AU2008205424A1 - Structural systems and elements therefor - Google Patents

Description

00 P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "STRUCTURAL SYSTEMS AND ELEMENTS THEREFOR" The following statement is a full description of this invention, including the best method of performing it known to us: 00 1

STITLE

STRUCTURAL SYSTEM AND ELEMENTS THEREFOR FIELD OF THE INVENTION This invention relates to an improved structural system and elements therefor.

The invention relates particularly although not exclusively to 00 o improvements in structural beams and structural beams and structures incorporating same.

BACKGROUND OF THE INVENTION Generally speaking, most building structures are designed for construction with a standardised range of commonly available materials including roof and wall cladding sheets, tubular steel structural members, hot rolled steel beams (RSJ's) such as universal beams, and cold rolled steel beams including C and Z section purlins and girts.

Although some structural members such as portal frames, roof trusses and the like are individually fabricated for a specific application, "one-off' or specially fabricated structural members are avoided where possible due to very high costs. Often it is more economical to use a structural beam with a capacity far in excess of its design load merely to avoid the need for a purpose built structural beam and the costs associated therewith.

As most of the standard cold formed structural sections such as C and Z section members are supplied with connection apertures punched at predetermined spacings, the use of high capacity beams in conjunction with standard beams can give rise to problems in securing mismatched beams 00 2 C together or otherwise lead to design constraints in a building structure. For example, the practice of using hot rolled universal beams as floor bearers with C-section purlins as floor joists on top gives rise to a floor structure which occupies a spatial volume much greater than might otherwise be c 5 necessary as typically the joists are supported on, and transversely to, the bearers.

00 oo Accordingly it is an aim of the present invention to overcome or c ameliorate at least some of the problems associated with prior art structural members and structural systems incorporating same.

SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a structural member having a variable load capacity, said structural member comprising:at least one generally elongate metal beam having a generally Cshaped cross-section with spaced flange members separated by an intermediate web member, said flange members extending in substantially parallel planes in the same direction orthogonal to a plane of said web, said web including a plurality of apertures therein at predetermined spacings; and, at least one elongate stiffening member removably securable against said intermediate web by fasteners extending through aligned apertures in said strip and said intermediate web.

Suitably said stiffening member is securable against said intermediate web between said spaced flange members.

If required said stiffening member is securable against said intermediate web opposite said flange members.

00 3

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N The structural member may comprise a pair of C shaped metal beams secured by fasteners extending through aligned apertures in respective intermediate webs and said at least one metal strip.

Preferably said at least one stiffening member is located between said pair of C shaped metal beams.

OIf required a stiffening member may be secured against a respective 00 Sweb of each C-shaped metal beam between respective flanges thereof.

The stiffening member may comprise a flat or profiled strip of metal, plywood, timber or a composite material such as a fibre reinforced plastics material or laminates thereof.

The at least one generally C shaped elongate metal beam may include an inwardly facing stiffening rib extending along respective distal edges of said flanges.

Suitably said flanges include apertures at predetermined spacings.

The reinforcing ribs may be continuous or alternatively the ribs may be discontinuous defining notched apertures at predetermined spacings.

According to another aspect of the invention there is provided a structural frame comprising a pair of spaced generally C shaped crosssection bearer members, each bearer member having spaced flange members separated by an intermediate web member, said spaced bearer members defining channel-like members having respective channel-like recesses facing each other; and, a plurality of spaced joist members of generally C shaped crosssection each having spaced flange members separated by an intermediate 00 4

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N web member extending between said bearer members, respective free ends of said joist members being secured to respective bearer members between _spaced flange members of said bearer members.

Suitably said joist members are secured to said bearer members by fasteners extending through aligned apertures in respective flange members Oof said joist members and said bearer members.

o00 aIf required one or more of said bearer members may include one or more elongate stiffening members secured to a respective intermediate web of said one or more bearer members.

Additionally or alternatively, one or more of said joist members may include one or more elongate stiffening members secured to a respective intermediate web of said one or more joist members.

According to yet another aspect of the invention there is provided a method of erecting a suspended structural frame assembly comprising the steps of:mounting on respective supports a pair of spaced bearer members of generally C shaped cross-section, each bearer member having spaced flange members separated by an intermediate web member, said spaced bearer members defining channel like members having respective channel like recesses facing each other; and, securing between said bearer members a plurality of spaced joist members of generally C-shaped cross-section, each joist member having spaced flange members separated by an intermediate web member, the free ends of said joist members being located within respective channel-like 00

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Nrecesses of said bearer members and secured thereto by fasteners extending through aligned apertures in flange members of said bearer members and said joist members.

If required, at least one of said bearer members may be mounted on spaced upright walls.

OAlternatively at least one of said bearer members may be mounted on 00 0 spaced upright load bearing members.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the various aspects of the invention may be more readily understood and put into practical effect, reference will now be made to preferred embodiments illustrated in the accompanying drawings in which:- FIG. 1 shows a cross-sectional view of one embodiment of the invention.; FIG. 2 shows an alternative configuration of the embodiment of FIG. 1.; FIG. 3 shows yet another configuration; FIG. 4 shows a cross-sectional view of an alternative embodiment; FIG. 5 shows a different configuration of the embodiment of FIG. 4; FIG. 6 shows a partial view of a junction of a bearer member and a joist member of a structural frame according to the invention; FIG. 7 shows a mezzanine floor construction according to the invention; FIG. 8 shows an alternative embodiment of the arrangement in FIG. 7; For the sake of simplicity like reference numerals are employed for 00 6 N like features where appropriate.

DETAILED DESCRIPTION OF THE DRAWINGS In FIG. 1 a structural beam 1 comprises a standard C-section purlin 2 having flanges 3 separated by an intermediate web 4.

Located within the channel-like recess 5 between flanges 3 is a metal strip 6 secured to web 4 by fasteners 7 such as a nut and bolt assembly 00 oo extending through aligned apertures 8, 9 in web 4 and metal strip 6.

Fastening apertures 8, 9 are spaced both transversely of the width of web 4 and longitudinally of the purlin/metal strip assembly as required depending upon the load bearing requirements for the structural member 1.

As will be readily apparent to a person skilled in the art, the rigid bolted attachment of metal strip 6 to web 4 along the length of the purlin substantially increases the load bearing capacity of the purlin without increasing its depth and width as might otherwise be required. Typically, purlins 2 are manufactured with punched fastener apertures 8 at spaced intervals along the length thereof and spaced apertures may also be punched in flanges 3 as required. Metal strip 6 has punched fastener apertures 9 with the spacings corresponding to the web 4 of the purlin to enable ready attachment therebetween by fasteners extending between aligned apertures.

The metal strip 6 typically will have a thickness substantially the same as that of the web 4 although if required it may have a greater or lesser thickness. Alternatively, the metal strip 6 may be replaced with a flat or contoured strip of timber, plywood, a composite structure formed from glass 00 7 N reinforced plastics or the like or a lamination of these materials where mass may be a consideration.

As shown in FIG. 2 metal strip 6 may be attached to web 4 on an outer face of the web.

Depending upon the load bearing capacity required of purlin 2, two or more metal strips may be secured to web 4 as shown in FIG. 3. The metal oo 00 0strips 6 may be located on both sides of web 4 as shown or they may be located against either an inner or outer face of web 4.

FIG. 4 shows an alternative embodiment wherein the load capacity of structural beam 1 is increased by fastening a pair of purlins 2, 2a in back to back juxtaposition with metal strip 6 sandwiched therebetween.

FIG. 5 shows a variation of the configuration of FIG. 4 in that a pair of metal strips 6 are located within respective recesses 5, 5a of purlins 2, 2a.

FIG. 6 shows a partial view of a junction of members of a structural frame according to another aspect of the invention.

A structural frame (not shown) comprises a pair of spaced rolled steel bearers 10 having planar flanges 11 separated by an intermediate web 12 located at respective ends of spaced rolled steel joists 13 having a generally C-shaped cross-section as shown in FIGS. 1 to 5. Joists 13 comprise flanges 14 having a reinforcing rib or "toe" formation 15 extending along the outer edges of flanges 14, which flanges 14 are separated by an intermediate web 16.

In certain applications, it may be desirable to secure plywood or particle board flooring directly on to the upper surface of the structures 00 8 C formed in accordance with the invention. To avoid the necessity of having to form recesses in the rear face of the flooring panels the region around the bolt apertures in the upper surface of the bearer members and corresponding apertures of the joists may be formed as dished recesses to accommodate the head of the fixing bolt.

FIG. 7 shows a structure embodying a number of aspects according to 00 oo the invention.

SIn the construction of a mezzanine a floor bearer member 20a of a generally C-shaped cross-section is bolted to a wall 21 by anchor bolts 22 or the like. A pair of bearer members 20b, 20c in back to back relationship with a metal strip 23 sandwiched therebetween is supported at one end by angle brackets 24 bolted to wall 25 and at an opposite end by a tubular steel column 26 having bearer pads 27 at both ends for securing by bolts to the beam formed by bearers 20b, 20c and to the floor 28.

A further bearer member 20d is secured at one end by angle brackets 24 to wall 25 and at an opposite end by column 26. A metal strip (not shown) is secured within the channel like recess of bearer member 20d by spaced bolts 29 to increase the load bearing capacity of bearer Extending between bearer members 20a and 20b as well as 20c and 20d are joists 30 of generally C-shaped cross-section having respective ends thereof located within the channel like recesses of bearer members 20c and 20d and secured therein by fasteners such as bolts 31 extending through aligned apertures in the flange members of the bearer members and the joist members.

00 9 C FIG. 8 shows an alternative configuration to that of FIG. 7.

In FIG. 8 a bearer member 20 is secured to wall 25 by anchor bolts 22 or the like. An end joist 30 is bolted to wall 21 also by anchor bolts 22 with one end located within the channel like recesses of bearer 20 secured to wall 0A load bearing beam 32 in the form of a bearer member 20 has 00 o located within its channel like recess a metal strip (not shown) secured to the cweb member 33 of bearer 20 by bolts 34 extending through aligned apertures in the metal strip and web 33. Beam 32 is supported at one end by being located over a free end of end joist 30 bolted to wall 21. If required, an angle bracket (not shown) may extend between respective webs of bearer and end joist 30. The free end of beam 32 is supported by an upright tubular steel column 26.

A plurality of spaced joist members 30 extend between bearer members 20 with respective free ends of the joist members being secured within the channel-like recesses of bearers 20 by bolts 35 extending through aligned apertures in respective bearer and joist flanges.

It readily will be apparent to a person skilled in the art that load bearing structural frames according to the invention such as the mezzanine floor frames shown in FIGS. 7 and 8 are both simple and rapid to erect and easily can be tailored to meet design load requirements without using overrated structural members. Moreover, as shown, the structures are compact in that the bearers and joists are located in the same plane rather than one upon the other as with prior art frame structures.

00 C By reinforcing the web of a bearer member with a metal strip as described and, in addition supporting the bearer flanges at spaced intervals by bolted joints with the joist flanges, the load capacity of the simple Csection bearers is greatly enhanced by supporting the flanges in c 5 compression against buckling.

Any form of fastener may be employed to secure the bearers and o 00 0joists together. Such fasteners may be of the self piercing type such as "TEK" (trade mark) self drilling, self tapping screws or the like. Preferably however the bearers and joists are punched with bolting apertures at predetermined spacings during a manufacturing process to facilitate a simple bolted assembly requiring unskilled or semi-skilled labour only.

The system according to the invention effectively means that with the addition of a small range of punched steel strips, an existing range of steel purlins or the like can be adapted for a wider range of load bearing capabilities and applications while optimising the steel content of structures.

With appropriate connectors or other fittings, the various aspects of the invention may be applied to a wide variety of building structures including floor, wall and roof frames.

Throughout this specification and claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers.

Claims (22)

1. A structural member having a variable load capacity, said structural member comprising:- at least one generally elongate metal beam having a generally C- c 5 shaped cross-section with spaced flange members separated by an 0intermediate web member, said flange members extending in substantially (N 00 oo 0parallel planes in the same direction orthogonal to a plane of said web, said web including a plurality of apertures therein at predetermined spacings; and, at least one elongate stiffening member removably securable against said intermediate web by fasteners extending through aligned apertures in said strip and said intermediate web.

2. A member as claimed in claim 1 wherein said stiffening member is securable against said intermediate web between said spaced flange members.

3. A member as claimed in claim 1 wherein said stiffening member is securable against said intermediate web opposite said flange members.

4. A member as claimed in any one of claims 1 to 3 comprising a pair of C-shaped metal beams secured by fasteners extending through aligned apertures in respective intermediate webs and said at least one metal strip.

5. A member as claimed in claim 4 wherein said at least one stiffening member is located between said pair of C shaped metal beams.

6. A member as claimed in claim 4 wherein a stiffening member is secured against a respective web of one or both C-shaped metal beam between respective flanges thereof. 00 12 C

7. A member as claimed in any preceding claim wherein the stiffening member comprises a flat or profiled strip of metal, plywood, timber or a composite material such as a fibre reinforced plastics material or laminates thereof.

8. A member as claimed in any preceding claim wherein at least one generally C-shaped elongate metal beam includes an inwardly facing oo 00 0stiffening rib extending along respective distal edges of said flanges.

9. A member as claimed in any preceding claim wherein said flanges include apertures at predetermined spacings.

10. A member as claimed in claim 8 wherein said reinforcing ribs are discontinuous defining notched apertures at predetermined spacings.

11. A structural frame comprising a pair of spaced generally C shaped cross-section bearer members, each bearer member having spaced flange members separated by an intermediate web member, said spaced bearer members defining channel-like members having respective channel-like recesses facing each other; and, a plurality of spaced joist members of generally C shaped cross- section each having spaced flange members separated by an intermediate web member extending between said bearer members, respective free ends of said joist members being secured to respective bearer members between spaced flange members of said bearer members.

12. A structural frame as claimed in claim 11 wherein said joist members are secured to said bearer members by fasteners extending through aligned apertures in respective flange members of said joist members and said 00 13 N bearer members.

13. A structural frame as claimed in claim 11 or claim 12 wherein one or more of said bearer members includes one or more elongate stiffening members secured to a respective intermediate web of said one or more bearer members.

14. A structural frame according to any one of claims 11 to 13 wherein oo (N 00 one or more of said joist members includes one or more elongate stiffening Smembers secured to a respective intermediate web of said one or more joist members.

15. A method of erecting a suspended structural frame assembly comprising the steps of:- mounting on respective supports a pair of spaced bearer members of generally C shaped cross-section, each bearer member having spaced flange members separated by an intermediate web member, said spaced bearer members defining channel like members having respective channel like recesses facing each other; and, securing between said bearer members a plurality of spaced joist members of generally C shaped cross-section, each joist member having spaced flange members separated by an intermediate web member, the free ends of said joist members being located within respective channel-like recesses of said bearer members and secured thereto by fasteners extending through aligned apertures in flange members of said bearer members and said joist members.

16. A method as claimed in claim 15 wherein at least one of said bearer 00 14 C members is mounted on spaced upright walls.

17. A method as claimed in claim 15 wherein at least one of said bearer members is mounted on spaced upright load bearing members.

18. A method as claimed in any one of claims 15 to 17 wherein one or c 5 more stiffening members are secured to a respective intermediate web of 0said one or more bearer members. 00 o

19. A method as claimed in any one of claims 15 to 18 wherein one or more stiffening members are secured to a respective intermediate web of said one or more joist members.

20. A structural member substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.

21. A structural frame substantially as hereinbefore described with reference to the accompanying drawings.

22. A method of erecting a structural frame substantially as hereinbefore described with reference to the accompanying drawings.