AU2017201117A1 - Improved box beam and C-section structural member therefor - Google Patents

Abstract

The present invention relates to a C-section structural member and, in particular, to a structural member having a substantially C-shaped cross section adapted for engagement with a second identical and inverted C-shaped member to form a box beam having improved 5 bending strength characteristics. The resulting box beam is intended for particular use in verandahs and other roofing structures.

Description

2 2017201117 20 Feb 2017

Improved box beam and C-section structural member therefor FIELD OF THE INVENTION

The present invention relates to a C-section structural member and, in particular, to a structural member having a substantially C-shaped cross section 5 adapted for engagement with a second identical and inverted C-shaped member to form a box beam having improved bending strength characteristics. The resulting box beam is intended for particular use in verandahs and other roofing structures.

BACKGROUND OF THE INVENTION

Closed box beams are well known in the roofing industry and are typically 10 constructed as one-piece beams having a rectangular cross section, or two-piece beams comprising two engaging structural members which are appropriately shaped and sized to form a box shape. In the latter case, each structural member typically includes a central web with one or two parallel flanges extending perpendicularly from the upper and lower edges of the central web, with appropriately positioned 15 striations in the faces of each member for strength.

The present Applicant has recognised a number of deficiencies in existing box beams of this type. Most prominent of these deficiencies is the poor bending strength capacity of the beams resulting from non-uniformity in the beam thickness/layering at each of the four sides. An example of this is where a box beam has an upper side with 20 two layers of material (which may be the upper mating flanges of two structural members forming the beam), and only a single layer of material at the opposed lower side. Poor bending strength means that the beam is more prone to failure under certain conditions.

It is therefore an object of the present invention to overcome some of the 25 aforementioned problems or at least provide the public with a useful alternative.

SUMMARY OF THE INVENTION

Therefore in one form of the invention there is proposed an elongate structural member including: a substantially upright web portion; 3 2017201117 20 Feb 2017 two flanges projecting outwardly from the ends of the web portion in the same direction to thereby form a C-section structure; and wherein each of said flanges include longitudinal striations extending along their length configured such that when two inverted structural members engage, a box 5 beam is formed having two flanges at upper and lower ends thereof with mating striations, increasing the bending strength of the beam.

In having two mating flange portions at both the upper and lower ends of the beam, the bending strength capacity of the beam is increased. Also, the striations appear similar to the striations typically found in wood, and so the resulting beam is 10 also visually attractive.

Preferably when two inverted structural members engage, a lower flange of a first structural member receives a lower flange of the second structural member, and the upper flange of the second structural member received the upper flange of the first structural member. 15 In preference each flange terminates in a rounded lip extending substantially perpendicularly towards the other flange, whereby when two inverted structural members engage, the lips engage rounded comers of the structural members.

Preferably said web portion includes at least one stiffening recess extending at least partially along its length. 20 In preference said web portion includes two stiffening recesses adjacent each flange, each recess being equidistant from said flanges.

Preferably said web portion includes a central stiffening swage extending along its length.

Advantageously said structural member is an extruded length of cold roll 25 formed steel.

In a further form of the invention there is proposed a box beam comprising two mating structural members as defined above. 4 2017201117 20 Feb 2017

In a still farther form of the invention there is proposed a box beam including: a first substantially C-shaped structural member including an upright web portion defining a first vertical side of said beam, and two flanges projecting outwardly from the ends of the web portion in the same direction, each of said flanges including 5 longitudinal striations extending along their length; a second inverted C-shaped structural member including an upright web portion defining a second vertical side of said beam, and two flanges projecting outwardly from the ends of the web portion in the same direction, each of said flanges including longitudinal striations extending along their length; and 10 wherein the lower flange of the second structural member is received in the lower flange of the first structural member and the upper flange of the first structural member is received in the upper flange of the second structural member, whereby each upper and lower mating flange pair defines the respective upper and lower horizontal sides of said beam. 15 In preference each flange terminates in a rounded lip extending substantially perpendicularly towards the opposed flange of the same structural member, whereby when two inverted structural members engage, the lips engage rounded comers of the structural members.

Preferably said web portion of each structural member includes at least one 20 stiffening recess extending at least partially along its length.

In preference said web portion of each structural member includes two stiffening recesses adjacent each flange, each recesses being equidistant from said flanges.

Preferably said web portion of each structural member includes a central 25 stiffening swage extending along its length.

In preference said structural members are crimped together along their length.

Advantageously each structural member is an extruded length of cold roll formed steel.

BRIEF DESCRIPTION OF THE DRAWINGS 5 2017201117 20 Feb 2017

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings:

Figure 1 illustrates a cutaway perspective view of four C-section structural members of different heights in accordance with the present invention; 10

Figure 2 illustrates a cross-sectional view of the four C-section structural members of Figure 1 engaging four opposed identical C-section structural members to form a box beam in accordance with the present invention;

Figure 3 illustrates a cross-sectional view of four box beams constructed in accordance with the present invention;

Figure 4 illustrates a cutaway perspective view of the four box beams of Figure 3; and

Figure 5 illustrates a verandah structure including a plurality of interconnecting cross beams of the present invention, and an enlarged perspective view of the connection between two aligned box beams above a vertical supporting beam.

20 DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. 25 Figure 1 shows four structural members 10a, 10b, 10c and lOd in accordance with the present invention, each member being configured similarly but differing in height. Figures 2-4 illustrate the same four structural members engaging four identical and inverted structural members to thereby form box beams 11a, lib, 11c and lid respectively. 6 2017201117 20 Feb 2017

Each structural member 10 is preferably cold formed from roll reduced steel to form a C shape. Each of the differently sized structural members 10a, 10b, 10c and lOd shares certain common features and so these will only be described once with reference to member 10a and referenced using like numerals. 5 The structural member 10a includes a substantially central web 12 with two parallel flanges or flange portions 14 and 16 extending in the same direction to form a substantially C-shaped stucture. The flanges 14 and 16 extend outwardly and substantially perpendicularly from the ends of the central web 12. Flange 16 is adapted to be slightly narrower than flange 14 to thereby accommodate flange 14 10 when two members 10a are engaged to form a box beam 11 a as shown in Figure 2.

In addition, the upper and lower flanges 14 and 16 of the structural member 10a terminate in a lip 18 and 20 respectively, extending from the ends of each flange. In the embodiment shown, the upper and lower lips 18 and 20 project substantially perpendicularly from their respective flange portions in a curved configuration. The 15 curve is shaped correspondingly with the rounded comers at the opposed junction between the central web and the flange such that when one member is inverted and nestled inside the other, the respective comers and lips abut in a snug fit relationship as shown in Figures 3-4. The lips 18 and 20 serve to provide additional strength to the structural member. 20 The member 10a includes a number of further strengthening means. For example, in order to strengthen the central web and allow for long structural members, there are two recesses 26 present at an upper and lower position adjacent the rounded comers forming the junctions between the central web and each flange, and also a central swage 27 therebetween. Structural member 1 Od does not include the central 25 swage 27 because of its shorter height, and it is to be understood that the present invention is not intended to be limited to use of stiffening means in the central web portion. The upper and lower central web recesses 26 are positioned so that they are equidistant from the respective flange portions. A plurality of longitudinally extending stiffening striations 28 are also located 30 on the upper and lower flange components 14 and 16 respectively. These stiffening striations 28 provide strength to the flange portions. The striations on the top and 7 2017201117 20 Feb 2017 lower flange are positioned such that when a second member engages the first member to create a box beam, the striations of the two abutting flanges on the top and bottom of the box beam form a snug fit. Figures 3-4 illustrate clearly the cross-section of two engaging structural members forming a box beam whereby the lower flange of 5 the second member is nestled inside the lower flange of the first member, and the upper flange of the first member is nestled inside the upper flange of the second member. The result is a box beam having a single layer of material on the two vertical sides, and a double layer of material on the top and bottom sides including mating striations. 10 When two structural members engage they need to be locked together and, in preference, the engaging members are crimped at suitable intervals along the length of the beams. The beams are typically some 2-3 metres in length for standard applications, but they could well be manufactured longer or shorter depending on specific job specifications. 15 It has been found through testing that the overlapping flange configuration on both the upper and lower sides of the box beam provides superior bending strength characteristics in the box beam. Such beams are also visually appealing in that the striations, winch provide obvious strength advantages, appear similar to the striations typically found in wood. Thus a roof structure which utilises the box beams of the 20 present invention can be more aesthetically pleasing than hitherto known box beams in that they resemble wooden beams. Figure 5 illustrates an example of one application of the present invention being a verandah 30 including a web of interlocking box beams.

The skilled addressee should now appreciate the benefits of the present 25 invention. The C-shaped structural members embodied herein are configured so that they are structurally robust by having lip returns and longitudinal striations, and box beams formed by two such structural members have been found to provide significant improvements over conventional box beams of the type in terms of bending strength capacity and appearance. 30 Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown 2017201117 20 Feb 2017 8 and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent 5 devices and apparatus.

Claims (15)

1. An elongate structural member including: a substantially upright web portion; two flanges projecting outwardly from the ends of the web portion in the same direction to thereby form a C-section structure; and wherein each of said flanges include longitudinal striations extending along their length configured such that when two inverted structural members engage, a box beam is formed having two flanges at upper and lower ends thereof with mating striations, thereby increasing the bending strength of the beam.

2. An elongate structural member according to claim 1 wherein when two inverted structural members engage, a lower flange of a first structural member receives a lower flange of the second structural member, and the upper flange of the second structural member receives the upper flange of the first structural member.

3. An elongate structural member according to claim 1 or claim 2 wherein each flange terminates in a rounded lip extending substantially perpendicularly towards the other flange, whereby when two inverted structural members engage, the lips engage rounded comers of the structural members.

4. An elongate structural member according to any one of claims 1 -3 wherein said web portion includes at least one stiffening recess extending at least partially along its length.

5. An elongate structural member according to claim 4 wherein said web portion includes two stiffening recesses adjacent each flange, each recess being equidistant from said flanges.

6. An elongate structural member according to claim 4 or claim 5 wherein said web portion includes a central stiffening swage extending along its length.

7. An elongate structural member according to any one of the above claims wherein said structural member is an extruded length of cold roll formed steel.

8. A box beam comprising two mating inverted structural members as defined in any one of claims 1-7.

9. A box beam including: a first substantially C-shaped structural member including an upright web portion defining a first vertical side of said beam, and two flanges projecting outwardly from the ends of the web portion in the same direction, each of said flanges including longitudinal striations extending along their length; a second inverted C-shaped structural member including an upright web portion defining a second vertical side of said beam, and two flanges projecting outwardly from the ends of the web portion in the same direction, each of said flanges including longitudinal striations extending along their length; and wherein the lower flange of the second structural member is received in the lower flange of the first structural member and the upper flange of the first structural member is received in the upper flange of the second structural member, whereby each upper and lower mating flange pair defines the respective upper and lower horizontal sides of said beam.

10. A box beam according to claim 9 wherein each flange terminates in a rounded lip extending substantially perpendicularly towards the opposed flange of the same structural member, whereby when two inverted structural members engage, the lips engage rounded comers of the structural members.

11. A box beam according to claim 9 or claim 10 wherein said web portion of each structural member includes at least one stiffening recess extending at least partially along its length.

12. A box beam according to claim 11 wherein said web portion of each structural member includes two stiffening recesses adjacent each flange, each recesses being equidistant from said flanges.

13. A box beam according to claim 11 or claim 12 wherein said web portion of each structural member includes a central stiffening swage extending along its length.

14, A box beam according to any one of claims 9-13 wherein said structural members forming said box beam are crimped together at spaced apart distanced along their length.

15. A box beam according to any one of claims 9-14 wherein each structural member is an extruded length of cold roll formed steel.