AU3400300A - Structures - Google Patents

Description

1 JOINING STEEL FRAMING This invention relates to improvements to steel frame structures and/or composite steel/wood structures.

This invention has particular application to steel frame structures utilising rolled hollow section steel in the formation of roof trusses for pitched roofs.

This invention also relates to forming joints on site.

BACKGROUND OF INVENTION Structural beams and trusses formed of metal sections are usually factory 10 formed with welded joints to ensure trueness of the frame. Factory jigs and fixtures S. 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.

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 lie° such trusses have traditionally exceeded that of timber trusses even though a smaller number of steel trusses have been required.

Lightweight metal frame trusses formed of open roll formed sections may fail under load due to eccentric loading or damage of a member such as a flange. When such frame structures are prefabricated, they are prone to damage during transport or they incur additional transport costs due to the nature of the article being transported. Also welded steel frames for buildings are prone to corrosion near weld joints.

SUMMARY OF THE INVENTION 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 2 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 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 10 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 15 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 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.

Hereinafter, the term fold includes within its meaning unfold where the context requires, such as, for example, 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 for many applications it is preferred that the fastening means be in the form of a screwed joint and suitably using self drilling and self tapping screws. Suitably the sections are hollow metal sections and preferably rolled hollow box sections having a square or 3 rectangular cross-section. Preferably the sections are formed from steel but if desired they may be formed from other materials such as a suitable aluminium.

The hollow box sections are also suitably formed of high tensile steel and the offset end portions are opened to a substantially planar configuration 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 10 portions of a rolled hollow section may be folded to be substantially flat, but the roll- S 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 roll-formed bend would 15 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 or extension of a truss member such as an upper chord. Suitably, 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.

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 joint, and wherein said bottom corner joint is a joint as hereinbefore defined.

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 4 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 inter-connection being performed with the aid of a screw gun through the readily accessible overlap portion of the hollow section top and bottom chords. 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 10 frame to place the fasteners on the other side of the frame. Thus the present invention provides a building element which may be utilised in the construction of 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 be used for forming a roof truss using the joints 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 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 defined.

The overlap portions may be formed by cutting the respective sections to a pattern and folding the metal to the required shape.

BRIEF DESCRIPTION OF THE DRAWINGS In order that this invention may be more readily understood and put into 10 practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein:- FIG. 1 is a front elevation of a typical building made in accordance with aspects of this invention; Vo.o* FIG. 2 is a typical section through the building of Fig. 1; FIG. 3 illustrates a composite timber/steel construction; FIG. 4 illustrates a typical framing arrangement; FIG. 5 illustrates flooring details; FIGS. 6 to 10 illustrate further details of the elevated floor structure; FIG. 11 illustrates a method of shielding top and bottom plates of a timber framed structure; FIGS. 15 to 17 illustrate a chord joint for a roof truss of the building of Fig. 1; FIG. 19 is a schematic diagram illustrating a screw fixing pattern for a truss utilising the joint of FIG. FIG. 21 illustrates the layout and screw fixing pattern for a 7.5 metre truss; FIGS. 23 illustrates the layout and screw fixing pattern for a 9 metre truss; FIGS. 24 and 25 illustrate a truss to a column joint in side and end views; FIG. 26 illustrates an alternative arrangement for connecting a top chord of a truss to the bottom chord of the truss; FIGS. 27 is a sectional view of a low pitch angle roof using the alternative arrangement of FIG. 26; FIG. 28 is a partial sectional view of a low pitch angle roof using the alternative joining arrangement of FIG. 26; 6 FIGS. 29 to 33 illustrate diagrammatically arrangements for a pivotal rafter connection for trusses; FIGS. 47 and 48 illustrate part formation of the overlap portions of a hollow metal section; FIGS. 49 to 53 illustrate the formation of the overlap portions, and FIGS. 54 to 57 illustrate four tools or jigs for forming offset overlap portions.

DESCRIPTION OF TYPICAL EMBODIMENTS The building 17 illustrated in Figs. 1 to 10 utilises steel roof trusses assembled on site and spanning between side walls formed with composite 10 steel/wood framing 18. Such a structure could be advantageously used in a remote area where timber for studs is readily available.

As illustrated in Fig. 3 the composite wall framing 18 includes open steel channel top and bottom plates 19 and 21 and timber studs 22. The bottom plates 21 are supported on a steel floor which rests on steel bearers 23 supported above the ground by steel posts 24.

The composite wall frames 18 are formed in traditional timber frame manner, on the floor with the studs 22 secured through side walls of the channel shaped plates by through nailing, either through the base flange as illustrated at 25 and/or through the side flanges as illustrated at 26. After nailing, the frames are stood up and located in position such as by screwing into the decking through the base flange of the bottom plate 21. Diagonal bracing may not be required as sufficient frame stiffness may be achieved through nailing through the side flanges as at 26.

Typical details of the floor and support are shown in Figs. 6 to 10. It will be seen that in this embodiment the metal floor is formed from ribbed BONDECK sheeting 27 covered with plywood sheets 28 between walls.

An advantage of this arrangement is that while timber studs, nogging and braces, window and door framing and the like are used in conventional manner and thus provide the advantages of ease attaching sheeting and trim thereto, ease of through drilling for location of service pipes and cables, they are not prone to termite attack as with a conventional timber frame. Furthermore the use of steel top and bottom chords provides compatibility for attaching to a metal framed floor and metal roof trusses.

In addition top plates may be of convention U-shaped channel form or of stiffened top-hat section form to achieve additional strength without substantially changing the basic structure or its method of erection.

In this respect it will be seen that the floor is elevated and thus can be readily inspected for signs of termite paths and that the path to the timber studs is barred by the steel flooring and the steel bottom plates in which the studs are captive.

In this embodiment the roof trusses 10 are formed of box section steel which may also be fabricated on site on a floor in a conventional manner. That is the trusses are formed from easily handled steel sections which have ends pre-formed or 10 formed on site to permit connection by a tradesman equipped with a screw gun and self drilling and tapping screws.

This termite proofing method utilising timber top and/or bottom plates captively secured in a metal open channel sections which forms a continuous barriers at the S"wall/roof/floor interface to shield against upward travel of termites into the top/bottom plates constitutes a further aspect of this invention. Fig. 11 collectively illustrates the use of various vermin proofing aspects of this invention to a timber framed structure.

Referring to Figs. 15, 16 and 17, the chord joint 5 between the top chord 11 and bottom chord 12 is formed by slitting the bottom chord upper wall 43 as shown in eelo detail in Fig. 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 Fig. 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 Figs. 19, 21 and 23 the top king post joint 1 is formed by providing eight screws as 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 their respective intersections with the centreline of the top chord 11. This is achieved by having the strut 15 connected to the top chord 11. The overlap portions of the strut 15 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 15 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 o* 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 o°*The bottom strut joint 4 is formed by providing five fasteners through the S 15 bottom of the queen post 14 and screwed into the bottom chord 12. The chord joint is formed by providing seven fasteners through the bottom chord 12 into the top chord 11 in the cases of the six metre truss of Fig. 19 and the 7.5 metre truss of Fig.

21.

In the nine metre truss, where the bottom chord facing walls 42 are wider, there are sixteen screws 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 7.5 metre trusses.

An extra strut joint 6 is required for the nine metre truss shown in Fig. 23. The extra strut joint 6 is arranged with the centrelines of the queen post 14 and strut 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 between the strut 15 and the queen post 14 attached to the top chord 11 described in relation to Fig. 19.

Referring to Figs. 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 joint 5 and the bracket 81.

Referring to Fig. 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 Figs. 15 to 17.

Referring to Figs. 27 and 28, 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 FIG. 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 S the low pitch angle truss 85. For the block wall 89, a J-bolt 90 is provided for connection to block reinforcing 91.

S.00 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 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 Figs. 29 to 33, in a slight modification of the alternative form of the chord joint 5, a veranda connection assembly 100 has a veranda rafter 104 attached to the 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 FIG. 33 where, for a 200 pitch on the truss, the veranda rafter 104 is shown at 200, 150, 100 and 50 from the horizontal.

Overlapping side wall or wall portions for uprights may be formed in a rolled hollow section 51 by providing four corner slits 50 as shown in FIG. 47. The four corner 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.

Referring in particular to FIG. 48, the retained wall portions 54 are folded outwardly as shown and subsequently back towards alignment with the walls of the rolled hollow section 51 in accordance with respective arrows 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 FIG. 49 so that extended retained wall 10 portions 58 are provided having respective wall extensions 59 provided as shown in Figs. 52 and 53. Because the wall extensions 59 are formed by unfolding a roll S" 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.

.o S"The extended retained wall portions 58 may be provided with an offset 48 as shown in particular in Fig. 51 by folding outwardly the extended retained wall portions 0 58 in a similar fashion to that shown in Fig. 52 and then folding the extended retained wall portions 58 back to approximately parallel as shown in Fig. 53.

The offset 48 shown in Fig. 51 is applicable to the embodiment shown in both Figs. 50 and 53.

20 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 Figs 48 and 52 respectively.

In order to provide the offset, the fold of the retained wall portions 54 or for the extended retained wall portions 58 to be folded back to substantially parallel, but offset from alignment with the walls of the rolled hollow section 51 from which they were folded, an insert tool 62 is provided as shown in FIG. 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 11 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 FIG. 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.

10 In order to provide for other folds such as the strut wall extension 20 and bottom chord wall extension 41 as shown in Fig. 15, a grooved tool 68 is provided as shown in FIG. 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 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.

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 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 50 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 50 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 12 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 10 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 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 joists 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 to fall within the broad scope and ambit of the invention as claimed in the following claims.

Claims (12)

1. A joint for joining two 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 o fixing means fixing said overlap portions to said other section. *4

2. A joint as claimed in claim 1, wherein said end portions include additional material from at least some of an adjoining respective interconnecting wall portion. 0 o

3. A joint as claimed in claim 1 or claim 2, wherein said sections are rolled hollow o metal box sections having a square or rectangular cross-section. 064*4 6

4. A joint as claimed in any one of the preceding claims, wherein said projecting end portions are modified to permit attachment of a third section.

5. A joint as claimed in any one of the preceding claims, wherein said projecting end portions are modified to permit pivotal attachment of a third section.

6. A joint as claimed in any one of claims 1 to 3, wherein two sections are provided with said projecting end portions for joining to a third section, wherein the 14 centrelines of the two sections converge substantially at the centreline of the third section.

7. Steel framing including inter-connected hollow section framing members extending angularly to one another with the 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 substantially flush against a side wall portion of the other frame member whereby the inter-connection may be formed by a mechanical fastener or fasteners passing through the terminal lateral wall portion and the side wall portion.

8. A triangular roof supporting frame including:- an apex and two bottom corners; two top chords connected to one another at said apex and a bottom chord 15 extending between and connected to each said top chord at said respective bottom oooo corners to form a bottom corner joint, and wherein said bottom corner joint is a joint as claimed in any one of claims 1 to 6.

9. A method of joining 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 as claimed in claim 9, and including removing part of one of the spaced wall portions whereby only one projecting end portion is formed.

11. The method as claimed in claim 9, wherein at least some of the removed end .portion of said interconnecting wall portion is retained to form an extended end 0 portion by bending the retained portion into alignment with the remainder of said projecting end portion.

12. A termite proofing method wherein the wall frames utilise timber studs captively secured in metal open channel bottom sections to form continuous barriers at the wall/floor interface to prevent upward travel of termites beyond the floor. •go* DATED THIS Tenth DAY OF May 2000. LIONEL DESMOND HILL BY PIZZEYS PATENT TRADE MARK ATTORNEYS