GB2339219A

GB2339219A - Load-bearing bracket

Info

Publication number: GB2339219A
Application number: GB9913168A
Authority: GB
Inventors: Jonathan Moffett
Original assignee: WMB STAINLESS Ltd
Current assignee: WMB STAINLESS Ltd
Priority date: 1998-06-08
Filing date: 1999-06-08
Publication date: 2000-01-19
Anticipated expiration: 2019-06-08
Also published as: GB9913168D0; GB2339219B; GB9812234D0; IE990477A1

Description

2339219 A Load-Bearing Bracket The present invention relates to a

load-bearing bracket, for example, for coupling the structural frame of a building with a spaced-apart outer wall. The invention is particularly suitable for use with cavity wall buildings in which the structural frame is formed from concrete and the outer wall, or leaf, is formed from conventional brickwork.

A cavity-walled building, or structure, has an inner structural frame and an outer wall, mutually spaced-apart by a cavity. It is a well known problem in cavity-walled buildings, particularly of two storeys or more, that the different physical properties of the structural frame and the outer wall causes relative movement between them over - a period of time. For example, a concrete structural frame tends to shrink as it cures and creeps under load while an outer wall of clay brickwork tends to expand over a period of time. Conventionally, load- bearing support systems are employed to restrict the relative vertical movement between the structural frame and the outer wall. Typically, such systems include a load-bearing bracket which is mountable on the structural frame using a conventional bolt, nut and washer arrangement. An elongate bolt-receiving aperture is formed in the bracket and, in use, the longitudinal axis of the aperture is vertically disposed. Thus, the bolt can be inserted into the structural frame through the aperture at a number of different vertically displaced locations. This is conventionally deemed to be a requirement for such brackets since obstructions, such as reinforcement bars, 5 may be present in the structural frame.

Such conventional systems, however, suffer from the disadvantage that the load on the system is most often borne by the inter-engagement of the washer and the bracket and not by the inter-engagement of the bolt with the bracket - this limits the load bearing capacity of the system. Furthermore, if the location of the aperture coincides with a vertically disposed obstruction, then the bolt cannot be inserted into the structural frame and the bracket cannot be mounted thereon.

Attempts have previously been made to overcome the former of the aforementioned disadvantages by providing the mouth of the aperture with serrated portions which project, in use, outwardly with respect to the structural frame. The serrated portions inter-engage with a similarly serrated washer to enhance the load-bearing capacity of the system. This suffers from the disadvantage, however, that the bracket is more expensive to manufacture since additional milling is required to form the serrations and since nonconventional washers are required. Furthermore, it is undesirable to have serrated portions at the load-bearing region of the bracket since the serrations, by their nature, reduce the volume of the bracket at its load- bearing region thereby weakening the bracket and reducing its load- bearing capacity.

It is an object of the present invention to provide a load-bearing bracket which mitigates the aforementioned disadvantages of the prior art.

Accordingly, the present invention provides a load-bearing bracket for coupling a load to a support member, the bracket comprising a back plate for fixing to the support member and at least one member extending forwardly of the back plate for supporting the load, the back plate having one or more apertures providing a set of bolt- receiving locations distributed in directions both parallel and normal to the load bearing direction of the bracket and at each of which locations an edge of the aperture may directly engage and bear upon the bolt substantially in the load bearing direction.

In the present specification the term "bolt" means a bolt, screw or nail or any similar fixing means which may be driven or inserted through an aperture in the base plate to fix the bracket to the support member.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which like numerals are used to represent like parts and in which:

Figure 1 is a perspective view of a first embodiment of a load-bearing bracket according to the invention, the bracket being fixed to a section of angle-iron; Figure 2 is a perspective view of a plurality of the loadbearing brackets of Figure 1, each being fixed to a section of angle iron to form a support system according to an embodiment of the invention; Figure 3 is a side view of the load-bearing bracket of Figure 1 and of the support structure of Figure 2 in situ in a cavity wall structure; Figure 4 is a plan view of the bracket of Figure 1 in an 15 unfolded state; Figure 5 is a plan view of a second embodiment of a bracket according to the invention in an unfolded state; and; 20 Figure 6 is a schematic view of alternative mounting aperture arrangements of alternative embodiments of the invention.

Referring now to Figure 1, a first embodiment of a loadbearing bracket 10 according to the present invention comprises an elongated back plate 12 and two spacing members in the form of side plates 14. The side plates 14 are integrally formed with the back plate 12 and project substantially perpendicularly forwardly from the back plate 12 but substantially parallel with one another so that the bracket 10 is substantially U-shaped in transverse cross-section. Each side plate 14 has a respective leading, or free, end 16. In use, as will be described with reference to Figs. 2 and 3, the bracket 10 is mounted to a support member 30 with the longitudinal axis of the back plate 12 substantially vertical, i.e. substantially parallel to the load-bearing direction A, Fig. 3.

A pair of vertically spaced mounting apertures 18, 20 are formed in the back plate 12. The mounting apertures 18, 20 are elongate in shape and have respective longitudinal axes which are substantially parallel with one another and perpendicular to the load bearing direction A. The apertures 18, 20 have upper and lower edges 19, 21 and 23, 25. Preferably, the mounting apertures 18, 20 are substantially obround in shape.

A positioning aperture 22 is also formed in the back plate 12, spaced from the mounting apertures 18, 20. The positioning aperture 22 is elongate in shape and has a longitudinal axis which substantially vertical, i.e.

parallel to the load bearing direction A. Preferably, the positioning aperture 22 is substantially obround in shape.

In Figure 1, the bracket 10 is fixed to a load-engaging member in the form of an angle-iron 24. The angle-iron 24 comprises a first plate 26 and a second plate 28 which are so disposed relative to one another that the angle-iron 24 is substantially L-shaped in transverse cross-section. The first plate 26 is fixed, by a conventional method such as welding, to the respective free ends 16 of the side plates 14.

It will be appreciated that the side plates 14 need not necessarily be integrally formed with the back plate 12 but rather, in an alternative embodiment (not shown), can be fixed thereto in a conventional manner such as welding. It will further be appreciated that there need not necessarily be two side plates 14. A single side plate, or other suitable spacing member, may suffice, or more than two may be required, depending on the application.

The mounting apertures 18, 20 are shaped and dimensioned to receive a load-bearing bolt 40 (not shown in Figure 1), or other suitable fixing element. In particular, the length of each mounting aperture 18, 20 is greater than the diameter or width of the bolt so that the bolt is insertable through either one of the mounting apertures 18, 20 in more than one horizontal location. Thus, together, the mounting apertures 18, 20 provide a set of bolt-receiving locations distributed in directions both parallel and normal to the load bearing direction A of the bracket and, by selecting one or other aperture 18, 20 and a articular horizontal position within that selected p aperture, the user can insert the bolt through the back plate at a position which avoids obstructions within the support member 30. Typically, the length of the mounting apertures 18, 20 is 2-3 times greater than the diameter of the load-bearing bolt. The height or width of the apertures 18, 20 is preferably substantially equal to the diameter of the bolt.

The positioning aperture 22 is shaped and dimensioned to receive a positioning element in the form of a positioning bolt or nail (not shown) and washer as appropriate. The length of the positioning aperture 22 is greater than the diameter or width of the positioning nail so that the nail is insertable through the positioning aperture in a number of locations, each location being displaced from each other location along the longitudinal axis of the positioning aperture 22. Typically, the length of the positioning aperture 22 is 2-3 times greater than the diameter of the nail. The width of the aperture 22 is preferably substantially equal to the diameter of the nail.

Preferably, the load-bearing bracket is formed from stainless steel, particularly austentic stainless steel. Alternatively, galvanised mild steel can be used. A skilled person will appreciate that other metallic or nonmetallic materials are suitable depending on the application.

Figure 2 shows a plurality of mutually spaced-apart load bearing brackets 10 fixed to a length of angle-iron 24.

Each bracket 10 is mounted to a support member in the form of a masonry unit such as a concrete beam 30 as may be found in the structural frame (not shown) of a building.

A respective load-bearing bolt 40 (not shown in Figure 2) is inserted through a respective mounting aperture 18, 20 to fix each bracket 10 to the beam 30. The brackets 10, the angle-iron 24 and the bolts together form a support system 33 for coupling a load to the support member or beam 30.

Figure 3 shows a side elevation of the support system 33 in situ in a cavity-walled structure, generally indicated at 32. The cavity-walled structure 32 comprises a support member in the form of the concrete beam 30 spaced-apart from a load in the form of an outer brickwork wall 34 by a cavity 35. The brickwork wall 34 comprises a plurality of layers of conventional clay bricks 36 joined in conventional manner by layers 38 of mortar.

The load-bearing bolts 40 (only one visible) are inserted into.the concrete beam 30 through a respective mounting aperture 18, 20 (not visible in Figure 3) of a respective bracket 10 to fix the brackets 10 to the beam 30 such that the respective back plates 12 engage with an outer face 31 of the beam 30. In this position, the respective side plates 14 project substantially perpendicularly with respect to the outer face 31. The second plate 28 of the angle-iron 24 is located between two adjacent layers of bricks 36 and is substantially perpendicular with respect to the plane in which the wall 34 is disposed. A layer of suitable compressible filler 42 is located beneath the second plate 28 and a gap 44 is provided above the plate 28. The gap 44 is typically filled with conventional mortar (not shown).

The particular advantages of the present invention can be readily appreciated by considering the installation and performance of the support system 33. To install the system 33, one or more users position the support system 33 in approximately the desired location with the respective back plates 12 against the beam 30. The user then inserts at least one nail through a respective positioning aperture 22 to temporarily hold the system in the approximate desired location. Preferably, respective nails are inserted through the brackets 10 adjacent the opposite free ends of the length of angle-iron 24. The location and orientation of the support system 33 can then be more precisely adjusted by a single user using a hammer (not shown), or similar tool, to tap the or each appropriate bracket 10 up or down to adjust the location of the respective bracket 10 relative to the beam 30.

Thus, the or each nail, when in the respective positioning aperture 22, must be coupled to its respective back plate 12, by a washer or similar object, to provide sufficient load-bearing capacity between the nail and respective back plate 12 to support the weight of the brackets 10 and angle-iron 24 while enabling a single user to readily displace the back plate 12 relative to the nail using a hammer. Thus, the positioning apertures 22 and respective nails enable the respective brackets 10 to be precisely positioned with respect to the beam 30 by a single user.

Once the brackets 10 have been precisely positioned, and are held in place by the or each nail, the user then selects a respective location in relation to each bracket 10 through which to insert a respective load-bearing bolt 40. The user can select either of the vertically separated mounting apertures 18, 20 and can further select any one of a plurality of horizontal locations within each aperture 18, 20. Thus, in the event that one or more reinforcement bars (not shown) are present in the concrete block, the user can select where to insert each bolt 40 from a plurality of locations which are distributed in directions both parallel and normal to the load bearing direction A of the bracket so that the bolt, when inserted, does not impinge upon a reinforcement bar, irrespective of the orientation of the reinforcement bar with respect to the bracket 10. Once a suitable respective location has been selected for a bolt 40, the user drills a socket into the concrete beam 30 and inserts the bolt 40 in conventional manner.

In addition to facilitating the installation of the support system, the mounting apertures 18, 20 improve the load-bearing capacity of the system in comparison with conventional systems. Since the longitudinal axes of the mounting apertures 18, 20 are substantially perpendicular to the load bearing direction A, a bolt 40 inserted through a respective aperture 18 or 20 will be directly engaged by the upper edge 19 or 23 of the aperture which will bear downwardly on the bolt in the load bearing direction A. Thus, in use, at least some of the load is borne by the direct inter-engagement of the bolt 40 and the back plate 12 thereby increasing the load-bearing capacity of the system.

Preferably, a respective washer (not shown), or similar object, is located around the bolt 40 in conventional manner for engagement with the back plate 12. In use, the washer distributes at least part of the load over portions of the back plate 12 which are adjacent the respective aperture 18, 20 and engaged by the washer. It is further preferred to use washers of relatively large surface area to maximise the degree to which the load is distributed over the back plate 12. For example, washers are typically selected whose radius is approximately equal to the spacing between the adjacent mounting apertures 18, 20. It will also be noted that, in the absence of serrations around the apertures 18, 20, the volume of back plate material around the apertures 18, 20, i.e. in the load-bearing region, is maximised. Moreover, to maximise the surface area of the loadbearing regions of the back plate 12, it is preferred that the width or height of the apertures 18, 20 is substantially equal to the width or diameter of the bolt 40.

By maximising the volume and surface area of the back plate 12 in the load-bearing regions, and by causing at least part of the load to be borne by the direct interengagement of the back plate 12 and the bolt 40, the loadbearing capacity of the support system is relatively high in comparison with alternative conventional systems.

The invention further provides a method of manufacturing a load-bearing bracket. Figure 4 illustrates a bracket 10 in an unfolded state in which the back plate 12 and the side plates 14 lie in substantially the same plane. The bracket 10 is formed initially in the unfolded state when it is cut from a sheet of source material (not shown). Each side plate 14 is shaped to define a spacing member in the form of a respective elongate wing portion 50, the size of which wing portion 50 determines the distance of the respective free end 16 from its respective back plate 12. In use, the unfolded bracket 10 is folded at broken lines X and Y to form the folded bracket 10 illustrated in Figures 1 to 3.

It will be appreciated that the dimensions of the support system 33 are determined by the size of the cavity into which the system 33 is to be placed. Thus, to accommodate cavities of different sizes, the bracket 10 of the invention is formed with said wing portions 50 of sufficient length to enable the support system 33 to fit the largest cavity which could ordinarily be expected in normal applications. Therefore, when a user is constructing a support system 33 for a particular application, the specific size of the cavity in question is measured and the wing portions 50 are cut or trimmed to the appropriate size. Preferably, the wing portions 50 are provided with a number of spaced- apart calibration markings C to facilitate the trimming operation.

Figure 5 shows an alternative embodiment of the bracket 10 in an unfolded state. In this embodiment, the side plates 14 do not have wing portions. Thus, for the system 33 to fit a cavity of a particular size, it is necessary to fix respective spacing portions (not shown), by welding for example, to the free ends 16 of the side plates 14. The embodiment of Figure 4 is preferred since the provision of integral wing portions 50 obviates the need for fixing spacing portions to the bracket 10 in a separate operation.

Figures 1 to 5 illustrate the preferred embodiments. Alternative embodiments are, however, also suitable. Figure G shows four schematic representations I, II, III and IV of some alternative arrangements of mounting apertures in the back plate 12. As in Figs. 1 and 3, the load bearing direction of the bracket is indicated by the arrow A.

In schematic I, the mounting apertures are arranged in two sets 61, 62, each set having two apertures and having a respective longitudinal axis which is substantially perpendicular to the direction A. In schematic II, the apertures are not arranged in sets but rather are arranged along a common axis, the axis being obliquely disposed with respect to the direction A. In schematic III, the apertures are arranged in two sets 63, 64, the sets being mutually spaced-apart in the direction A and having respective longitudinal axes which are substantially parallel with one another but obliquely disposed with respect to the direction A. In schematic IV, the apertures are arranged in two sets 65, 66, the set 65 comprising one aperture and the set 66 comprising three apertures.

It will be appreciated that there are many other suitable arrangements for the mounting apertures and it will be noted that there need not necessarily be more than one mounting aperture - for example, a single aperture can be used which is elongate in shape, has a longitudinal axis which is obliquely disposed with respect to the direction A and which has a crenate or notched rim portion for seating a bolt in a plurality of locations (not illustrated).

The present invention provides a load-bearing bracket which is relatively simple and inexpensive to manufacture, relatively easy to install and which has an increased load-bearing capacity in comparison with alternative conventional brackets.

The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.

Claims

CLAIMS:

1. A load-bearing bracket for coupling a load to a support member, the bracket comprising a back plate for fixing to the support member and at least one member extending forwardly of the back plate for supporting the load, the back plate having one or more apertures providing a set of bolt-receiving locations distributed in directions both parallel and normal to the load bearing direction of the bracket and at each of which locations an edge of the aperture may directly engage and bear upon the bolt substantially in the load bearing direction.

2. A load-bearing bracket as claimed in claim 1, comprising a first aperture elongated in a direction substantially normal to the load bearing direction and providing a plurality of bolt-receiving locations along said aperture, and at least one further aperture displaced from the longitudinal axis of the first aperture in a direction parallel to the load bearing direction.

3. A load-bearing bracket as claimed in claim 2, wherein the further aperture is also elongated and its longitudinal axis is substantially parallel to that of the first aperture.

4. A load-bearing bracket as claimed in claim 2, wherein there are a plurality of further apertures each defining an individual bolt-receiving location.

S. A load-bearing bracket as claimed in claim 1, wherein there are a plurality of apertures each defining an individual bolt-receiving location.

5

6. A load-bearing bracket as claimed in any preceding claim, the back plate further including an aperture elongated in a direction substantially parallel to the load bearing direction to allow adjustable temporary fixing of the bracket.

7. A load-bearing bracket as claimed in any preceding claim, wherein the back plate is elongated and the load bearing direction is substantially parallel to the longitudinal axis of the back plate.

8. A load-bearing bracket substantially as described herein with reference to Figs. 1 to 3, or to any one of Figs. 4, 5 and GI to GIV of the accompanying drawings.

9. A support system for a cavity-walled structure, the support system comprising at least one load-bearing bracket as claimed in any preceding claim fixed by its back plate to a support member forming, or forming part of, an interior wall, and an exterior wall spaced from the interior wall and supported at least in part by the forwardly-extending member.