EP2072707A1

EP2072707A1 - Chair for reinforcement

Info

Publication number: EP2072707A1
Application number: EP08172413A
Authority: EP
Inventors: Petar Uscumlic
Original assignee: ITW Construction Systems Australia Pty Ltd
Current assignee: ITW Construction Systems Australia Pty Ltd
Priority date: 2007-12-21
Filing date: 2008-12-19
Publication date: 2009-06-24
Also published as: NZ574114A; AU2008255244B2; AU2008255244A1

Abstract

The chair for a reinforcing bar of a reinforcing grid is a one-piece plastics moulding and comprises an upper part with at least one pair of opposed seats (24) for the bar, and a set of outwardly splayed legs (8) extending downwardly from the upper part, adjacent legs being interconnected at or adjacent their lower ends by transverse bracing (12) extending between the adjacent legs (8).

Description

The present invention relates to a chair for supporting reinforcement for a cast concrete component and more particularly to a chair for a reinforcing bar within a grid or mesh of such bars.
Concrete reinforcement in the form of a grid or mesh (hereinafter referred to simply as a "grid") is often used when constructing large flat concrete areas such as roadways, pathways, floors or concrete wall panels. The reinforcement is supported from the substrate on which the concrete is to be cast by chairs applied to individual bars within the grid. Typically, the chair is in the form of a one-piece plastics moulding and incorporates a clip to enable the chair to be applied to the grid before laying so that the chairs applied at appropriate positions throughout the grid will hang from the grid while the grid is being laid into position. With reinforcement in the form of a grid it is inevitable that during setting up of the reinforcement prior to casting, workers will need to be walk on the grid and therefore it is necessary that the chairs have sufficient strength to carry the weight of persons standing on the grid, without the chairs breaking. In one previously proposed form of chair for this purpose the legs of the chair are formed as beams of approximately T-section. The primary strength of the leg is determined by the central stem of the T-section and this is made of sufficient thickness to achieve the necessary column strength in the legs. While this is quite satisfactory from a structural standpoint, this type of leg design uses a relatively large amount of plastics material in its manufacture and this is of significance because the production cost of the chair is mainly dependent on the quantity of plastics material used in its manufacture.
The present invention provides a chair which requires a reduced amount of plastics material in its manufacture whilst still having adequate column strength in its legs.
According to the present invention there is provided a chair for a reinforcing bar of a reinforcing grid, the chair being a one-piece plastics moulding and comprising an upper part with at least one pair of opposed seats for the bar, and a set of outwardly splayed legs extending downwardly from the upper part, adjacent legs being interconnected at or adjacent their lower ends by transverse bracing extending between the adjacent legs.
Further according to the invention, there is provided a chair for a reinforcing bar, the chair being a plastics moulding and comprising an upper part with seating for the bar and a set of outwardly splayed legs extending downwardly from the upper part, the legs being interconnected at or adjacent their lower ends by bracing extending between adjacent legs.
In a preferred embodiment, the overall body of the chair is of a generally polygonal (rectangular for example) or triangular shape in transverse cross-section and the legs are located at the corner portions of the body as downward continuations of the upper part of the body, the legs being generally V-shaped in cross-section.
Preferably the upper part of the chair includes a clipping arrangement whereby to clip the chair onto the bar such that the chair is suspended from the bar during laying of the reinforcing grid.
Particularly advantageously, the upper part of the chair includes two or more pairs of seats of different depths to support the bar at different heights from the substrate on which the chair rests in use. In that case, the clipping arrangement is designed to ensure that when the chair is clipped to the bar, the bar is aligned with the selected pair of seats of appropriate depth.
Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 is an isometric view of a chair in accordance with a first embodiment of the invention;
Figure 2 is a side view of the chair;
Figure 3 is a top view of the chair;
Figure 4 is a bottom view of the chair;
Figure 5 is a section on line A-A of Figure 3;
Figure 6 is an isometric view of a chair in accordance with a second embodiment of the invention;
Figure 7 is a view of the chair from one side;
Figure 8 is a view of the chair from an adjacent side; and
Figure 9 is a top view of the chair.

The chair shown in Figures 1 to 5 of the accompanying drawings is in the form of a one-piece plastics moulding and comprises an upper part with first and second pairs of opposed seats 2, 4 for reinforcing bar. The respective pairs of seats are offset by 90° about the vertical axis of the chair and are of different depths (as shown, the seats 4 are deeper than the seats 2) to permit the reinforcing bar to be located at one of two predetermined heights above the substrate on which the chair rests. The upper part also includes a set of resilient hook-like clips 6 which engage over the bar so as to attach the chair to the bar whereby the chair will be suspended from the grid during laying of the grid. It will be noted there are four such clips 6 each located between adjacent seats 2, 4 and the orientation of the bar relative to those clips will determine which pair of seats will be brought into active engagement with the bar when the grid with chair attached is lowered onto the substrate.
The overall body of the chair is of polygonal shape (as shown, rectangular) in cross-section transverse to its vertical axis, the body progressively tapering in cross-sectional size from its lower end to its upper end. Below the upper part of the body in which the two pairs of seats are formed, the body is formed with a set of four outwardly splayed legs 8 each located at a corner portion of the rectangular section body whereby each leg 8 is substantially V-shaped in cross-section. The lower ends of the legs 8 terminate in foot portions 10 which rest on the substrate in use. A transverse bracing member 12 extends horizontally between each pair of adjacent legs at, or adjacent to the lower ends of the legs.
The incorporation of legs 8 of V cross-section in conjunction with the transverse bracing of the legs and the outwards splaying of the legs from their upper ends to their lower ends provides substantial column strength for the lower part of the chair structure formed by the legs while permitting a reduction in the amount of plastics material needed to form the legs and their associated transverse braces. In particular, the quantity of plastic material required to form the chair is markedly less than that needed to form a chair of the type discussed at the outset of comparable load bearing capacity.
It is to be noted that the chair is of hollow construction within its interior and due to its divergent cross-section from top to bottom, series of chairs can be stacked in a compact nested configuration for storage and transportation.
The chair shown in Figures 6 to 9 is generally similar to that of Figures 1 to 5 except the body is of a triangular transverse cross-section in its overall shape. In this embodiment the transverse bracing members for the legs 8 are united to form a bar 14 extending peripherally around the array of three legs 8 at the lower ends thereof.
Apart from the differences just noted, the triangular form of the body enables the structure of the upper part of the body to be modified to form three pairs of bar seats 16, 18, 20 with each pair being of a different depth in order to provide even greater versatility in use. In each pair of seats, one of the seats is formed in one of the three outer walls of the body and the other seat is formed in a secondary wall 22 parallel to the outer wall and spanning an opposed corner portion of the body. As there are now three pairs of seats, the upper part of the body has six hooks 6 located between the adjacent seats to enable the chair to be clipped onto a reinforcing bar in which the chair is mounted to the bar in an orientation in which the bar will engage into the required pair of seats of selected depth.
The embodiments have been described by way of example only and modifications are possible within the scope of the invention. For example the clipping arrangement may be different to that shown and the cross-sectional shape of the chair may be different.

Claims

A chair for a reinforcing bar of a reinforcing grid, the chair being a one-piece plastics moulding and comprising an upper part with at least one pair of opposed seats for the bar, and a set of outwardly splayed legs extending downwardly from the upper part, adjacent legs being interconnected at or adjacent their lower ends by transverse bracing extending between the adjacent legs.
A chair according to claim 1, wherein the upper part and the legs of the chair define a chair body of a generally polygonal or triangular shape in transverse cross-section, and the legs being located at the corner portions of the body as downward continuations of the upper part of the body.
A chair according to claim 2, wherein each leg is generally V-shaped in transverse cross-section.
A chair according to any one of the preceding claims, wherein the upper part of the chair includes a clipping arrangement whereby to clip the chair onto the bar such that the chair can be suspended from the bar during laying of the reinforcing grid.
A chair according to claim 4, wherein the upper part of the chair includes two or more pairs of seats of different depths to support the bar at different heights from a substrate on which the chair rests in use, the clipping arrangement being so configured that when the chair is clipped to the bar, the bar will be aligned with a selected pair of the seats as determined by the orientation of the chair relative to the bar.
A chair according to any one of claims 1 to 4, wherein the upper part of the chair includes two or more parts of seats of different depths to support the bar at different heights from a substrate on which the chair rests in use.
A chair according to any one of the preceding claims, wherein the chair is of open structure within its interior to enable a series of like chairs to be nested one inside another for transportation and storage.
A chair for a reinforcing bar, the chair being a plastics moulding and comprising an upper part with seating for the bar and a set of outwardly splayed legs extending downwardly from the upper part, the legs being interconnected at or adjacent their lower ends by bracing extending between adjacent legs.
A chair according to claim 8, wherein the legs define corner portions of the body of the chair beneath the upper part.
A chair according to claim 8 or claim 9, wherein the legs are of angled shape in transverse section.
A chair according to any one of claims 8 to 10, wherein the upper part of the chair includes clips to clip the chair onto the bar whereby the chair can be suspended from the bar with the bar aligned with the seating.
A chair according to any one of claims 8 to 11, wherein the bracing extends generally horizontally between adjacent legs.
A chair substantially as hereinbefore described with reference to the accompanying drawings.