AU735297B2 - Bar chair - Google Patents

Description

Regulation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: The Reinforcement Bar Spacer Co Pty Ltd Actual Inventor: John Wolfe St Alban 4 Address for Service: MADDERNS, 1st Floor, 64 Hindmarsh Square, Adelaide, South Australia, Australia Invention title: BAR CHAIR Details of Associated Provisional Application No: PO 6142 dated 11th April 1997 The following statement is a full description of this invention, including the best method of performing it known to us.

method of performing it known to us.

This invention relates to apparatus suitable for supporting reinforcement and conduits prior to and during the placement of concrete into a cast concrete element or reinforced concrete structure.

BACKGROUND

Devices for supporting reinforcement and conduits often referred to as "bar chairs" and "placing aids" have been in use for as long as reinforcement has been used in concrete structures. These terms are not universal throughout the industry but are used in this specification to conveniently refer to those types of devices in their broadest sense.

Concrete bar chairs were common in past times most of which were formed with an open substantially U-shaped channel which readily located rods and 15 portions of reinforcement mesh in a raised position above the prepared surface during the pouring of concrete into a prepared formwork. Bar chairs made of concrete were used because it was thought that they integrated with the concrete to form a watertight bond (essential to resist the ingress of moisture towards the corrosive reinforcement elements) between the concrete of the bar chair and the S 20 poured concrete of the finished structure.

Eventually, bar chairs of metal became available, typically having plastic covered ends which rested on a prepared surface. The prepared surface could comprise a variety of surface materials including form ply, precast or concrete slabs, steel plates or prepared ground covered with water impermeable plastic sheeting.

Metal bar chairs were configured to support rods and mesh in ways which were more secure than the prior concrete versions discussed above and were initially cheaper and more easily transported than prior concrete bar chairs.

More recently bar chairs made of plastic have become readily available, primarily because these products are cheaper than metal bar chairs and offer similar or increased benefits compared to metal bar chairs. However, plastic bar chairs are typically still similar in function and shape to metal bar chairs. Plastic bar chairs can be designed to provide strength so as to span large distances and withstand and spread large loads, such as for instance workers stepping on the rods and mesh during the preparation phase before pouring concrete into the prepared formwork, while being significantly cheaper to manufacture than their metal equivalents.

It is a relatively recent requirement for thicker concrete structures to be made and consequently the height at which reinforcement needs to be supported within those structures has also become higher than was previously the case.

Consequently the first response to this need has comprised the provision of S taller bar chairs. The configuration of these taller bar chairs is not markedly different S. to bar chairs used for lower heights.

Unfortunately, this resulted in bar chairs which merely provided a single level of support or in the case of crossed bars, a means to support the two crossed bars at right angles one above the other.

S.Typically the manufacturing processes for taller bar chairs have been the same 20 as for smaller bar chairs except for the size of the forming elements, typically a die in the case of plastic injection moulded bar chairs. These dies were custom made for o°oo.

e each height required of the bar chair.

The perceived need to provide a large number of different bar chair sizes, sometimes varying in height as little as 5mm, not only increased the number of dies required for manufacture but added to confusion on the construction site as different but similar heights of bar chairs would be deceptively similar to others.

The inventors have designed a bar chair which not only provides greater height but incorporates features advantageous to the user of the bar chair as well as building/structure design engineers. Furthermore, the bar chair is also made in such a way that manufacturing costs are minimised because more than one type/configuration/height of bar chair can be made from essentially the same die.

Other features will become apparent in the following broad statements of the invention. These features aim to overcome or minimise the problems described.

BRIEF DESCRIPTION OF THE INVENTION In its broadest form the invention is a reinforcement and ducting support [O apparatus for supporting reinforcement or ducting elements in a reinforced concrete structure wherein said apparatus comprises: a support framework adapted to support downward or lateral forces exerted by said elements, and -"two or more vertically aligned and spaced seats on said support framework, a .15 lowermost said seat being located on said support framework and each said seat is adapted for positioning at least one said element, wherein each said seat, except an uppermost seat, is connected to a seat above.

In a yet further aspect of the invention said support framework further :20 comprises at least two spaced apart substantially upright support elements adapted to support each other and support downward or lateral forces exerted by said elements located in one or more of said seats.

In a yet further aspect of the invention each of said seats has an upper surface having a groove therein for locating a said element thereon.

In a further aspect of the invention said connection between said seats comprises at least one severable join.

In a yet further aspect of the invention at least one of said joins is adapted to allow said seat above to pivot about a said join if one or more of other of said joins is severed.

In a further aspect of the invention said seat below said severed join is adapted thereby to retain said element on said seat.

In a further aspect of the invention wherein all the joins between two adjacent seats are severed said apparatus is shortened.

In a yet further aspect of the invention said severed apparatus portion forms a S useable apparatus for supporting an element.

In a further aspect of the invention there are a pair of connections between 15 vertically spaced seats.

In a yet further aspect of the invention said pair of connections are severable joins.

20 In a further aspect of the invention said seats are equally spaced.

In a further aspect of the invention two of said seats are connected with only one connection located so as to allow the placement of an element onto a lower seat through a gap left by the absence of a further connection between said seats.

In a further aspect of the invention said device has a base integral with free ends of said support framework.

In a further aspect of the invention said base is broader than said support framework.

In a further aspect of the invention said base excludes a portion of the area below said apparatus so as to increase the stability of said device on an uneven supporting surface.

In a yet further aspect of the invention said base is annular and substantially flat bottomed.

In a yet further aspect of the invention said device is made from plastic material.

In a further aspect of the invention a plastic injection mould for forming said apparatus according claims 5 to 19 comprises S. a cavity of fixed volume and length which is adjustable in longitudinal length S* and volume by the placement of an insert wherein said insert is locatable in place of a S: 15 said pair of said severable joins so as to prohibit formation of said joins above a said seat.

Specific embodiments of the invention will now be described in some further detail with reference to and as illustrated in the accompanying figures. These embodiments are illustrative, and not meant to be restrictive, of the scope of the invention.

BRIEF DESCRIPTION OF THE FIGURES Fig. 1 depicts a perspective view of a bar chair according to the invention; Fig. 2 depicts a side view of a bar chair similar to that depicted in Fig. 1; Fig. 3 depicts a view of another side view of the bar chair depicted in Fig. 2; Fig. 4 depicts a side view of a bar chair as depicted in Fig. 2 having an annular base; Fig. 5 depicts a bottom perspective view of one form of a base for a bar chair according to the invention; and Fig. 6 depicts a bar chair according to the invention showing examples of the way in which reinforcement and ducting elements can be supported by the vertically aligned seats and supporting framework of the bar chair.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION The bar chair 10 depicted in Figs 1-4 is but one embodiment of a bar chair according to the invention. Like elements in each of the Figures of this specification will be identified with like numerals. It will also be noted that the bar chair is S. illustrated with a nominal break between seat portions 12 so as to depict that its manufactured height is variable. Seat portions 12 are also referred to as seats in this specification and may have different shapes to that depicted in this specification.

Bar chairs depicted in relation to the embodiments described herein are shown standing upright and it will be recognised that this is the primary orientation for its use. However, this bar chair may also be used in the horizontal orientation for S 20 example in a formwork or in a column on its side for the purpose of maintaining the distance of reinforcement rods and conduit away from the outer surface of the prepared vertical formwork during the concrete pouring process.

Bar chair 10 comprises a plurality of seat portions, like the seat portion 12, and a support frame 14. In this embodiment the support framework is arranged to provide a support base having a generally broader purchase on the prepared surface than the seat portions. The term support frame work used in this specification and in the claims is indicative of the likely structure of the portion of the spacer below the seat portion since for economy of manufacture it is typical to use easily formed panels and webs rather than a solid structure. However, the term should not be interpreted to limit the form of the portion of the spacer below the seat portion. The support framework of this embodiment comprises two major panels 16 and 18 which are inwardly sloped so as to form a trapezoidal shaped main frame. This shape is used because it is a stable shape for relatively tall structures especially when side ways and downward forces are exerted upon the upper apex region of the trapezoidal framework.

The two panels 16 and 18 of bar chair 10 are of the form of broad panels which also have a trapezoidal outer form as can be seen in the side view of the bar chair in Fig. 3.

Unfortunately, although the panels 16 and 18 will suffice in some conditions to support the seat portions which themselves are supporting reinforcement rods and ducting, it is preferable to brace these panels so as to strengthen them and stabilise the bar chair. One preferable means includes the use of lateral reinforcement ribs 20 and 22 located on the outer surfaces of panels 16 and 18 respectively. These S 15 ribs comprise trapezoidal webs which extend outwards at the base of the panels and reduce in depth like a buttress towards the upper portion of the panel.

Preferably further bracing within the framework is located between the panels in the form of crossed webs 24 and 26 which extend from the bottom of each panel to 20 the top of the opposite panel. The shape and thickness of these webs is similar to the panels 18 and 16 depicted in Figs. 1 and 2.

It is also preferable to have additional bracing members within the framework, such as that shown between the region where the crossed webs 24 and 26 merge as well as at the lower regions of the panels where the crossed webs 24 and 26 respectively merge with the panels 16 and 18.

Bracing members 28 and 30 are used at the upper portion of the support framework and a further bracing member 32 is preferably located between the zone at which the webs and panels merge.

Preferably, the bracing members used comprise panels or bars integrally formed within the framework of the bar chair at the time of manufacture.

Each brace has been strategically located and sized with a view to minimising the amount of material used while providing the maximum amount of strength to the support framework of the bar chair.

Above the support framework is located two or more vertically spaced seat portions 12 within which one or more reinforcing or ducting elements can be located.

The first seat 12 bridges across the top of the support frame and preferably across the top of the apex of the panels 18 and 16. In this embodiment the first seat 12 is formed integrally with the top portion of the support frame so as to brace and prevent the panels moving with respect to each other thus making the bar chair more 15 stable.

S* The first seat 12 has a groove or upwardly open U-shaped slot 34 running S: parallel to the plane of the panels 16 and 18. This groove 34 is also shown in side view in Fig. 2. The groove 34 has a size so as to be suitable to cradle a reinforcement .20 bar or duct in the manner depicted in Fig. 6. However, a relatively light duct having an outer diameter greater than the width of the seat portion can be placed on a top Seo most seat portion tied on to the bar chair and still be adequately supported.

The groove in this embodiment is semi-circular in shape but it may be Vshaped or U-shaped as long as it is capable of locating a suitably sized reinforcement bar or conduit as required. It is also preferable that the groove be shaped so as to centre the resting reinforcement bar or conduit in the groove but that is not essential.

The space between the bottom surface 36 of the seat 12' located directly above the seat 12 and the bottom of the groove 34 is such as to allow the outer diameter of a suitably sized reinforcement bar or duct to fit therebetween.

Even though the outer diameter of some reinforcement or ducting elements are smaller than the space available it is still possible to secure the rod or duct by tying it onto the bar chair. Such tying, fixing or twitching can be achieved by using a wire strung around the top of the element on one side of the seat, passing that wire through the aperture below the seat upon which the element rests up and over the element, returning to the other side of the bar chair via the aperture previously mentioned and tying the ends of the wire above the element, thereby securing the element to the bar chair.

The fixing method (twitching) described above is but one of many ways available to a worker using this type of bar chair as will be non-wire means to secure the reinforcement or conduit element to the bar chair.

The seat 12' located directly above seat 12 has in this embodiment, exactly the same dimensions and configuration as seat 12. A connection between seats on at least one side of the bar chair between the seats 12 and 12' is formed by a cylindrical joint element 38 which preferably extends the full width of the seat as depicted in Fig. 1.

The use of the term joint element is meant to indicate that in some uses the join between seats acts like a joint in that the seats can be moved relative to one another 20 but the use of the term is not meant to restrict the form of the join between seats of the invention.

The cylindrical shape is but one shape of many that could be used for the joint element.

A plastic injection mould which is used to manufacture the bar chair described, and, as will be described in further detail later in the specification, is preferably arranged to use, or not use, inserts of cylindrical form at the location of the joint element 38. If an insert is absent, the plastic injection mould will fill the cavity to form a join between one side of a chair and the same side of a chair above or below it. If the insert is in place, it prevents the flow of plastics into the area otherwise occupied by the joint element 38 and leaves a gap between a lower seat and an upper seat on one side of the bar chair. The result of this later configuration is depicted at 38' in Fig. 6.

Advantageously in one further embodiment of the invention the manufactured or user created absence of a join on one side of a chair allows reinforcement for ducting to be placed into a chair from that side rather than via the aperture formed between the groove and the underside of the next higher chair. This is particularly convenient when a bar chair needs to be located intermediate the ends of a long length of reinforcement rod or conduit.

For example, as depicted in Fig. 6, the bar chair can be placed into location anywhere along the length of a reinforcement rod by inserting the rod through the pre-moulded gap between seats. If the rod diameter is larger than the gap provided the remaining join between seats acts like a joint, flexure element, hinge or pivot, allowing the gap to be widened so as to allow the rod to pass into the seat portion and rest in the groove provided therein. The gap typically returns to its manufactured size, thus, forming a barrier to the movement of the rod out of the seat it was placed into.

20 Since it is advantageous for a reinforcement rod or a duct to be located at a constant height above the level upon which the bar chair is placed, the user can easily oo.. count the number of chairs up from the lowest chair to ensure the rods and conduits are located above the correct minimum height required for the prepared formwork.

A further advantage of the configuration of this embodiment is that if the seats are equally spaced the user will quickly learn and become familiar with the spacings and measurements associated with them. However, this does not preclude the use of seats having varied heights between them or the array of apertures being placed such as to conform to typical minimum height standards for rods and ducts placed in a typical formwork arrangement.

The arrangement of seat 12 with respect to seat 12' as described is easily repeated to produce a bar chair comprising a plurality of vertically spaced seats.

A bar chair comprising one or more such seats can be used to locate more than just reinforcement rods and ducts one above the other. Higher or lower other seats can be used to support one or more of these elements and the top most seat can be used to support either of these elements or a portion of a reinforcement mesh, as depicted in Fig. 6.

A bar chair according to the invention can also be used to support reinforcement and ducts which need to be sloped relative to the supporting surface of the formwork. For example, a conduit may be located in the uppermost seat at one end of a ducting run and at appropriately spaced bar chairs along that run the next lower seat can be used to gradually reduce the height of the duct relative to the base 15 of the bar chair and the supporting surface it has been placed upon.

o .A yet further arrangement achievable with a bar chair according to the invention comprises the use of a preformed plastic member (not depicted) or a Srelatively short off-cut of reinforcement bar located, at any desired height in an 20 appropriate seat which when in place supports a portion of reinforcement mesh or other element offset from the vertical centre of the bar chair. Since there exists a "°variety of seats at different heights a bar chair of this invention may be used to set the reinforcement, duct or mesh at any one of the available heights as well as support other reinforcement and ducting elements as required.

A yet further application of bar chairs according to the invention is achieved by spacing two such bar chairs apart, facing each other, and placing a bridging element from one to the other, using any one of the seats at a required height above the supporting surface. A bridging element (not depicted) may comprise a preformed plastic member shaped at its ends for insertion and possible engagement with the bar chair. Alternatively, the element may comprises an off-cut of a reinforcement bar or any other suitable material available on the construction site.

With the bridging element as described in place, a variety of formwork elements can be placed at a required height above the prepared surface.

Advantageously, the bridging arrangement is very strong and can be used to support large reinforcement and ducting elements as well as other large elements such as pipes etc that are also used within a concrete structure and need to be spaced from the formwork and the prepared surface during the concrete pour.

Furthermore, a tall bar chair of this configuration can be used for any intermediate height requirement in one or more of the configurations described, because it can be easily and suitably modified by hand on site. This can be achieved by manually cutting the joins between seats of the bar chair to the maximum height required.

15 This approach is very cost effective and convenient to the user and site manager. The alternative has been to determine the exact quantity of each of many different sizes of bar chairs required which is always difficult to estimate as it is also equally difficult to ensure that there are enough stocks on site of each bar chair at the time they are required. It is also very difficult for users to sort the available stocks 20 and then ensure that the correct size bar chair is used.

A single tall bar chair of the type described can be adapted on site in a variety of ways. Firstly, the maximum height of the bar chair may be adjusted by removing or cutting at the joins. Secondly, the height of the bar chair can be adjusted by cutting across the complete width of a join or by the complete removal of a join, thereby providing a gap for the access of a reinforcement bar or conduit into the space above a seat. Furthermore, it is possible for the joined seat portions removed from the top of a bar chair to be used as a bar chair itself. It is also possible to use the removed upper seat portions of a bar chair with a base adaptor to increase its stability and provide yet another bar chair for use on the site.

The bar chair of the invention can also be integrally formed with a base which will advantageously increase the stability of the bar chair. A flat base having a broader area than that circumscribed by the base of the bar chair advantageously increases the stability of the bar chair.

It may also be preferable to form the base to occupy only a portion of the area below the bar chair wherein such an arrangement can provide increased stability on uneven prepared surfaces. In this particular embodiment, the shape of the base is annular, but other shapes are also possible. For example, the use of pads (joined or unjoined) below each of the panels 16 and 18 could be useful in spreading the load of those panels. The load spreading achieved with the base is preferable when these bar o: chairs are located on a prepared covered surface, on the covering comprises moisture impenetrable membranes which may otherwise be punctured by the bottom surface :of the bar chair.

It is also a preferable but not a necessary feature of the manufacture of this bar chair that the base for the bar chair is added by appending an appropriate mould to the mould described briefly above. This approach allows the inclusion of a base as an optional feature and by using different base thicknesses with different appended dies 20 the final height of the bar chair can be varied.

A plastic injection mould suitable for the manufacture of bar chairs preferably has the following features. These features result in a cost and time effective plastic injection mould for the manufacture of bar chairs according to the invention.

It is an aspect of the invention that the plastic injection mould for forming the bar chair according to the above mentioned descriptions comprises a cavity into which plastic can be injected. A single cavity having the maximum height of a bar chair is created as the base mould, and by using inserts, the single cavity can be changed to produce a bar chair of a desired lesser height.

The design of the mould determines where the joins between seats of the bar chair described are located and its design is such that when an insert is placed within the void created to form a joining member, the seat below the join is terminated and plastic material injected into the mould does not flow higher than the insert. If two inserts are used above the same seat then the maximum height of the bar chair formed from that injection mould is the height of the top of that particular seat. Such an arrangement also makes it possible for one or more of the inserts along one or either of the sides of the bar chair to be inserted so as to prohibit a join being formed and thereby form one or more gaps 38' as depicted in Fig. 6. The gaps formed by this arrangement allow for the access of reinforcement and or conduit elements onto the respective seat/s.

As mentioned previously the join between seats could be formed of different o 0.

shapes, however a cylindrical shape is preferable.

06o0o It will be appreciated by those skilled in the art, that the invention is not restricted in its use to the particular application described nor is it restricted to the features of the preferred embodiments described herein. It will be appreciated that various modifications can be made without departing from the principles of the invention, therefore, the invention should be understood to include all such modifications within its scope.

Claims (22)

1. A reinforcement and ducting support apparatus for supporting reinforcement or ducting elements in a reinforced concrete structure wherein said apparatus comprises: a support framework adapted to support downward or lateral forces exerted by said elements, and two or more vertically aligned and spaced seats on said support framework, a lowermost said seat being located on said support framework and each said seat is O adapted for positioning at least one said element, wherein each said seat, except an :0 uppermost seat, is connected to a seat above. oo,

2. A reinforcement and ducting support apparatus according to claim 1 wherein 0 said support framework further comprises at least two spaced apart substantially upright support elements adapted to support each other and support downward or lateral forces exerted by said elements located in one or more of said seats.

3. A reinforcement and ducting support apparatus according to claim I wherein each of said seats has a upper surface having a groove therein for locating a said element thereon. .0e.

4. A reinforcement and ducting support apparatus according to claim 1 wherein said connection between said seats comprises at least one severable join.

5. A reinforcement and ducting support apparatus according to claim 4 wherein at least one of said joins is adapted to allow said seat above to pivot about said join if one or more of other of said joins is severed.

6. A reinforcement and ducting support apparatus according to claim 1 wherein at least one of said joins is severed and said seat below said severed join is thereby available to support a said element passed through said severed join and placed thereon.

7. A reinforcement and ducting support apparatus according to claim 1 wherein said seat below said severed join is adapted thereby to retain said element on said seat.

8. A reinforcement and ducting support apparatus according to claim 1 wherein all said joins between two adjacent seats are severed said apparatus is shortened. S..0

9. A reinforcement and ducting support apparatus according to claim 8 wherein said severed apparatus portion forms a useable apparatus for supporting an element.

A reinforcement and ducting support apparatus according to claim 1 further comprising a pair of connections between each vertically spaced seats.

11. A reinforcement and ducting support apparatus according to claim wherein said pair of connections are severable joins. o:20

12. A reinforcement and ducting support apparatus according to claim 1 wherein two of said seats are connected with only one connection located so as to allow the placement of an element onto a lower seat through a gap left by the absence of a further connection between said seats.

13. A reinforcement and ducting support apparatus according to claim 1 wherein said seats are equally vertically spaced from each other.

14. A reinforcement and ducting support apparatus according to claim 1 said support framework further comprises at least two spaced apart upright support elements and a base integral with free ends of said at least two support elements.

A reinforcement and ducting support apparatus according to claim 14 wherein said base is broader than said support framework.

16. A reinforcement and ducting support apparatus according to claim 14 wherein said base excludes a portion of the area below said apparatus so as to increase the stability of said apparatus on an uneven supporting surface.

17. A reinforcement and ducting support apparatus according to claim 16 said base is annular and substantially flat bottomed. S

18. A reinforcement and ducting support apparatus according to claim 1 said apparatus is made from plastic material. *oo.

19. A plastic injection mould for forming said apparatus according claim 1 15 comprises •00o0 a cavity of fixed volume and length which is adjustable in longitudinal length and volume by the placement of at least one insert wherein said insert is locatable 0 between said seats to prohibit formation of a connection above a said seat and thus limit the longitudinal length of said cavity and thereby a plastic injected apparatus formed in said cavity.

A plastic injection mould for forming said apparatus according claims 4 to 18 comprises a cavity of fixed volume and length which is adjustable in longitudinal length and volume by the placement of an insert wherein said insert is locatable in place of a said pair of said severable joins so as to prohibit formation of said joins above a said seat.

21. A plastic injection mould for forming said apparatus according claim further comprises the placement of at least one insert wherein said insert is locatable in place of a said severable join so as to prohibit formation of one or more of said joins.

22. A reinforcement and ducting support apparatus as described herein with reference to Figs 1 to 6. Dated this 7th day of May, 2001. The Reinforcement Bar Spacer Co Pty Ltd By their Patent Attorneys MADDERNS *r