to connect members made from timber as desired or required. Thus, a roofing frame may be constructed from rolled hollow section as described above, or combination of timber and rolled hollow section as required.

The overlapping wall or wall portions described above may be formed in a rolled hollow section 51 by providing •four corner slits 50 as shown in Figure 47. The four corner 15 slits 50 thus provide for two removed wall portions 52 which .".are subsequently removed along the respective removal lines 53 and two retained wall portions 54.

o: .Referring in particular to Figure 48, the retained wall portions 54 are folded outwardly as shown and subsequently S 20 back towards alignment with the walls of the rolled hollow o section 51 in accordance with respective arrows 55 to provide a member having characteristic end features as shown in Figure 5, 6, 9, 10, 13 and 14 above. It will be appreciated that the respective retained wall portions 54 may be shaped to accommodate desired joint configurations S Ssuch as those shown in Figures 3, 7 and 11.

Alternatively, a longitudinal slit 56 and a cross slit 57 may be made in the walls of the rolled hollow section 51 as shown in Figure 49 so Ithat extended retained wall portions 58 are provided having respective wall extensions 59 provided as shown in Figures 52 and 53. Because the wall extensions 59 are formed by unfolding a roll formed bend, a work hardened outwardly extending ridge 49 is formed as shown so that the roll formed bend is undisturbed in the unfolding process.

The extended retained wall portions 58 may be provided with an offset 48 as shown in particular in Figure 51 by folding outwardly the extended retained wall portions 58 in a similar fashion to that shown in Figure 52 and then 17 folding the extended retained wall portions 58 back to approximately parallel as shown in Figure 53.

The offset 48 shown in Figure 51 is applicable to the embodiment shown in both Figures 50 and 53. It will be appreciated that the alternative form of overlapped join may be configured into alternative arrangements such as that shown in Figures 15, 16 and 17.

In order to fold retained wall portions 54 or extended retained wall portions 58 as described above, a slotted tool 60 is provided having a slot 61 into which a retained wall portion 54 or extended retained wall portion 58 may be inserted in through the slot 61. Accordingly, the extended retained wall portions 58 or retained wall portions 54 may be folded outwardly as shown in Figures 48 and 52 15 respectively.

In order to provide the offset, the fold of the retained *..wall portions 54 or for the extended retained wall portions S 58 to be folded back to substantially parallel, but offset from alignment with the walls of the rolled hollow section 20 51 from which they were folded, an insert tool 62 is provided as shown in Figure 56 having a plug 63 which may be inserted into the bore of the rolled hollow section 51 to the extent allowable before a lip 64 engages with the end of the rolled hollow section 51.

The slotted tool 60 is then used to fold the retained wall portion 54 or extended retained wall portion 58 back to substantially parallel against a bearing surface 65 on the insert 62. A complementary bearing surface 66 thereby offsets the retained wall portion 54 or extended retained wall portion 58 to be substantially parallel with an extension of the wall section of the rolled hollow section from which the respective retained wall portion or extended retained wall portion 58 was folded.

Referring to Figure 57, an alternative insert 72 having two tongues 71 may be used to provide a bearing surface 73 on the side of the alternative insert 72 opposite the respective tongue 71 against which the complementary bearing surface 66 of the slotted tool 60 may bear to cause the extended retained wall portion 58 or retained wall portion 54 to be folded back to substantially parallel with the respective wall section from which it was folded and provide an offset from same.

In order to provide for other folds such as the strut wall extension 20 and bottom chord wall extension 41 as shown in Figures 7 and 15 respectively, a grooved tool 68 is provided as shown in Figure 55 having a groove 67 into which the respective wall extension may be inserted and folded as desired.

A truss may be assembled from joints of this invention by providing members cut to size and shape as hereinbefore described. The assembly of the truss may be accomplished by connecting the two top chords 11 together with the connecting plate 16 and making the chord joint 5 as 15 described above. Next, the struts may be put into place and .fastened by providing two screws through strut wall extension 20 into the bottom chord upper wall 43 and then connecting the king post 13 to the bottom chord 12 and top chord 11.

20 The respective queen posts 14 are then inserted into place at skewed angle and brought up to a close fit with the top chords 11 and bottom chord 12 and subsequently, the respective struts 15 fastened thereto. The fasteners provided to a truss member constructed as hereinbefore described may be provided on one side of the truss only, or O *on both sides of the truss if desired.

A roof truss formed in accordance with this invention may have a top chord with nominal dimensions of 50 mm by mm in 1.6 mm gauge steel, preferably of high tensile grade such as, for example, Tubemakers C450 grade (Tubemakers is a trade mark). The bottom chord may be 50 mm by 50 mm, but for wide spans, such as 9 m or 12 m, the bottom chord may be mm wide and 80 mm high. Moreover, the bottom chord may be increased up to for example 50 mm x 160 mm or more as required for wider spans or heavier loads. The nominal width of the sections used therefore is kept the same, permitting different dimensions in the orthogonal directions for struts, posts and the like.

A roof truss or roof framing made in accordance with this invention may be secured to the top plate of a wall frame, or to a cyclone tie or the like in a block wall, by passing a bolt vertically through apertures provided substantially at the joint between the top and bottom chords or rafter and ceiling joist and providing a slant washer under the head of the bolt. With such an arrangement, the top chord or rafter may be extended to provide an overhang for eaves or a veranda, and sheeting need not be cut around rafters extending outward from the walls for vermin proofing because the only extension above the top plate or top of the wall is the depth of the top chord.

Because of the added strength of the trusses of the present invention, they may be spaced two or three metres 15 apart. However, to permit smaller sizes of material for the roof battens and ceiling battens, extra rafters and ceiling joists may be provided as described above. Extra ceiling Sjoists also provide easier access in the roof space if they are spaced apart at a convenient pacing or stepping distance for personnel.

It will of course be realised that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed 25 to fall within the broad scope and ambit of the invention as claimed in the following claims.

Claims

6- 8-01;12:43 ;PIZZEYS B/ 8 CLAIMS 1. A method for obliquely joining a hollow, substantially rectangular member to a second rectangular member, wherein the rectangular members are of the same dimension normal to the respective longitudinal axes parallel to the line of intersection, wherein said method comprises the steps of; forming a pair of opposed flanges from the proximal surface of the hollow substantially rectangular member; and opening said pair of opposed flanges, whereby the second rectangular member abuts the end of the proximal surface; and engaging said opposed flanges over the corresponding side walls of the second rectangular member. 2. The method as claimed in claim 1, and including the step of fixing the pair of 15 opposed flanges to the corresponding opposed side walls of the second rectangular member. 0 3. The method as claimed in claim 9, where the step of fixing the opposed flanges to the corresponding opposed side walls of the second rectangular member 20 comprising bolting. 4. A joint for obliquely joining a hollow substantially rectangular member to a second rectangular member wherein the rectangular members are of the same dimension normal to the respective longitudinal axes parallel to the line of intersection wherein said joint is formed from said hollow rectangular member and comprises a pair of opposed flanges formed from the proximal surface of the hollow substantially rectangular member said flanges being disposed parallel to the side walls of the hollow rectangular member where the second rectangular member may be received therebetween. DATED THIS SIXTH DAY OF AUGUST 2001 LIONEL DESMOND HILL BY PIZZEYS PATENT TRADE MARK ATTORNEYS 06/08 '01 MON 12:52 [TX/RX NO 5481]