BACKGROUND TO THE INVENTION Examples of a top-plate-hung bracket and stud bracket as currently used for building scaffolding are shown respectively in figures 1 and 1A. With the bracket of figure 1 the upper end of the vertical leg 1 is adapted to hang over the top plate 2 of a stud wall frame 2A and the lower end 3 bears against a spreader 4 which is secured across the outer faces of at least three studs including the one shown. A plank support member 5 extends horizontally out from the vertical leg and is braced by a diagonal strut 6. In use two or more such brackets are fitted along the frame of a building structure and planks are placed across them to produce a working platform in accordance with the relevant building codes including Australian Standard AS6001-1999. This bracket can be time consuming and difficult to set up as access over the top plate for both installation and removal is necessary. There are limitations on the vertical positioning of the bracket due to the use of the top plate for support. There is a substantial bending moment placed on the frame resulting from loading concentrations on the top plate and bottom spreader which causes the stud to twist and deform laterally. The bracket also puts a heavy reliance on welded joints at the upper end of the leg which must carry substantially the whole weight of the assembly. With the stud bracket of figure 1A the horizontal plank support 6A and strut 6B are attached directly to upper and lower spreaders 6C and 6D which extend across stud 6E and the adjacent studs. In this case the majority of the load is carried by the lower spreader which is only nailed or pinned in place. Also, the opposite directed point loads from the spreaders creates a pinching action on stud 6E which deforms it.

SUMMARY OF THE INVENTION It is therefore an object of this invention to ameliorate the aforementioned disadvantages and accordingly a bracket is disclosed for use in building construction, said bracket having a support leg with at least one attachment point for fixing onto a building frame component, said attachment point including a gripping member mounted on a pivotal linkage extending from said support leg whereby in use of the bracket to carry a working load said leg and gripping member can be located against opposite faces of the building component so that the working load generates a clamping force on said component between the gripping member and support leg which resists movement of said bracket.

Preferably but not essentially said gripping member comprises a friction member. It is further preferred that the friction member includes a plate with a fluted or grooved surface for enhanced grip on the building component.

It is further preferred that said linkage means comprise a U-shaped strap.

BRIEF DESCRIPTION OF THE DRAWINGS The currently preferred embodiments of this invention will now be described with reference to the attached drawings in which:- figure 2 is a schematic side elevation view of a scaffold bracket according to said invention, figure 2A is an end elevation view of the bracket of figure 2 along the direction of arrow A, figure 3 is a schematic side elevation view of the bracket of figure 2 with a stanchion socket fitted, figures 4 and 4A show a schematic side elevation view and perspective view of a second embodiment of the invention, figure 5 shows a schematic side elevation view of a third embodiment of the invention, figures 6 and 6A show a schematic side elevation view and perspective view of a fourth embodiment of the invention, and figures 7 and 7A show a schematic side elevation view and perspective view of a fifth embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to figures 2 and 2A there is shown a scaffold bracket of welded steel construction. In accordance with known design it comprises a vertical support leg 7, horizontal platform support or plank support 8 and diagonal brace 9. An end plate 10 is also provided at the outer end of the plank support which is of sufficient height to contain overlapping platform planks (not shown).

The cross-sectional dimensions of the members used to construct this bracket are in accordance with the relevant industry standards and would be known to a person skilled. in the art. The size of the bracket can be varied depending upon whether a single or multi-plank platform is used.

In accordance with this invention the vertical leg 7 of the bracket is fixed to a building frame stud 11 at upper and lower attachment points indicated generally as 12, 13. The upper point comprises a U-shaped strap 14 which is pivotally attached across its open end to the leg 7 by a bolt or pin 15. The opposite closed end 16 of the strap extends around the inner face 11A of the stud as well as a friction plate 17. The strap is also pivotally attached to the friction plate by a second bolt or pin 17A. A clearance space is provided between the end 16 of the strap and the plate 17 to allow for pivoting movement.

The lower attachment point 13 comprises a pair of flanges 18 which extend out from the leg 7 and closely straddle opposite sides 11B of the stud. In order to comply with industry standards spreaders 19, 20 are nailed in place adjacent the upper and lower attachment points to distribute or share the loading across adjacent studs (not shown) on each side. Spreader 19 is preferably located immediately above the friction plate. Spreader 20 is preferably located in a niche formed between a shoulder 21 extending down from the bottom of the leg 7 and the stud 11. In order to allow for vertical movement of the leg when the bracket is loaded a gap 21A of at least 20 mm between the spreader 20 and said leg 7 is preferred.

When the bracket is installed as shown and carries a load B from a working platform the surface resistance between the friction plate 17 and stud 11 together with the downward force on leg 7 generates a turning moment or couple 21 on the strap which clamps the stud 11 at this point and compresses it along a vertical plane between said plate 17 and leg 7. The magnitude of this clamping force on the stud is determined by the size of the platform load. The inventor has found that this novel clamping arrangement reduces twisting and lateral deformation of the stud as is encountered with prior art brackets. A scaffold bracket according to this invention thus provides a stronger and safer support for working platforms.

Although the plate 17 may be fluted or grooved to increase grip on the stud as described earlier the depth of these flutes or grooves is preferably chosen to limit excessive penetration or biting into the stud which could reduce strength. A clout 22 is also preferably driven through the strap and into the stud adjacent the friction plate to hold said plate at the position shown prior to loading.

This version of the bracket may also be fitted with a stanchion socket 23 as shown in figure 3 which contains the planks instead of the end plate 10. The socket is adapted to receive a guard-rail stanchion (not shown) for edge protection. Additional support for the guardrail against transverse loading can be obtained by fitting a gusset 23A between the socket 23 and horizontal member 8.

With the second to fifth embodiments of the invention shown respectively in figures 4 to 7A the main components that correspond in function to those of figures 2 and 2A are identified by the same numbers which however are primed ('), ("), ("') and ("") to distinguish them.

With reference to figures 4 and 4A the second embodiment of the invention comprises a floor edge rail bracket. There is a vertical stanchion 24 with guard-rails 25 which is attached to the support leg 7'by a pair of short horizontal bars 26 so that it is positioned up against the floor joist 26A and close to the edge of an elevated deck area 27. There is a single attachment point near the lower edge of the leg with pivoted strap 14'and friction plate 17'which in use of the bracket are secured close under the top plate 28 on a wall stud 11'. With this embodiment the angle A of the strap 14'should be not more than about 20 degrees to the horizontal.

The third embodiment of the bracket shown in figure 5 is a roof rail bracket and post assembly where the stanchion 29 is shown fitted into socket 23". The strut 9"in this case is located above the horizontal member 8". The lower attachment point also comprises a second U-shaped strap 31 which is bolted at 32 to the vertical leg 7"and is held in position against the stud 11"by a clout 33". This strap 31 operates in the same way as the flanges 18 of the first embodiment but has the advantage of being readily removable at the completion of brickwork. There is a reinforcing gusset 23" fitted between the socket 23"and strut 9".

The fourth embodiment of the bracket shown in figures 6 and 6A is another form of roof rail bracket and post assembly.

Here the support leg 7"'is adapted for fitting horizontally along the underside of a roof truss 34. There is a friction plate 17"'at one end of the support leg 7"' with a single pivotal strap 14"'which extends around the roof truss member 34 and is orientated to hold the other end of the leg 7"'hard against the inside of the top plate 35. The stanchion 36 with guard-rails 37 fits into a socket assembly 38 welded to the leg 7"'and is positioned over said top plate (figure 6). Alternatively the socket and stanchion can be mounted further out on an extension arm 39 (figure 6A).

The fifth embodiment of figures 7 and 7A is a roof rail gable bracket. In this case the horizontal support leg 7"" is adapted to fit along the top of a block 40 between adjacent roof trusses 40A and 40B. There is also a second U-shaped strap 41 and friction plate 42 located at the opposite end of the support leg 7"". These straps are angled in opposite directions as shown to lock the bracket against transverse movement along the block. The stanchion 43 with guard-rails 44 fits into a socket assembly 45 welded to the outboard end of the support leg 7""which extends out onto the gable outrigger 46.

It will thus be appreciated that this invention at least in the form of the embodiments disclosed provides a novel and improved form of scaffold bracket for working platforms and/or edge rail protection. Clearly however the examples described are only the currently preferred forms of the invention and a wide variety of modifications may be made which would be apparent to a person skilled in the art. For example the size and design of the bracket as well as the shape and configuration of the straps and friction member may be changed according to installation requirements.

Also, the contacting surface of the friction member could use means other than flutes or grooves such as a layer of rubber or other non-slip material to obtain a frictional grip without departing from the scope of the invention. The invention is further not limited to any specific material for constructing the bracket although a structural steel conforming to the requirements of the relevant industrial standards is preferred for the described embodiments.