GB2459376A

GB2459376A - Attachment for a reinforcing cage

Info

Publication number: GB2459376A
Application number: GB0906886A
Authority: GB
Inventors: Stephen Render
Original assignee: Romtech Ltd
Current assignee: Romtech Ltd
Priority date: 2008-04-22
Filing date: 2009-04-22
Publication date: 2009-10-28
Anticipated expiration: 2029-04-22
Also published as: PL2112295T3; GB2459376B; GB0807274D0; ES2406907T3; EP2112295A1; EP2112295B1; GB0906886D0

Abstract

A linear attachment 10 for a reinforcing cage carries a set of couplers for connector bars 46, which may be used to provide a connection to a partition wall. The couplers may comprise coupler supports 44, into which extension pieces 60 are mounted and secured by bolts 52, and the connector bars 46 may be threaded into the extension pieces 60. The attachment may comprise four linear carrier bars [34, fig. 4] interconnected by U-shaped bridges [36, fig. 4], whose sides may diverge away from the base. The reinforcement cage may comprise vertical linear cage bars 22 supported between frames 24 and 26, with the attachment 10 in parallel to the cage bars. The reinforced structure may be constructed by covering the couplers with a temporary cover, locating the cage in a piling hole, pouring concrete around the cage, removing the cover and fixing connector bars into selected couplers once the concrete has set.

Description

ATTACHMENT FOR A REINFORCING CAGE, ASSEMBLED REINFORCING

CAGE AND METHOD OF CONSTRUCTING A PART OF A REINFORCED

CONCRETE STRUCTURE

FIELD OF THE INVENTION

This invention relates to an attachment for a reinforcing cage, to an assembled reinforcing cage, and to a method of constructing a part of a reinforced concrete structure. The attachment is designed to facilitate ease of fitment of connectors from an assembled reinforcing cage to other parts of the reinforced concrete structure.

The invention is likely to find its greatest utility as an attachment to a pile cage of an underground reinforcing structure, and the following description will therefore refer primarily to pile cages and underground structures. The invention could, however, also be used with the reinforcing cage for a column, wall or other above-ground structure.

In the following description, directional and orientational terms such as "top", "upper" etc. refer to the normal orientation of use, with the longitudinal axis of the reinforcing cage being substantially vertical.

BACKGROUND TO THE INVENTION

Reinforced concrete structures are used in the foundations of buildings and the like. The structure often comprises at least one pile cage embedded in concrete, the pile cage acting as reinforcement for the concrete and also as a means to link the various parts of the structure together so as to form a substantially unitary reinforced concrete structure. The pile cage comprises a number of metallic cage bars substantially aligned with the longitudinal axis of the pile cage. The cage bars are interconnected by one or more frames which maintain the separation and alignment of the cage bars. In many designs of pile cage the frame comprises a helical wire which surrounds and interconnects the cage bars.

Often the pile cage is assembled off-site at a dedicated manufacturing plant, and is delivered to the site for insertion into a hole created for the pile.

A structure comprising a pile cage embedded in concrete is referred to hereafter as a reinforced concrete pile.

In the particular application to which the present invention is most suited, a number of reinforced concrete piles are embedded into the ground to form a line of pile cages. A design of a modern high-rise building may for example include the provision for an underground car park, and to provide this four lines of reinforced concrete piles can be sunk, in the form of a rectangle. When the concrete has set a chosen depth of earth within the rectangle is removed to define an underground chamber which will form the car park. The reinforced concrete piles are sunk to a depth significantly greater than the required depth of the car park, and when the earth is removed the piles form the walls of the underground chamber and hold back the surrounding earth. Adjacent concrete piles may be separated slightly in an arrangement referred to as contiguous piling, or they may interengage in an arrangement known as secant piling.

It is not likely that such a structure will require an open underground chamber, and typically the chamber will be fitted with partitioning walls and floors. The partitioning walls and floors are themselves made of reinforced concrete and it is necessary to link the walls and floors to the surrounding reinforced concrete piles.

DESCRIPTION OF THE PRIOR ART

In a known method of linking the partitioning walls and floors to the surrounding reinforced concrete piles, the pile cages which are located at the position of a partitioning wall will be fitted with a number of couplers, the couplers being secured to the pile cage prior to pouring of the concrete. The pile cage is fitted with a temporary cover (typically polystyrene and/or timber) which overlies a part of the pile cage, and in particular overlies the ends of the couplers, so that when the concrete is poured the ends of the couplers are protected by the temporary cover and do not become filled with or embedded within the concrete.

Only the ends of the couplers are protected by the temporary cover, however, so that the majority of the coupler becomes embedded within the concrete. When the concrete has set (and the chamber has been excavated) the temporary cover can be removed which exposes the ends of the couplers.

The couplers typically have a female thread formed therein, the thread usually being protected by a plug as well as the temporary cover. When the plug is removed a respective connector bar (typically a straight length of reinforcing bar) with a corresponding male thread is screwed into the coupler. When all of the is connector bars have been inserted into the respective couplers a line of connector bars will project from the concrete wall of the chamber at the desired location for the partitioning wall. The reinforcing cage for the partitioning wall is assembled with its reinforcing bars interspersed with, or perhaps secured to, the connector bars. When concrete is subsequently poured around the reinforcing cage and connector bars the partitioning wall is connected by the connector bars to the pile cages so providing a substantially unitary reinforced concrete structure.

The above-described method requires a large number of couplers to be fitted to one or more of the pile cages. Typically, the fitment of the couplers will take place at a dedicated facility, although it may take place at the construction site. It is necessary that all of the couplers are substantially aligned, and also that adjacent couplers are appropriately positioned so that the fitted connector bars (which are often required to overlap one another) do not interengage and therefore foul one another.

The fitment of the couplers is necessarily restricted by the location of cage bars and frames of the pile cage, i.e. it is not possible to fit the couplers into open space within the pile cage and instead the couplers must be fitted (suitably by way of a holding tube and a suitable grub screw or the like) to a cage bar or to a part of the frame of the pile cage. The spacing and relative positioning of the couplers, and therefore the connector bars, is therefore determined by the structure of the pile cage, and is not necessarily optimised.

Also, considerable care must be taken by the fitter to ensure that each coupler is correctly oriented and positioned so that it lies in the desired position upon the pile cage, where it can be protected by the temporary cover. If for example one of the couplers projects too far from the pile cage (i.e. if it projects beyond its io neighbours) it might cause the temporary cover to lie away from one or more of the other couplers, allowing concrete to encroach between those couplers and the temporary cover. If one of a line of couplers lies inside its neighbours concrete may encroach underneath the temporary cover adjacent to that coupler. In either case one or more of the couplers may become completely embedded within the concrete and therefore unavailable for the fitment of a connector bar.

Clearly, the couplers must be sufficiently securely fitted to the pile cage so that their relative positions are maintained during construction of the pile, including movement of the assembled pile cage around the construction site, and during pouring of concrete. This typically requires the couplers to be welded to the pile cage. If the couplers are to be fitted at the construction site particular care needs to be taken to ensure the couplers are secured into place with the required accuracy, and also to ensure that the welds are free of voids and other deficiencies typically encountered during "on-site" welding. Also, it is often necessary to clean out the threads of the coupler after the coupler has been welded into place, as welding material often enters the threads or the welding process melts part of the thread.

SUMMARY OF THE INVENTION

The present invention provides an attachment for a reinforcing cage which seeks to reduce or avoid the disadvantages with the present reinforcing pile cages and the present method of use.

According to the invention therefore, there is provided an attachment for a reinforcing cage, the attachment comprising a substantially linear carrier upon which a set of couplers can be mounted.

Accordingly, the set of couplers can be mounted upon the carrier and in order to assemble the couplers to the reinforcing cage it is only necessary to mount the attachment upon the reinforcing cage.

The attachment can therefore provide a predetermined array of couplers which can be mounted in a single operation to a reinforcing cage. The attachment can be made at a dedicated facility in order to ensure that all of the couplers are correctly positioned and aligned. The attachment permits the relative spacing between the couplers to be optimised for a particular reinforced concrete structure, i.e. the spacing of the couplers is not limited by the structure of the reinforcing cage to which the attachment is to be fitted.

The couplers can be securely mounted to the attachment so that relative movement between a coupler and the attachment is substantially prevented, and therefore relative movement between respective couplers is substantially prevented. Accordingly, the relative positioning and alignment of the couplers is determined by the attachment and not by any on-site assembly, and it can therefore be arranged that adjacent connector bars can if desired closely overlap each other without likelihood of adjacent connector bars interengaging.

The mounting of the attachment can be undertaken at the construction site, or at a dedicated facility, as desired (the same dedicated facility would typically manufacture the reinforcing cage and the attachment and so could assemble the attachment to the reinforcing cage if desired). Mounting the attachment at the construction site allows all of the reinforcing cages to be constructed similarly, and a set of similar reinforcing cages to be delivered to the construction site. The operator can thereafter select the reinforcing cage to which the attachment is to be mounted.

Manufacturing complexity and cost can be reduced by manufacturing the pile cage and the attachment at the same dedicated facility. The attachment is made separately to the pile cage and does not therefore impact upon the assembly of the pile cage. The attachment can be made upon dedicated jigs to ensure accurate and repeatable positioning of the couplers. Once the pile cage and the attachment have been assembled the attachment can be fitted to the pile cage as a separate manufacturing step, which again does not impact upon the assembly of the (next) pile cage. The attachment can be fitted to the pile cage using dedicated jigs to ensure accurate and repeatable positioning of the attachment.

It is not necessary to weld the attachment to the reinforcing cage, though that is possible if desired. However, since the relative positions of the couplers is provided by the attachment it may be sufficient for the attachment to be mounted to the reinforcing cage by a number of wire ties or bolts or clamps, avoiding the requirement for welding, and in particular on-site welding. Wire ties are normally expected to be sufficient since they must only resist the tendency of the attachment to move during movement of the reinforcing cage around the construction site and during pouring of the concrete. The linear form of the carrier, and the resulting large number of points of engagement with the reinforcing cage, will facilitate the securing of the attachment to the reinforcing cage whatever method of securement is chosen.

Preferably, the carrier comprises a number of carrier bars interconnected by a number of bridges. Thus, whilst it would be possible to make the carrier as a channel section for example, it is often preferred to minimise the surface area of metal within a reinforced concrete structure, and instead it is preferred to form the carrier as a "skeleton" of carrier bars and bridges.

Desirably, the bridges are of "U" section, with two sides and a base. Desirably also the sides diverge away from the base. The provision of diverging sides enables the couplers to be fitted in orientations which permit the connector bars to converge and overlap.

Preferably, the carrier comprises four carrier bars, the carrier bars being substantially linear. In the assembled carrier, when viewed in cross-section, two of the carrier bars define the junction of the base with a respective side, and the other two of the carrier bars define the ends of the respective sides.

Preferably, each coupler is located adjacent to a bridge, so that the bridge provides a location for mounting of the coupler. Since the attachment can be made at a dedicated facility appropriate jigs and tools can be provided in order to ensure that the carrier bars and bridges are appropriately positioned prior to these parts being secured together (suitably by welding). Suitable jigs and tools will ensure that a number of substantially identical attachments can be manufactured, resulting in a high degree of standard isation. Thus, it is expected that the cross-sectional form of the attachment can be substantially standardised for many different reinforced concrete structures, with only the length of the attachment (i.e. the length of the carrier bars) being varied to suit a particular structure.

The junction of one or more carrier bars and a bridge can serve as a reliable location against which the coupler is placed as it is secured (again suitably by welding) to the carrier.

In a preferred embodiment the attachment comprises a number of carrier bars and bridges and a number of coupler supports, and each coupler is provided by an extension piece which can be mounted to a coupler support. The extension piece can be adapted to engage other parts of the reinforcing cage, so as to provide additional support and securement for the coupler. Desirably, the coupler can be secured to its coupler support by a removable fastener, usefully a grub screw or the like. In such an embodiment it may be necessary to fit the couplers to the respective coupler supports after the remainder of the attachment has been secured to the reinforcing cage. Accordingly, the attachment comprising the carrier and the coupler supports would be assembled, as would the reinforcing cage, and then these parts would be assembled together. The couplers could thereafter be mounted to their coupler supports, with the respective extension pieces locating (or being mounted upon) a cage bar or other part of the reinforcing cage.

The invention also provides an assembled reinforcing cage comprising a number of substantially linear cage bars, at least one frame for substantially maintaining the relative positions of the cage bars, the reinforcing cage having an attachment secured thereto, the attachment comprising a substantially linear carrier, the longitudinal axis of the carrier being substantially aligned with the longitudinal axes of the cage bars, the attachment further comprising a number of couplers being secured to the attachment.

There is also provided a method of constructing a part of a chamber including the steps of: {i} providing at least one reinforcing cage {ii} providing at least one attachment as herein defined {iii} mounting a number of couplers upon the attachment {iv} securing the attachment to the reinforcing cage to form a reinforcing cage assembly {v} covering the couplers of the attachment with a temporary cover {vi} locating the reinforcing cage assembly and temporary cover in a piling hole {vii} pouring concrete around the assembled reinforcing cage and temporary cover and allowing the concrete to set so as to form a reinforced concrete column or pile {viii} excavating earth adjacent to the reinforced concrete column or pile so as to expose the temporary cover {ix} removing the temporary cover so as to expose the ends of the couplers, and {x} fitting connector bars into selected couplers.

The connector bars can be used to interconnect the reinforced concrete column or pile to other parts of a reinforced concrete structure. Connector bars can be fitted to all or just some of the couplers. Thus, a standard attachment can be provided with more couplers than are necessary for a particular reinforced concrete structure, and the operator can determine those couplers which are to be used for the particular structure.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which: Fig.1 shows a schematic representation of part of an underground chamber is surrounded by reinforced concrete piles; Fig.2 shows a plan view of a pile cage fitted with an attachment according to a preferred embodiment of the invention, with couplers mounted to the attachment and connector bars fitted to the couplers; Fig.3 shows a side view of part of the attachment of Fig.2; Fig.4 shows an end view of the complete attachment of Fig.2; and Fig.5 shows an end view of the linear carrier of the attachment.

DETAILED DESCRIPTION

The invention concerns an attachment 10 (Figs. 2-4) for fitment to a pile cage 12 (Fig.2) of a reinforced concrete pile 14 (Fig.1), the reinforced concrete pile 14 being one of several reinforced concrete piles which together providing a retaining wall 16 of an underground chamber 20 (Fig.1). It will be understood, however, that whilst the figures show an underground chamber and the consequent use of reinforced concrete piles, the invention similarly concerns above-ground structures and the consequent use of reinforced concrete columns.

As above described, the chamber 20 is created by excavating the earth from inside a set of (typically four) interconnecting walls 16, the walls 16 each being formed by a series of engaging reinforced concrete piles (in this case formed by secant piling, though it will be understood that other embodiments can use contiguous piling). The reinforced concrete piles each include a pile cage such as 12, but only selected reinforced concrete piles 14 contain an attachment 10, the reinforced concrete piles 14 being located at the desired positions of partitioning walls (not shown) within the chamber 20.

As shown in Fig.2, each pile cage comprises a number of substantially linear cage bars 22 interconnected by at least one frame. In the embodiment of Fig.2 there are two frames 24 and 26. The frame 24 is one or more discrete inner bands around which the cage bars 22 are arranged, and the frame 26 is a helical wire surrounding the cage bars 22. In other embodiments the frame 24 is omitted, and in yet further embodiments the cage bars are interconnected by a number of discrete cage formers located at spaced positions along the length of the cage bars. The detailed structure of the pile cages is not directly relevant to the present application, and the attachment of the present invention can be used with most if not all of the known pile cage structures.

It will be understood that the reinforced concrete piles are sunk into the earth, the final surface of the earth being approximately flush with the upper surface 30 of the concrete of the reinforced concrete piles. As shown in Fig.1, the cage bars 22 project beyond the upper surface 30 and thereby provide a means of linking or tying the above-ground building structures to one or more of the reinforced concrete piles, in known fashion.

In a typical method of secant piling, a hole is drilled into the earth corresponding to the position of alternate reinforced concrete piles, a rectangular pile cage is sunk into each of the holes, and the concrete is poured therearound. When the concrete has set a hole is drilled for each of the remaining piles (in secant piling these holes will cut into the concrete which has been previously poured, but will not cut into the rectangular reinforcing cages), and the respective pile cages sunk thereinto and the concrete poured.

Typically, four contiguous lines of reinforced concrete piles are sunk, in the form of a rectangle, and when all of the concrete has set a chosen depth of earth between the lines of piles is excavated to provide an underground chamber 20 io surrounded by the walls 16 of reinforced concrete piles.

Typically, the underground chamber 20 will not be open, and instead it will be designed to contain partitioning walls, and/or partitioning floors, and/or ramps, and/or additional reinforced concrete piles forming additional parts of the building structure. The positions of these additional components is determined in advance, and a chosen pile cage 12 is fitted with an attachment 10 according to the present invention.

As is clear from Fig.3, the attachment is elongate, having a longitudinal axis A-A.

The attachment 10 is adapted to be inserted into the pile cage 12 so that its longitudinal axis A-A lies substantially parallel with the longitudinal axis X (Fig.2) of the pile cage.

The attachment 10 comprises a carrier 32 (see Fig.5) which in this embodiment comprises four substantially linear carrier bars 34, joined together at spaced intervals by bridges 36. The bridges 36 are substantially of "U"-shape, with two sides 40 joined by a base 42. The bridges 36 and carrier bars 34 are of metal, and are secured together by welding, and provide a substantially rigid "skeleton" substantially in the form of a "U"-shaped channel.

It will be understood that the "U"-shaped channel could be formed from a continuous or perforated sheet of metal or plastic/composite material, but the presence of large areas of metal in a reinforced concrete structure is not always acceptable, and it is generally preferred to provide a "skeleton" structure such as that shown, which allows the concrete to surround the respective parts.

The carrier bars 34 are ideally of a length slightly greater than the desired length of the partitioning wall to be installed in the chamber 20. It is not necessary that the carrier bars be the same length as the cage bars 22, since it will be understood that a significant length of the cage bars 20 lies below the bottom of the chamber 20 in order to provide the necessary support to retain the earth surrounding the chamber 20.

In this preferred embodiment the attachment 10 also includes a number of coupler supports 44. In this embodiment two coupler supports 44 are secured adjacent to each of the bridges 36. The coupler supports 44 in this embodiment comprise a metal tube having a hole 46 formed therein. A nut 50 is welded adjacent to the hole, and a bolt 52 is inserted into the nut (the nut and bolt are not present in Fig.2). It will be understood that as the bolt 52 is rotated it projects into the tube, and it can thereby secure a component within the tube (as described below).

The number of coupler supports 44 which are required and/or the required spacing between adjacent coupler supports, is determined in advance, and the spacing between the bridges 36 is determined accordingly. In this embodiment two coupler supports 44 are mounted adjacent to each of the bridges 36, the coupler supports being welded to the bridges 36 and/or to the carrier bars 34.

Since the carrier comprising the carrier bars 34 and bridges 36 is substantially rigid, the relative positions of the coupler supports 44 are thereby maintained.

The assembler of the attachment 10 can therefore determine the relative positions and orientations of the coupler supports according to the required relative positions and orientations of the connector bars 46 which are subsequently fitted thereto. Thus, the number and spacing of the connector bars 46 will be predetermined according to the requirements of the particular reinforced concrete structure. Also, whether the connector bars must overlap (as do the connector bars 46 as shown in Fig.2) or not will be predetermined. The attachment 10 will be designed and assembled to cater for those requirements.

Alternatively, but less desirably, a standard attachment 10 can be assembled with the maximum number of coupler supports 44 which would be required, permitting the operator only to utilise certain of those coupler supports in a particular reinforced concrete structure.

In this embodiment the coupler (i.e. that component to which a connector bar 46 can be secured) is provided by a separate component 56 which is secured to the coupler support 44. The coupler comprises an opening (not seen) having a female thread formed in the end of an extension piece 60. The extension piece in this embodiment is an "L"-shaped length of reinforcing bar having a diameter slightly smaller than the inner diameter of the coupler support 44.

It will be understood that in most applications the operator requires the extension piece to be of a minimum length (e.g. 1.5 metres) so as to provide a predetermined anchorage within the concrete. In larger pile cages the predetermined anchorage can be provided by a substantially linear extension piece spanning all of part of the pile. In a smaller pile cage it may be necessary to provide an extension piece of "U"-shape, for example.

Following assembly of the attachment 10 and the pile cage 12, the attachment 10 is inserted into the pile cage 12 and secured thereupon. The extension pieces 60 are then fed through the cage bars 22 and into the respective coupler supports 44. The bolt 52 is tightened so as to secure the extension piece and coupler to the pile cage.

The length of the extension piece 60 is chosen so that when the angled part 62 engages a cage bar as shown, the female threaded end providing the coupler is located within the coupler support 44, and is therefore hidden from view.

Preferably, the female threaded end lies close to the outer end of the coupler support 44.

In some embodiments having an extension piece 60 which engages a cage bar as shown, the bolt 52 could be omitted and the extension piece and its coupler could be secured in place by welding or otherwise securing the extension piece to the cage bar. Since the extension pieces could be secured at the dedicated manufacturing facility these embodiments would not require any on-site welding or the like.

As above indicated, once the pile cage has been assembled with the attachment 10 and the extension pieces 60, a plug is inserted into each of the threaded ends of the couplers. All of these assembly operations could be undertaken off-site at a dedicated manufacturing facility, using appropriate jigs and fixtures to ensure that accurate pile cages can be produced economically. Either at the dedicated manufacturing facility or on-site, a temporary cover (not shown) of polystyrene and/or timber is placed over the ends of the coupler supports 44. The pile cage and temporary cover is then inserted into a piling hole and concrete is poured therearound. When the concrete of the reinforced concrete piles has set the chamber 20 is excavated to expose the temporary cover. Removal of the temporary cover exposes the ends of the coupler supports 44 and removal of the plugs exposes the threaded ends of the couplers. A connector bar 46 having a corresponding (male) threaded end is inserted into the coupler, and screwed thereinto. This results in a line of connector bars 46 projecting from the wall 16 as shown in Fig.1.

In known fashion, the reinforcing structure of the partitioning wall is assembled around the connector bars 46 and concrete is poured therearound so as to form the partitioning wall, the partitioning wall being tied to the reinforced concrete pile 14 by way of the connector bars 46.

It would be possible for the couplers to be secured directly to the carrier 32, i.e. a short length of bar having a female threaded recess could be welded directly to the carrier bars 34 and/or bridges 36. It would also be possible for a separate component comprising a short length of bar having a female thread to be secured to the coupler support 44. However, the use of an elongate separate component such as 56 is preferred as this provides much greater support for the coupler within the pile cage, and in particular ensures that the connector 46 is tied into the body of the reinforced concrete pile.

The shape of the bridges 36, and in particular the coverging form of the sides of the bridges, results in the connector bars 46 overlapping as shown in Fig.2. It will be necessary for the carrier supports 44 to be offset from one another in order that the connector bars 46 do not interengage, and this offsetting could be provided by securing the carrier supports 44 on one side of the carrier to the right of the bridges 36 (as in Fig.3), and the carrier supports 44 on the other side of the carrier to the left of the bridges 36.

Alternatively, the operator may decide to fit connector bars to only some of the couplers, i.e. a particular reinforced concrete structure may require fewer connector bars than the couplers which are provided, and for example the operator could fit a connector bar to selected couplers to ensure there is no interengagement. One possible structure could for example utilise one of each pair of couplers, in an alternating pattern along the length of the attachment.

Alternatively again, the attachment may be configured so that the connector bars do not overlap, i.e. the bridges have a reduced (or zero) divergence (or perhaps a convergence) away from the base. A carrier having bridges with substantially parallel sides would enable the couplers at the opposed sides of the attachment to be substantially parallel, permitting two substantially parallel lines of connector bars to project from the reinforced concrete pile. In yet other embodiments only a single line of connector bars is required.

As above indicated, much of the assembly of the pile cage can be handled away from the construction site, suitably at a dedicated facility. Even if some of the assembly is conducted at the construction site, however, the complexity and therefore time taken in the assembly procedures is reduced over the prior art arrangement of welding each individual coupler in place. Thus, the assembly of the attachment to the pile cage, and the subsequent insertion and securement of the extension pieces if present, are straightforward tasks requiring no specialised tooling or expertise, so that the on-site activity is made much simpler and less expensive.

It will be understood that the invention has utility in all applications in which a partitioning wall or other component is required to be connected to a reinforced concrete structure.

Claims

CLAIMS1. An attachment for a reinforcing cage, the attachment comprising a substantially linear carrier adapted to locate a set of couplers.
2. The attachment according to Claim 1 having a predetermined array of mounting locations for the couplers.
3. The attachment according to Claim 1 or Claim 2 in which the carrier comprises a number of carrier bars interconnected by a number of bridges.
4. The attachment according to Claim 3 in which the bridges are of "U" section,
5. The attachment according to Claim 4 in which the sides of the bridge diverge away from the base.
6. The attachment according to any one of Claims 3-5 in which each of the bridges defines a mounting location for a coupler.
7. The attachment according to any one of Claims 1-6 in which the carrier comprises four carrier bars, each of the carrier bars being substantially linear.
8. The attachment according to any one of Claims 1-7 further comprising a number of coupler supports.
9. The attachment according to Claim 8 in which each coupler support provides a mounting for an extension piece, and in which the extension piece provides a coupler.
10. The attachment according to Claim 9 in which the coupler support has a fastener to secure the extension piece.
11. An assembled reinforcing cage comprising: a number of substantially linear cage bars, each of the cage bars having a longitudinal axis, the longitudinal axes of the cage bars being substantially parallel, at least one frame for substantially maintaining the relative positions of the cage bars, an attachment secured to at least one of the cage bars and/or to the frame, the attachment comprising a substantially linear carrier, the carrier having a longitudinal axis which is substantially aligned with the longitudinal axes of the cage bars, and a number of couplers mounted upon the attachment.
12. An assembled reinforcing cage according to Claim 11 in which the attachment has a number of coupler supports.
13. An assembled reinforcing cage according to Claim 12 in which a respective extension piece is fitted to each of the coupler supports, the extension piece also engaging another part of the pile cage.
14. A method of constructing a part of a reinforced concrete structure including the steps of: {i} providing at least one reinforcing cage comprising a number of cage bars and at least one frame, each of the cage bars having a longitudinal axis, the longitudinal axes of the cage bars being substantially parallel; {ii} providing an attachment comprising a substantially linear carrier, the carrier having a longitudinal axis; {iii} mounting a number of couplers upon the attachment; {iv} securing the attachment to the reinforcing cage, with the longitudinal axis of the carrier substantially aligned with the longitudinal axis of the cage bars; {v} covering the couplers with a temporary cover; {vi} locating the reinforcing cage, attachment and temporary cover in a piling hole; {vii} pouring concrete around the reinforcing cage, attachment and temporary cover and allowing the concrete to set so as to form a reinforced concrete column or pile; {viii} excavating earth adjacent to the reinforced concrete column or pile so as to expose the temporary cover; {ix} removing the temporary cover so as to expose the ends of the couplers; and {x} fitting connector bars into selected couplers.
15. The method according to Claim 14 in which step {iii} is carried out after step {iv}.
16. The method according to Claim 15 in which the attachment has a number of coupler supports, and in which the couplers are provided by extension pieces fitted to the coupler supports, the extension pieces being passed between adjacent cage bars of the pile cage and secured into the coupler supports.
17. The method according to any one of Claims 14-16 in which the reinforced concrete structure is a below-ground structure, and the reinforcing cage is a pile cage.
18. An attachment for a reinforcing cage constructed and arranged substantially as described in relation to Figs. 2-5 of the accompanying drawings.