AU675814B2

AU675814B2 - Improvements in wall frames

Info

Publication number: AU675814B2
Application number: AU56498/94A
Authority: AU
Inventors: Campbell John Seccombe
Original assignee: BHP Steel JLA Pty Ltd
Current assignee: BHP Steel JLA Pty Ltd
Priority date: 1993-03-02
Filing date: 1994-03-01
Publication date: 1997-02-20
Anticipated expiration: 2014-03-01
Also published as: AU5649894A

Description

II_ P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "IMPROVEMENTS IN WALL FRAMES" The following statement is a full description of this invention, lo including the best method of performing it known to the Applicant:- This invention relates to wall frames for buildings, in particular those in which the elongate structural members of the frame are cold rolled, pressed or folded from relatively light gauge sheet metal, for 15 example steel coated with a zinc or an aluminium/zinc alloy coating.

Conventionally, such frames comprise a bottom plate, a top plate, and a plurality of spaced apart studs extending from one plate to the other. U 'ally the plates and studs are essentially channels, comprising a web and two flanges. The ends of the studs are inserted into the trough of each plate (the stud flanges being a neat fit between the plate flanges) and are fixed to the plates by fastening the overlapping flange portions to each other, for example by screws or rivets extending through those overlapping flange portions.

2 As is well known, buildings with walls comprising such frames clad on at least one side by cladding sheets, find widespread use as dwellings, sheds, small commercial buildings and the like. To render such lic',tweight buildings suitable for use in cyclone prone or other high wind areas, it is necessary for the walls to be firmly anchored and to be able to withstand the considerable uplift forces that may be generated by high speed winds blowing across the roof.

Normally the wall frame is anchored to a brick or masonry foundation, a concrete floor slab or other underlying base, by hold down lo fasteners extending through the web of the bottom plate into that base.

Thus the uplift forces tensioning the studs are transmitted from the stud flanges to the bottom plate flanges, to the bottom plate web and then, by the hold down fasteners, to the base. This has required, in studs and plates conforming generally to established industry standards insofar as their major dimensions are concerned, a metal thickness of 1.2 mm or thereabouts to ensure the integrity of the plate and the studs, in particular to prevent tearing of the overlapping flanges of the stud and plate or the plate web where those parts are pierced by fasteners.

In this field there is a good deal of competition, and every effort is 20 made to reduce the material content, and thus the cost, of the frames to the minimum consistent with the required durability of the building. An object of the present invention is to enable such a reduction, by comparison with prior known constructions, to be made.

It is also desirable to reduce costs by simplifying and reducing the on-site activity involved in assembling and installing the wall frames.

3 Hitherto there have been two commonly used modes of anchoring the wall frames. In one instance, bolts are positioned before the concrete base is poured so that they protrude from the set concrete along the line of the bottom plate. Those bolts are subsequently used as the frame's hold down fasteners. This involves positioning and holding the bolts during the concrete pour and thereafter marking and drilling the web of the bottom plate with appropriately placed bolt holes.

The second operation is required because it is difficult to position the bolts with sufficient accuracy to enable pre-punched bolt holes to be lo provided in the bottom plate.

In the other instance the concrete is drilled to receive an expanding bolt after the wall frame has been temporarily put in place.

This is less objectionable, but, at least when conventional expanding bolts are used, suffers to some extent because of the cost of such bolts and because of the need to drill a relatively a large diameter hole, which S* is more difficult and time consuming than is the drilling of a smaller diameter hole.

In both instances the web of the bottom plate is called upon to withstand the uplift force between itself and the hold down bolt, and this usually requires a reinforcing plate to be provided between that web and the nut of the hold down bolt, so as to spread the load over a large area of the web.

The present invention provides an alternative which allows bottom plates and studs of thinner material to be used, and removes the need for a plate web reinforcing plate.

4 The invention achieves those objects primarily by providing a plurality of hold down brackets respectively attachable to the webs of at least some of the wall studs of a wall frame, and each adapted to be engaged by a hold down fastener extending from the bracket through the web of the frame's bottom plate into the base, whereby the plate is held down, the stud u nd bottom plate are held together without the need for other fasteners, and uplift tensions in the stud are transmitted directly from its web through the bracket and hold down fastener to the underlying base.

o 10 In one aspect the invention consists in a wall frame comprising a sheet metal bottom plate having a plate web, a plurality of spaced apart, sheet metal studs, each having a stud web, extending upwardly from the plate, and, in respect of each of at least some of the studs, a hold down bracket secured to said each stud's web and a hold down fastener 15 extending from the bracket through the web of the bottom plate into an *a• S.underlying base wherein the hold down bracket is L shaped and comprises a lug pierced by the hold down fastener and a flange secured to said each stud's web, and wherein the bracket is secured to said each stud's web by virtue of a hook shaped end part of the flange being hooked over an edge of a hole in the stud web, whereby said each stud is secured to the plate and the frame is anchored to the base.

In preferred embodiments of the invention, the hold down bracket is L shaped and comprises a lug adapted to be pierced by a hold down

I.

fastener and a flange adapted to be secured to the stud web. The bracket flange may be so adapted by having a hooked shaped free end, and the bracket is secured to the stud web by hooking the free end of the flange over an edge of a hole in the stud web.

For preference the hole in the stud web is also useable as a passage for power or communication cables or the like, such as are conventionally provided in wall frame members for reticulation purposes.

In that event the hole may be circular and the hooked end of the bracket flange is saddle shaped so as to conform to an arc of the hole's lo circumference. This ensures that the reaction force of the bracket, counteracting the uplift forces in the stud, is spread over a considerable line of contact with the web and is thus lessened in intensity.

Therefore, the invention further consists in an L shaped hold down bracket comprising a lug and a flange perpendicular thereto, wherein the 15 flange has a hooked and saddle shaped free end.

By way of example, an embodiment of the above described invention is described in more detail hereinafter with reference to the :**":accompanying drawings.

Figure 1 is a perspective view of a hold down bracket according to the invention, shown as in place in relation to portions of a bottom plate and stud of a wall frame according to the invention, the stud and bottom plate portions being shown in ghost.

Figure 2 is a front elevation of the bracket of figure 1.

Figure 3 is a side elevation of the bracket of figure 1.

6 Figure 4 is a plan view of the bracket of figure 1.

Figure 1 shows a bottom wall plate 5, being a length of a sheet metal channel, comprising a plate web 6 and plate flanges 7. It may rest with the underside of the plate web 6 lying upon a concrete floor slab or other substantially immovable supporting base.

A wall stud 8, being a length of a generally channel shaped, sheet metal section, comprises a stud web 9 and stud flanges The stud 8 is secured to the base by a hold down bracket 11 and hold down fastener (not shown), and, as a consequence the plate 5 is 10o fixed to the stud 8 and the frame as a whole is anchored to the base.

o:o• The hold down bracket 11 comprises a hold down lug 12 and a fixing flange 13. The bracket is of robust construction, being formed from steel sheet somewhat thicker than that from which the stud and plate are made. The junction of the lug 12 and flange 13 is rigidified by gussets 14.

The free end of the flange 13 is retul. -and shaped to form a saddle shaped hook 15, and is thus adapted to engage snugly over an arcuate length of the edge of a circular hole 16 in the stud web 9. That hole may be pre-punched in the web during the forming of the stud before its delivery to the building site.

The bracket lug 12, as supplied for use, preferably has a relatively small guide hole 17 piercing it. To erect the frame, the bracket may be hooked in place over the edge of hole 16. Then a masonry drill may be centred on the hole 17, and operated to drive it through the web 6, which may be only 0.6 mm thick or thereabouts, to form a fastener clearance hole 18 extending through the lug 12, the web 6 and into the concrete base. This is a simple operation that overcomes any problem of alignment between the wall plate and the hold down fasteners. An appropriate hold down fastener is then inserted into the drilled hole 18 and tightened up.

a

Claims

1. A wall frame comprising a sheet metal bottom plate having a plate web, a plurality of spaced apart, sheet metal studs, each having a stud web, extending upwardly from the plate, and, in respect of each of at least some of the studs, a hold down bracket secured to said each stud's web and a hold down fastener extending from the bracket through the web of the bottom plate into an underlying base, wherein the hold down bracket is L shaped and comprises a lug pierced by the hold down io fastener and a flange secured to said each stud's web, and wherein the bracket is secured to said each stud's web by virtue of a hook shaped end part of the flange being hooked over an edge of a hole in the stud web, whereby said each stud is secured to the plate and the frame is anchored to the base. o 15

2. A wall frame according to claim 1 wherein said end part of .0 the flange is saddle shaped and the hole in the stud web is circular. o• *0000

3. A wall frame as claimed in claim 1, wherein said flange of said bracket is perpendicular to said lug.

4. A wall frame according to claim 1, wherein said bracket further comprising at least one stiffening gusset extending from the lug to the flange. 9 A wall frame substantially as described herein with reference to figure 1 of the accompanying drawings. Applicant BHP STEEL (JLA) PTY LTD Date 21 November 1996 Attorney ROBERT G. SHELSTON F.I.P.A.A. of CARTER SMITH BEADLE S. *9 S S ABSTRACT A wall frame comprises a sheet metal, channel sectioned bottom plate and a plurality of spaced apart, sheet metal channel sectioned studs extending upwardly from the plate. Each stud is secured to the plate, and the frame is secured to an underlying base, by means of an L shaped hold down bracket (11) comprising a flange having a saddle shaped end (15) hooked over the edge of a circular hole in the web of the stud, and a lug (12) pierced by a hold down fastener extending through the web of the plate into the base. Uplift forces on the stud are transferred by the bracket directly to the base, rendering the frame particularly suitable for use in high wind areas. Figure 1.