GB2601992A

GB2601992A - Stirrup for access tubes in cage reinforcement structures

Info

Publication number: GB2601992A
Application number: GB2016833.2A
Authority: GB
Inventors: Render Stephen
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-10-23
Filing date: 2020-10-23
Publication date: 2022-06-22
Also published as: GB202016833D0

Abstract

A stirrup device 20 for attachment to a cage bar 12 of a pile or reinforcement cage 2, for supporting and/or retaining a longitudinally arranged sonic logging or inclinometer reservation access or guide tube 6 within the cage 2 and for incorporation into a pile or other structure for the purpose of subsequent testing or monitoring thereof, the stirrup device 20 comprising a closed loop 22 of substantially rigid material, 10 e.g. steel, through which the access tube 6 can translatably and longitudinally move, wherein the closed loop 22 of the stirrup device 20 comprises at least one internal supporting or retaining face 26, and at least a portion of the said internal supporting or retaining face 26 is convexly arcuate or curved in profile. An arrangement of a stirrup and reinforcement cage is also claimed, along with a method of supporting and/or retaining one or more access tubes within a reinforcement cage.

Description

STIRRUP FOR ACCESS TUBES IN CAGE REINFORCEMENT STRUCTURES

TECHNICAL FIELD

This invention relates to a support stirrup for an access or guide tube used in piling and other reinforcement structures which employ pile or reinforcement cages. More particularly the invention relates to a support stirrup for use in supporting and/or retaining an access or guide tube that is carried on or within a pile or reinforcement cage during the construction of a pile or other reinforcement structure.

BACKGROUND OF THE INVENTION AND PRIOR ART

In the construction of concrete piles, diaphragm walls and other reinforced structures in a wide range of civil engineering and construction applications, e.g. in the construction of buildings, underground car parks, road or rail or other bridges, and other structures, it is typically necessary -especially where a drilling fluid has been deployed to support the sides of the excavation -to incorporate into the body of each formed pile or other structure one or more, especially a symmetrical arrangement of e.g. 2, 3, 4, or more, elongate hollow access or guide tubes which can subsequently be used for acoustic and other testing or verification of the pile or structure for parameters such as structural integrity and/or verticality. Such tubes include sonic logging tubes On view of the common case of such tubes being used for acoustic or sonic testing) and also inclinometer reservation tubes (for monitoring the verticality of the installed pile or other reinforced structure during subsequent works).

In a typical piling or other structure-forming procedure, the access or guide tubes (which terms "access tube" or "guide tube" may be used interchangeably herein), e.g. of mild steel, are installed in a pre-drilled hole or shaft together with a reinforcement cage, with the tubes being arranged within the cage and each one retained in a desired position relative to the cage walls by virtue of being held in place by a tie or stirrup, which is typically welded to one or more of the cage bars and projects radially inwardly therefrom. Each stirrup typically takes the form of a closed loop or ring, e.g. of steel, welded to a backplate which is itself secured by welding to the respective cage bar. The stirrup loop or ring is generally formed from a suitably shaped or formed narrow elongate length of steel plate which is bent back on itself, usually with a mid-bracing member welded between its "arms" which are then welded to the mounting backplate. The closed stirrup loop or ring is of a sufficient diameter or width to allow the respective access tube to slidably translate within it, in order that it can be appropriately positioned longitudinally of the arrangement both during the interconnection or splicing of adjacent access tube lengths together and during the overall splicing together of adjacent cages.

It is often the case however that each overall length of access tube carried in a respective cage, in order that it substantially matches the longitudinal length of a typical pile or reinforcement cage so that plural such lengths of access tubes can be connected together end-to-end along with the splicing together of adjacent cages in readiness for the forming of a pile or other structure of the required depth, is itself formed from a plurality of individual tube sections which are longitudinally joined together by an appropriate number of socket connectors. This is especially common practice given that many access or guide tubes are formed from standard stock steel tubing which comes in only modest length sections.

However, the use of conventional socket connectors, which are typically of the nature of tubular collars which are screw-threaded onto the respective ends of the tube sections to be joined, often creates a problem, because the socket connectors have an enlarged diameter compared with that of the tube sections themselves, and they usually have square-cut front/leading and rear/trailing faces/ends. There is therefore a common problem that such socket connectors foul or catch against the edges of the respective supporting/retaining stirrups as the tubes are slid therethrough within the cage arrangement.

This fouling or catching can occur not only during the initial insertion of the access tube lengths into their respective cages in the factory before the arrangements are brought to a site, but also once on-site during the process of correctly longitudinally positioning the access tube lengths during their own interconnection and the splicing together of adjacent cages.

This fouling or catching of the socket connectors against the edges of the respective supporting/retaining stirrups is depicted in simplified form in FIG. 1 of the accompanying drawings. As shown in that FIG. 1, a steel access or guide tube T is slidably received in a steel stirrup S. The access tube T comprises a pair of tube sections interconnected by a screw-threaded socket connector C which has square-cut end faces E. The stirrup S is formed from an elongate length of steel plate that has been bent back on itself to form a U-shape with flat side faces F, with a bracing member B welded between its arms which are welded to a mounting backplate (not shown) which is itself welded to a bar (or bars) of a pile or other reinforcement cage (also not shown) within which the access tube T is to be mounted. As represented in FIG. 1, as the access tube T longitudinally translates through the stirrup S, e.g. upon its initial insertion thereinto or during its on-site movement or adjustment relative to the cage for the purpose of connecting the access tube T to another like tube during the splicing of adjacent cages, the end faces E of the socket connector C and the flat side faces F of the stirrup S foul or catch against one another, owing to the weight of the tube T and the fact that it is difficult to guide it perfectly through the centre of the closed stirrup loop without considerable and tricky manual manipulation.

This fouling or catching is a nuisance, since it causes a slowing down of the overall tube insertion and positioning procedures at both locations, given that manual manipulation of what are typically quite heavy tubes is then required by workers in order to free them up, often repeatedly, and enable them to assume their correct or desired longitudinal positions relative to their respective cages. Such fouling/catching can also lead to damage to the components in question, and in the worst of cases could also lead to weakening of the joints between individual tube sections, which could have negative consequences on the ability of the tubes to provide accurate and reliable sonic or acoustic or other testing capability in the later life of the pile or other structure into which they are incorporated.

Furthermore, an additional especially cogent nuisance posed by this fouling or catching arises when the respective reinforcement cages are being spliced end-to-end in a vertical orientation over the pre-prepared hole or bore in the ground. In this condition the offending socket connector/stirrup joint(s) is/are often many metres above ground level and therefore inaccessible to the site operators/workers. Removing the interference between the socket connector(s)/stirrup(s) often then requires the use of an elevated access platform, which would otherwise not be a required on-site item. The expense of such extra plant hire and the consequent site delays caused by the deployment of such a platform all add to the contractor's budget. Moreover, the site operators are unnecessarily then also exposed to the hazards of working at height.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to solve or ameliorate, at least partially, at least some of the above problems associated with known access tube stirrup supporting and retaining devices.

Accordingly, in a first aspect the present invention provides a stirrup device for supporting and/or retaining a longitudinally arranged access tube for incorporation into a pile or other structure for the purpose of subsequent testing or monitoring thereof, the stirrup device comprising a closed loop of substantially rigid material through which the access tube can translatably and longitudinally move, wherein the closed loop of the stirrup device comprises at least one internal supporting or retaining face, and at least a portion of the said internal supporting or retaining face is convexly arcuate or curved in profile.

In a second aspect the present invention provides a reinforcement cage for incorporation into a pile or other structure during the formation thereof, the reinforcement cage having attached thereto, especially to a or each of one or more respective cage bars thereof, at least one, or one or more, stirrup device(s) according to the first aspect of the invention or any embodiment thereof. Thus, in embodiments of such a reinforcement cage of this second aspect, the or each of the at least one (or one or more) stirrup device(s) is for supporting and/or retaining in the said cage a, or a respective, longitudinally arranged access tube, or a portion of a, or a respective, longitudinally arranged access tube, also for incorporation into the pile or other structure for the purpose of subsequent testing or monitoring thereof, with the or each respective access tube being translatably and longitudinally moveable through the closed loop of a or a respective said stirrup device.

In a third aspect the present invention provides, in combination, a reinforcement cage for incorporation into a pile or other structure during the formation thereof, and one or more longitudinal access tubes arranged within the said cage and also for incorporation into the pile or other structure for the purpose of subsequent testing or monitoring thereof, wherein the or each access tube is supported and/or retained in a or at least one, or one or more, stirrup device(s) according to the first aspect of the invention or any embodiment thereof, the or each stirrup device being attached to the said reinforcement cage, especially to a or a respective one or more cage bars thereof.

In a fourth aspect the present invention provides a method of supporting and/or retaining one or more longitudinally arranged access tubes within a reinforcement cage for incorporation into a pile or other structure during the formation thereof, the one or more access tubes also being for incorporation into the pile or other structure for the purpose of subsequent testing or monitoring thereof, the method comprising: providing at least one, or one or more, stirrup device(s) according to the first aspect of the invention or any embodiment thereof, and attaching the or each said stirrup device to the said reinforcement cage, especially to a or each of one or more respective cage bars thereof; and longitudinally passing the or each respective access tube through the closed loop of a or a respective one of one or more said stirrup devices, whereby the or each respective access tube is supported and/or retained in the or the respective one of the one or more said stirrup devices whilst being translatably and longitudinally moveable through the closed loop thereof.

In many embodiments of the invention, since the stirrup device may, strictly speaking, typically be thought of as only supporting and/or retaining the respective longitudinally arranged access tube at a site at which the particular stirrup device is located, in the context of definitions of the various aspects of the invention or embodiments thereof referring to the stirrup device as being a "stirrup device for supporting and/or retaining a longitudinally arranged access tube", such definitions should be construed as including cases where the stirrup device is a "stirrup device for supporting and/or retaining a portion of, or at least a portion of, a longitudinally arranged access tube".

In many practical embodiments of the invention in its various aspects, a plurality of stirrup devices may be provided or employed, and one or more stirrup devices may be attached to any given one of one or more of the cage bars of the cage. Thus, in some such embodiments, any given cage bar of the cage may have attached thereto one or more said stirrup devices, or optionally a plurality of (e.g. 2, 3, 4 or perhaps even more than 4 of) said stirrup devices longitudinally spaced apart therealong. Indeed, in some such embodiments, each of one or more, or even each of a plurality of, cage bars of the cage may have attached thereto a plurality of (e.g. 2, 3, 4 or perhaps even more than 4 of) the said stirrup devices, longitudinally spaced apart therealong. In this manner any given access tube supported and/or retained by a plurality of such stirrup devices attached to a single given cage bar and longitudinally spaced apart therealong, may be supported and retained at a plurality of spaced-apart points along its length in an optimally supported fashion.

In embodiments where a plurality of stirrup devices are attached, longitudinally spaced apart, to each of one or more individual cage bars, the stirrup devices may be located at any suitable locations at which they collectively fulfil their optimum supporting and/or retaining function for the or the respective access tube to be supported and/or retained thereby. In some such embodiments the plurality of stirrup devices may be uniformly or symmetrically or equidistantly distributed along the length of the or the respective cage bar, or along at least a major portion of the length of the or the respective cage bar.

However, it may still be within the scope of certain embodiments of the invention for any given cage bar to have attached thereto one stirrup device only, e.g. in the case of particularly short access tubes or cage lengths, or where just one point of support and/or retention of a given access tube is acceptable or desired.

In accordance with the present invention, the stirrup device comprises a closed loop of substantially rigid material through which the access tube can translatably and longitudinally move, wherein the closed loop of the stirrup device comprises at least one internal supporting or retaining face, and at least a portion of the said internal supporting or retaining face is convexly arcuate or curved in profile. In practising embodiments of the invention, therefore, the convexly arcuate or curved profile shape of the relevant portion(s) of the at least one internal supporting or retaining face of the closed loop may serve to guide -or direct or deflect -an open free end of the respective access tube, and/or a leading edge of a connector socket which interconnects a pair of access tube sections (if that type of access tube is employed), with far less propensity for, or even substantially with elimination of, fouling or catching thereof against the side faces of the closed loop of the stirrup device as the access tube is inserted into, or is longitudinally moved within, the stirrup device.

In many practical embodiments of the above-defined stirrup device of the invention, the stirrup device may include means for attachment thereof to a portion of, especially to at least one respective cage bar of, the reinforcement cage within which the respective access tube is to be mounted whilst being supported and/or retained by the stirrup device. Such attachment means may comprise a backplate or baseplate, onto one side of which the closed loop of the stirrup device is affixed or attached, e.g. by welding (or by other suitable affixing/attachment means appropriate to the material from which the stirrup device is formed), with the opposite side of the backplate or baseplate being affixable or attachable, e.g. by welding etc, to the respective cage bar or bars.

In embodiments, the affixing or attachment of the backplate or baseplate to the relevant cage bar(s) may be such that the closed loop of the stirrup device projects generally transversely or radially inwardly of the cage, especially in a generally perpendicular direction relative to the longitudinal axis of the cage and/or of the respective access tube to be supported and/or retained by the stirrup device, and such that the closed loop of the stirrup device itself defines its own central axis which is substantially perpendicular to the general plane of the closed loop and is substantially coincident with the longitudinal axis of the respective access tube once it has been positioned in the closed loop of the stirrup device and properly supported and retained thereby/therein.

In some embodiments of the stirrup device of the invention, the closed loop may comprise a U-shaped loop of the substantially rigid material, with a bracing member attached (e.g. by welding, or by other suitable affixing/attachment means appropriate to the material from which the stirrup device is formed) to and between the two arms of the "U" to create the closed loop therebetween, through which closed loop is passable the respective access tube (or a portion of a given access tube) to be supported and/or retained by the stirrup device. Alternatively, in certain other embodiments, such a bracing member could be dispensed with and instead the backplate or baseplate via which the U-shaped loop is affixed or attached to the cage bar may perform the same function as the bracing member to form the closed loop between the two arms of the "U".

The U-shaped arms of the stirrup may be formed of e.g. steel, and may be formed from an elongate length of the relevant material that has, on at least a portion of at least one internal supporting or retaining face thereof, the characteristic convexly arcuate or curved profile shape (as will be further discussed and defined further below). For forming the U-shaped loop, the length of the material may be bent or formed back on itself, with the characteristic convexly arcuate or curved profile shaped portion of the at least one internal supporting or retaining face of the loop facing generally towards the interior of the loop, so that the resulting pair of arms of the U-shaped loop extend substantially parallel to one another from a curved or arcuate bridging portion of the "U" and the at least one internal supporting or retaining face of the loop presents at least its portion with the characteristic convexly arcuate or curved profile shape interiorly of the closed loop for supporting and/or retaining the respective access tube therein once it has been located or positioned within the closed loop.

In many practical embodiments of the invention, in order to optimise the access tube-guiding or -directing function of the convexly arcuate or curved profile shape of the at least one portion of the at least one internal supporting or retaining face of the closed loop, the closed loop of the stirrup device may comprise a plurality of such internal supporting or retaining faces, which together face internally of the closed loop along substantially its entire loop length or are located on substantially all of its sections passing around the closed loop, each of which internal supporting or retaining faces having at least a portion which has the said convexly arcuate or curved profile shape. Thus, in such embodiments, where a U-shaped length of the substantially rigid material is used to form the closed loop of the stirrup device, with a bracing member (or alternatively a backplate/baseplate) to close the loop, each one of the said U-shaped length of material and the bracing member (or alternatively the backplate/baseplate) may include a respective said internal supporting or retaining face of which at least a portion thereof has the said convexly arcuate or curved profile shape, whereby the access tube-guiding or -directing function of the closed loop is fulfilled along all sections thereof passing around the closed loop.

In certain embodiments of the stirrup device of the invention, the closed loop of the stirrup device may comprise a said at least one internal supporting or retaining face of which only a portion thereof, which portion is located or faces to one longitudinally-directed side thereof, is formed with and presents the said convexly arcuate or curved profile shape, and that convexly shaped portion is provided on that one longitudinally-directed side of the closed loop which is proximal to or faces towards one longitudinal end only of the access tube to be supported/retained by that closed loop. In this manner such an embodiment stirrup device may be considered to be "mono-directional", in that the characteristic convexly arcuate or curved profile shaped portion of the closed loop enables the respective access tube to be readily inserted into the stirrup device and/or longitudinally moved within the stirrup device, substantially without fouling or catching the side faces of the closed loop, from that one longitudinal end direction only.

Alternatively in certain other embodiments of the stirrup device of the invention, the closed loop of the stirrup device may comprise a said at least one internal supporting or retaining face of which each of two longitudinally adjacent portions thereof -which may be contiguous with, or merge into, one another -is formed with and presents a respective one of a pair of discrete convexly arcuate or curved profile shapes, and each of said convexly shaped portions is provided on a respective one of the two longitudinally-directed sides of the closed loop which are proximal to or face towards each of the two opposite longitudinal ends of the access tube to be supported/retained by that closed loop. Such discrete convexly arcuate or curved profile-shaped longitudinally adjacent portions of the at least one internal supporting or retaining face may have or be defined by substantially the same curve function or geometric shape as each other, or (more usually in such embodiments) they may have or be defined by substantially different curve functions or geometric shapes from each other, albeit optionally (yet desirably) with the proviso that the two discrete portions may be contiguous with, or merge into, one another, especially at or along the longitudinally-directed midpoint or mid-line across the said at least one internal supporting or retaining face of the closed loop. In this manner such an embodiment stirrup device may be considered to be "asymmetrically bi-directional", in that the discrete characteristic convexly arcuate or curved profile shaped internal supporting or retaining face portions of the closed loop enable the respective access tube to be readily inserted into the stirrup device and/or longitudinally moved within the stirrup device, substantially without fouling or catching the side faces of the closed loop, from either one of the two opposite longitudinal end directions but (usually in such embodiments) with an unequal degree of ease or readiness when so inserted or moved from one longitudinal end direction as compared with from the other.

However, in other, usually more desirable, embodiments of the stirrup device of the invention, the closed loop of the stirrup device may comprise a said at least one internal supporting or retaining face of which substantially the whole thereof is formed with and presents a single said convexly arcuate or curved profile shape, and that convexly shaped substantially entire internal supporting or retaining face extends to, or spans between, both longitudinally-directed sides of the closed loop which are proximal to or face towards both opposite longitudinal ends of the access tube to be supported/retained by that closed loop. In this manner such an embodiment stirrup device may be considered to be "symmetrically bi-directional", in that the characteristic convexly arcuate or curved profile shaped internal supporting or retaining face of the closed loop enables the respective access tube to be readily inserted into the stirrup device and/or longitudinally moved within the stirrup device, substantially without fouling or catching the side faces of the closed loop, equally easily or readily from either one of the two opposite longitudinal end directions.

In various embodiments of the stirrup device of the invention, the convexly arcuate or curved profile shape of the relevant portion of the at least one internal supporting or retaining face of, or the at least one internal supporting or retaining face itself of, the closed loop may have any suitably shaped convexly arcuate or curved profile shape, which may be of any suitable or appropriate size, scale or radius of curvature. Suitable such profile shapes may be selected from any of the following, for example: semi-circle, part-circle (or any arc of a circle), semi-ellipse, part-ellipse (or any arc of an ellipse), parabola (or any arc of a parabola), hyperbola (or any arc of a hyperbola), or other symmetrical or asymmetrical (or possibly even freeform) geometric curve of a generally convex nature or configuration.

In certain useful practical embodiments, therefore, where the closed loop of the stirrup device is formed from a U-shaped length of the substantially rigid material, together with a bracing member (or alternatively a backplate/baseplate) to close the loop, each one of the said U-shaped length of material and the bracing member (or alternatively the backplate/baseplate) may be formed from a selected length cut from a single supplied stock material which has the required convexly arcuate or curved profile shape.

In practising many practical embodiments of the invention, and in particular in embodiments of combinations according to the third aspect of the invention, the or each access tube may typically comprise a plurality of access tube sections interconnected in one or more end-to-end pairs by one or more socket connectors, e.g. screw-threaded onto the respective ends of the access tube sections to be interconnected, the or each socket connector being of enlarged external transverse width or diameter compared with the access tube sections themselves. Furthermore, the or each socket connector may comprise one or more, especially a pair of longitudinally opposite (i.e. leading and trailing), ends faces.

In some such embodiments, at least one of, and especially both of, the said longitudinally opposite (i.e. leading and trailing) ends faces of the or each socket connector may be bevelled or chamfered. This shaping of those end faces, as compared with known socket connectors used in conventional arrangements as discussed above, may help to further assist and optimise the access tube-guiding or -directing function of the convexly arcuate or curved profile shape of the at least one portion of the at least one internal supporting or retaining face of the closed loop of the or each stirrup device through which such socket connectors have to pass as the respective access tube is inserted therethrough and/or longitudinally moved therewithin.

In some practical implementations of embodiments of the present invention, and in particular in embodiments of combinations according to the third aspect of the invention, the or each access tube may be fitted or provided with a temporary locking device for selective actuation to either (i) lock the access tube in a substantially fixed longitudinal position relative to the cage, e.g. for preventing unwanted longitudinal movement of the access tube relative to the cage during its transit to an on-site location, or (ii) permit sliding longitudinal movement of the access tube relative to the cage (or vice versa), e.g. so that the access tube is free to longitudinally move, relative to the cage (or vice versa) -assisted by its relatively or substantially unhindered longitudinal movement through the closed loop(s) of the one or more stirrup devices of this invention -for the purpose of correctly positioning the access tube during its interconnection or splicing to/with a longitudinally adjacent access tube length during the overall splicing together of adjacent cages, and also for the purpose of allowing a cage to which a given stirrup device is attached to be lowered relative to such a respective interconnected/spliced access tube during the splicing of that cage to an adjacent cage therebelow. Practical examples of such temporary locking devices may be either already known in the art, or may be the subject of a separate invention for use with the stirrup device of the present invention presented herein.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. Thus, any one or more features referred to or described with reference to one particular embodiment should be construed as being applicable to any or all embodiments, unless expressly stated otherwise or such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the present invention in its various aspects will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: FIGURE 1 is a photograph showing the manner in which a prior art stirrup device, with a typical known plural-sectioned access tube slidably received therein, leads to fouling or catching of the access tube socket connectors against the side faces of the stirrup, and has already been described; FIGURE 2 is a perspective view of an example of a pile or reinforcement cage arrangement according to an embodiment of the cage aspect of the present invention, in which a number of access or guide tubes are each supported and retained within the cage by a series of stirrup devices, each stirrup device being in accordance with an embodiment of that aspect of the invention; FIGURE 3 is an enlarged perspective view of the portion labelled III-Ill in FIG. 2, of one of the stirrup devices used in the cage arrangement of FIG. 2; FIGURE 4 is a side-on view of the stirrup device alone as shown in FIG. 2; FIGURE 5 is a photograph corresponding in its view to that of FIG. 1, but showing the stirrup device of the embodiment of the present invention as shown in FIGS. 3 & 4 in use, and illustrating the manner in which a plural-sectioned access tube slidably received in the stirrup device can readily move longitudinally within the closed loop thereof substantially without fouling or catching against the side faces of the stirrup device; and FIGURE 6 is a perspective view, of the portion labelled VI-VI in FIG. 2, of one of the plural-sectioned access tubes used in the cage arrangement of FIG. 2 and slidably received in the stirrup devices thereof.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring firstly to FIG. 2, here there is shown an example of the general arrangement of a typical pile or reinforcement cage 2, which has mounted therewithin a series of three parallel, equi-angularly arranged access or guide tubes (e.g. sonic logging or inclinometer reservation tubes) 6, each of which is supported and retained within the cage by a series of three longitudinally equi-spaced apart stirrup devices 20 each being according to an embodiment of the present invention. In FIG. 2 the stirrup devices 20 associated with only one of the access or guide tubes 6 is shown, for clarity. The cage 2, which in this example is generally cylindrical in configuration, is formed from an assembly or network of a plurality (e.g. at least about 6 or 8, or possibly up to about 12, as shown in this FIG. 2 example) of steel cage bars (or "rebars") 12 extending in a generally longitudinal direction (defined as a direction parallel to the central axis of the pile or structure to be formed around the cage 2) and anchored together or interconnected by one or more transverse frame elements (not shown), e.g. one or more wires or other supporting frame members, which maintain the relative positioning, separation and alignment of the cage bars 12. The access or guide tubes 6 are equi-angularly disposed around the cage 2.

As is seen in the prior art arrangement shown in FIG. 1, but also as is shown in the more desirable alternative configuration of access/guide tubes 6 shown in FIG. 6 which are especially designed for use with stirrup devices 20 of embodiments of the present invention, each tube 6 comprises a plurality of access tube sections 65 interconnected in one or more end-to-end pairs by one or more respective socket connectors 6C, e.g. screw-threaded onto the respective ends of the access tube sections 65 to be interconnected, the or each socket connector 6C being of enlarged external transverse width or diameter compared with the access tube sections 6S themselves, and each socket connector 6C comprising a pair of longitudinally opposite -i.e. leading and trailing -end faces 46.

The construction and physical arrangement of each stirrup device 20 is shown more clearly in FIGS. 3, 4 & 5. Each stirrup device 20 comprises a closed loop 22 of substantially rigid material, e.g. steel (although optionally a suitably strong and rigid plastics material, e.g. a suitable PVC, could be used instead), through which the respective access tube 6 can translatably and longitudinally move, such as when the tube 6 is initially inserted into the cage arrangement before being brought to site and/or when the tube 6 needs to be longitudinally slid into a desired position, relative to the cage 2, during its interconnection end-to-end to another like access/guide tube or during splicing of one cage 2 to another. The closed loop 22 of the stirrup device 20 comprises an internal supporting or retaining face 26 all the way around it, which face 26 is characteristically convexly arcuate or curved in profile. It is this convexly arcuate or curved profile shape of the internal supporting or retaining face 26 that, in accordance with the present invention, serves to guide -or to direct or deflect or assist to "ride up and over the boundary of" -an open free end of the tube 6, and/or a leading edge 46 of a connector socket 6C which interconnects a pair of the access tube sections 65 (if that type of access tube 6 is employed), with far less propensity for, or even substantially with elimination of, fouling or catching thereof against the side faces (corresponding to the side faces F of the prior art stirrup of FIG. 1) of the closed loop 22 of the stirrup device 20 as the access tube 6 is inserted into, or is longitudinally moved within, the stirrup device 20. This internal sliding relative movement of the access tube 6 through the stirrup device 20 is shown happening in FIG. 5.

The stirrup device 20 includes a backplate or baseplate 30 for attaching the U-shaped portion of the closed loop 22 of the stirrup device 20 to a rebar 12 (or possibly more than one rebar 12) of the cage 2, e.g. by welding, such as by fillet welds 38B. The closed loop 22 of the stirrup 20 is formed in part by a U-shaped loop of the relevant substantially rigid material, e.g. steel, with the required cross-sectional convexly arcuate or curved profile shape, which is typically cut from a suitable length of stock steel material of that cross-sectional shape. The appropriate length of that steel material is then formed, using any suitable known technique and apparatus, into the desired U-shape by being bent back on itself to form the "U", and its free ends then welded to the backplate/baseplate 30, e.g. by fillet welds 38A. A transverse bracing member 24 is welded (again by fillet welds 38A) between the arms of the "U", in order to form the finally closed loop 22 of the stirrup 20. The bracing member 24 is also cut from the same convexly arcuate or curved profiled stock steel material, so that it too (like the U-shaped portion of the closed loop 22) presents a corresponding convexly arcuate or curved internal supporting or retaining face 26 to the inside of the overall closed loop 22 on that side thereof opposite the curved/arcuate U-shaped portion thereof. In this manner, the entire arrangement of internally directed and internally facing supporting or retaining faces 26 of the closed loop 22 of the stirrup 20-i.e. all the way around the closed loop 22 passing along its loop sections including both the curved U-shaped portion and the bracing member portion -all present the same convexly arcuate or curved profile shape, whereby the access tube-guiding or -directing function of the closed loop 22 is fulfilled along all sections thereof passing completely around the closed loop 22.

The affixing or attachment of the backplate or baseplate 30 to the relevant cage bar(s) 12 is such that the closed loop 22 of the stirrup device 20 projects generally transversely or radially inwardly of the cage 2, i.e. generally perpendicularly relative to the longitudinal axis of the cage 2 and/or of the respective tubes 6 to be supported and/or retained by the stirrup device 20, so that the closed loop 22 of the stirrup device 20 itself defines its own central axis which is substantially perpendicular to the general plane of the closed loop 22 and is substantially coincident with the longitudinal axis of the respective access tube 6 once it has been positioned in the closed loop 22 of the stirrup device 20 and properly supported and retained thereby/therein.

In this illustrated example embodiment, the actual convexly arcuate or curved profile shape of the stock steel used to form the internal supporting or retaining faces 26 of the closed loop 22 of the stirrup 20 may be of any appropriate or suitable geometric curve or function. A general "half-moon", or arc (or sector) of a circle, shape may be typically employed, although any other suitable profile shapes may be used instead, such as any of the following, for example: semi-circle, semi-ellipse, part-ellipse (or any arc of an ellipse), parabola (or any arc of a parabola), hyperbola (or any arc of a hyperbola), or other symmetrical or asymmetrical (or possibly even freeform) geometric curve of a generally convex nature or configuration.

In this illustrated example embodiment, the convexly arcuate or curved profile shaped internal supporting or retaining faces 26 of the closed loop 22 of the stirrup 20 are shown as extending right across the stirrup 20 from one longitudinally directed side thereof to the opposite longitudinal side thereof, so that the stirrup device 20 is in effect "symmetrically bidirectional", so that the characteristic convexly arcuate or curved profile shaped internal supporting or retaining faces 26 of the closed loop 22 enable the respective access tube 6 to be readily inserted into the stirrup device 20 and/or longitudinally moved within the stirrup device 20, substantially without fouling or catching the side faces of the closed loop 22, equally easily or readily from either one of the two opposite longitudinal end directions.

However, it may be, in certain alternative embodiments of the stirrup device 20, that each internal supporting or retaining face 26 of the closed loop 22 comprises two different half-portions located or facing to each of the two opposite longitudinally-directed sides thereof, each of which half-portions is formed with and presents its own discrete convexly arcuate or curved profile shape with its own convexly arcuate or curved geometric curve or function. Those respective convexly arcuate or curved geometric curves or functions of those respective convexly arcuate or curved half-portions may be different from each other, so that each discrete half-portion presents a differently shaped internal supporting or retaining face on/to each of the two opposite longitudinally-directed sides of the stirrup, in which case the stirrup may be considered to be "asymmetrically bi-directional", in that the discrete characteristic convexly arcuate or curved profile shaped internal supporting or retaining face half-portions of the closed loop enable the respective access tube 6 to be readily inserted into the stirrup device and/or longitudinally moved within the stirrup device, substantially without fouling or catching the side faces of the closed loop, from either one of the two opposite longitudinal end directions but (usually in such embodiments) with an unequal degree of ease or readiness when so inserted or moved from one longitudinal end direction as compared with from the other.

Furthermore, and further still, in certain other embodiment forms, it may even be the case that the characteristically convexly arcuate or curved profile shaped internal supporting or retaining face of the closed loop is provided on one longitudinally-directed half-portion only, and not the other (which could be of any shape), so that such an embodiment stirrup device may be considered to be "mono-directional", in that the characteristic convexly arcuate or curved profile shaped portion of the closed loop enables the respective access tube 6 to be readily inserted into the stirrup device and/or longitudinally moved within the stirrup device, substantially without fouling or catching the side faces of the closed loop, from one longitudinal end direction only.

As shown in FIG. 6, for use with stirrup devices 20 of the invention embodiment, it may be particularly useful to employ modified socket connectors 60 for interconnecting adjacent access/guide tube sections 6S, which have bevelled or chamfered leading and/or trailing end faces 46. These modified end faces 46 of such socket connectors 60 may assist in the even more efficient insertion into and uninterrupted passage through the closed loop 22 of the or each stirrup device 20 of the relevant tube 6.

As is shown by way of example in FIG. 2, in practising many practical embodiments of the present invention which focus on the stirrup devices 20, the or each access tube 6 may -if desired or if appropriate -be fitted or provided with a temporary locking device 60 for selective actuation to either (i) lock the tube 6 in a substantially fixed longitudinal position relative to the cage 2, e.g. for preventing unwanted longitudinal movement of the tube 6 relative to the cage 2 during its transit to an on-site location, or (ii) permit sliding longitudinal movement of the tube 6 relative to the cage 2 (or vice versa), e.g. so that the tube 6 is free to longitudinally move, relative to the cage 2 (or vice versa) -assisted by its substantially (or relatively) unhindered longitudinal movement through the closed loop(s) 22 of the stirrup devices 20 of this invention -for the purpose of correctly positioning the tube 6 during its interconnection or splicing to/with a longitudinally adjacent tube length during the overall splicing together of adjacent cages 2, and also for the purpose of allowing the cage 2 to which a given stirrup device 20 is attached to be lowered relative to such a respective interconnected/spliced access tube 6 during the splicing of that cage 2 to an adjacent cage therebelow. Practical examples of such temporary locking devices 60 may be either already known in the art, or may be the subject of a separate invention for use with the stirrup devices 20 of embodiments of the present invention presented herein.

It is to be understood that the above description of some specific embodiments of the invention in terms of their various features and aspects has been by way of non-limiting example(s) only, and various modifications may be made from what has been specifically described and illustrated whilst remaining within the scope of the invention as claimed.

Throughout the description and claims of this specification, the words "comprise" and "contain" and linguistic variations of those words, for example "comprising" and "comprises", mean "including but not limited to", and are not intended to (and do not) exclude other moieties, additives, components, elements, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless expressly stated otherwise or the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless expressly stated otherwise or the context requires otherwise.

Features, components, elements, integers, characteristics, properties, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith or expressly stated otherwise.

Claims

CLAIMS1. A stirrup device for supporting and/or retaining a longitudinally arranged access tube for incorporation into a pile or other structure for the purpose of subsequent testing or monitoring thereof, the stirrup device comprising a closed loop of substantially rigid material through which the access tube can translatably and longitudinally move, wherein the closed loop of the stirrup device comprises at least one internal supporting or retaining face, and at least a portion of the said internal supporting or retaining face is convexly arcuate or curved in profile.
2. A stirrup device according to claim 1, further including means for attachment thereof to a portion of, especially to at least one respective cage bar of, the reinforcement cage within which the respective access tube is to be mounted whilst being supported and/or retained by the stirrup device.
3. A stirrup device according to claim 2, wherein the attachment means comprises a backplate or baseplate, onto one side of which the closed loop of the stirrup device is affixed or attached, with the opposite side of the backplate or baseplate being affixable or attachable to the respective cage bar(s) of the cage.
4. A stirrup device according to any preceding claim, wherein the closed loop comprises a U-shaped loop of the substantially rigid material, with a bracing member attached to and between the two arms of the "U" to create the closed loop therebetween, through which closed loop is passable the respective access tube, or a portion of a respective access tube, to be supported and/or retained by the stirrup device.
5. A stirrup device according to claim 4, wherein the U-shaped arms of the stirrup device are formed from an elongate length of the substantially rigid material that has, on at least a portion of at least one internal supporting or retaining face thereof, the said convexly arcuate or curved profile shape.
6. A stirrup device according to any preceding claim, wherein the closed loop of the stirrup device comprises a plurality of the said internal supporting or retaining faces, which together face internally of the closed loop along substantially its entire loop length or are located on substantially all of its sections passing around the closed loop, and each of which internal supporting or retaining faces has at least a portion which has the said convexly arcuate or curved profile shape
7. A stirrup device according to claim 6, as dependent through claim 3 or claim 4, wherein each one of the said U-shaped length of material and the bracing member, or alternatively each one of the said U-shaped length of material and the backplate/baseplate (as the case may be), includes a respective said internal supporting or retaining face of which at least a portion thereof has the said convexly arcuate or curved profile shape, whereby the access tube-guiding or -directing function of the closed loop is fulfilled along all sections thereof passing around the closed loop.
8. A stirrup device according to any one of claims 1 to 7, wherein the closed loop of the stirrup device comprises a said at least one internal supporting or retaining face of which only a portion thereof, which portion is located or faces to one longitudinally-directed side thereof, is formed with and presents the said convexly arcuate or curved profile shape, and that convexly shaped portion is provided on that one longitudinally-directed side of the closed loop which is proximal to or faces towards one longitudinal end only of the access tube to be supported/retained by that closed loop, whereby the stirrup device is "mono-directional" in that the said convexly arcuate or curved profile shaped portion of the closed loop enables the respective access tube to be readily inserted into the stirrup device and/or longitudinally moved within the stirrup device, substantially without fouling or catching the side faces of the closed loop, from that one longitudinal end direction only.
9. A stirrup device according to any one of claims 1 to 7, wherein the closed loop of the stirrup device comprises a said at least one internal supporting or retaining face of which each of two longitudinally adjacent portions thereof is formed with and presents a respective one of a pair of discrete convexly arcuate or curved profile shapes, and each of said convexly shaped portions is provided on a respective one of the two longitudinally-directed sides of the closed loop which are proximal to or face towards each of the two opposite longitudinal ends of the access tube to be supported/retained by that closed loop, and wherein the said discrete convexly arcuate or curved profile-shaped longitudinally adjacent portions of the at least one internal supporting or retaining face have or are defined either by (i) substantially the same curve function or geometric shape as each other, or (h) substantially different curve functions or geometric shapes from each other, albeit with the proviso that the two discrete portions are contiguous with or merge into one another, optionally at or along a longitudinally-directed midpoint or mid-line across the said at least one internal supporting or retaining face of the closed loop, whereby the stirrup device is "asymmetrically bi-directional" in that the said discrete convexly arcuate or curved profile shaped internal supporting or retaining face portions of the closed loop enable the respective access tube to be readily inserted into the stirrup device and/or longitudinally moved within the stirrup device, substantially without fouling or catching the side faces of the closed loop, from either one of the two opposite longitudinal end directions but with an unequal degree of ease or readiness when so inserted or moved from one longitudinal end direction as compared with from the other.
10. A stirrup device according to any one of claims 1 to 7, wherein the closed loop of the stirrup device comprises a said at least one internal supporting or retaining face of which substantially the whole thereof is formed with and presents a single said convexly arcuate or curved profile shape, and that convexly shaped substantially entire internal supporting or retaining face extends to, or spans between, both longitudinally-directed sides of the closed loop which are proximal to or face towards both opposite longitudinal ends of the access tube to be supported/retained by that closed loop, whereby the stirrup device is "symmetrically bi-directional" in that the said convexly arcuate or curved profile shaped internal supporting or retaining face of the closed loop enables the respective access tube to be readily inserted into the stirrup device and/or longitudinally moved within the stirrup device, substantially without fouling or catching the side faces of the closed loop, equally easily or readily from either one of the two opposite longitudinal end directions.
11. A stirrup device according to any preceding claim, wherein the convexly arcuate or curved profile shape of the relevant portion of the at least one internal supporting or retaining face of, or the at least one internal supporting or retaining face itself of, the closed loop has a profile shape selected from any of the following: semi-circle, part-circle or any arc of a circle, semi-ellipse, part-ellipse or any arc of an ellipse, parabola or any arc of a parabola, hyperbola or any arc of a hyperbola, or other symmetrical or asymmetrical or even freeform geometric curve of a generally convex nature or configuration.
12. A stirrup device according to any preceding claim, as dependent through claim 3 or claim 4, wherein each one of the said U-shaped length of material and the bracing member, or alternatively each one of the said U-shaped length of material and the backplate/baseplate (as the case may be), is formed from a selected length cut from a single supplied stock material which has the required convexly arcuate or curved profile shape.
13. A reinforcement cage for incorporation into a pile or other structure during the formation thereof, the reinforcement cage having attached thereto, especially to a or each of one or more respective cage bars thereof, at least one, or one or more, stirrup device(s) according to any one of claims 1 to 12, whereby the or each of the at least one, or one or more, stirrup device(s) is for supporting and/or retaining in the said cage a, or a respective, longitudinally arranged access tube, or a portion of a, or a respective, longitudinally arranged access tube, also for incorporation into the pile or other structure for the purpose of subsequent testing or monitoring thereof, with the or each respective access tube being translatably and longitudinally moveable through the closed loop of a or a respective said stirrup device.
14. An arrangement comprising, in combination, a reinforcement cage for incorporation into a pile or other structure during the formation thereof, and one or more longitudinal access tubes arranged within the said cage and also for incorporation into the pile or other structure for the purpose of subsequent testing or monitoring thereof, wherein the or each access tube is supported and/or retained in a or at least one, or one or more, stirrup device(s) according to any one of claims 1 to 12, the or each stirrup device being attached to the said reinforcement cage, optionally to a or a respective one or more cage bars thereof.
15. A reinforcement cage according to claim 13 or an arrangement according to claim 14, wherein the or each stirrup device is a stirrup device according to claim 3, and wherein the affixing or attachment of the backplate or baseplate to the relevant cage bar is such that the closed loop of the stirrup device projects generally transversely or radially inwardly of the cage, optionally in a generally perpendicular direction relative to the longitudinal axis of the cage and/or of the respective access tube to be supported and/or retained by the stirrup device, and such that the closed loop of the device itself defines its own central axis which is substantially perpendicular to the general plane of the closed loop and is substantially coincident with the longitudinal axis of the respective access tube once it has been positioned in the closed loop of the stirrup device and properly supported and retained thereby/therein.
16. A reinforcement cage according to claim 13 or claim 15 or an arrangement according to claim 14 or claim 15, wherein a plurality of the said stirrup devices are provided or employed, and one or more of the stirrup devices is/are attached to any given one of one or more of the cage bars of the cage at longitudinally spaced apart locations therealong, whereby any given cage bar of the cage has attached thereto one or more said stirrup devices, or a plurality of said stirrup devices, longitudinally spaced apart locations therealong.
17. A reinforcement cage according to claim 13 or an arrangement according to claim 14, either being as defined in claim 16, wherein the plurality of the said stirrup devices are uniformly or symmetrically or equidistantly distributed along the length of the or the respective cage bar, or along at least a major portion of the length of the or the respective cage bar.
18. An arrangement according to any one of claims 14 to 17, wherein the or each access tube comprises a plurality of access tube sections interconnected in one or more end-toend pairs by one or more socket connectors, the or each socket connector being of enlarged external transverse width or diameter compared with the access tube sections themselves.
19. An arrangement according to claim 18, wherein the or each socket connector comprises one or more, optionally a pair of longitudinally opposite, leading and trailing, ends faces, and wherein at least one of, optionally both of, the said longitudinally opposite leading and trailing ends faces of the or each socket connector is/are bevelled or chamfered.
20. An arrangement according to any one of claims 14 to 19, wherein the or each access tube is fitted or provided with a temporary locking device for selective actuation to either (i) lock the access tube in a substantially fixed longitudinal position relative to the cage, for preventing unwanted longitudinal movement of the access tube relative to the cage during its transit to an on-site location, or 00 permit sliding longitudinal movement of the access tube relative to the cage (or vice versa), so that the access tube is free to longitudinally move, relative to the cage (or vice versa) -assisted by its relatively or substantially unhindered longitudinal movement through the closed loop(s) of the one or more said stirrup devices -for the purpose of correctly positioning the access tube during its interconnection or splicing to/with a longitudinally adjacent access tube length during the overall splicing together of adjacent cages, and also for the purpose of allowing a cage to which a given stirrup device is attached to be lowered relative to such a respective interconnected/spliced access tube during the splicing of that cage to an adjacent cage therebelow.
21. A method of supporting and/or retaining one or more longitudinally arranged access tubes within a reinforcement cage for incorporation into a pile or other structure during the formation thereof, the one or more access tubes also being for incorporation into the pile or other structure for the purpose of subsequent testing or monitoring thereof, the method comprising: providing at least one, or one or more, stirrup device(s) according to any one of claims 1 to 12, and attaching the or each said stirrup device to the said reinforcement cage, optionally to a or each of one or more respective cage bars thereof; and longitudinally passing the or each respective access tube through the closed loop of a or a respective one of one or more said stirrup devices, whereby the or each respective access tube is supported and/or retained in the or the respective one of the one or more said stirrup devices whilst being translatably and longitudinally moveable through the closed loop thereof.