AU2010324521B2

AU2010324521B2 - Structural element

Info

Publication number: AU2010324521B2
Application number: AU2010324521A
Authority: AU
Inventors: Keith Woolf
Original assignee: Metroll Tech Pty Ltd
Current assignee: METROLL TECHNOLOGY Pty Ltd
Priority date: 2009-11-27
Filing date: 2010-11-16
Publication date: 2016-05-05
Anticipated expiration: 2030-11-16
Also published as: NZ627155A; AU2010324521A1; NZ600216A; US20120266562A1; WO2011063447A1

Abstract

A structural element comprising a web, a pair of substantially oppositely directed flanges projecting outwardly from respective ends of the web, wherein the web comprises two or more channels formed therein, and wherein at least two of the two or more channels project into the web in opposed orientation to one another.

Description

WO 2011/063447 PCT/AU2010/001534 1 Structural Element Field of the Invention. The present invention relates to a structural element. In particular, the present 5 invention relates to a structural element intended to be used as a load bearing element in a skeletal structure, and especially as a purlin for use in a roof supporting building structure. Background Art. i0 Purlins have long been used as load bearing elements in the construction of buildings and other similar structures. Conventional purlins are typically cold formed from roll reduced steel into sections having either a generally Z shaped or C shaped cross section. 15 Some attempts have been made to design purlins having increased strength relative to basic Z-section or C-section purlin configurations. For instance, -Australian patent number 707074 discloses a Z-section purlin having increased strength due to the addition of lip returns. However, this arrangement suffers from the drawback that the purlins are difficult to stack, which therefore makes the handling and storage of the 20 purlins difficult. Thus, there would be an advantage if it were possible to provide a structural element having improved load bearing strength that was also stackable and easy to handle. 25 It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country. Throughout this specification; the term "comprising" and its grammatical equivalents 30 shall be taken to have an inclusive meaning unless the context of use indicates otherwise.

WO 2011/063447 PCT/AU2010/001534 2 Object of the Invention. It is an object of the present invention to provide a structural element which may overcome at least some of the abovementioned disadvantages, or provide a useful or 5 commercial choice. In one aspect, the invention resides broadly in a structural element comprising a web, a pair of substantially oppositely directed flanges projecting outwardly from respective ends of the web, wherein the web comprises two or more channels formed therein, 10 and wherein at least two of the two or more channels project into the web in opposed orientations to one another. Each of the pair of flanges may be disposed at any suitable angle to the web. However, in a preferred embodiment of the invention, both of the pair of flanges are 1s disposed substantially at right-angles to the web. Thus, in this embodiment of the invention, the pair of flanges are located substantially parallel to one another. Each of the pair of flanges may be of any suitable width. However, it is preferred that the width of each of the flanges is less than the height of the web. Each of the pair of 20 flanges may be of the same or different width to one another. Preferably, one of the pair of flanges is wider than the other of the pair of flanges. This allows for the structural elements to be readily stacked together for transportation and storage, or joined in an overlapping relationship. 25 In a preferred embodiment of the invention, at least one of the pair of flanges may be provided with a lip extending therefrom. Preferably, the lip extends from, or adjacent to, an end of the at least one flange located furthest from the web. In some embodiments of the invention, each of the pair of flanges may be provided with a lip. 30 The lip (or lips if present) may be disposed at any suitable angle to the flange from which it extends. Preferably, however, each of the lip or lips are disposed at an included angle of less than 180* to the flange or flanges.

WO 2011/063447 PCT/AU2010/001534 3 In embodiments of the invention in which each of the pair of flanges is provided with a lip, each of the lips may be disposed at the same angle to its respective flange, or each of the lips may be disposed at a different angle to its respective flange. In some 5 embodiments, at least one of the lips is disposed substantially at a right angle to the flange. In embodiments in which the flange is disposed at substantially a right angle to the web, the at least one lip will therefore be disposed substantially parallel to the web. 10 In a most preferred embodiment of the invention, each of the pair of flanges is provided with a lip. The lip associated with a first flange is preferably disposed at an included angle of approximately 900 to the first flange, while the lip-associated with a second flange is preferably disposed and included angle of between 90* and 180* to the second flange. In this embodiment, it is preferred that the width of the first flange 15 is less than that of the second flange. The lip (or lips if present) may be of any suitable size, shape or configuration. For instance, each of the lips may be substantially linear along its entire length, may be curved or bent, or may be substantially linear along a portion of its length and curved 20 or bent along a portion of its length. In embodiments of the invention the lip is curved or bent along at least a portion of its length, it is envisaged that the lip may be provided with one or more curves or bends that extend in any suitable direction. For instance, an inner radius of the one or more 25 curves or bends may be located on the side of the lip closest to the web, or the side of the lip furthest from the web. Alternatively, if the lip is provided with two or more curves or bends, the inner radius of at least one of the two or more curves or bends may -be located on the side of the lip closest to the web, while an inner radius of at least another of the two or more curves or bends may be located on the side of the lip 30 furthest from the web. In some embodiments, the at least one lip may be provided with a lip return. The lip WO 2011/063447 PCT/AU2010/001534 4 return may be disposed at any suitable angle to the lip. Preferably, the lip return extends from at or adjacent the end of the lip remote from the flange. The lip return may be of any suitable width. Further, the lips returns may be of any suitable configuration. For instance, the lip returns may be substantially linear along their 5 entire length, may be curved or bent, or may be substantially linear along a portion of their length and curved or bent along a portion of their length. In preferred embodiments of the invention, each of the lips may be provided with a lip return. The lip returns may be of the same configuration as one another, or may be of 10 different configurations to one another. Each of the two or more channels may be of any suitable size, shape or configuration. Preferably, both of the two or more channels extend at least partially along the length of the web. In some embodiments of the invention, both of the two or more channels is may extend continuously along the length of the web, while alternatively, one or more of the two or more channels may comprise a plurality of discrete channels extending coaxially along the length of the web. The two or more channels may be provided with any suitable shape. For instance, the 20 two or more channels may be substantially U- or V-shaped, or may comprise a pair of sidewalls interconnected by a bottom wall, or a combination thereof. However, regardless of the shape or configuration of the two or more channels, it is preferred that adjacent channels are spaced apart from one another by a portion of the height of the web. 25 In a preferred embodiment of the invention, the two or more channels may be of different sizes to one another. For instance, the two or more channels may project different distances into the web as one another. In addition, the distance between the opposing walls of the channels may vary between channels. In this way, positive 30 lapping of structural elements may be achieved. While the shape and distance each of the two or more channels projects into the web WO 2011/063447 PCT/AU2010/001534 5 is not critical, it is preferred that each of the two or more channels is shaped so as to enhance one or more of the torsional, vertical and lateral strengths of the structural element. 5 In some embodiments of the invention, the size and shape of the two or more channels is preferably sufficient to restrict the movement of adjacent or lapped structural elements along an axis of the web. This is particularly advantageous when the structural elements are used in conditions of high load and/or high stress. 10 Preferably, the channels may be used to provide both structural support and engagement enhancement for the use of one or more bridging members. In addition, the channels may provide a structural engagement mechanism for connection means (such as brackets or the. like) for use in various applications (such as suspended ceilings). 15 The two or more channels may be located at any suitable position along the height of the web. However, in a preferred embodiment of the invention, a first channel of the at least two channels that project into the web in opposed orientation to one another is located in a first portion of the height of the web between the middle of the web and a 20 first flange, while a second channel of the at least two channels that project into the web in opposed orientation to one another is located in a second portion of the height of the web between the middle of the web and a second flange. Desirably, the at least two of the two or more channels are located an approximately equal distance from the middle of the web as one another. By providing the two or more channels in these 25 locations, the structural element of the present invention is provided with increased strength relative to that obtained from conventional structural elements of this kind. It is envisaged that further channels may be provided on the web as required. The exact position and orientation of these further channels is not critical. However, 30 additional increases in strength or other physical characteristics of the element such as torque resistance may be gained dependent upon the position of the additional channels.

WO 2011/063447 PCT/AU2010/001534 6 The structural element may be fabricated from any suitable material using any suitable technique. Preferably, however, the structural element is fabricated from a metal or metal alloy (and, in particular, steel or aluminium) and is fabricated by rolling (either 5 cold or hot rolling) or extrusion. It is envisaged that the structural element of the present invention may be fabricated in a wide variety of sizes depending on the application in which the structural element is to be used. In addition, the thickness of the structural element may also vary 10 depending on the application in which the structural element is to be used. For instance, the structural element may be formed from 2mm thick steel if the load it is to bear is relatively small, whereas if the load is relatively high, the structural element may be formed from 3mm thick steel, and so on. A skilled addressee will realize that these thicknesses are mentioned by way of illustration only, and the structural element 15 may be formed of any suitable thickness. Further, the thickness of the structural element may be substantially constant across its entire cross-section or may vary across the cross-section. Preferably, the structural element is fabricated as a unitary structure. Alternatively, 20 however, the structural element may be formed as a number of individual components which are adapted for connection to one another, such as by welding, brazing, soldering, or the like. In this aspect of the invention, the structural element may be a purlin. In particular, 25. the structural element may be a purlin having a substantially Z-shaped cross-section. In another aspect, the invention resides broadly in a structural element comprising a web, a pair of flanges projecting outwardly in substantially the same direction from respective ends of the web, wherein the web comprises two or more channels formed 30 therein, and wherein at least two of the two or more channels project into the web in the same orientation as one another.

WO 2011/063447 PCT/AU2010/001534 7 Each of the pair of flanges may be disposed at any suitable angle to the web. However, in a preferred embodiment of the invention, both of the pair of flanges are disposed substantially at right-angles to the'web. Thus, in this embodiment of the invention, both of the pair of flanges are located substantially parallel to one another. .5 Each of the pair of flanges may be of any suitable width. However, it is preferred that the width of each of the flanges is less than the height of the web. Each of the pair of flanges may be of the same or different width to one another. Preferably, one of the pair of flanges is wider than the other of the.pair of flanges. This allows for the 10 structural elements to be readily stacked together for transportation and storage, or joined in an overlapping relationship. In a preferred embodiment of the invention, at least one of the pair of flanges may be provided with a lip extending therefrom. Preferably, the lip extends from or adjacent 15 to an end of the at least one flange located furthest from the web. In some embodiments of the invention, each of the pair of flanges may be provided with a lip. The lip (or lips if present) may be disposed at any suitable angle to the flange from which it extends. Preferably, however, each of the lip or lips are disposed at an 20 included angle of less than 1800 to the flange or flanges. In embodiments of the invention in which each of the pair of flanges is provided with a lip, each of the lips may be disposed at the same angle to its respective flange, or each of the lips may be disposed at a different angle to its respective flange. In some 25 embodiments, at least one of the lips is disposed substantially at a right angle to the flange. In embodiments in which the flange is disposed at substantially a right angle to the.web, the lip will therefore be disposed substantially parallel to the web. In a most preferred embodiment of the invention, each of the pair of flanges is 30 provided with a lip. In this embodiment, it is preferred that both of the lips are disposed at an included angle of about 90* to their respective flanges.

WO 2011/063447 PCT/AU2010/001534 8 The two or more channels may be of any suitable size, shape or configuration. Preferably, the two or more channels extend at least partially along the length of the web. In some embodiments of the invention, the two or more channels may extend continuously along the length of the web, while alternatively, one or more of the two 5 or more channels may comprise a plurality of discrete channels extending coaxially along the length of the web. Preferably, the at least two of the two or more channels extend into the web in the same direction as the flanges. 10 The two or more channels may be provided with any suitable shape. For instance, the two or more channels may be substantially U- or V-shaped, or may comprise a pair of sidewalls interconnected by a bottom wall or a combination thereof. However, regardless of the shape or configuration of the two or more channels, it is preferred 15 that adjacent channels are spaced apart from one another by a portion of the height of the web. In a preferred embodiment of the invention, the two or more channels may be of different sizes to one another. For instance, the two or more channels may project 20 different distances into the web as one another. In addition, the distance between the opposing walls of the channels may vary between channels. In this way, positive lapping of structural elements may be achieved. Further, configuring the two or more channels in this way ensures the correct orientation and. assembly of other constructions members (brackets and the like). This is particular of use for kit 25 products and the like. While the shape and distance each of the two or more channels projects into the web is not critical, it is preferred that each of the two or more channels is shaped so as to enhance one or more of the torsional, vertical and lateral strength of the structural 30 element. Preferably, the channels may be used to provide both structural support and WO 2011/063447 PCT/AU2010/001534 9 engagement enhancement for the use of one or more bridging members. In addition, the channels may provide a structural engagement mechanism for connection means (such as brackets or the like) for use in various applications (such as suspended ceilings). 5 In this embodiment of the invention, the two or more channels project into the web in the same direction that the flanges extend. By projecting into the web in this direction, an engagement mechanism is created for other construction members (brackets or the like) that is both flush and positive.. This is particularly of use in 10 situations in which conjoined members of the same or a differing nature are required. The two or more channels may be located at any suitable position along the height of the web. However, in a preferred embodiment of the invention, a first channel of the at least two channels that project into the web in the same orientation to one another is 15 located in an upper portion of the height of the web, while a second channel of the at least two channels that project into the web in the same orientation to one another is located in a lower portion of the height of the web. Desirably, at least two of the two or more channels are located an approximately equal distance from the middle of the web as one another, although it will be understood that the two or more channels 20 could also be located at different distances from the middle of the web as one another if desired. By providing the two or more channels in these locations, the structural element of the present invention is provided with increased strength relative to that obtained from conventional structural elements of this kind. 25 It is envisaged that further channels may be provided on the web as required. The exact position and orientation of these further channels is not critical. Again however, additional increases in strength or other physical characteristics of the element such as torque resistance may be gained dependent upon the position of the additional channels. 30 The structural element may be fabricated from any suitable material using any suitable technique. Preferably, however, the structural element is fabricated from a metal or WO 2011/063447 PCT/AU2010/001534 10 metal alloy (and, in particular, steel or aluminium) and is fabricated by rolling (either. cold or hot rolling) or extrusion. It is envisaged that the structural element of the present invention may be fabricated in 5 a wide variety of sizes depending on the application in which the structural element is to be used. In addition, the thickness of the structural element may also vary depending on the application in which the structural element is to be used. For instance, the structural element may be formed from 2mm thick steel if the load it is to bear is relatively small, whereas if the load is relatively high, the structural element 10 may be formed from 3mm thick steel, and so on. A skilled addressee will realize that these thicknesses are mentioned by way of illustration only, and the structural element may be formed of any suitable thickness. Preferably, the structural element is fabricated as a unitary structure. Alternatively, 15 however, the structural element may be formed as a number of individual components which are adapted for connection to one another, such as by welding, brazing, soldering, or the like. In this aspect of the invention, the structural element may be a purlin. In particular, 20 the structural element may be a purlin having a substantially C-shaped cross-section. EXAMPLE A number of comparative tests were performed in which the torsional strength of a conventional purlin (Purlin A) was compared to that of a-structural element according 25 to the present invention (Purlin B). Specifically, the torsional strength of the purlins were tested at different spans, and under different bridging conditions, that is with different numbers of bridging elements between two spaced apart purlins. The results of these tests are summarized 30 in Table 1. It will be clearly seen that the structural element of the present invention demonstrated WO 2011/063447 PCT/AU2010/001534 11 increased torsional strength across all spans tested and under all tested bridging conditions. Thus, it may be seen that the structural element of the present invention provides increased strength and stability during construction than conventional purlins.

WO 2011/063447 PCT/AU2O1O/001534 12 (N 4 00 0) 00. c 0 0 14 N' ( n E - - 00 m Wf) cc1 'i 0 _ N (Nt 0 N C) 0') f) 0 ~ _; 0 0 0c0 0 '.0 '~- ( N .0 r .5 0> 000 - m n '0 C)0 (N) 0n %-D. f) r -6 %6 (Nt It~ (N 14 C, 00 m * cq '~ ( -,t r 0) 6~ If) '. m )r -0 a, c- cq . 0* 6 0 C)C >0C C - C) C ' 0 C) (N C) C WO 2011/063447 PCT/AU2010/001534 13 The results set out in Table 1 are represented graphically in Figures 11-14. Brief Description of the Drawings. An embodiment of the invention will be described with reference to the following 5 drawings in which: Figure 1 illustrates an end view of a Z-shaped purlin according to an embodiment of the present invention; Figure 2 illustrates a perspective view of a Z-shaped purlin according to an embodiment of the present invention; lo Figure 3 illustrates an end view of a C-shaped purlin according to an embodiment of the present invention; Figure 4 illustrates a perspective view of a, C-shaped purlin according to an embodiment of the present invention; Figures 5-10 illustrate end- views of Z-shaped purlins according to alternative 15 embodiments of the present invention; and Figures 11-14 illustrate comparative graphs of span distance (mm) vs torsional strength (kN/m) for a prior art purlin and the structural element of. the present invention. 20 Detailed Description ofthe Drawings. It will be appreciated that the drawings have been provided for the purposes of illustrating preferred embodiments of the present invention and that the invention should not be considered to be limited solely to the features as shown in the drawings. 25 In Figures 1 and 2 there is illustration a Z-shaped purlin 10 according to an embodiment of the present invention. The purlin 10 comprises a web 11, a first flange 12 extending outwardly from a first end of the web 11 in a first direction, and a second flange 13 extending outwardly from a second end of the web 11 in a second direction. The first flange 12 and the second flange 13 extend outwardly from the web 30 11 substantially parallel to one another but in opposite directions. The width of the first flange 12 is less than the width of the second flange 13, thereby WO 2011/063447 PCT/AU2010/001534 14 facilitating easy stacking, storage, transportation and use of the purlins 10. The first flange 12 is provided with a lip 14 extending from an end of the first flange 12 furthest from the web 11. In the embodiment of the invention illustrated in Figures 5 1 and 2, the lip 14 is disposed at an included angle 01 of about 90* to the first flange 12. Similarly, the second flange 13 is provided with a lip 15 extending from an end of the second flange 13 furthest from the web 11. In the embodiment of the invention 10 illustrated in Figures 1 and 2, the lip 15 is disposed at an included angle 02 of between 90* and 1800 to the second flange 13. The web 11 is provided with a first channel 16 extending into the web 11 in a first direction, and a second channel 17 extending into the web 11 in a second direction 15 opposite to the first direction. The first channel 16 and second. channel 17 are substantially U-shaped channels in the web 11 that extend continuously along the entire length of the web 11. The first channel 16 and the second channel 17 are spaced apart from one another by a portion of the height of the web 11. The first channel 16 is located in a first portion of the web II between the middle 18 of the 20 height of the web 11 and the second flange 13, while the second channel 17 is located in a second portion of the web 11 between the middle 18 of the height of -the web 11 and the first flange 12. In Figures 3 and 4 there is illustration a C-shaped purlin 20 according to an 25 embodiment of the present invention, The purlin 20 comprises a web 21, a first flange 22 extending outwardly from a first end of the web 21 in a first direction, and a second flange 23 extending outwardly from a second end of the web 21 in substantially the same direction as the first flange 22, such that the first flange 22 and the second flange 23 extend substantially parallel to one another. 30 The first flange 22 is provided with a lip 24 extending from an end of the first flange 22 furthest from the web 21. In the embodiment of the invention illustrated in Figures WO 2011/063447 PCT/AU2010/001534 15 1 and 2, the lip 24 is disposed at an included angle 01 of about 900 to the first flange 22. Similarly, the second flange 23 is provided with a lip 25 extending from an end of the 5 second flange 23 furthest from the web 21. In the embodiment of the invention illustrated in Figures .1 and 2, the lip 25 is also disposed at an included angle 62 of about 900 to-the second flange 23.. The web 21 is provided with a first channel 26 extending into the web 21 in a first 10 direction, and a second channel 27 extending into the web 21 in the same direction as the first channel 26. The first channel 26 and second channel 27 are substantially U shaped channels in the web 21 that extend along the entire length of the web 21. The first channel 26 and the second channel 27 are spaced apart from one another by a portion of the height of the web 21. The first channel 26 is located in a first portion of 15 the web 21 between the middle 28 of the height of the web 21 and the second flange 23, while the second channel 27 is located in a second portion of the web 21 between the middle 29 of the height of the web 21 and the first flange 22. In Figure 5 there is shown a Z-shaped purlin 30 according to an alternative 20. embodiment of the present invention. In this Figure, the purlin 30 is very similar to that illustrated in Figures 1 and 2 with the exception that a first lip 31 is provided with a lip return 32 extending from the end of the lip 31 furthest from a first flange 33. Similarly a second lip 34 extends from a second flange 35, the second lip 34 being 25 curved along a portion of its length. In this embodiment, the inner radius of the curve 36 is located on the side of the lip 34 furthest from the web 37. In Figure 6, a similar purlin 30 to that illustrated in Figure 5 is shown, with the exception that the lip'return 32 extends from the first lip 31 at a more obtuse angle. 30 In Figure 7, a similar purlin 30 to that illustrated in Figure 6 is shown, with the exception that the lip 31 extending from the first flange 33 is curved along a portion of WO 2011/063447 PCT/AU2010/001534 16 its length. In this embodiment the inner radius of the curve 38 is located on the side of the lip 31 closest to the web 37. In Figure 8, there is shown a Z-shaped purlin 30 that is very similar to that shown in 5 Figure 6, with the exception that the second lip 34 is provided with a 'more pronounced curve therein. In Figure 9, a purlin 30 is illustrated in which the first lip 31 is provided with a lip return 32 that extends from the end of the lip 31 furthest from the first flange 33. The 1o lip return 32, while similar to that illustrated in Figures 5 and 6, extends at an even more obtuse angle from the lip 31 than the lip returns shown in Figures 5 and 6. In addition, the second lip 34 is a substantially linear lip, and is provided with a lip return 39 that extends at an acute angle to the lip 34, such that the lip return 39 15 extends in a direction generally towards the web. 37. The purlin 30 of Figure 10 is very similar to that shown in Figure 6, with the exception that the second lip 34 is substantially linear and is provided with a lip return 39. The lip return 39 extends from the second lip 34 in a direction that is substantially 20 parallel to the second flange 35. Further, the lip return 39 extends in a direction towards the web 37. In Figures 11-14 there is illustrated graphs of span distance (nun) vs torsional strength (kN/m) for a prior art purlin and the structural element of the present invention. In 25 Figure 11, a comparison between the torsional strength of the prior art purlin (represented by the grey column) and the torsional strength of a purlin of the present invention (represented by the white column) is shown wherein no pieces of bridging are located between spaced apart purlins. It will be noted in this Figure that, across all span distances, the torsional strength of the purlin of the present invention is greater 30 than that of the prior art purlin. In Figure 112 a comparison between the torsional strength of the prior art purlin WO 2011/063447 PCT/AU2010/001534 17 (represented by the grey column) and the torsional strength of a purlin of the present invention (represented by the white column) is shown wherein one piece of bridging is located between spaced apart purlins. It will be noted in this Figure that, across all span distances, the torsional strength of the purlin of the present invention is greater 5 than that of the prior art purlin. In Figure 13, a comparison between the torsional strength of the prior art purlin (represented by the grey column) and the torsional strength of a purlin of the present invention (represented by the white column) is shown wherein two pieces of bridging 10 are located between spaced apart purlins. It will be noted in this Figure that, across all span distances, the torsional strength of the purlin of the present invention is greater than that of the prior art purlin. In Figure 14, a comparison between the torsional strength of the prior art purlin 15 (represented by the grey column) and the torsional strength of a purlin of the present invention (represented by the white column) is shown wherein three pieces of bridging are located between spaced apart purlins. It will be noted in this Figure that, across all span distances, the torsional strength of the purlin of the present invention is greater than that of the prior art purlin. 20 The major advantage of the present invention is that, due to the position and orientation of the channels in the web, the load-bearing properties of the purlins are significantly improved over conventional purlin designs. In addition, the relatively simple cross-section of the purlins of the present invention ensure the cost of 25 materials, as well as the cost and complexity of manufacturing the purlins, are relatively low, Those skilled in the art will appreciate that the present invention may be susceptible to variations and modifications other than those specifically described. It will be 30. understood that the present invention encompasses all such variations and modifications that fall within its spirit and scope.

Claims

1. A structural element comprising a web, a pair of substantially oppositely directed flanges projecting outwardly from respective ends of the web, one of the pair of flanges being wider than the other of the pair of flanges, wherein the web comprises two or more 5 channels formed therein, each of the two or more channels being shaped so as to be symmetrical about a central axis of each channel, wherein at least two of the two or more channels project into the web in opposed orientation to one another, and wherein each of the pair of flanges is provided with a lip, the lip associated with a first of the pair of the flanges being disposed at an angle of approximately 900 to the first of the pair of flanges, 0 and the lip associated with a second of the pair of flanges being disposed at an angle of between 900 and 1800 to the second of the pair of flanges.

2. A structural element according to claim 1 wherein the pair of flanges are disposed substantially parallel to one another.

3. A structural element according to claim 1 or claim 2 wherein the pair of flanges are 5 disposed substantially at right-angles to the web.

4. A structural element according to any one of the preceding claims wherein at least one of the lips is bent or curved along at least a portion of its length.

5. A structural element according to any one of the preceding claims wherein at least one of the lips is provided with a lip return. 0

6. A structural element according to any one of the preceding claims wherein the two or more channels are spaced apart from one another by a portion of the height of the web.

7. A structural element according to any one of the preceding claims wherein the two or more channels are shaped so as to enhance one or more of the torsional, vertical and lateral strengths of the structural element. 25

8. A structural element according to any one of the preceding claims wherein the two or more channels are adapted to provide engagement enhancement for the use of one or more bridging members.

9. A structural element according to any one of the preceding claims wherein the at least two of the two or more channels are located an approximately equal distance from the 30 middle of the web as one another.

10. A structural element according to any one of the preceding claims wherein the structural element is a purlin.