AU2001258053B2 - Support chair for reinforcing rods in reinforced concrete - Google Patents

Description

WO 01/90505 PCT/AU01/00581 SUPPORT CHAIR FOR REINFORCING RODS IN REINFORCED CONCRETE FIELD OF THE INVENTION This invention relates to support chairs for locating reinforcing bars or mesh in reinforced concrete during laying or forming such concrete, such concrete generally being laid with the use of suitable formwork. The invention especially relates to an improved support chair having not only means to optionally retain the reinforcing bars or mesh prior to pouring the concrete but also additional facilities for forming a void below the chair, which coupled with means to allow other building components to be suspended therefrom, provides duality of purpose.

BACKGROUND OF THE INVENTION It is common practice to employ so-called chairs to support reinforcing bars or mesh when laying or forming a reinforced concrete slab. Although the following description refers primarily to concrete slabs, this is meant to encompass not only concrete slabs per se, but other structural concrete components including bulkheads and other engineered concrete sections. Any reference to a slab is meant to encompass any reinforced concrete structure for floors or ceilings and the like, whether suspended or not, where by suitable modification if necessary, the invention may be adapted and employed. However, it will be appreciated of course that all the advantages of the present invention will only be available in suspended floor/ceiling environments, where access is available to the underneath side of such structural component. Nevertheless, the invention should not be construed as being limited thereto.

As is expected, it is necessary to have reinforcing materials approximately located in the centre of laid slabs of concrete to provide the desired reinforcing effect. If left otherwise unsupported, the reinforcing material would sink to the base of the concrete being laid.

Instead, to overcome this, a variety of support chairs have been developed to allow reinforcing mesh or bars to be supported at intervals, whereby the reinforcing is kept above the plane of the bottom surface of the concrete during pouring of the concrete. Because the WO 01/90505 PCT/AU01/00581 2 concrete being poured can upset or dislodge such reinforcing from the support chairs, it is also usual practice to tie off the bars or mesh to the chairs to prevent dislodgement therefrom, either from workmen moving about the site prior to pouring, or during pouring of the concrete itself.

Furthermore, where a concrete slab is being laid as a suspended slab, that is to say, the lower surface forms a ceiling to the area below, it is often necessary or desirable to drill into the underside of the concrete slab at a later time or otherwise insert therein by suitable means, attachment means by which suspended ceilings, or a variety of other building components, such as electrical or air conditioning ducting etc, may be hung.

From the foregoing, it will be apparent that it would be advantageous to provide an inexpensive support chair, capable of not only supporting the appropriate reinforcing bars or mesh, but which has the added advantages of optionally being able to retain the reinforcing material in situ whilst concrete is being poured and/or providing means, once the formwork is removed, to facilitate fixing of suspended building components underneath the laid slab.

OBJECT OF THE INVENTION It is therefore an object of the present invention to ameliorate some or all of the limitations in currently known designs for support chairs by providing a support chair with duality of function, in that it is capable of not only supporting, and where required securing, the reinforcing bars or mesh against dislocation, but also of providing a void in the lower surface of the concrete slab, which coupled with suitable means associated therewith, provides the additional functionality of being able to have other building components suitably suspended therefrom. At the very least, the invention provides an alternative to presently proposed support chairs for locating reinforcing bars or mesh material when laying reinforced concrete slabs.

WO 01/90505 PCT/AU01/00581 3 DISCLOSURE OF THE INVENTION According to the present invention, there is provided a support chair for locating reinforcing bars or mesh at a predetermined height within a slab of reinforced concrete to be laid, the chair comprising a void forming base element, such that a void is formed in the lower surface of the concrete slab during pouring of the concrete; a support cradle located at the top of the base element for locating the reinforcing bars or mesh, and means located within the void for later attachment, as and when required, of suspended building components therefrom, once formwork is removed and the void exposed, the attachment means having the necessary strength to support same.

Preferably the void forming base element is manufactured in the form of an inverted cup-like element. However, it will be readily understood that many designs will function equally well depending upon the ultimate use to which the void/suspension attachment means is to be put. Thus the void may be any useful regular or irregular geometric shape or cavity depending on the possible applications to which it is expected that it will be put.

Particularly suitable shapes include those of generally circular cross section, including frusto-conical sections as well as pyramidal or frusto-pyramidal sections. Alternatively, the shape may be considerably more irregular, for example more in the form of a slot or groove.

It will be also appreciated that any suitable material may be utilised in the construction of the support chair, provided only that the base and support cradle should have the design capability of withstanding the forces applied to them during laying of the concrete. In other words, the chair must be substantially able to support itself and the associated reinforcing materials during the forming of any concrete structure and be able to exclude, by design, concrete from a particular void, the void then being exposed by removal of formwork, which in turn allows access to suitable attachment means, utility couplings or connectors within the formed void.

WO 01/90505 PCT/AU01/00581 4 Similarly, the same consideration extends to the attachment means located in the void itself, where sufficient strength and durability must be provided to suit the purpose for which such means will be put to use. Preferably, the attachment means is manufactured from materials of a highly durable nature such as steel, galvanised steel or stainless steel, high density reinforced plastics or combinations thereof, thereby producing a highly useful and durable product.

Although it may be envisaged that the components of the invention, namely the void forming base, support cradle and suspension attachment means are integral with one other, in a preferred form of the invention, the base is manufactured from suitable plastics material, whilst the cradle and suspension attachment means are themselves integrally formed from a single piece ofgalvanised steel or stainless steel or other suitable strong and durable material, thereby creating a single component to be used in conjunction with the base.

In this embodiment, a slit is provided in the base in the vicinity of the top or apex thereof (depending on the particular geometry thereof), a steel strip or other suitable integral component passing therethrough so that on the one hand that portion which extends upwardly from the base is fashioned or shaped so as to form a cradle for the reinforcing bars or mesh, whilst on the other hand, the lower portion extends into the void to be formed, designed so as to enable the particular means, by which any ceiling or other building component is suspended therefrom, to be suitably engaged therewith. With advantage, the upper cradle, by virtue of its inherent geometry, prevents the integral component from passing downwardly through the slit, which facilitates use of the support chair in this form prior to it being imbedded in the concrete. That is to say, the cradle is supported by the base.

WO 01/90505 PCT/AU01/00581 With advantage, the cradle is provided with one or more fingers which are able to be readily bent around the reinforcing mesh or bar placed in the cradle to secure it against being dislodged.

Preferably, the lower portion of the integral component is in the form of a simple plate through which one or more holes are drilled or otherwise formed, for engagement of a hook element therein, such hook elements being useful in hanging the required suspended building elements therefrom. In this arrangement, such plate portion may be easily slid though the slit in the base from above. Thus, instead of having the support chair already assembled, it will be economical to have a supply of bases (which can generally be readily made to stack given the cup-like nature of many of the possible designs), so that on site, it is simply a matter of inserting an integral cradle/attachment component through the slot in each base and placing the thus formed chair with associated cradle element on the formwork or upon the ground, depending upon which of the two the slab is being laid on.

Irrespective, of whether fingers as described above are used, it will be appreciated that once the concrete has been laid the integral component will be held in place by the set concrete, if only by virtue of the cradle like shape with which it has been designed. However, where fingers are used, then there will be substantially increased strength since the load will not be taken by the concrete itself but will be transmitted to the reinforcing bar or mesh about which the fingers of the integral component are folded.

Alternatively, a number of other mechanisms may be employed to allow connection between the attachment means of the chair and the relevant connecting means of the suspended ceiling or other building component. For example, a looped band may be utilised to provide an attachment point or points for the subsequent fixing or suspension of other building components such as air conditioning ducting, suspended ceilings, cable troughs and the like.

WO 01/90505 PCT/AU01/00581 6 In a further variation, the attachment means may also have associated therewith a sliding plate arrangement, wherein the attachment means functions telescopically to allow extension beyond the region of the void and thereby attachment at a level below the plane of the concrete slab.

Although, it is envisaged that the foregoing attachment means, may be relatively simple in scope to allow for example a hook to be easily suspended therefrom, more complicated means of attachment, including threaded rods may be substituted, as required.

It will be also generally understood that the base will remain in place after the concrete is formed and the formwork removed. However, in some applications it may be preferred to remove the base, leaving in place only the attachment means for suspension of other building components, as the only exposed element of the original chair structure, the cradle portion of course being embedded in the concrete. On the other hand, where it is specifically desired that the base remain in place, suitable indentations and the like may be made in the surface of the base which comes into contact with the concrete to improve adhesion for example by providing key-like retention.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred form of this invention will now be described with reference to the attached drawings in which: Fig. 1 shows a top view of the base of a chair for supporting reinforcing rods in reinforced concrete according to one embodiment of the invention, Fig. 2 shows a side view of the base of a chair depicted in Fig. 1, Fig. 3 shows an end elevation of the base of a chair depicted in Figs. 1 and 2, WO 01/90505 PCT/AU01/00581 7 Fig. 4 shows an end elevation of a support cradle with attachment means for use with the base of the chair of Figs. 1 to 3, Fig. 5 shows the side elevation of the support cradle depicted in Fig. 4, Fig. 6 shows schematically, in side elevation, the components of Fig. 1 to 5, together with reinforcing rod and formwork, prior to both assembly and pouring the concrete, Fig. 7 shows in cross section the base of the chair and support cradle of Figs. 1 to 5 in place (without formwork shown), after assembly and prior to pouring the concrete, Fig. 8 shows, in end elevation, the chair assembly of Fig. 7, after pouring the concrete, but prior to removal of the formwork, and Fig. 9 shows, in end elevation, the chair assembly of Fig. 8 after removal of the formwork and after insertion of a hanging element from the lower region of the support cradle providing attachment means in the form of a simple hole for insertion of a hook therein.

BEST MODE OF CARRYING OUT THE INVENTION Referring generally to Figs. 1 to 5, there is illustrated a pair of components for a support chair, namely a void forming base 11 and a support/attachment component 12, for location therein.

The base 11 comprises a substantially rigid structure of generally pyramidal shape 13 extending upwardly from a support platform 14. The base 12 is made of suitable plastics material. A slot 15 is formed in the top portion of the base 11.

WO 01/90505 PCT/AU01/00581 8 The support/attachment component 12 is of generally Y-cross section, and is made from suitable material having sufficient tensile capacity to support the expected load which may be hung therefrom in use, and comprises an upper cradle portion 16 and a lower attachment portion 17.

The cradle portion 16 of component 12 consists of a number of fingers 18. The lower portion 17 of component 12 consists of a plate 19, which is provided with a hole formed therethrough, for example by drilling.

The assembly of the components 11 and 12 to form the support chair assembly, generally referenced 21, and the use thereof in the ultimately formed concrete 22 is shown in Figs. 6 through 9.

Fig. 6 schematically shows the assembly of components 11 and 12, together with reinforcing rod 23 and formwork 24. Slot 15 allows insertion of the lower attachment portion 17 of component 12 through the base 11 from above. Thus, when combined, the lower portion 17 of the cradle/attachment component 12 extends through the base 11 and into the volume 25 which will ultimately become a void in the concrete 22 once formed.

The components 11 and 12, after assembly are simply placed on suitable formwork 24 and rod 23 is laid in the cradle 16 of the component 12. The assembled chair 21 with rod 23 fitted is depicted in Fig. 7 (although the formwork, shown elsewhere as item 24 is not shown in this illustration).

As mentioned, the cradle portion 16 of component 12 consists of a number of fingers 18, in this case four, which are designed to receive the reinforcing rod 23 or equivalent section of mesh as shown lengthwise in Figs. 6 and 7 and also in cross section in Figs. 8 and 9, so that upon location of the rod 23 in the cradle 16, the fingers 18 may be conveniently bent around the rod 23 to prevent sideways dislodgment of the rod 23 from the support chair assembly WO 01/90505 PCT/AU01/00581 9 21, prior to pouring the concrete 22, the result after the concrete 22 has been poured being depicted in Figs. 8 and 9.

As many fingers 18 as required may be thus bent about the bar 23, however in practice it may be found beneficial to leave some fingers (shown marked 18' in Figs. 8 and 9) outstanding to increase the interlocking of the cradle portion 16 of the chair assembly 21 in the concrete 22, once it is laid.

As mentioned before and shown specifically in Fig. 8 and 9, once the concrete 22 is poured, a void 25 is created between the base 11 and the formwork 24.

Referring specifically to Fig. 9, once the formwork 24 has been removed, the void becomes accessible and a hook or similar element 26 may be passed through the hole 20, so that building components such as suspended ceilings, air-conditioning ducts or other conduits etc (not illustrated) can be suspended therefrom.

The foregoing describes only some embodiments of the present invention, and modifications obvious to those skilled in the art can be made thereto without departing from the scope of the present invention.

Claims (13)

1. A support chair for locating reinforcing bars or mesh at a predetermined height within a slab of reinforced concrete to be laid, the chair comprising a void forming base element, such that a void is formed in the lower surface of the concrete slab during pouring of the concrete; a support cradle located at the top of the base element for locating the reinforcing bars or mesh, the cradle having one or more fingers which are able to be readily bent around the reinforcing mesh or bar placed in the cradle so as to secure it against being dislodged, and means located within the void for later attachment, as and when required, of suspended building components therefrom, once formwork is removed and the void exposed, the attachment means having the necessary strength to support same.

2. A support chair according to claim 1, in which the void forming base element is manufactured in the form of an inverted cup-like element.

3. A support chair according to either claim 1 or claim 2, in which the void is of generally circular cross section, including frusto-conical sections or of pyramidal or frusto-pyramidal section.

4. A support chair according to either claim 1 or claim 2, in which the shape of the void is irregular, including being in the form of a slot or groove.

A support chair according to any one of the preceding claims, in which connection between the attachment means of the chair and the relevant connecting means of the suspended ceiling or other building component includes a simple hole in a plate or a looped band for suspension of other building components such as air conditin tinn suspended ceilings, cable troughs and the like. 7 BaLcn No: AMENDED SHEET IPENAU PCT/AU001/00581 Received 27 March 2002 11

6. A support chair according to any one of the preceding claims in which, the attachment means also has associated therewith a sliding plate or other suitable arrangement, wherein the attachment means functions. telescopically to allow extension beyond the region of the void and thereby attachment at a level below the plane of the concrete slab.

7. A support chair according to any one of the preceding claims, in which the void forming base, support cradle and suspension attachment means are integral with one other.

8. A support chair according to any one of claims 1 to 6, being an assembly, in which the void forming base is manufactured from suitable material including plastics, whilst the cradle and suspension attachment means are integrally formed from a single piece of galvanised steel or stainless steel or other suitable strong and durable material, including high density reinforced plastics or combinations thereof, thereby creating a single component to be used in conjunction with the base.

9. A support chair assembly according to claim 8, in which a slit is provided in the void forming base in the vicinity of the top or apex thereof, a steel strip or other suitable integrally formed component passing therethrough so that the portion which extends upwardly from the base is fashioned or shaped so as to form a cradle for the reinforcing bars or mesh, whilst the lower portion extends into the void to be formed, designed so as to enable the particular means, by which any ceiling or other building component is suspended therefrom, to be suitably engaged therewith. A support chair assembly according to claim 9, in which, the upper cradle, by virtue of its inherent geometry, prevents the integral component from passing downwardly through the slit, thereby facilitating use of the support chair prior to it being imbedded in the concrete, by virtue of the cradle being supported by the base.

AMENDED SHEET IPEAJAU PCT/AUOO 1/00581 Received 27 March 2002 12

11. A support chair assembly according to either claim 9 or claim 10, in which the lower portion of the integral component is in the form of a simple plate through which one or more holes are drilled or otherwise formed, for engagement of a hook element therein, such hook elements being useful in hanging the required suspended building elements therefrom.

12. A support chair according to any one of the preceding claims, wherein the base remains in place after the concrete is formed and the formwork removed.

13. A support chair according to any one of claims 1 to 11, in which the base is removed from the formed concrete, leaving in place only the attachment means for suspension of other building components, as the only exposed element of the original chair structure, the cradle portion being embedded in the concrete. AMENDED SHEET IPENAU