AU777108B2 - Bar chair - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

r rrri Name of Applicant: Actual Inventors: Address for Service: Invention Title: Modfix Australia Pty Ltd KUDELKA, Thomas, Carl and O'LOUGHLIN, Andrew Emden DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, Victoria 3000.

Bar chair Details of Associated Provisional Application: Australian Provisional Patent Application No. PQ4099/99 filed 17 November 1999 The following statement is a full description of this invention, including the best method of performing it known to us: P:\OPER\DCD\PROVS\MODFIX\MODFIX COMPLETE DOC 1711/00 -2- Bar chair The present invention relates to a bar chair for supporting reinforcing bars or mesh for concrete and is particularly concerned with a ribbed bar chair for use in concrete slabs.

Bar chairs are commonly used to support reinforcing for concrete slabs of a variety of compositions, shapes and configurations for use in many different applications. For example, bar chairs may be used in the preparation of foundational and other building structures poured in situ. Bar chairs have also been proposed for use with reinforcing for tilt slabs and pre-cast concrete in which the reinforced concrete product is cast in a mould defined by formwork and once cast and set is moved to a desired location for installation. There is an increasing tendency to make these concrete slabs thicker than has previously been the case. Since the building regulations in many jurisdictions require the reinforcing to be a constant 15 predetermined depth from the surface of the slab, this tendency calls for taller bar chairs which i'"'"can withstand the forces applied to them, particularly the weight of the supported reinforcing as well as of people and items on the reinforcing before the concrete is poured.

ooooe :*ooeo Existing taller bar chairs, for example above 100mm, are commonly formed from wire and comprise two inverted substantially U-shaped wire components orientated at right angles to each other and secured together so as to form a substantially pyramidal shaped wire frame having four legs with an upper recess for locating the reinforcing bars. A disadvantage of ooooe such bar chairs is that the legs tend to spread when weight is applied to the bar chair before concrete is poured, so that the reinforcing may not be supported at the correct height.

25 Furthermore, the feet of such wire bar chairs are often exposed to the surface of the slab, •allowing access for moisture to the concrete and especially to the wire bar chairs. Over a period of time the steel from which these bar chairs are formed may be subjected to rusting and may eventually completely deteriorate allowing access for moisture to the reinforcement itself. A separate base plate may be supplied for use with these wire bar chairs to alleviate this problem, but this increases costs and is cumbersome to use so a separate base tends not to be used in practice.

P:\OPER\DCD\PROVSMODFIX\MODFIX COMPLETE.DOC 17/11/00 -3- Plastic bar chairs have also been produced in an effort to overcome the problems of undesired deformation and rusting and are specified for concrete structures in coastal regions.

Bar chairs have been described comprising a support having three or more legs depending from a substantially cylindrical body portion. The body portion generally includes diametrically opposed pairs of recesses for supporting reinforcing or mesh and the legs are optionally supported by a base plate to evenly distribute the downward forces applied to the support. These types of bar chairs also optionally include a cylindrical insert adapted to be received in the cylindrical body portion to provide a means of adjusting the height of the bar chair to in turn support reinforcing at different heights. Such bar chairs require the manufacture of a complex and high cost mould which would not be readily modified to vary the height at which the reinforcing or other material is supported.

Less complex moulds have been described in which a single legged bar chair may be manufactured using a two part mould. However, such designs do not enable the mould to be i readily modified to vary the height of the bar chair. The height of the bar chair required for a particular application may vary with the slab width required. It would be a distinct ooooo advantage to have flexibility in the height of each bar chair used in a particular application combined with an efficient and economic means for manufacturing same.

The bar chair described in AU 564990 includes a separable base plate and upstanding stem which may be slidably engaged by a T-shaped flange on the baseplate. The broad underside surface of the baseplate presents the same disadvantage as the above described prior art in that in tilt-slab applications where the formwork is removed the baseplate may be left visible when 25 placed in position and it may require extra effort to conceal same. Moreover, this design of bar chair involves the use of a comparatively large amount of material relative to the degree of strength and stability obtained.

It is therefore an object of the present invention to provide a bar chair in which one or more of the disadvantages of the described prior art is alleviated or to at least provide a useful alternative.

According to the present invention, there is provided a multiple-component bar chair for supporting reinforcing for concrete including: a leg component of substantially ribbed configuration having seat means at its upper end to support the reinforcing; and an upstanding support component adapted to stand on formwork and to support the leg component in an upright position, wherein the leg component has an engagement member capable of engaging with a complementary engagement member on the support component such that the leg component is supported in said upright position.

Each of the components accordingly may be modular. Any one of a variety of support components having different functionalities may be used in conjunction with any one of a range of leg components having different lengths and functionalities because the engagement means provides a common fit in each case. The leg component may vary in length from a stub-like structure to an elongate structure to provide a range of bar chair pea: sizes suitable for a corresponding range of applications.

The leg component may include a shank extending between the engagement means and o°°oo the seat means and may constitute the major portion of the leg component which is of 20 ribbed configuration. The shank may be curved, tapered or may have a substantially constant cross-section along a major part of its length. Preferably the shank is of too constant cross-section along its entire length. Preferably the shank is solid for maximum structural stability but it may have, for example, a hollow core formed by a simple removable pin insert in the mould or material-saving openings therethrough.

The shank may have a variety of constructions accommodating the ribbed configuration.

The shank may have a V-shaped or otherwise multi-armed cross-sectional configuration. The shank is substantially of ribbed cross-section to maximise the strength of the leg component whilst using a minimum amount of material for the purposes of economy. Most preferably the ribbed cross-section does not include a central core.

P:\OPER\DCD\PROVS\MODFIX\MODRX COMPLETEDOC 17/11/00 The ribs of the leg component extend longitudinally and are preferably located in one of two perpendicular planes, the first plane corresponding to the joint line of a two part mould in which it may be manufactured and the second plane being vertical and perpendicular relative to the first plane. The ribbed cross-section may be, for example, cruciform shaped. The ribs of the leg component may also located in three or more planes wherein at least one plane is perpendicular to the others, and said other planes are parallel to one another. The ribbed crosssection accordingly may be, for example, substantially H-shaped.

The seat means located at the upper end of the leg component may simply comprise the upper end of the shank contoured to receive the reinforcing by defining a recess having a depth suitable to the particular application. In one embodiment the leg component may include further seat means attached to or integrally formed with the shank intermediate its length. The seat means advantageously includes an integrally or separately moulded saddle which is suitably configured to receive reinforcing. The saddle may be broader in width than the shank oo.. to more stably support the reinforcing. The saddle may include any suitable configuration whereby the reinforcing is retained in place when subjected to the normal conditions oo# associated with the preparation of the reinforcing which is required prior to pouring the oooo concrete. Preferably the saddle is of the type having a recess on which the reinforcing rests 20 and upper walls adapted to retain the reinforcing in place. The recess walls may define S.channel- or V-shaped saddles into which the reinforcing may be freely placed or removed therefrom. Preferably, however, the walls of the saddle curve upwards and inwardly towards o••o• each other to more securely retain the reinforcing once in place. The ends of the walls may join or overlap, but most preferably the recess and walls define a broken ring into which the 25 reinforcing may be received. Preferably the ends of the saddle walls each taper towards a point defining a deflectable tab to allow flexibility at their tips. The deflectable tabs may be abutting but preferably are separated by a small gap. The small gap is preferably smaller than the width of the reinforcing to be supported. The tabs are preferably sufficiently deflectable to receive the reinforcing which may securely rest in the saddle and have sufficient flexibility to allow purposeful removal of the reinforcing if required.

The upstanding support component includes a variety of configurations capable of stably standing on the formwork whereby to support the leg in an upright position. The support component may include a cylindrical, block or skeletal frame configuration.

The support component in cross-section may be otherwise multi-faceted whereby to form a stable The support component not a "base" in accordance with the standard meaning of the term applied by persons skilled in the art and accordingly is not a substantially flat member adapted to rest in a horizontal plane. However, it should be appreciated by those skilled in the art that a base in the form of a planar disc may be used in particular applications where visibility of the base in the finished product is not in issue. The base may be adapted to be placed under the support component and to rest on the surface onto which the concrete is to be poured. Preferably the base is adapted to provide a surface which is not easily penetrated by the lower-most portions of the support component to prevent any breach by the support component of the formwork or other surface defining the mould surface for the concrete slab.

The support component is preferably a solid structure but it may have, for example, a hollow core formed by the simple removal of a pin inserted in the mould or have 20 material-saving openings therethrough similar to that described in relation to the shank.

The support component may include one or more legs. The support component may S include substantially vertical and/or inclined structural members.

.The support component preferably includes a first pair of ribs located in the same plane as the joint line. To stabilise the first pair of ribs, the upstanding support component preferably includes one or more lateral reinforcing members. The lateral reinforcing members may be in the form of ribs. Preferably these lateral ribs extend in a vertical plane substantially perpendicular relative to the first pair of ribs, although it is not necessary for the purposes of the invention that the lateral ribs be in an absolutely vertical plane or perpendicular relative to the first pair of ribs. For example, the lateral ribs may be oriented at an angle of about 15 to about 75 degrees relative to the first pair of ribs.

Each rib of the support component may or may not be in a plane corresponding to a rib -7of the leg component. The support component may have a different number of ribs orientated in different planes compared to the leg component. Preferably, however, the first pair of ribs together with the lateral ribs correspond directly to the respective ribs of the shank and are adapted to be located in the same respective planes.

In a particularly preferred embodiment the leg and support components each include a first pair of ribs in a first vertical plane integral with at least one second pair of ribs in at least one second vertical plane perpendicular to the first plane. The support component may in horizontal cross-section be cruciform- or H-shaped as described above in relation to the leg component. The outermost edges of the support component may be considered to define linear boundaries of a first area including and extending between the ribs of the support component in a horizontal plane. A second area defined by the support component when viewed in plan may be described as the projectional crosssectional area of the support component. The projectional cross-sectional area of the support component is preferably less than or equal to 5% of the first area.

In another embodiment of the invention, the support component has attached thereto or i integrally formed therewith lower seat means to support at least one lower layer of reinforcing. The lower seat means may be located strategically on any suitable part of 20 the support component. The lower seat means may comprise a seat located on at least S"one member of the first pair of ribs. The lower seat means may include a first lower seat located on one member of the first pair of ribs and a second lower seat may be located ,n the opp mmb rct of h first ,pr of ribs. Thc first and second lower seats may v v U r s t p a l r L, Li sLnd support reinforcing at the same or at different levels in the same or different directions 25 depending on the requirements of a particular application.

In yet another embodiment of the invention, the support component includes projections which are adapted to space the support component from the formwork. The projections may be in the form of pins, knobs, lugs and the like which collectively form a small contact surface area compared to the projectional cross-sectional area of the support component.

The engagement members on the leg and support components may include a variety of configurations or arrangements as will be appreciated by the person skilled in the art.

-8- For example, the engagement means may include interlocking parts, snap fit parts or parts adapted for a friction fit. The engagement means may include male and female parts. Preferably, the support component includes a male part and the leg component includes a female part, See o *•e p:\OPER\DCD\PROVS\MODFRX\MODFIX COMPLETE.DOC- 17/ 11/00 -9although in practical terms it would be appreciated that the parts are interchangeable between the components. However, where the support component includes the male part this may assist in decreasing the amount of grit etc. which may adhere to the support component and interfere with the operation of the engagement members. The combination of the complementary engagement members will hereinafter be referred to as the engagement means.

As will be appreciated by the skilled person, each component of the bar chair can be readily injection moulded in a simple two-part mould as described in AU 671734 and AU 703307.

The two parts of the mould may define respective sides, usually respective halves, of each component. Such a mould may facilitate the manufacture of thinner wall sections in the mould than, for example, is possible using the design of AU-S-92837. It enables faster production times and lower manufacturing, packing and freight costs. This particularly so in the moulding of the leg wherein inserts may be used to vary the length of the shank, thereby assisting to reduce the cost of each mould and therefore of each mould product made therefrom, particularly for bar chairs over about 60mm high and most especially for bar chairs between 100mm and 220mm high. In one embodiment a two-part mould corresponds to the upper and lower portions of the support component, rather than the respective sides. This method is ""!particularly convenient when projections are formed on the lower portion of the support o• component.

The features of the bar chair, including seat means and engagement means, are preferably orientated such that in manufacture the two parts of the mould are able to slide in and out •o without the need for sliders to define, for example, the saddle recess. Accordingly, where a simple moulding process is required, the surfaces of the saddle are preferably substantially 25 at right angles to the plane of the joint line of the two part mould in which the parts travel i horizontally. However, where a more complex design is required and depending on the orientation of the seat means, it may be necessary to use sliders in the moulding process. An example of this is where the longitudinal axis of the seat means or a cavity of the engagement means is transverse to the direction of travel of the two mould parts. Accordingly, where the engagement means includes a female part on one of the components, that female part may be defined in the mould using a slider. However, the need for a slider to define the female part P:\OPER\DCD\PROVS\MODRXWMODFIX COMPLETEDOC- 17/11(IM may be avoided by using a two-part mould in which the mould parts travel in a direction corresponding to the vertical axis of the component including the female part. Moreover, persons skilled in the art will appreciate that the selection of mould parts which travel either vertically or horizontally relative to the moulded product is dependent on the particular features of that product.

The processes for moulding a bar chair or component thereof described herein represent further aspects of the invention.

The components may be made of any suitable plastic material or combination of polymer materials. For example, the plastic material may include acrylonitrile butadiene styrene (ABS) graft terpolymers, polypropylene, polycarbonate, high density polyethylene, or an alloy thereof.

In purely functional terms, ABS and polycarbonate are preferred since they give greater support strength, allowing thinner sections, faster production times and higher softening 15 temperatures. However, in terms of economy and availability, polypropylene may be the Q preferred material in practice.

A plurality of bar chairs made according to the invention may be used in making a concrete slab in a mould defined by formwork. The plurality of bar chairs may each have single or multiple levels of seat means to support the reinforcing. Preferably, each bar chair includes an upper and a lower level seat means to support two corresponding levels of reinforcing spaced from the surface of the slab at predetermined distances. The slab may include a first layer of reinforcing close to a first surface of the slab and a second layer of reinforcing close O6 OI S°to a second opposite surface of the slab, the closeness in practice being determined by the 6 25 building or other regulations which apply in a particular jurisdiction. The first and second layers of reinforcing may be separated by a distance defined by the total slab thickness less the combined minimum distance the first and second layers are permitted to be set from the first and second slab surfaces, respectively.

P:\OPEROCD\PROVS\MODF1XIMODFIX COMPLETEDOC 17/11/00 -Il- Description of the Drawings The invention will now be more fully described, by way of non-limiting examples only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a bar chair according to one embodiment; Figure 2 is a side plan view of a bar chair according to a second embodiment; Figure 3 is a perspective view of a support component according to the first embodiment; Figure 4 is a perspective view of the shank portion of a leg component of the first embodiment; and Figure 5 is a schematic top plan view of the bar chair according to the first embodiment.

V Referring to Figure 1 there is shown a bar chair according to a first embodiment of the ooeoo 20 invention. The bar chair comprises a support component and a leg component :°oooe The support component comprises a first pair of ribs (4a, 4b) located in a plane corresponding to the joint line of the two part mould (not shown) from which the support component is formed. The first pair of ribs (4a, 4b) include recessed portions on their oooo* 25 upper surface which provide lower seat means (5a, 5b). The lower seat means (5a, 5b) each include a planar horizontal rest (6a, 6b) at the respective ends of which extend upwardly, at •a sharp inclination, retaining walls (7a, 7b) which taper in the upward direction. The lower "!seat means (5a, 5b) present a broader surface than the thin wall of the first pair of ribs (4a, 4b) with which to support the lower seat means (5a, 5b). The outermost edge of each of the pair of first ribs (4a, 4b) depends downward from the tapered ends (8a, 8b) terminates in an outer projection (9a, 9b). Intermediate the lower surface of each member of the first pair of ribs (4a, P:\OPER\DCD\PROVS\MODFX\MODFIX COMPLETEDOC 17/1100 -12- 4b) is located and inner projection (10b) so that in total the first pair of ribs (4a, 4b) include four projections (9a, 9b, 10 Oa, The support component includes a second lateral or transverse pair of ribs (1 la, 1 b) orientated normal to the first pair of ribs (4a, 4b) in a vertical plane. Each member of the second pair of ribs (1 la, 1 lb) comprises a substantially triangular planar panel integrally formed with and intersecting the first pair of ribs (4a, 4b) midway along its length. The outer lower portion of each member of the second pair of ribs (1 la, 1 Ib) includes second outer projections (12a, 12b) in the same horizontal plane as the four projections (9a, 9b, 10a, The under surface of the second pair ribs (1 la, 1 ib) extends substantially horizontally to where the ribs (4a, 4b, 1 la, 11 b) meet. The upper surface of each of the second pair of ribs (1 la, 1 lb) extend from the second outer projections (12a, 12b) upwardly at an inclination and terminate at a small horizontal ledge (13a).

The upper inner walls of each of the ribs (4a, 4b, 11 a, 11 b) together fonrm an engagement member (not shown) which is cruciform-shaped in cross-section (refer to description of Figure 3).

The leg component includes a shank (14) of substantially constant cross-section corresponding to the cross-section of the support engagement means. The lower portion of .oo.

the shank (14) terminates in leg engagement member (15) comprising a cruciform-shaped sleeve with a complementary shape to receive the male engagement member of the support S component in a tight friction fit. The upper portion of the shank (14) terminates in an upper seat means The upper seat means (16) comprises a saddle (17) which is substantially Vshaped and has a narrow recess (18) at the apex of the V adapted to receive a reinforcing bar.

The arms of the extend upwardly and outwardly and terminate in inwardly projecting tabs The tabs (20) taper towards one another and are separated by a gap (21) which is smaller :"oi than the width of the reinforcing bar to be received by the upper seat means The tabs are deflectable whereby to allow intentional entry or removal of a reinforcing bar to or from the upper seat means respectively.

P:\OPER\DCD\PROVS\MODFIX\MODFIX COMPLETEDOC 17/11/00 13- A bar chair (30) according to a second embodiment of the invention is shown in Figure 2 and illustrates that the lower seat means (5a, 5b) may be adapted to support reinforcing at different levels. This drawing also illustrates that the features of the bar chair such as the upper seat means the second pair of ribs (11 a) of the support component and the corresponding second pair of ribs (14a) of the leg component, and the lower seat means (5a, 5b) are each orientated in the direction of travel of the parts of the two part mould where the parts travel along a horizontal axis. The lower seat means (5a, 5b) are perpendicular to the upper seat means (16) in the final use of the bar chair. The remaining features of the bar chair (30) are located along the joint line of the two part mould in which the components of the bar chair (30) are formed with the exception of the leg engagement member (15) which requires the insertion of a slider during the moulding process. In this manner, the bar chair according to the present invention can be efficiently and economically manufactured using the two-part mould described.

The engagement member of the support component is best shown in Figure 3 in which the upper portions of each of the ribs (4a, 4b, 11 a, 1 b) combine to form a male portion having a cross-sectional cruciform-shape. The male portion (40) is configured to minimise i •the collection of unwanted grit and debris on its surface to assist in providing a clean fit of the leg component engagement means Accordingly, the upper portions of the ribs (4a, 4b, 20 11 a, 11 b) forming the male portion (40) may be bevelled or tapered towards its upper end, .o.o although it would be appreciated by a person skilled in the art that this is not essential for the effective operation of the engagement means. With reference to Figure 4, the leg component engagement member (15) includes a sleeve (41) having a female portion (42) of substantially cruciform-shape complementary to the male portion said female portion (42) being defined by the sleeve The sleeve (41) may be flared at the opening corresponding to the female portion (42) to assist in the easy alignment and initial engagement of the male and °female portions (40, 42) and the female portion (42) may internally narrow to provide a tight i fit for the engagement means. The ledge (13a) of the support component provides a resting surface for the female portion (42).

P:\OPER\DCD\PROVS\MODFIX\MODFIX COMPLETEDOC 17/11/00 14- With final reference to Figure 5, there is shown a plan view of the bar chair (seat means not shown). The outermost edges of the support component define linear boundaries of an area A including and extending between the ribs and is identified by all the areas marked with crosses, dots and stripes. The projectional cross-sectional area B of the support component corresponding to the formwork contacting area of the projections and identified by the areas marked with stripes and dots is less than or equal to 5% of area A. The formwork contacting areas C of the projections marked with stripes are up to about 30% of the projectional cross-sectional area B.

In practice the bar chair is provided in two separately moulded components, the support component and the leg component and are assembled together prior to being manually placed on the formwork at strategic positions on the formwork depending on the reinforcing requirements of a particular slab. The leg component is provided in a variety of predetermined lengths which may be colour-coded or moulded with the length embossed to enable easy distinguishability on sight. The appropriate sized leg component is selected and the bar chair is preassembled and then placed on the formwork in an upstanding position ready to receive one or more layers of reinforcing. The cruciform shaped bar chair (1) provides a stable structure capable of bearing the weight of reinforcing and operators walking thereon and is not easily distorted in shape or tipped over. As is standard in the art, the 20 concrete is then poured and cured, the formwork removed and, unless formed in situ, the cast :°ooo• product is transported to the site of installation. Because the formwork contacting area C of the projections (9a, 9b, 10a, 10b) is small, the visibility of the lower most portions of the bar chair is minimised on the underside surface of the slab thereby improving the aesthetic appearance of that surface.

.o.ooi An alternative embodiment of the support component is shown in Figure 6. In this embodiment each of the four ribs (21a, 21b, 21 c and 21d) is provided with seat means (22a, 22b, 22c and 22d) for supporting lower layers of reinforcing. The seat means on the ribs are provided at different heights so that simple rotation about the cruciform axis can change the height at which the lower layer of reinforcing is set. The seat means are marked with tabs (23a, 23b) to indicate the height of the seat. In the embodiment shown tabs 23a and 23b P-XOPER\DCD\PROVS\MODF1X\MODFlX COMPLETE.DOC 17/11/00 indicate heights of 25mm and 30mm respectively. The heights of seats 22a and 22d are and 40mm respectively. The support component shown in Figure 6 is prepared in a two part mould joined along mould line 24.

The invention has been described by way of non-limiting example only. Many modifications and variations may be made thereto without departing from the spirit and scope of the invention as hereinbefore described.

**ee

Claims (18)

1. A multiple-component bar chair for supporting reinforcing for concrete including: a leg component of substantially ribbed configuration having seat means at its upper end to support the reinforcing; and an upstanding support component adapted to stand on formwork and to support the leg component in an upright position, wherein the leg component has an engagement member capable of engaging with a complementary engagement member on the support component such that the leg component is supported in said upright position.

2. A multiple-component bar chair according to claim 1 wherein the leg component is provided in variety of lengths.

3. A multiple-component bar chair according to claim 1 or claim 2 wherein the leg component includes a shank extending between the engagement means and the seat means.

4,O 4. A multiple-component bar chair according to claim 3 wherein the shank has a .oo" substantially constant cross-section along its length.

5. A multiple-component bar chair according to claim 4 wherein the shank has a cruciform shaped cross-section.

6. A multiple-component bar chair according to any one of claims 1 to 5 wherein the seat means includes a saddle which is configured to receive reinforcing.

7. A multiple-component bar chair according to claim 6, wherein the saddle has a configuration which is v-shaped. 25

8. A multiple-component bar chair according to any one of claims Ito 7 wherein the support component has two pairs of transverse ribs, one pair of ribs being oriented substantially perpendicular to the other pair of ribs.

9. A multiple-component bar chair according to claim 3 wherein the two pairs of ribs of the support component correspond in orientation with two pairs of ribs located on the shank.

A multiple-component bar chair according to any one of claims 1 to 9 wherein -17- the leg and support components each include a first pair of ribs in a first vertical plane integral with at least one second pair of ribs in at least one second vertical plane perpendicular to the first vertical plane.

11. A multiple-component bar chair according to any one of claims 1 to 10 wherein a projectional cross-sectional area of the support component is preferably less than or equal to 5% of the area including and extending between the ribs of the support component in the horizontal plane.

12. A multiple-component bar chair according to any one of claims 1 to 11 wherein the support component has attached thereto or integrally formed therewith lower seat means to support at least one lower layer of reinforcing.

13. A multiple-component bar chair according to any one of claims 1 to 12 wherein the engagement member on the leg component is adapted to interlock, snap fit or friction fit with the engagement member on the support component.

14. A multiple-component bar chair according to any one of claims 1 to 13, wherein the engagement member and the support component includes a male part and the engagement member on the leg component includes a female part for receiving the male part to interengage the components.

15. A multiple-component bar chair according to any one of claims 1 to 14, wherein the support component includes a plurality of projections adapted to space the support component from the formwork, the projection including a contact surface area for contacting the formwork, the contact surface area being at most i •30% of the projectional cross-sectional area of the support component. o

16. A multiple-component bar chair according to claim 15, wherein the projections *are in the form of pins, knobs, lugs and the like which collectively form a small 25 contact surface area compared to the projectional cross-sectional area of the i: support component. 0

17. A multiple-component bar chair for supporting reinforcing for concrete, substantially as hereinbefore described with reference to what is shown in the accompanying drawings.

18- Dated: 15 June, 2004 PHILLIPS ORMONDE FITZPATRICK Attorneys for: MODFD( AUSTRALIA PTY LTD 0~ a.. 9 S 0 a. 0 SQ. ObS* 9~J* I 0* 9 555* S p IS C 9 C0**SS S