Title of Invention

AN ELONGATE STRUCTURAL MEMBER, A CHORD FOR A TRUSS AND A TRUSS

Abstract

An elongated structural member (10) comprises a minor flange (12), a major flange (13), parallel thereto and a web (14) interconnecting the flanges and having a section axis (11a) at right angles to the longitudinal axis of the structural member, wherein : the web has a linear portion (17) coincident with the section axis, and a divergent portion (18) extending to one side of the section axis ; the minor flange laterally extends from the section axis to said one side ; the major flange extends from the divergent portion to the opposite side of the section axis, and has a major flange return (20) spaced from said opposite side of the section axis by a distance not less than the distance by which the minor flange extends from said one side of the section axis, and whereby a like sectioned structural member can be inverted, inclined and nested with said structural member with the respective linear portions abutting each other and with each minor flange in an abutting relationship with the adjacent major flange whereat it is partially confined by the major flange return such that separation of the abutting linear portions is prevented.

Full Text

FIELD OF THE INVENTION The invention relates to an elongate structural member, a chord for a truss, and a truss for construction of buildings such as houses, the invention has particular but not exclusive application in use as a chord for forming a roof truss for a building. PRIOR ART A metal roof truss is commonly constructed with box-section chords and C-section web members. The box section chords are formed by two C-sections individually roll formed and then further fabricated by dimple formation for locating and/or fastening by welding, riveting, hole punched and bolted or screwed to close the two C-sections. The fabrication of the section is a specialised operation and adds additional cost and time to the manufacture of a chord. Open sections are generally quicker and cheaper to manufacture than box-sections comprising two C-sections, but they lack the strength and stiffness required for chords. Thus, whenever open sections, such as channel and Z-sections are used in the fabrication of building frames and roof trusses, additional precautions such as providing oversized sections or additional structural support must be taken to compensate for their inherent strength deficiencies. This of course increases the cost of many structures formed therefrom. -2- In addition, effecting the joints between top and bottom chords and between web members and chords mostly requires specialised joining members or shaping for welding which adds to the cost and complexity of such structures. SUMMARY OF THE INVENTION It is an object of this invention to provide an alternative structural member suitable for forming the chord of a truss or other structural member. The present invention provides an elongate structural member having a minor flange, a major flange, which is longer than said minor flange and extends parallel to said minor flange, and a web interconnecting said flanges and having a section axis at right angles to the longitudinal axis of the structural member, wherein: said web has a linear portion which extends substantially coincident with said section axis, and a divergent portion which extends to one side of said section axis ; said minor flange laterally extends from said section axis to said one side ; said major flange extends from said divergent portion to the opposite side of said section axis, and is provided with a major flange return which is spaced from said opposite side of the section axis by a distance not less than the distance by which the minor flange extends from said one side of the section axis, and the section configuration being such that a like sectioned structural member can be inverted, inclined and nested with said structural member with the respective linear portions abutting each other and with each minor flange in an abutting relationship with the adjacent major flange whereat it is partially confined by the major flange return such that separation of the abutting linear portions is prevented. -3- The linear portion may be of any suitable length but preferably the linear portion extends along a major portion of the section axis between the flanges. The term "suitable" is qualified by the particular use of the open structural member and where a corresponding member is used the length of the linear portion suitably enables overlap of the linear section portions or portions thereof. The divergent portion may have any suitable shape. The divergent portion may be curved, straight, or comprise a series of straight segments. In a preferred embodiment the divergent portion is a single straight portion and the major flange extends at an acute angle from the divergent portion. The linear portion connects to the minor flange at its end opposite the divergent portion. Preferably the minor flange extends from the linear portion at an angle of substantially 90°. Alternatively, the linear portion may include a second divergent portion which extends to the minor flange. The second divergent portion may be curved, straight, or comprise a series of straight segments. The minor flange is preferably shorter than the major flange and most preferably is shorter than the section of the major flange which extends between the section axis and the end of the major flange remote from the divergent portion, and hereinafter referred to as its "free edge". Preferably the intersection with the section axis occurs about midway across the major fiange. -4- Preferably the flanges are substantially flat or at least parts which are substantially diagonally opposite with respect to the section axis are substantially flat. Preferably the flanges or at least the flat parts are substantially parallel. Preferably the open structural member includes limiting means to restrict lateral movement with respect to the section axis of connected members along the section axis. Preferably the limiting means is a return flange extending along the free edge of the major flange. The major and/or the minor flanges preferably both terminate in a return flange. The return flange preferably returns substantially parallel to the section axis. Preferably, the return flange of the major flange is spaced from the opposite side of the section axis by a distance not less than the distance by which the minor flange extends from said one side of the section axis. This means to say that the return flange of the major flange is spaced further from the section axis than the free edge of the minor flange so that a reversed and inverted corresponding open structural member may nest within the structural member. The open structural member is preferably asymmetrical in shape and allows the nesting of an inverted and reversed corresponding open structural member with the minor flange of one open structural member locatable within the major flange of the open structural member and overlapping of the linear section portions. -5- The present invention farther provides an elongate open structural member having a minor flange, a major flange, and a web interconnecting said flanges and having a planar web portion extending at right angles to the minor and major flanges, wherein: said web includes a divergent portion which extends to one side of said planar portion ; said minor flange extends to said one side of said planar portion; and said major flange extends from said divergent portion to the opposite side of said planar portion; said minor flange and said major flange each have a return along the configuration being such that an Inverted and reversed corresponding open structural member is locatable with its planar portion along side the planar portion of said structural member and each minor flange including its return being iocatable within the confine defined by the adjacent flange return of the major flange. in another aspect, the present invention provides a truss comprising upper and lower chords formed by the above elongate structural members wherein the longitudinal axes of the upper and lower chords are inclined at an acute angle with respect to each other; the linear portions abut adjacent the eave line of the truss for connection to one another; and the minor flange of each one of the chords abuts the major flange of the other chord at the eave line and is partially confined by the major flange return of the other chord such that separation of the abutting linear portions is prevented. -6- In a still further aspect, the present invention provides a chord for a truss, said chord comprising in section : a minor flange ; a major flange spaced from and parallel to the minor flange, said major flange being longer than the minor flange and having a major flange return ; and a web interconnecting the minor flange and the major flange, said web having a linear portion, wherein the chord is configured such that a second like-sectioned chord can be inverted, inclined and nested with the chord, with the respective linear portions of the webs abutting and with the minor flange of each chord abutting the flange of the other chord and partially confined by the major flange return of the other chord, whereby separation of the abutting linear portions of the webs is prevented. In a yet another aspect, the present invention provides a chord for a truss, said chord comprising a minor flange ; a major flange spaced from and parallel to the minor flange, said major flange having a length greater than the minor flange and having a major flange return ; and a web interconnecting the minor flange and the major flange, the web having a linear portion, wherein the chord is configured such that a second like-sectioned chord can be inverted, inclined and nested with the chord, with the respective linear portions of the webs abutting and with the major flange and major flange return of each chord closely enveloping the minor flange of the other chord whereby separation of the abutting linear portions of the webs is prevented. -7- In a further aspect, the present invention provides a truss comprising a pair of chords as described above, wherein the upper chord has the major flange uppermost, and the lower chord has the major flange lowermost; the longitudinal axes of the upper and lower chords are inclined with respect to each other; and the upper and lower chords intersect and nest together at the eave line. In another aspect, the present invention provides a chord for a truss, said chord comprising in section : a first flange ; a longer second flange spaced from and parallel to the first flange, the second flange having a second flange return ; and a web interconnecting the first flange and the second flange, wherein the chord is configured such that a second like-sectioned chord can be inverted, inclined and nested with the chord, with the respective webs abutting and with the first flange of each chord abutting the second flange of the other chord and partially confined by the second flange return of the other chord whereby separation of the abutting webs is prevented. In another aspect, the present invention provides a chord for a truss, said chord having in section : a first flange ; a longer second flange spaced from and parallel to the first flange, the second flange having a second flange return ; and a web interconnecting the first flange and the second flange, wherein the chord is configured such that a second like-sectioned chord can be inverted and nested with the chord, with the respective webs abutting and with the second flange and second flange return of each chord closely enveloping and abutting the first flange of the other chord whereby separation of the abutting webs is prevented. -8- In a further aspect, the present invention provides a truss comprising a pair of chords as described above, wherein the upper chord has said second flange uppermost, and the lower chord has said second flange lowermost ; the longitudinal axes of the upper and lower chords are inclined with respect to each other; and the upper and lower chords intersect and nest together at the eave line. In another aspect the present invention provides a truss comprising a lower chord having in section - a web having a linear portion and a divergent portion which extends to one side of the linear portion ; a minor flange extending from the linear portion to the one side of the web ; and a longer major flange extending from the divergent portion back to the other side of the web and having a major flange return ; and an upper chord having the same section as the lower chord, wherein the upper chord is inverted and inclined with respect to the lower chord ; and the upper and lower chords nest together at the eave line of the truss with the respective linear portions abutting and with the respective minor flanges abutting the respective major flanges and partially confined by the major flange returns. In another aspect, the present invention provides a truss comprising a lower chord having in section a web, a minor flange, and a longer major flange ; and an upper chord having the same section as the lower chord, wherein the upper chord is inverted with respect to the lower chord ; and the upper and lower chords nest together at the eave line of the truss with the respective webs abutting and with the respective minor flanges abutting the respective major flanges. -9- In another aspect the present invention provides a truss comprising :-a lower chord having in section a web, a first flange, and a second flange ; and an upper chord having the same section as the lower chord ; wherein the upper chord is inverted with respect to the lower chord ; and the upper and lower chords nest together at the eave line of the truss with the respective webs abutting and with the respective first flanges abutting the respective second flanges. The present invention also provides a method of forming a truss comprising : providing a pair of like-sectioned chords, each chord having in section a web, a minor flange and a major flange ; inverting one chord relative to the other and inclining the longitudinal axes of the chords with respect to each other and intersecting and nesting the chords at the eave line of the truss such that the respective webs abut and such that the respective minor flanges abut the respective major flanges. The present invention further provides a method of forming a truss comprising : providing a pair of like-sectioned chords, each chord having in section a web, a first flange and a second flange ; inverting one chord relative to the other and inclining the longitudinal axes of the chords with respect to each other and intersecting and nesting the chords at the eave line of the truss such that the respective webs abut and such that the respective first flanges abut the respective second flanges. -10- In another aspect the present invention provides a chord member for a truss, each chord member of the truss being an open structural member as described above whereby the chord member may be disposed with its major flange outermost and with interconnections between intersecting chord members being made by extending the web and minor flange of one intersecting chord member across the web and minor flange of the other chord member with the webs overlying one another enabling through fastening together. In such arrangement the webs overlap at joints for connection to one another such as by bolting or screwing or welding and, if desired disposed with their minor flanges nested within the major flanges of the opposing chord member. tt is also preferred that the chords of said truss are interconnected by truss members which may be open section members suitably terminated for web to web connection to the webs of the top and bottom chord members. The assembled truss with the open structural member forming the top and bottom chord members with C-section truss members preferably has the chord members proud of the truss members thereby allowing stacking of the assembled truss and transportation of the stacks without risk of damage to the truss members by the overlying chord members. In contrast conventional box section chords have C-section truss members joined at their flat surfaces thereby causing the truss members to be proud of the chord members and exposing the truss members to damage during stacking and their transportation. -11 - In a further aspect, the invention broadly resides in a composite beam formed by the nesting of two open structural members as described variously above in an inverted and reversed orientation with respect to each other with the minor flange of one member located within the major flange of the other member and overlapping of the planar portions and fastening means connecting the open structural members together. The open structural members may be prevented from lateral displacement with respect to one another by the fastening means but preferably they include returns along the free edges of the major flanges which restrain lateral displacement of the open structural members with respect to one another. Preferably the nesting of the open structural members as described above forms two closed sections thereby providing strength to the beam. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Several typical embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: FIG. 1 is an end elevation of an elongate open structural member; FIGS. 2, 3, 4 are perspective views of the member; FIG. 5 is an end elevation of two members nested in reverse and inverted orientation with respect to each other; FIG. 6a is a front elevation of an assembled truss with open structural members as top and bottom chord members; -12 - FIGS. 6b-g show various connections on the truss shown in Fig. 6a ; FIGS. 7a-c are views of the interconnection of two open structural members; FIGS. 8a-c are views of different attachments of C-section truss member to a chord; FIGS. 9a-c show alternative connections between chords and truss members; and FIG. 10 shows an alternative structural member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In Figs. 1 to 4 there is shown an elongated open structural member 10 having a minor flange 12 and a major flange 13 separated by a web 14. A longitudinal axis 11b of the member 10 is shown in Fig 2. The web 14 includes a linear portion 17 (preferably a planar portion) and a divergent portion 18. A section axis 11a is coincident with the linear portion 17. The minor flange 12 extends from the linear portion 17 at 90°. The minor flange 12 includes a return flange 15. The return flange 15 is parallel to the section axis 11a. The divergent portion 18 diverges from the section axis 11a at an acute included angle indicated by a. The divergent portion 18 is connected to the major flange 13. The major flange 13 includes a broad planar flange portion 19 which is connected to the divergent portion 18 forming an acute included angle. The major flange 13 also includes a return flange 20 parallel to the section axis. -13- As shown in Fig. 5, two elongate open structural members 30, 31 as described above are able to be nested with one member being in reverse and inverted orientation with respect to the other. To effect nesting, minor flanges 32a and 32b are located within major flanges 33b and 33a respectively in abutting relationship. In this position the respective web portions 34a, 34b partly overlie each other thereby allowing fasteners to join both members 30, 31 to prevent lateral movement. The abutting relationship of the respective flanges 32a, 32b, 33a, 33b prevents movement along the section axis. The nesting of the two elongate members forms two closed sections 35, 36 which provide strength and stiffening to the composite member. Roof trusses 40 as shown in Figs. 6a-g are constructed with elongate open structural members forming top and bottom chords 41, 42 and C-section truss members. The connection of the top chord 41 to the bottom chord 42 is shown in fig. 6b. The major flanges 44, 45 of the top and bottom chords 41 and 42 respectively are outermost. The minor flange 46 of the top chord 41 is partially located and confined in major flange 45. The rearward flat side 47 of top chord 41 partly overlaps frontward flat side 48 of the bottom chord 42. There is shown an intermediate connection plate 49 between sides 47 and 48. The connection plate 49 is attached to the bottom chord 42 by bolts 50, 51 and to the top chord 41 by bolts 50, 52. An alternative connection is shown in Fig. 9c where top chord 60 is bolted to bottom chord 61 at 62. Connections of the truss members 43 to the chord members 41, 42 is shown in Figs. 6c, 6d, 6f In Fig. 6d, the truss members 43 are crimped and joined -14- to the top chord 41 by bolt 70. In Fig. 6e the truss members 43 are attached to the bottom chord 42 by bolt 72. The underlying truss members are at least crimped to accommodate the connection. The connection shown in Fig. 6c has the truss member 43 connected by bolt 71 to the bottom chord 42. The chords 41, 42 are proud of the truss members 43 in the truss 40. The apex 80 of the truss 40 is shown in Figs. 6f, 6g. An apex plate 81 serves to connect top chords 41 by bolts 82. The apex plate 81 has recessed ribs 83 to provide additional stiffening. The apex plate 81 also has a recess 84 for the location of a C-section truss member 43. The C-section truss member 43 is connected to the apex plate 81 by bolt 85. Alternative connections in an apex are shown in Figs. 9a and 9b. In Fig. 9a, top chords 63 and C-section truss members 64 are connected by bolt 65. Similarly in Fig. 9b the top chords 66 and C-section truss member 67 are connected by bolt 68. In Figs. 7a-c there is shown chords 90, 91 with major flanges 92, 93 outermost and minor flange 94 located partially within the major flange 92. In Figs. 8a-c there is shown attachment of crimped C-section truss members 95 to elongate open structural member chords 96 by bolts 97. The C-section truss member 95 has end 98 crimped presenting a flat surface 99 for connecting to the chord 96. The flat surface 99 is attached to the side of the web portion 100 opposite the narrow flange 101. -15- The embodiment described above provides a number of advantages including efficient roll forming for chord production; provision of a strengthened and stiffer open section member chord with proper orientation of the major flange outermost ; the ability to treat or coat the entire chord or composite beam or truss having open sections prior to use ; compact truss stacking with chords being proud of truss web members thereby minimising damage to the truss members during transportation and reducing transport and storage costs ; the ability of the chords to overlap for interconnection while maintaining the overlapped chords in line one above the other for symmetry of the truss and to be easily fastened together at terminations. It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other 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 this invention as is herein set forth. -16- WE CLAIM: 1. An elongate structural member having a minor flange, a major flange, which is longer than said minor flange and extends parallel to said minor flange, and a web interconnecting said flanges and having a section axis at right angles to the longitudinal axis of the structural member, wherein: said web has a linear portion which extends substantially coincident with said section axis, and a divergent portion which extends to one side of said section axis; said minor flange laterally extends from said section axis to said one side; said major flange extends from said divergent portion to the opposite side of said section axis, and is provided with a major flange return which is spaced from said opposite side of the section axis by a distance not less than the distance by which the minor flange extends from said one side of the section axis, and the section configuration being such that a like sectioned structural member can be inverted, inclined and nested with said structural member with the respective linear portions abutting each other and with each minor flange in an abutting relationship with the adjacent major flange whereat it is partially confined by the major flange return such that separation of the abutting linear portions is prevented. -17- 2. An elongate structural member as claimed in claim 1, wherein said linear portion of the web extends from the minor flange end along a major portion of the section axis between the flanges and said divergent portion extends at an acute angle from the section axis. 3. An elongate structural member as claimed in claim 1, wherein the minor flange is provided with a minor flange return, said minor flange return abutting the major flange return of an inverted, inclined and nested like-sectioned member. 4. A truss comprising upper and lower chords formed by elongate structural members as claimed in any one of claims 1 to 3, wherein the longitudinal axes of the upper and lower chords are inclined at an acute angle with respect to each other; the linear portions abut adjacent the eave line of the truss for connection to one another; and the minor flange of each one of the chords abuts the major flange of the other chord at the eave line and is partially confined by the major flange return of the other chord such that separation of the abutting linear portions is prevented. 5. A chord for a truss, said chord comprising in section: a minor flange; a major flange spaced from and parallel to the minor flange, said major flange being longer than the minor flange and having a major flange return; and -18- a web interconnecting the minor flange and the major flange, said web having a linear portion, wherein the chord is configured such that a second like-sectioned chord can be inverted, inclined and nested with the chord, with the respective linear portions of the webs abutting and with the minor flange of each chord abutting the major flange of the other chord and partially confined by the major flange return of the other chord whereby separation of the abutting linear portions of the webs is prevented. 6. A chord for a truss, said chord comprising : a minor flange; a major flange spaced from and parallel to the minor flange, said major flange having a length greater than the minor flange and having a major flange return ; and a web interconnecting the minor flange and the major flange, the web having a linear portion, wherein the chord is configured such that a second like-sectioned chord can be inverted, inclined and nested with the chord, with the respective linear portions of the webs abutting and with the major flange and major flange return of each chord closely enveloping the minor flange of the other chord whereby separation of the abutting linear portions of the webs is prevented. -19- 7. A truss comprising a pair of chords as claimed in claim 5 or 6 wherein the upper chord has the major flange uppermost, and the lower chord has the major flange lowermost; the longitudinal axes of the upper and lower chords are inclined with respect to each other; and the upper and lower chords intersect and nest together at the eave line. 8. A truss comprising: a tower chord having in section - a web having a linear portion and a divergent portion which extends to one side of the linear portion, a minor flange extending from the linear portion to the one side of the web, and a longer major flange extending from the divergent portion back to the other side of the web and having a major flange return; and an upper chord having the same section as the lower chord, wherein the upper chord is inverted and inclined with respect to the lower chord, and the upper and lower chords nest together at the eave line of the truss with the respective linear portions abutting and with the respective minor flanges abutting the respective major flanges and partially confined by the major flange returns. 9. A truss comprising: a lower chord having in section a web, a minor flange, and a longer major flange; and -20- an upper chord having the same section as the lower chord, wherein the upper chord is inverted with respect to the lower chord; and the upper and lower chords nest together at the eave line of the truss with the respective webs abutting and with the respective minor flanges abutting the respective major flanges. 10. A truss as claimed in claim 9, wherein the major flange is provided with a major flange return, the minor flange being partially confined by the major flange return such that separation of abutting webs is prevented. 11. A method of forming a truss comprising : providing apair of like-sectioned chords, each chord having in section a web, a minor flange and a major flange ; inverting one chord relative to the other and inclining the longitudinal axes of the chords with respect to each other and intersecting and nesting the chords at the eave line of the truss such that the respective webs abut and such that the respective minor flanges abut the respective major flanges. 12. A method as claimed in claim 11, wherein the major flange is provided with a major flange return, the minor flange being partially confined by the major flange return such that separation of abutting webs is prevented. -21- -22- 13. An elongate structural member, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. 14. A chord for a truss, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. 15. A truss, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. 16. A method of forming a truss, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. 17. A composite beam incorporating an elongate structural member as claimed in any of claims 1 to 3. An elongated structural member (10) comprises a minor flange (12), a major flange (13), parallel thereto and a web (14) interconnecting the flanges and having a section axis (11a) at right angles to the longitudinal axis of the structural member, wherein : the web has a linear portion (17) coincident with the section axis, and a divergent portion (18) extending to one side of the section axis ; the minor flange laterally extends from the section axis to said one side ; the major flange extends from the divergent portion to the opposite side of the section axis, and has a major flange return (20) spaced from said opposite side of the section axis by a distance not less than the distance by which the minor flange extends from said one side of the section axis, and whereby a like sectioned structural member can be inverted, inclined and nested with said structural member with the respective linear portions abutting each other and with each minor flange in an abutting relationship with the adjacent major flange whereat it is partially confined by the major flange return such that separation of the abutting linear portions is prevented.

Documents:

00779-cal-1998 abstract.pdf

00779-cal-1998 claims.pdf

00779-cal-1998 correspondence.pdf

00779-cal-1998 description(complete).pdf

00779-cal-1998 drawings.pdf

00779-cal-1998 form-1.pdf

00779-cal-1998 form-13.pdf

00779-cal-1998 form-2.pdf

00779-cal-1998 form-3.pdf

00779-cal-1998 form-5.pdf

00779-cal-1998 g.p.a.pdf

00779-cal-1998 letters patent.pdf

00779-cal-1998 priority document.pdf

00779-cal-1998 reply f.e.r.pdf

778-CAL-2004-FORM-27.pdf

779-CAL-1998-CORRESPONDENCE.pdf

779-CAL-1998-FORM 27 1.1.pdf

779-CAL-1998-FORM 27.pdf

779-CAL-1998-FORM-27-1.pdf

779-CAL-1998-FORM-27.pdf

779-cal-1998-granted-abstract.pdf

779-cal-1998-granted-claims.pdf

779-cal-1998-granted-description (complete).pdf

779-cal-1998-granted-drawings.pdf

779-cal-1998-granted-form 2.pdf

779-cal-1998-granted-specification.pdf

779-cal-1998-priority document.pdf