Transverse reinforcing bar array

Abstract

A method of installing a transverse reinforcing bar array comprises installing a guidance structure to a transverse reinforcing bar array. The transverse reinforcing bar array comprises a plurality of reinforcing bars connected to a support structure. Installing a guidance structure comprises inserting each of the reinforcing bars into a hole of the guidance structure. The method comprises arranging the transverse reinforcing bar array such that the support structure is above the guidance structure. The holes of the guidance structure are aligned with a first mesh comprising holes such that a distal end of each of the reinforcing bars is aligned with respect to a hole of the mesh. The transverse reinforcing bar array is lowered such that a lower face of the guidance structure comes in to contact with an upper surface of the first mesh. Further lowering the transverse reinforcing bar array is done such that the transverse reinforcing bars pass through the guidance structure and the holes of the mesh.

Description

Transverse Reinforcing Bar Array

[0001] The present disclosure relates to a method and associated apparatus for guiding the installation of an array of transverse reinforcing bars.BACKGROUND

[0002] Reinforcing bars, or rebars, are used to reinforce concrete slabs to improve the tensile strength of the concrete when in use. Generally, layers of parallel rebars with each layer being orthogonal to the next are in a stacked arrangement in upper and lower regions of a concrete slab. Where the slab is subject to high shear forces, additional transverse rebars are used, positioned transverse to (also referred to as perpendicular to) the stacked layers. The centre of the slab usually has no steel except for the transverse bars which “connect” the top and bottom steel layers together.

[0003] The examples described herein are not limited to examples which solve problems mentioned in this background section.SUMMARY

[0004] Examples of preferred aspects and embodiments of the invention are as set out in the accompanying independent and dependent claims.

[0005] In various examples there is a method of installing a transverse reinforcing bar array comprising: installing a guidance structure to the transverse reinforcing bar array wherein the transverse reinforcing bar array comprises a plurality of reinforcing bars connected to a support structure and installing a guidance structure comprising inserting each of the reinforcing bars in to a hole of the guidance structure; arranging the transverse reinforcing bar array such that the support structure is above the guidance structure; aligning the holes of the guidance structure with a first mesh comprising holes such that a distal end of each of the reinforcing bars is aligned with respect to a hole of the mesh; lowering the transverse reinforcing bar array such that a lower face of the guidance structure comes in to contact with an upper surface of the first mesh; further lowering the transverse reinforcing bar array such that the transverse reinforcing bars pass through the guidance structure and the holes of the mesh.

[0006] By using the guidance structure an efficient, safe way to install transverse rebar arrays is achieved. Since the guidance structure has holes as claimed it is possible to achieve alignment even on construction sites where access is limited and where the transverse rebar is long and heavy such that lifting equipment is used.

[0007] Preferably the method comprises further lowering the transverse reinforcing bar array by lowering the array of transverse reinforcing bars such that a lower face of the support structure is brought into contact with an upper surface of the guidance structure. This is a straightforward way for engineers on site to know when the lowering is to end.CMS REF N00572.00317Confidential

[0008] Preferably, arranging the transverse reinforcing bar array comprises rotating the array of transverse reinforcing bars from a horizontal orientation to a vertical orientation. In this way, lengthy transverse rebar arrays may be transported horizontally on a flat bed of a lorry and once on site, moved to a vertical orientation for installation. Because of the support structure5 and the guidance structure rotation is facilitated.

[0009] In some examples the method comprises installing a second guidance structure below the first mesh such that, when lowered, the distal ends of the transverse reinforcing bars passes through holes of the second guidance structure. This gives an efficient way to construct a complex installation on site.10

[0010] Preferably the second guidance structure is aligned with a second mesh such that when lowered the distal ends of the transverse reinforcing bars pass through holes of the second mesh. In this way installation to a second mesh is achieved safely and efficiently on site.

[0011] In some examples, removing the guidance structure is done by disassembling a plurality of elements of the guidance structure. This saves resources since the guidance structure can be re used.

[0012] The disassembling may comprise detaching the elements from one another and removing the first guidance structure. By detaching the elements removing the elements is facilitated.

[0013] In some cases the second guidance structure is the first guidance structure thus saving resources.

[0014] In some examples the distal end of each of the reinforcing bars being aligned with respect to a hole of the mesh comprises a centre of the reinforcing bars being aligned with a centre of the hole of the mesh or a point offset from the centre of the hole of the mesh. This facilitates installation.

[0015] In some cases the method further comprises lifting the transverse reinforcing bar array25 from a first connection point and a second connection point wherein the first connection point is attached to the support structure and the second connection point is attached to the guidance structure. Using two points improves lifting accuracy and safety.

[0016] In some cases the method further comprises installing a stopper on the distal end of at least one of the transverse reinforcing bars wherein the width of the stopper is wider than the width of the hole of the guidance plate such that when the stopper is installed after the guidance plate, the guidance plate is prevented from sliding off the distal end of the transverse reinforcing bar. This improves safety.

[0017] In some examples the method comprises pouring a media, such as concrete, through a second set of holes of the guidance system. In this way curing of a concrete slab is facilitated.35

[0018] In some examples, aligning the guidance structure with the holes of the mesh comprises using a positioning device installed on the guidance structure. By using a positioning device which is on the guidance structure it is possible to efficiently and effectively achieve alignmentCMS REF N00572.00317Confidential even in confined spaces. Because the positioning device is installed on the guidance structure there is no need for separate parts so minimizing the complexity on the construction site.

[0019] In some examples the positioning device is an angled plate which protrudes from a face of the guidance structure. The angled plate comes in to contact with the mesh during5 installation and the angled plate reacts against the mesh to align the holes of the guidance structure with the holes of the mesh.

[0020] In some examples the method comprises aligning the distal end of the at least one transverse reinforcing bar with the holes of the mesh by using an alignment device installed on the distal end of the transverse reinforcing bar. Installing an alignment device on the end10 of the transverse rebar is straightforward. The alignment device facilitates fast, effective installation on the construction site.

[0021] In an example the method comprises moving the alignment device into contact with a lower surface, such as base concrete, or a surface of another structure on the construction site. The method may comprise deforming the alignment device by a downwards force exerted on the alignment device by the transverse reinforcing bar. A challenge is that the alignment device may contact any base concrete before the transverse bar is in it’s correct vertical position. Where this is a possibility, the alignment device may be designed to collapse under the self-weight of the transverse bar.

[0022] In some examples the method comprises connecting an end of one of the reinforcing bars to a structure. This enables larger or more complex reinforced structures to be constructed. A rebar coupler may be used to connect the end of the reinforcing bar to another reinforcing bar and this gives a convenient to implement and strong connection.

[0023] In various examples the support structure is a metal plate, or a metal substrate, and the reinforcing bars are welded to the plate or substrate.25

[0024] According to another aspect of the technology there is a guidance structure comprising: a substrate formed from a material suitable for holding rebar; a first plurality of holes in the substrate, each one of the first plurality of holes sized and shaped to enable a rebar to pass through the substrate, the first plurality of holes being spaced apart from one another in the substrate according to a specified spacing interval; a second plurality of holes in the substrate, the second plurality of holes being interspersed between the first plurality of holes.

[0025] The guidance structure is strong and light as a result of the holes and so is able to hold rebar in position, such as during installation of a transverse rebar array into one or more rebar meshes arranged generally perpendicular to the transverse rebar array. By having the35 second plurality of holes it is possible to pour concrete or other media through the second plurality of holes and thus between the transverse rebars and the mesh in order to cast a reinforced concrete slab.CMS REF N00572.00317 3Confidential

[0026] Preferably the substrate is formed from a plurality of segments which are removably attached to one another. Since the segments are removably attached to one another, installation and removal of the guidance structure from a transverse rebar array is facilitated. For example, the guidance structure can be removed if it is accessible and economical to do5 so. If it is undesirable, or not feasible, to remove the guidance structure it can be left in place without negatively impacting the final structure.

[0027] In an example, a first one of the segments comprises a plurality of the second holes and a plurality of recesses, and at least one other of the segments comprises a plurality of recesses that cooperate with the plurality of recesses of the first segment to form ones of the first holes.10 In this way the segments can be easily inserted between and removed from between rebars.

[0028] In some cases the guidance structure comprises a positioning device arranged to align the first plurality of holes of the guidance structure with holes of a mesh. By having the positioning device integral with or attached to the guidance structure the installation process is simplified.

[0029] In some examples the guidance structure is a plate. By having a planar structure for the guidance structure it is easy for engineers to see when the plate is orthogonal to the transverse rebars. Using a plate, as compared to a cuboid substrate, provides ease of manufacture. Alternatively, the guidance structure is a cuboid substrate. Using a cuboid substrate, such as made from cold rolled sections, can provide advantages due to reduced weight and less wastage during manufacture, compared to a plate.

[0030] In some examples the guidance structure comprises bars for removably attaching the segments to one another. This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is25 it intended to be used to limit the scope of the claimed subject matter.

[0031] It will also be apparent to anyone of ordinary skill in the art, that some of the preferred features indicated above as preferable in the context of one of the aspects of the disclosed technology indicated may replace one or more preferred features of other ones of the preferred aspects of the disclosed technology. Such apparent combinations are not explicitly listed above under each such possible additional aspect for the sake of conciseness.

[0032] Other examples will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrate by way of example the principles of the disclosed technology.BRIEF DESCRIPTION OF THE DRAWINGS35

[0033] FIG. 1 is a schematic illustration of a transverse reinforcing bar array;

[0034] FIG. 2 is a schematic illustration of a guidance structure;

[0035] FIG. 3A and B schematically illustrate manoeuvring of a transverse reinforcing bar array;CMS REF N00572.00317Confidential

[0036] FIG. 4A to 4D illustrate the installation of a transverse reinforcing bar array;

[0037] FIG. 5A is a schematic diagram of a removable guidance structure;

[0038] FIG. 5B is a schematic diagram of another example of a removable guidance structure;

[0039] FIG. 50 is a schematic diagram of installing a removable guidance structure;5

[0040] FIG. 6A and 6B illustrate the use of a removable guidance structure;

[0041] FIG. 7A is a plan view of a guidance structure;

[0042] FIG. 7B is a side view of a guidance structure;

[0043] FIG. 8A-C schematically illustrate an alignment means;

[0044] FIG. 9 is a flow diagram of a method of installing a transverse reinforcing bar array.10

[0045] FIG. 10 is a schematic diagram of another example of a guidance structure, where the guidance structure has retractable elements.

[0046] The accompanying drawings illustrate various examples. The skilled person will appreciate that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the drawings represent one example of the boundaries. It may be that in some examples, one element may be designed as multiple elements or that multiple elements may be designed as one element. Common reference numerals are used throughout the figures, where appropriate, to indicate similar features.DETAILED DESCRIPTION

[0047] The following description is made for the purpose of illustrating the general principles of the present technology and is not meant to limit the inventive concepts claimed herein. As will be apparent to anyone of ordinary skill in the art, one or more or all of the particular features described herein in the context of one embodiment are also present in some other embodiment(s) and / or can be used in combination with other described features in various possible combinations and permutations in some other embodiment(s).25

[0048] The terms top, bottom, upper and lower and other relative terms as used herein are intended to identify the location of features of the present invention relative to one another and do not infer, or limit, the orientation of any of the apparatus or structures described herein.

[0049] In substantial infrastructure projects such as nuclear power stations or offshore structures, reinforced concrete slabs can be several metres thick. The slab typically comprises a number of layers of top and bottom rebars, successive layers being orthogonal to each other. Where the slab is subject to high shear forces, additional transverse rebars are placed to run between the bottom steel layer and the top steel layer. These transverse bars act in tension and prevent horizontal splitting of the concrete slab.

[0050] In some arrangements the transverse bars hook around the bottom and top rebars. An35 alternative is to use headed bars which terminate just outside the bottom and top rebars.

[0051] In thin, lightly loaded slabs, techniques have been developed to install transverse bars in rows or arrays by hand. In the thicker, heavily loaded slabs associated with substantial infrastructure projects, the weight of each transverse rebar can be 10kg to 70kg which is tooCMS REF N00572.00317 5Confidential heavy to handle in an array, hence transverse bars are installed individually. The heavier bars require several operatives to put in place, and often the use of a crane which is time consuming and complex.

[0052] The present technology is concerned with how to efficiently and safely install arrays of5 transverse rebar which require handling by lifting equipment such as a crane. An array of transverse rebar is a generally planar arrangement of a plurality of rebar placed in parallel and held by a carrier assembly at one end of the rebars so that spacing intervals between the rebar are generally equal. The installation is performed on a construction site where access may be restricted. The installation of the transverse rebar array is performed with respect to one or10 more planar meshes of rebar that are already installed at the construction site. A planar mesh of rebar comprises a first plurality of parallel rebar spaced at intervals over a plane and a second plurality of rebar orthogonal to the first plurality of rebar and also spaced at intervals over the plane. The planar meshes may be stacked generally in alignment with one another so that bars of the transverse rebar array may be inserted into “grid cells” of the stacked meshes. In some cases, rather than having meshes, arrays with rebar in one direction only over the plane are used. Once the transverse rebar array is in place, concrete may be poured around the stacked meshes and transverse rebar array and then cured to form a concrete slab.

[0053] A number of problems with installation of transverse rebar arrays have been recognised.

[0054] Due to the size of a transverse rebar array, it is often necessary to transport the array with the transverse bars horizontal (resting on the flat bed of a transport lorry). In such a scenario, free ends of the bars are free to oscillate which can expose sections of the array to excessive bending moments resulting in plastic deformation and damage. For installation it is often necessary to lift the array in the horizontal orientation or to rotate the array from the horizontal orientation to a vertical orientation. Due to the bars only being connected at a single end, this25 can result in clashing between the bars and overloading of individual bars.

[0055] The free ends of the bars will be a significant distance from the carrier assembly. The natural tolerances on reinforcing bars means that the free ends of some of the transverse bars may not pass through the gaps between the horizontal bars. This applies particularly with headed bars. The result is that the array cannot be lowered into final position.

[0056] A typical array may be 2m x 2m in plan, with bars on 400mm centres (36 bars total). With a potential bar length greater than 4m, the array will need to be transported horizontally, i.e. , the bars are cantilevering out from the carrier assembly. At site the array will need to be upended by lifting from the carrier assembly. During the rotation operation the weight of the array will be carried by any bars in contact with the trailer bed. Depending on sling lengths and35 the free end support conditions, the entire weight may momentarily be carried by one bar. This risks plastically bending and hence deforming the bar, risking a clash as the bar array is lowered into a mesh. As a very minimum it will require the connection to the carrier assembly to be significantly stronger than it would otherwise need to be.CMS REF N00572.00317 6Confidential

[0057] FIG.1 of the accompanying drawings is a schematic illustration of a transverse reinforcing bar (rebar) array 100. The transverse rebar array 100 comprises a support structure 104 and transverse rebars 106 which, when installed, are broadly perpendicular to the support structure 104. In use, each of the transverse rebars 106 are connected to the support structure 104. The5 support structure 104 can be a plate to which an end of each of the transverse rebars 106 is attached. In some examples, the transverse rebars 106 extend through the support structure such that the support structure 104 is offset from the ends of the transverse rebars 106. In such an example, a section of the transverse rebars 106 which extends beyond the support structure 104 can be connected to a construction element, such as a wall. For example,10 wherein the wall is perpendicular to the transverse rebars 106, transverse rebars 106 can lap with rebars within the wall so as to facilitate a connection. In some examples, the section of transverse rebars 106 which extends beyond the support structure 104 is connected to an additional rebar via a rebar coupler.

[0058] In some examples, a first end 102 of each of the transverse rebars 106 is fixedly attached to the support structure 104. For example, each first end 102 of each transverse rebar 106 may be welded to the support structure 104. The transverse rebars are arranged in parallel rows in some cases, which form the array. The transverse rebar array is arranged in any suitable configuration. For example, the transverse rebars may be arranged in a 4 x 4, 4 x 6, 3 x 5, 6 x 6, or 8 x 8 configuration. The support structure 104 acts to hold a plurality of rebar with generally fixed spaces between the rebar. In an example the support structure is a plate, such as a metal or steel plate. However, it is not essential to use a plate as other shapes and forms of support structure may be used where these hold the rebar at generally fixed intervals. In various examples the support structure is fixed to the transverse rebars such as by welding. A guidance structure 200, when installed, limits the movement of distal ends of the individual25 rebars. The term “distal end” refers to an end of a rebar which is furthest away from the support structure 104. A guidance structure acts to hold a plurality of rebar with generally fixed spaced between the rebar. In various examples the guidance structure is not permanently fixed to the transverse rebar, unlike the support structure. In such a way, the support structure 104 provides a fixed point on the transverse rebars 106 to prevent axial movement of the rebar relative to the support structure and the guidance structure 200 guides the transverse rebars 106 and can move axially along the rebars when installed. [The transverse rebars may be any length suitable for an intended installation. For example each transverse rebar could be 1m, 2m, 3m, 4m, 5m, 6m or 7m in length where m denotes metre.

[0059] FIG. 2 is a schematic illustration of a guidance structure 200. The guidance structure 200,35 when installed on the transverse rebar array 100 is slidable with respect to the transverse rebar array 100. The guidance structure 200 of FIG.2 has a first set of holes 202 and a second set of holes 204. The second set of holes 204 are arranged to allow a media, for example concrete, to flow through the holes when the transverse rebar array 100 is installed. The first set of holesCMS REF N00572.00317 7Confidential202 is arranged to receive second, or distal, ends 108 of the transverse rebars 106. When installed, the guidance structure 200 is confined to move axially along the transverse rebars 106. For example, the guidance structure 200 can move along a first axis towards and away from the support structure 102. The guidance structure 200 limits the movement of the5 transverse rebars 106 perpendicular to the first axis. In the orientation shown in FIG.2, the first axis is a vertical y-axis and movement along the corresponding z and x- axes is restricted by the guidance structure 200. Due to the length of the transverse rebars 106, a relatively small angular offset from the first axis of the transverse rebar 106 can result in a relatively large offset of the distal end 108 of the transverse rebar 106. This can prevent, or complicate, correct10 installation of the transverse rebar array. By limiting the movement of the transverse rebars 106, the guidance structure 200 minimises the offset of the distal ends 108 such that installation is easier and more efficient.. The guidance structure 200 can be a plate and in particular can be a metal plate such as a steel plate. The dimensions of the plate can be 4m x 4m or 5m x 5m and the plate can be 12mm, 14mm or 16mm thick. Alternatively, the guidance structure 200 can be formed from several beam elements arranged together to form a grid pattern.

[0060] The first set of holes 202 are such that they can receive each of the distal ends of the transverse rebars 106. . . In some examples, heads are installed to the distal ends of the rebars 106 following installation of the guidance structure, such as via welding. In some examples, the transverse rebars 106 do not have a head and instead, once the rebar has passed through the hole 202 a removable stopper is attached to the distal end of the rebar to prevent the transverse rebar passing back through the hole 202. Preferably, the guidance structure 200 is a removable guidance structure which is installed in parts such that the heads can be installed to the distal ends 108 of the transverse rebars prior to installation of the removable guidance25 structure. In such a way, the guidance structure can be installed at a mid-point of the transverse rebars 106 between the support structure and the distal ends of the transverse rebars 106.

[0061] FIG.3A and FIG.3B illustrate lifting and manoeuvring of the transverse rebar array 100, respectively. As shown in FIG.3A, the support structure 104 provides a first connection point for lifting the transverse rebar array 100 and the guidance structure 200 provides a second such connection point for lifting the transverse rebar array 100. For example, the connection points can provide an attachment point for attaching to a lifting device such as a crane. When the transverse rebar array 100 is lifted by the first connection point without the guidance structure 200 installed, the support structure is liable to bend and cause the transverse rebars 106 to rotate towards the centre of the support structure 104. This can cause plastic35 deformation in both the support structure 104 and the transverse rebars 106 as well as causing the transverse rebars 106 to clash against one another. Further, this can introduce a bending movement at the connection point between the transverse rebars 106 and the support structure 100.CMS REF N00572.00317 8Confidential

[0062] Without the guidance structure 200 installed, an operator is able use one or more of the individual rebars 106 as the second connection point. In such examples, the individual rebars 106 acting as the second connection point may experience loading which results in plastic deformation. By providing the guidance structure 200 it is possible to avoid such overloading5 and resulting damage. In the lifting scenario illustrated, the guidance structure 200 is in contact with a plurality of rebars 106 and as such the weight of the transverse rebar array 100 is shared between the plurality of rebars 106. Preferably, the guidance structure 200 distributes the load between all of the transverse rebars 106.

[0063] FIG. 3B illustrates the transverse rebar array 100 being lifted from the first connection10 point such that the transverse rebar array 100 is rotated from a horizontal orientation towards a vertical orientation. As shown in FIG. 3B, the transverse rebar array 100 is lifted from the support structure 104. The distal ends 108 of the transverse rebars 106 are constrained by the guidance structure 200. In such a way, during the rotation, the rebars are prevented from clashing with one another. The guidance plate 200 maintains orientation of the rebars broadly perpendicular to the support structure 104 and maintains space between the rebars 106. In such a way, the introduction of a bending moment between the individual rebars 106 and the support structure 104 is minimised. As this reduces the load placed on the connection between the rebars 106 and the support structure 104, a wider range of connection options are available. For example, a less substantial weld can be applied to prevent the rebar 106 becoming disconnected from the support structure 104. The use of the guidance structure 200 therefore improves the ease and safety of such manoeuvring operations. This is particularly advantageous because, due to the size of the transverse rebar array 100, it is preferable to transport the transverse rebar array 100 in the horizontal orientation. This then requires the rotation of the transverse rebar array 100 to the vertical orientation prior to installation.25 Conventional techniques include tying the ends of the individual rebars 106 to minimise movement. This is time consuming and requires removal of the ties prior to installation of the individual rebars 106. Further, this removal occurs when the transverse rebar array 106 is suspended and therefore presents safety concerns. The present technology improves this process by preventing damage to the transverse rebar array 100 as well as improving the ease, safety and efficiency of the operation.

[0064] FIG. 4A to 4D schematically illustrate an example of the installation of a transverse rebar array 100. The transverse rebar array 100 is installed into at least one other rebar array, referred to below as a mesh 300. The transverse rebar array and the other rebar array are both generally planar. The installation comprises inserting or threading the transverse rebar35 array into the other rebar array, so that the planes of the transverse rebar array and the other rebar array are generally perpendicular to one another. The transverse rebar array is referred to as “transverse” because it is intended to be installed generally perpendicular to anotherCMS REF N00572.00317Confidential rebar array. In some cases, the other rebar array has been installed at a construction site prior to the method of FIG. 4A to 4D being performed.

[0065] The transverse rebar array 100 is shown, in FIG. 4A in the vertical orientation prior to installation. The transverse rebar array 100 is orientated such that the support structure 104 is5 positioned above the guidance structure 200. The transverse rebar array 100 can be suspended using a crane or alternative lifting device. The transverse rebar array 100 is suspended by the support structure 104. The transverse rebar array 100 is suspended above a mesh 300. The mesh 300 of FIG. 4A is constructed from rebar in a horizontal orientation; that is, the mesh 300 is transverse (also referred to as perpendicular) to the transverse rebar10 array. The rebar of the mesh 300 is laid in a grid pattern to form regular holes within the mesh 300. For example, and as shown in FIG. 4A-4D, a first plurality of rebar 302 are laid parallel to one another with generally equal spacing between each of the rebar and a second plurality 304 of rebar are laid parallel to one another and substantially perpendicular to the first plurality and with generally equal spacing such that a square mesh is formed. In other examples, the mesh is formed from alternate layers of radial bars and circumferential bars. The mesh 300 comprises holes or grid cells. The vertical orientation of the transverse rebar array 100 is such that the transverse rebars 106 extend along on a y-axis, the first plurality of rebar 302 extend along the corresponding z-axis and the second plurality of rebar 304 extend along the corresponding x-axis. Any pattern which provides regular spacing and holes sufficient to accommodate the transverse rebars passing through is suitable. The pattern of the holes 202 of the guidance structure 200 corresponds to the pattern of holes of the mesh 300. In particular, the distance between the centres of the holes 202 of guidance structure 200 is the same as the distance between the centres of the holes of the mesh 300. The size of the holes of the mesh 300 are larger than the holes 202 of the guidance structure 200.25

[0066] As shown in FIG. 4A, the guidance structure 200 maintains distances between the transverse rebars 106 such that the transverse rebars 106 are aligned with the holes of the mesh 300 during installation. In some instances, manual manipulation of the suspended transverse rebar array 100 may be required to align the transverse rebars with the holes in the mesh. The guidance structure 200 provides means for manoeuvring the rebars as an array, so that individual alignments of individual rebars is unnecessary. In such a way, the alignment process is quicker and therefore more efficient. Further, the guidance structure 200 provides a significant safety advantage due to limiting action required under a suspended load by a construction site engineer.

[0067] As shown in FIG. 4B, as the rebar is further lowered the guidance structure 200 is brought35 into contact with the mesh 300. The guidance structure 200 cannot pass through the mesh 300. The guidance structure 200 is not attached to the transverse rebars 106. The guidance structure 200 is movable along the transverse rebars 106 in the directions towards and away from the support structure 104. Therefore, as the transverse rebar array 100 is lowered asCMS REF N00572.00317 10Confidential shown in FIG. 4B the transverse rebars 106 continue to descend while the guidance structure 200 remains on an upper surface of the mesh 300.

[0068] FIG. 4G illustrates the transverse rebar array 100 approaching a second mesh 310. In an example, a plurality of meshes of rebar array (300, 310) are already installed at a construction5 site. The plurality of meshes of rebar array have generally the same configuration and are stacked or aligned one above another so that grid cells of the meshes align. The meshes of rebar array are installed at a location on a construction site where concrete is to be set around the meshes of rebar array to form a structure such as a slab.

[0069] The transverse rebar array 100 is to be installed transverse to (i.e. generally perpendicular10 to) the meshes of rebar array such that the transverse rebars extend into grid cells of the meshes.

[0070] The second mesh may be generally planar and generally of the same configuration as the mesh 300. Beneficially, due to the location of the guidance structure 200 and the mesh 300, the movement of the transverse rebars 106 is restricted. This is because the distance between the distal ends 108 of the transverse rebars 106 and the nearest fixed, or restricted, point is shorter than the distance between the support structure 104 and the distal ends 108 without the presence of the mesh 300 or the guidance structure 200. A restricted point refers to a location on a transverse rebar which is in line with either the guidance structure 200 or the mesh 300. By shortening the distance from the nearest fixed or restricted point, the extent to which the distal end 208 of the transverse rebar 106 can move from the vertical orientation is reduced. In other words, the closer the guidance structure 200 is to the support structure 104 or mesh 300, the less guidance is provided to the transverse rebars 106 by the guidance structure 200. In such a way, the requirement for any intervention to align the transverse rebars 106 with the holes of the lower mesh 310 is reduced due the presence of the mesh 300 and / or25 the guidance structure 200.

[0071] FIG. 4D illustrates the transverse rebar array 100 in an installed position. The transverse rebar array 100 of FIG. 4D is shown across two meshes 300, 310. In some examples, the transverse rebar array 100 can be installed across 3, 4, 5 or more meshes 300, 310. The steel requirement of the end product impacts the number of meshes required. In certain applications, for example nuclear power plant construction, the steel content requirement of reinforced concrete is higher than the requirement of other applications and therefore necessitates the addition of further meshes 300, 310 The additional meshes can be multi-layer meshes. In some examples the number of layers top and bottom are similar.

[0072] The transverse rebars 106 shown in FIG. 4D each have a head located on the lower, or35 distal, end 108. The heads are each located below the lower mesh 310 i.e. on a side of the second mesh 310 furthest from the support structure 104. structure. The heads are such that they can pass through the holes of the first and / or second mesh 300, 310. The guidance structure 200 is located between the support structure 104 and the mesh 300. The supportCMS REF N00572.00317 11Confidential structure 104 sits slightly above the mesh 300 due to the presence of the guidance structure 200. In some examples, the guidance structure 200 is removed. Such examples are discussed in more detail below in relation to FIG.5A-C.

[0073] FIGS. 5A-5B illustrate an example of a removable guidance structure 250. The removable5 guidance structure 250 comprises several segments 252 which when arranged together form a removable guidance structure 250. This allows for the removable guidance structure 250 to be removed from the transverse rebar array 100, for example, after the transverse rebar array 100 has been installed in the mesh 300. Further, the removable guidance structure 250 can be re-installed below the mesh 300 for alignment of the transverse rebar array 100 with the10 second mesh 310.

[0074] FIG. 5A shows the individual segments 252 in an uninstalled configuration. In the example shown, the removable guidance structure 250 is made up of 5 segments 252 however this could be any suitable number of segments such as 3 or 4. The segments 252 may be secured together by a plurality of methods. For example, the segments 252 can be interlocking or have an interference fit. The segments 252 can each comprise at least one notch to ensure correct installation. In such a way, the segments 252 may be removably attached to one another. Alternatively or additionally, as shown FIG. 5B the individual segments 252 are secured together using rails 254 and / or secured using clamps or bolts 256. In FIG. 5B the rails 254 are installed to upper and lower faces of the removable guidance structure 250 across the divisions of the segments 252.

[0075] FIG. 5C illustrates the installation of a removable guidance structure 250 to a transverse rebar array 100. Advantageously, the removable guidance structure 250 may be installed when access to the distal ends 108 of the rebars 106 is not possible. As shown, one of the segments 252 is inserted between each row of transverse rebars 106. The segment 252 is broader than25 the gap between the transverse rebars 106. Accordingly, the segment is inserted in a vertical orientation such that the upper and lower faces, wherein upper and lower refer to the orientation of the guidance structure 250 when installed on a transverse rebar array 100 in the vertical orientation, both face the transverse rebars 106. The segment 252 is rotated 90 degrees such that the segment 252 is the horizontal orientation, which is the orientation of the removable guidance structure 250 when in situ. This process is repeated for each segment 252 until each of the segments are in place and can be secured to one another, as shown in FIG. 5C. Advantageously, the removable guidance structure 250 can be removed and reused either on the installation of the same transverse rebar array 100 or an alternative transverse rebar array. Further, wherein the need for a guidance structure 200 is identified mid-installation35 of the transverse rebar array 100, access to the distal ends 108 of the transverse rebars 106 can be prevented and as such a non-removable guidance structure 200 cannot be installed. In such instances, the removable guidance structure 250 can be installed such that alignment can be achieved. In various examples, the guidance structure holds the bar loosely so that theCMS REF N00572.00317 12Confidential bar can slide with respect to the guidance structure and positionally locates it. FIG. 50 shows one way of achieving removability. Other ways of removability comprise using jaws that come out of an element and encircle the bar in order to provide guidance. The guidance structure is retractable to facilitate removing of the guidance structure. The guidance structure is light5 enough to be handled manually whilst also being strong enough to perform the guidance function.

[0076] FIG.6A and 6B illustrate the re-use of the removable guidance structure 250 for installing the transverse rebar array 100. In FIG.6A the removable guidance structure 250 is installed on the transverse rebar array 100 above the mesh 300. Using the process described above, the10 removable guidance structure 250 restrains the transverse rebars 106 such that they enter the holes of the mesh 300. The removable guidance structure 250 is then removed from the transverse rebar array 100. In order to remove the guidance structure 250, the segments 252 of the removable guidance structure 250 are separated. Wherein the segments 252 are connected via bolts, clamps or rails, the connections are undone to allow the segments 252 to be disconnected. The segments 252 can then be removed by carrying out the operations for installation in reverse. In particular, the segments 252 can be rotated from the horizontal orientation shown in FIG. 6A by around 90 degrees to a broadly vertical orientation such that they can slide between the transverse rebars 106.

[0077] As shown in FIG. 6B, the removable guidance structure 250 can be re-installed to the transverse rebar array 100 below the mesh 300. In some examples, the removable guidance structure 250 is installed to align the transverse rebars 106 with the holes of a lower mesh (not shown in FIG. 6B). Once the distal ends of the transverse rebars 106 have been lowered below the mesh 300 the segments of the removable guidance structure 250 can be re-installed in the same way as they were first installed. In particular, they can be inserted in a vertical orientation25 and rotated to the required horizontal orientation for connection to the other segments 252. Once the segments 252 are in place, they can be re-connected. The segments 252 are attached via temporary attachment means. For example, rails and clamps or bolts which can be undone and redone a plurality of times. Once the removable guidance structure 252 is reinstalled, the transverse rebar array 100 can continue to be lowered. The removable guidance structure 252 then guides the transverse rebars 106 to the holes of the mesh 300. Optionally, the guidance structure 250 can then be removed. In some instances, wherein the transverse rebar array 100 is fitted to a plurality of meshes, the removable guidance structure 250 can be uninstalled and re-installed for each of the plurality of meshes.

[0078] FIG. 7A is a plan view of the guidance structure 200 superimposed over the top of the35 mesh 300. FIG. 7B is a side view of the same guidance structure 200 and mesh 300 and including the transverse rebars 106. As shown in FIG. 7B the width or diameter of the holes of the mesh 300 provide significant clearance for the individual transverse rebars 106. For example, the width of the holes of the mesh can be 2 or 3 times the width or diameter of theCMS REF N00572.00317 13Confidential individual transverse rebars 106. In some examples, the diameter of the transverse rebars is 30-50mm, for example 40mm, and the width of the holes of the mesh 300 is 100-200mm, for example 150mm. In the example shown in FIG. 7A and 7B, the rebars of the mesh 300 are arranged in a uniform grid pattern and the guidance structure 200 is arranged such that the5 holes 202 of the guidance structure 200 for receiving the transverse rebars 106 are centred with respect to the holes of the mesh 300. Due to the clearance provided by the size of the holes in the mesh, the centres of the holes 202 of the guidance structure 250 can be offset from the centres of the holes of the mesh 300 and still facilitate the guidance of the transverse rebars 106 through the holes of the mesh 300.10

[0079] As shown in FIG. 7B, the guidance structure 200 may comprise a positioning device 210. The positioning device 210 may be used as part of the removable guidance structure 250. In the example shown in FIG. 7B the positioning device 210 is a pair of cranked plates 210. The positioning device 210 is attached to a face of the guidance structure 250. The positioning device 210 may be removably attached to the guidance structure 200 or fixedly attached, for example via welding. In use, the face of the guidance structure 200 to which the positioning device 210 is attached is the lower face of the guidance structure 200. The positioning device 210 protrudes towards the mesh 200 to which the positioning structure 200 is to be aligned. During installation, the guidance structure 200 is prevented, by the positioning device 210, from sitting on the mesh 200 in any other location than in the desired alignment. For example, the guidance structure 200 can be designed for use with a particular size and / or shape of mesh 300. The positioning device 210 can then be designed for aligning the holes of the guidance structure 200 with the holes of the mesh 300. For example, the guidance structure 200 can be intended to align the transverse rebars 106 centrally within the holes of the mesh 300. Alternatively, the guidance structure 200 can be intended to install the transverse rebars 10625 at an offset from the centre of the holes of the mesh 300. For example, wherein there is overlapping of a plurality of meshes 300, the clearance of the transverse rebars 106 can be reduced which necessitates an offset from centre of the holes of at least one of the plurality of meshes 300. If a user attempts to install the guidance structure 200 in a wrong position the guidance structure 200 will either sit proud of the mesh 300 or at an angle such that one side of the guidance structure 200 is raised in comparison to the opposite side of the guidance structure. For the example shown, wherein the alignment device 210 is a pair of cranked plates, if one of the cranked plates is positioned in a hole in the mesh 300 and the other of the cranked plates is sitting on top of a rebar of the mesh 300 then the guidance structure 200 will be at an angle. Alternatively, if both of the cranked plates are sitting on top of rebar of the mesh 30035 then the guidance structure 200 may be horizontal but it will sit proud of the mesh 300. Therefore an obvious visual indication of incorrect installation is provided. The cranked plates, due to the bend or crank, ease installation by guiding the guidance structure 200 in to theCMS REF N00572.00317Confidential desired alignment. For example, wherein the angled section encounters part of the mesh 300, it will react against the mesh to push the guidance structure 200 towards the desired location.

[0080] As discussed above, in some examples the transverse rebar array 100 is installed through several meshes 300 arranged one above the other, or in a stack. In such examples, the centres5 of the holes of the plurality of meshes 300 can be offset from one another. Due to the size of the holes of the mesh 300 compared to the diameter or width of the individual rebars 106, the meshes 300 can still accommodate the transverse rebar array 100. In such examples, the clearance between the holes of the mesh 300 and the transverse rebars 106 is reduced. It can therefore be beneficial to include an alignment means on the distal ends 108 of the transverse10 rebars 106.

[0081] FIGS. 8A-8C illustrate examples of alignment means 110, 112 optionally attached to the distal end 108 of individual rebars 106. In the example shown in FIG. 8A the individual rebar 106 has a head 110 connected to the distal end 108 of the individual rebar 106. The head 110 has angled sides. The angled sides are angled such that the face of the head 110 facing the direction of travel of the transverse rebar 106 during installation is the narrowest point of the head 110. In such a way, the angled head upon contacting a rebar of the mesh 300 and continuing to experience a downward force, due to gravity or otherwise, will cause the transverse rebar 106 to move towards the holes of the mesh 300 as shown in FIG. 8A.

[0082] FIG. 8B and 8C illustrate a second example 112 of alignment means. In this example, the alignment means is a deformable element 112 attached to the distal end 108 of the transverse rebar 106. The deformable element 112 is shaped so as to have a narrowest end at the lowermost portion of the deformable element and broadening towards the distal end of the transverse rebar. The size and shape of the deformable element provides guiding means to guide the transverse rebar, upon contact with a rebar of the mesh 300, into an adjacent hole25 of the mesh. As shown in FIG. 8C the deformable means can be deformed upon contact with a lower surface. The lower surface can be concrete. The deformable element is deformable under the weight of the transverse rebar 106. During operation, once the deformable element is in contact with the lower surface, as the transverse rebar continues to descend the weight of the individual transverse rebar causes the deformable element to deform. In the example shown, the shape of the deformable element is such that transverse forces such as those exhibited by the rebar of the mesh to the deformable element during guiding do not cause deformation but the axial loading caused by the weight of the individual transverse rebar results in deformation, and in particular buckling, of the deformable element. In some examples the deformable element is a wire, or a plurality of wires arranged in a cage or a pair of wires at 9035 degrees to one another. By being deformable under the weight of the transverse rebar, the deformable element provides guidance means without preventing the transverse rebar from reaching the desired vertical position.CMS REF N00572.00317Confidential

[0083] FIG. 9 illustrates an example method of installing a transverse reinforcing bar array into a mesh of rebar. The mesh of rebar may already be installed at a construction site in a location where concrete is to be set in order to construct a structure such as a wall of a building.

[0084] FIG. 10 illustrates an example of a removable guidance structure 270 comprising5 retractable attachment means 272, 274. The removable guidance structure 270 comprises a plurality of segments 276 which, when installed, are located between the transverse rebars 106 and provide guidance to the transverse rebars via the retractable attachment means 272, 274. In some examples, the segments 276 are installed independently from one another. In such examples the location of the retractable attachment means 272, 274 relative to one10 another maintains the gap between rebars 106 within a row of transverse rebars of an array and the segments maintain the gap between rows of transverse rebars 106. Alternatively, the segments are fitted together, for example using bars which are fitted across the gap between segments that are then clamped to the segments. FIG. 10 illustrates two types of retractable attachment means 272, 274, however many alternatives are possible that do the function of providing releasable engagement with rebars of a transverse rebar array. Further, the removable guidance structure 270 can comprise retractable attachment means 272, 274 for attaching to each rebar 106 which is adjacent to the segment 276. The retractable attachment means 272, 274 can be a pair of jaws 272 which, when closed, encircle a transverse rebar 106. FIG.10 also illustrates open pairs of jaws 272. When the jaws 272 are opened the removable guidance structure 270 can be disconnected from the transverse rebar array. Alternatively, the retractable attachment means 272, 274 are telescopic pins 274 which, when expanded form a triangle which encloses the rebar 106. The telescopic pins 274 can be retracted so as to allow the removable guidance structure 270 to be installed and removed. The retractable attachment means 272, 274 are positioned relative to one another so as to25 maintain a spatial arrangement between the transverse rebars 106. The retractable attachment means 272, 274 facilitates radial movement of the removable guidance plate 270 along the transverse rebars 106. By using jaws 272 or pins 274, less material is required to form the removable guidance plate 270 compared with the use of holes. Further, the spacing between the jaws 272 or pins 274 provides gaps, or holes, which facilitate the flow of concrete through the guidance structure 270. The retractable attachment means 272, 274 when protracted, is arranged to encircle the transverse rebars 106 and when retracted, is arranged to allow removal of the removable guidance structure 270. The retractable attachment means 272 can be protracted and retracted automatically, for example were retractable attachment means are spring loaded, or manually.35

[0085] The method comprises installing 401 a guidance structure to an array of transverse reinforcing bars. The array of transverse reinforcing bars already has a support structure attached to it as described with reference to FIG. 1. The array of transverse reinforcing bars is then arranged 402 such that the support structure is above the guidance structure. ForCMS REF N00572.00317 16Confidential example, a lifting device is connected to the support structure and lifted such that the array of transverse reinforcing bars is rotated from a horizontal orientation to a vertical orientation. As described above, the presence of the guidance structure maintains the relative positions of the rebars of the array. In such a way, the guidance structure prevents bending movements which5 would otherwise be induced at connection points between the rebars and the support structure.

[0086] The holes of the guidance structure are then aligned 403 with the holes of a first mesh (where the first mesh is already installed at the construction site) such that a distal end of each of the reinforcing bars is aligned with respect to a hole of the mesh. The distal ends can be aligned such that they are centred with the respect to the hole of the mesh, alternatively they10 can be positioned at an offset from the centre of the hole of the mesh. This is particularly relevant wherein the transverse rebars are to be received by a plurality of stacked meshes which are overlapped such that the centre of the holes of the meshes are offset from one another. At operation 404 the array of transverse rebars is lowered such that a lower face of the guidance structure comes into contact with an upper surface of the first mesh. Upper and lower in this instance refers to the orientation when in use, i.e when the array of transverse reinforcing bars is being lowered towards the mesh. At operation 405 the array of transverse reinforcing bars are further lowered such that the transverse reinforcing bars pass through the guidance structure and the holes of the mesh. Once the transverse rebar array has been installed concrete may be poured over the transverse rebar array and mesh and allowed to cure thus forming a reinforced concrete structure such as a wall, floor, or other structure.

[0087] Any reference to 'an' item refers to one or more of those items. The term 'comprising' is used herein to mean including the method blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and an apparatus may contain additional blocks or elements and a method may contain additional operations or elements. Furthermore, the25 blocks, elements and operations are themselves not impliedly closed.

[0088] The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. The arrows between boxes in the figures show one example sequence of method steps but are not intended to exclude other sequences or the performance of multiple steps in parallel. Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought. Where elements of the figures are shown connected by arrows, it will be appreciated that these arrows show just one example flow of communications (including data and control messages)35 between elements. The flow between elements may be in either direction or in both directions.

[0089] Where the description has explicitly disclosed in isolation some individual features, any apparent combination of two or more such features is considered also to be disclosed, to the extent that such features or combinations are apparent and capable of being carried out basedCMS REF N00572.00317 17Confidential on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the 5 invention.CMS REF N00572.00317 18

Claims

ConfidentialCLAIMS1. A method of installing a transverse reinforcing bar array comprising: installing a guidance structure to the transverse reinforcing bar array wherein the5 transverse reinforcing bar array comprises a plurality of reinforcing bars connected to a support structure and installing a guidance structure comprises inserting each of the reinforcing bars in to a hole of the guidance structure; arranging the transverse reinforcing bar array such that the support structure is above the guidance structure;10 aligning the holes of the guidance structure with a first mesh comprising holes such that a distal end of each of the reinforcing bars is aligned with respect to a hole of the mesh; lowering the transverse reinforcing bar array such that a lower face of the guidance structure comes in to contact with an upper surface of the first mesh; further lowering the transverse reinforcing bar array such that the transverse reinforcing bars pass through the guidance structure and the holes of the mesh.

2. The method of claim 1 wherein further lowering the transverse reinforcing bar array comprises lowering the array of transverse reinforcing bars such that a lower face of the support structure is brought into contact with an upper surface of the guidance structure.

3. The method of claim 1 or claim 2 wherein arranging the transverse reinforcing bar array comprises rotating the array of transverse reinforcing bars from a horizontal orientation to a vertical orientation.25 4. The method of any preceding claim further comprising installing a second guidance structure below the first mesh such that, when lowered, the distal ends of the transverse reinforcing bars passes through holes of the second guidance structure.

5. The method of claim 4 wherein the second guidance structure is aligned with a second mesh such that when lowered the distal ends of the transverse reinforcing bars pass through holes of the second mesh.

6. The method of any preceding claim comprising removing the guidance structure by disassembling a plurality of elements of the guidance system.

357. The method of claim 6, further comprising detaching the elements from one another and removing the first guidance structure.CMS REF N00572.00317 19Confidential8. The method of any of claims 4 to 7 wherein the second guidance structure is the first guidance structure.

9. The method of any preceding claim wherein the distal end of each of the reinforcing bars5 being aligned with respect to a hole of the mesh comprises a centre of the reinforcing bars being aligned with a centre of the hole of the mesh or a point offset from the centre of the hole of the mesh.

10. The method of any preceding claim, further comprising lifting the transverse reinforcing10 bar array from a first connection point and a second connection wherein the first connection point is attached to the support structure and the second connection point is attached to the guidance structure.

11. The method of any preceding claim further comprising installing a stopper on the distal end of at least one of the transverse reinforcing bars wherein the width of the stopper is wider than the width of the hole of the guidance plate such that when the stopper is installed after the guidance plate, the guidance plate is prevented from sliding off the distal end of the transverse reinforcing bar.

12. The method of any preceding claim comprising pouring a media through a second set of holes of the guidance system.

13. The method of any preceding claim wherein aligning the guidance structure with the holes of the mesh comprises using a positioning device installed on the guidance system.2514. The method of any preceding claim comprising aligning the distal end of the at least one transverse reinforcing bar with the holes of the mesh by using an alignment device installed on the distal end of the transverse reinforcing bar.

15. The method of claim 14 further comprising moving the alignment device into contact with a lower surface and deforming the alignment device by a downwards force exerted on the alignment device by the transverse reinforcing bar.35 16. The method of any preceding claim comprising connecting an end of one of the reinforcing bars to a structure.CMS REF N00572.00317 20Confidential17. The method of claim 16 comprising using a rebar coupler to connect the end of the reinforcing bar to another reinforcing bar.

18. The method of any preceding claim wherein the support structure is a plate and the5 reinforcing bars are welded to the plate.

19. A guidance structure comprising: a substrate formed from a material suitable for holding rebar; a first plurality of holes in the substrate, each one of the first plurality of holes sized and shaped10 to enable a rebar to pass through the substrate, the first plurality of holes being spaced apart from one another in the substrate according to a specified spacing interval; a second plurality of holes in the substrate, the second plurality of holes being interspersed between the first plurality of holes.

20. The guidance structure of claim 20 wherein the substrate is formed from a plurality of segments which are removably attached to one another.

21. The guidance structure of claim 21 wherein a first one of the segments comprises a plurality of the second holes and a plurality of recesses, and wherein at least one other of the segments comprises a plurality of recesses that cooperate with the plurality of recesses of the first segment to form ones of the first holes.

22. The guidance structure of any one of claims 20 to 22 further comprising a positioning device arranged to align the first plurality of holes of the guidance structure with holes of a25 mesh.

23. The guidance structure of claims 20 to 23 wherein the guidance structure is a plate.

24. The guidance structure of any of claims 21 to 24 comprising bars for removably attaching the segments.

25. A guidance structure comprising: a plurality of segments wherein each segment comprises at least one pair of retractable guidance means;35 wherein the retractable guidance means are arranged to, when protracted, encircle a rebar such that the rebar can pass through the retractable guidance means and, when retracted, permit the installation and removal of the guidance structure to an array of rebar, the retractableCMS REF N00572.00317 21Confidential guidance means being spaced apart from one another according to a specified spacing interval.CMS REF N00572.00317 22

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