AU2014203324A1 - A combination edge-formwork, post-tension and facade fixing assembly - Google Patents

Abstract

The present disclosure relates to a combination assembly for casting and post tensioning of, and subsequent fixing of an external system to, a concrete structure, comprising, one or more tendon units adapted for post-tensioning of the concrete structure, each of the one or more tendon units comprising one or more strands, and a sheath adapted to receive the one or more strands therein; a channel adapted to be cast into an edge of the concrete structure, the channel comprising a partial luminal wall defining a longitudinal cavity within, and one or more slots adapted to receive the one or more strands therein; an anchor block being co operable with the channel, the anchor block having one or more through bores adapted to receive the one or more strands therein and permit sliding translation of the one or more strands perpendicular to the longitudinal axis of the channel, allowing the one or more strands to be tensioned relative to the channel; one or more locks adapted to lock the positions of the one or more strands relative to the anchor block, and thus the channel, in a tensioned configuration, and to allow adjustment of the one or more strands in a released configuration; and an external load transfer element being co-operable with the channel, the external load transfer element being connected to the external system, in use. *\ \\ \ \ \ \ N j j ! Is(C N If * *1' / N / ~*. r ozzi§IZZZ <'1 IL rt 1 C) * / / / Co z Cl

Description

1 A COMBINATION EDGE-FORMWORK, POST-TENSION AND FACADE FIXING ASSEMBLY FIELD OF THE INVENTION [0001] The present invention relates generally to combination assemblies for casting and post-tensioning of, and subsequent fixing of an external system to, a concrete structure. [0002] The invention has been developed primarily for use in the building industry and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use. BACKGROUND OF THE INVENTION [0003] Concrete structures are capable of resisting relatively high compressive loads, but are comparatively weaker in resisting tensile loads. To overcome this, reinforcement members, such as steel bars, with relatively high tensile capacities may be introduced during the casting process. To further increase the ability of the concrete structure in resisting the tensile loads, the concrete structure can be pre-tensioned or post tensioned. In pre-tensioning, one or more strands of, for example, steel cables contained within a tendon unit, are tensioned to a pre-determined limit, before wet concrete is poured. In post-tensioning, the one or more strands, usually held lubricated within a sheath, are positioned loosely before the wet concrete is poured. When the 2 concrete has cured to a predetermined strength, the one or more strands are tensioned, for example, by a hydraulic jack, and subsequently locked in place. [0004] In typical post-tensioning arrangements, formwork elements are first used to form a continuous perimeter that defines the outer edges of the concrete structure. The tendon units are then placed and held in position, for example, using tie wires and spacers that maintain the tendon units in a predetermined tendon profile. Subsequently, wet concrete is poured within the continuous perimeter forming the concrete structure. In use, some formwork elements, such as profiled steel sheets, may contribute to the tensile capacity of the concrete structure by acting in composite action with the concrete structure. In other arrangements, the formwork elements are temporary formwork elements that are stripped off the concrete structure after the tensioning operation. Although the temporary formwork elements can usually be reused, this process of stripping is often labour intensive and time consuming. [0005] In these post-tensioning arrangements, each of the one or more strands is typically received between a dead end anchor and a live end anchor. In use, the dead end anchor holds the strand in place, while the live end anchor receives the end of the strand which is to be connected to the hydraulic jack during the tensioning operation. In some configurations, the strand is deformed into a bulb configuration at the dead end anchor, the bulb configuration bearing against the dead end anchor when the strand is tensioned. In other arrangements, swages may be connected to the strand to provide bearing against the dead end anchor.

3 [0006] Typically, the live end anchor comprises an anchor block having one or more through bores adapted to receive the one or more strands therein. The one or more through bores are also adapted to receive one or more locking mechanisms, such as wedges, that function to lock the one or more strands relative to the anchor block after the tensioning operation. To prevent the live end anchor from protruding substantially beyond the edges of the concrete structure, anchor pockets adapted to accommodate the live end anchors are sometimes cast into the concrete structure. This requires specialised formwork elements that are pre-fitted before casting of the concrete structure. [0007] In some post-tensioning arrangements, each of the tendon units has a tendon profile that is characterised by high points and low points. For example, the dead end anchor and the live end anchor in the tendon profile may be specified as high points, and a medial point of the tendon profile may be specified as a low point. This is beneficial, for example, in concentrating the tensile forces in the one or more strands, and resultant compressive forces in the concrete, along a lower half of the concrete structure where the concrete is more susceptible to tensile failure due to, for example, dead load. [0008] Often, external systems such as curtain walls, green walls, masonry walls, secondary steel frames, cladding systems, temporary protection, balustrades, or signage, are required to be fixed to the concrete structure after the casting process. In the example of a concrete floor slab, fixing is conventionally desired at a top horizontal 4 face or a vertical edge of the floor slab. This is generally complicated in the cases of the pre-tensioned or post-tensioned concrete structure, since any drilling into the concrete structure may potentially penetrate and damage the tendon units. [0009] Alternatively, individual channels adapted for fixing of the external systems can be cast into in the concrete structure during the casting process. In the example of the concrete floor slab, this is routinely done on the top horizontal face of the floor slab, since the individual channels can be easily positioned without any clash with formwork elements. In circumstances wherein fixing is required at the vertical edge of the floor slab, one or more steps of, for example, on-site or off-site manipulation are typically required, such that the individual channels are integrated with the formwork elements prior to pouring of the wet concrete. This results in a labour intensive construction process, especially since the edge-formwork element is often required to be stripped off the floor slab after the casting process, in order for the individual channels to be revealed. [0010] There have been various attempts to overcome this by providing an edge formwork element with an externally opening channel being prefixed on the edge formwork element. This includes edge-formwork elements in the form or an L-shaped assembly, formed by welding or bolting a plurality of plates to the channel. Although the resulting element simplifies the construction process, the element is typically costly due to a labour intensive manufacturing process. Furthermore, in the cases of the pre tension or post-tensioned concrete structures, the individual channels and edge- 5 formwork elements may also clash with any of the elements used for pre-tensioning and post-tensioning. [0011] The present invention seeks to provide a combination assembly which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative. [0012] It is to be understood that, if any prior art is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country. SUMMARY OF THE INVENTION [0013]According to a first aspect of the present invention, there is provided a combination assembly for casting and post-tensioning of, and subsequent fixing of an external system to, a concrete structure, comprising: - one or more tendon units adapted for post-tensioning of the concrete structure, each of the one or more tendon units comprising one or more strands, and a sheath adapted to receive the one or more strands therein; - a channel adapted to be cast into an edge of the concrete structure, the channel comprising a partial luminal wall defining a longitudinal cavity within, and one or more slots adapted to receive the one or more strands therein; - an anchor block being co-operable with the channel, the anchor block having one or more through bores adapted to receive the one or more strands 6 therein and permit sliding translation of the one or more strands perpendicular to the longitudinal axis of the channel, allowing the one or more strands to be tensioned relative to the channel; - one or more locks adapted to lock the positions of the one or more strands relative to the anchor block, and thus the channel, in a tensioned configuration, and to allow adjustment of the one or more strands in a released configuration; and - an external load transfer element being co-operable with the channel, the external load transfer element being connected to the external system, in use. [0014] Advantageously, the channel is keyed into the concrete structure such that, in the tensioned configuration, a tension force in the one or more strands imparts an equal and opposite compression reaction on the anchor block, the compression reaction being transferred from the anchor block to the channel, before being distributed into the concrete structure. This is beneficial, in generating a compressive stress in the concrete structure which may be used to balance any tensile stress being generated, for example, by application of an applied load to the concrete structure, in use. [0015] Advantageously, in use, the compression reaction is distributed to the concrete structure along at least a portion of the longitudinal axis of the channel. This is beneficial, in minimising the concentration of the compression reaction in the vicinity of the one or more strands, thereby reducing the need for, for example, confinement reinforcement cages, in use.

7 [0016] Advantageously, the anchor block is located in the channel, in use, such that one or more anchor pockets typically required to prevent the anchor block from protruding substantially beyond the edges of the concrete structure are not required. This is beneficial, for example, in saving construction time and costs related to the initial set-out and subsequent grouting required for the one or more anchor pockets, in use. [0017] Advantageously, the anchor block is located in the channel, in use, such that any potential clashes between the anchor block and other construction elements, for example, formwork or other reinforcement elements, can be avoided. [0018] Advantageously, the external load transfer element allows direct attachment of the external system to the concrete structure without the need for any additional modification to the concrete structure, such as drilling. This is beneficial, for example, since any drilling into the concrete structure may potentially penetrate and damage the one or more tendon units, in use. [0019] Advantageously, the channel is keyed into the concrete structure such that, in use, an external load being received from the external system is distributed via the external load transfer element to the channel and the concrete structure, the channel and the concrete structure acting in composite action to resist the external load. [0020] Advantageously, the anchor block and the external load transfer element can occupy dissimilar positions along the longitudinal axis of the channel such that any potential clashes between the external system and the anchor block is avoided, in use.

8 [0021] Preferably, the anchor block is an integrated anchor block being integrated with the external load transfer element. [0022] Advantageously, the integrated anchor block and the external load transfer element can occupy a similar position along the longitudinal axis of the channel such that any potential clashes between the external system and the integrated anchor block is avoided, in use. [0023] Preferably, the channel is of a generally dovetail cross sectional geometry. [0024] Advantageously, the generally dovetail cross sectional geometry allows the channel to be keyed into the concrete structure such that, in the tensioned configuration, the compression reaction on the anchor block is transferred to a larger portion of the concrete structure. This is beneficial, in generating the compressive stress in the larger portion of the concrete structure which may be used to balance any tensile stress being generated, for example, by application of an applied load in to the concrete structure, in use. [0025] Advantageously, the generally dovetail cross sectional geometry allows the channel to be keyed into the concrete structure, such that, in use, the external load is distributed into the concrete structure, allowing the channel and the concrete structure to act in composite action to resist the external load. [0026] Preferably, the combination assembly further comprises an edge-formwork element for use in casting of the concrete structure, and the channel is an integrated 9 channel being integrated with the edge-formwork element such that the integrated channel is externally opening and horizontally disposed. [0027] Advantageously, the edge-formwork element acts as permanent formwork after the casting process, such that no stripping of the edge-formwork element is required. [0028] Advantageously, one or more steps of, for example, on-site or off-site manipulation typically required to position the channel with respect to the edge formwork element are not required. [0029] Preferably, the edge-formwork element comprises a horizontal base. [0030] Advantageously, the edge-formwork element is adapted to receive one or more horizontal formwork sheets such that, in use, a plurality of edge-formwork elements and horizontal formwork sheets being positioned, for example, in an edge to edge relationship, forms a continuous perimeter that allows casting of the concrete structure within. For example, in casting of a composite floor slab, the one or more horizontal formwork sheets define the floor slab base and the edge formwork element defines the floor slab edge. [0031] Preferably, the edge-formwork element further comprises a vertical wall extending from a longitudinal edge of the horizontal base, such that the integrated channel is integrated with the vertical wall.

10 [0032] Advantageously, a plurality of edge-formwork elements having vertical walls of various heights can be provided such that, in use, concrete structures of various corresponding thicknesses can be formed. [0033] Advantageously, a plurality of edge-formwork elements having integrated channels of various vertical positions can be provided such that, in use, the one or more strands can be received and locked at the various vertical positions. This is beneficial, for example, in circumstances wherein each of the one or more tendon units has a tendon profile that is characterised by high points and low points, since the high points and low points can be located at the various vertical positions. [0034] Preferably, the edge-formwork element further comprises a return lip extending from a top edge of the vertical wall. [0035] Advantageously, in use, the return lip is attached to one or more tension straps being in turn attached to the one or more horizontal formwork sheets, such that the vertical wall is substantially prevented from lateral movement, for example, when wet concrete bears against the vertical wall during the casting process. [0036] Advantageously, the return lip increases the weak axis section moment capacity of the vertical wall such that the vertical wall is stiffened and prevented from warping, for example, when wet concrete bears against the vertical wall during the casting process. [0037] Preferably, the horizontal base comprises a continuous indentation being longitudinally disposed.

11 [0038] Advantageously, the continuous indentation is keyed into the concrete structure during the casting process such that, in use, the edge-formwork element redistributes at least a portion of the external load via the continuous indentation to the concrete structure, the edge-formwork element and the concrete structure acting in composite action to resist the external load. [0039] Preferably, the edge-formwork element further comprises a upturn portion extending from a free edge of the return lip, such that the return lip and the upturn portion defines another continuous indentation, the another continuous indentation being longitudinally disposed. [0040] Advantageously, the another continuous indentation is keyed into the concrete structure during the casting process such that, in use, the edge-formwork element redistributes at least a portion of the external load via the another continuous indentation to the concrete structure, the edge-formwork element and the concrete structure acting in composite action to resist the external load. [0041] Advantageously, the another continuous indentation further increases the weak axis section moment capacity of the vertical wall such that the vertical wall is stiffened and prevented from warping, for example, when wet concrete bears against the vertical wall during the casting process. [0042] Preferably, the vertical wall further comprises one or more additional slots adapted to receive the one or more strands therein.

12 [0043] Advantageously, the one or more strands may be alternatively received at the one or more additional slots in the vertical wall. This is beneficial, for example, in circumstances wherein each of the one or more tendon units has a tendon profile that is characterised by high points and low points, since the high points and low points can be located at the one or more additional slots in the vertical wall. [0044] Preferably, the one or more additional slots are one or more through bores adapted to receive the one or more strands therein and permit sliding translation of the one or more strands perpendicular to the longitudinal axis of the edge-formwork element, allowing the one or more strands to be tensioned relative to the edge-formwork element. [0045] Preferably, the one or more locks are further adapted to lock the positions of the one or more strands relative to the edge-formwork element in the tensioned configuration, and to allow adjustment of the one or more strands in the released configuration. [0046] Advantageously, in the tensioned configuration, the tension force in the one or more strands imparts an equal and opposite compression reaction on the edge formwork element, the compression reaction being distributed into the concrete structure. This is beneficial, in generating a compressive stress in the concrete structure which may be used to balance any tensile stress being generated, for example, by application of an applied load to the concrete structure, in use.

13 [0047] Advantageously, the one or more strands can be locked relative to the edge formwork element without the need for an additional anchor block. [0048] Preferably, the combination assembly further comprises an additional anchor block having one or more through bores adapted to receive the one or more strands therein and permit sliding translation of the one or more strands perpendicular to the longitudinal axis of the edge-formwork element, allowing the one or more strands to be tensioned relative to the edge-formwork element, the additional anchor block being stiffer than the edge-formwork element, in use. [0049] Preferably, the one or more locks are further adapted to lock the positions of the one or more strands relative to the additional anchor block in the tensioned configuration, and to allow adjustment of the one or more strands in the released configuration. [0050] Advantageously, in the tensioned configuration, the additional anchor block stiffens the edge-formwork element such that the compression reaction is transferred to a larger portion of the concrete structure. This is beneficial, in generating the compressive stress in the larger portion of the concrete structure which may be used to balance any tensile stress being generated, for example, by application of an applied load in to the concrete structure, in use. [0051] Preferably, the additional anchor block is an integrated additional anchor block being integrated with the external load transfer element.

14 [0052] Advantageously, the integrated additional anchor block and the external load transfer element can occupy a similar position along the longitudinal axis of the edge formwork element such that any potential clashes between the external system and the integrated additional anchor block is avoided, is use. [0053] Preferably, the combination assembly is formed of a corrosion resistant material. [0054] Advantageously, in use, the combination assembly is of a suitable corrosion performance. [0055] Preferably, the combination assembly comprises one or more radiused corners adapted to reduced stress concentrations in the combination assembly, in use. [0056] Preferably, the one or more radiused corners are being radiused such that at least a portion of the combination assembly can be formed by bending of a sheet material in a bending operation. [0057] Advantageously, at least the portion of the combination assembly can be formed in a relatively simple and cost effective process. [0058] Preferably, the one or more radiused corners are being radiused such that at least the portion of the combination assembly can be formed by bending of a high strength sheet material, in the bending operation. [0059] Advantageously, the gauge of the sheet material being required is reduced.

15 [0060] Preferably, the one or more radiused corners are being radiused such that at least the portion of the combination assembly can be formed by bending of a sheet material having a corrosion resisting coat, in the bending operation. [0061] Advantageously, at least the portion of the combination assembly requires no additional corrosion treatment after forming which may, for example, distort the geometry of the combination assembly or increase manufacturing costs of the combination assembly. [0062] Preferably, the combination assembly is further adapted for pre-tensioning of the concrete structure. [0063] Advantageously, the combination assembly can also be used for pre-tensioning of the concrete structure. BRIEF DESCRIPTION OF THE DRAWINGS [0064] Fig. 1 is a partial perspective view of a combination assembly in accordance with an exemplary embodiment of the present invention; [0065] Fig. 2a is a perspective view a channel in the combination assembly of Fig. 1; [0066] Fig. 2b is a perspective view of a channel in accordance with another exemplary embodiment of the present invention; 16 [0067] Fig. 3 is a partial perspective view of the combination assembly comprising the channel of Fig. 2b; [0068] Fig. 4 is a partial perspective view of the combination assembly of Fig. 3 in accordance with another exemplary embodiment of the present invention; [0069] Fig. 5 is a partial perspective view of the combination assembly in accordance with another exemplary embodiment of the present invention; [0070] Fig. 6 is a partial perspective view of an edge-formwork element in the combination assembly of Fig. 5; [0071] Fig. 7 is a partial perspective view of the combination assembly, in accordance with another exemplary embodiment of the present invention; [0072] Fig. 8 is a partial perspective view of the combination assembly of Fig. 7, in accordance with another exemplary embodiment of the present invention; and [0073] Fig. 9 is a partial perspective view of the combination assembly of Fig. 7, in accordance with another exemplary embodiment of the present invention. DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS [0074] It should be noted in the following description that like or similar numerals in different embodiments denote the same or similar features.

17 [0075] According to a first embodiment of the present invention, and referring to Figs. 1 and 2a, there is provided a combination assembly, generally indicated by the numeral 10, for use in casting and post tensioning of, and subsequent fixing of an external system (not shown) to, a concrete structure (not shown). In this embodiment, the combination assembly 10 comprises one or more tendon units 20 adapted for post tensioning of the concrete structure (not shown), each of the one or more tendon units 20 comprising one or more strands 21, and a sheath 22 adapted to receive the one or more strands 21 therein. In this embodiment, each of the one or more strands 21 is a steel cable, for example, being formed of several steel wires arranged together in a coiled configuration. It will be appreciated, however, that in other embodiments, each of the one or more strands 21 may be of any other form consistent with the spirit of the present invention. For example, in another embodiment, each of the one or more strands 21 is a solid steel rod. In yet other embodiments, the one or more strands 21 may be formed of any other suitable material within the scope of the present invention. [0076] In this embodiment, the combination assembly 10 further comprises a channel 30 adapted to be cast into an edge of the concrete structure (not shown), the channel 30 comprising a partial luminal wall 31 defining a longitudinal cavity 32 within, and one or more slots 33 adapted to receive the one or more strands 21 therein; an anchor block 40 being co-operable with the channel 30, the anchor block 40 having one or more through bores (not shown) adapted to receive the one or more strands 21 therein and permit sliding translation of the one or more strands 21 perpendicular to the longitudinal axis of the channel 30, allowing the one or more strands 21 to be tensioned relative to 18 the channel 30; and one or more locks 41 adapted to lock the positions of the one or more strands 21 relative to the anchor block 40, and thus the channel 30, in a tensioned configuration, and to allow adjustment of the one or more strands 21 in a released configuration. In this embodiment, each of the one or more locks 41 is a steel ring adapted to wedge between the one or more strands 21 and the one or more through bores (not shown) in the tensioned configuration. In will be appreciated, however, the one or more locks 41 may be of any other form consistent with the spirit of the present invention. [0077] In use, the channel 30 is keyed into the concrete structure (not shown) such that, in the tensioned configuration, a tension force in the one or more strands 21 imparts an equal and opposite compression reaction in the anchor block 40, the compression reaction being transferred from the anchor block 40 to the channel 30, before being distributed into the concrete structure (not shown). This is beneficial, in generating a compressive stress in the concrete structure which may be used to balance any tensile stress being generated, for example, by application of an applied load to the concrete structure, in use. Advantageously, the compression reaction is distributed to the concrete structure (not shown) along at least a portion of the longitudinal axis of the channel 30. This is beneficial, in minimising the concentration of the compression reaction in the vicinity of the one or more strands 21, thereby reducing the need for, for example, confinement reinforcement cages (not shown), in use.

19 [0078] Advantageously, the anchor block 40 is located in the channel 30, in use, such that one or more anchor pockets (not shown) typically required to prevent the anchor block 40 from protruding substantially beyond the edges of the concrete structure are not required. This in beneficial, for example, in saving construction time and costs related to the initial set-out and subsequent grouting required for the one or more anchor pockets (not shown), in use. Furthermore, locating the anchor block 40 in the channel is beneficial such that any potential clashes between the anchor block 40 and other construction elements, for example, formwork (not shown) or other reinforcement elements (not shown), can be avoided. [0079] In this embodiment, each of the one or more tendon units 20 comprises a grout tube 60, adapted to be accessible from outside the concrete structure (not shown) after the casting process. In use, the grout tube 60 allows grout to be introduced into each of the one or more tendon units 20, such that the one or more strands 21 can be bonded by the grout after the tensioning operation. Advantageously, the grout provides an alkaline environment that may aid in the corrosion resistance of the one or more strands 21. It will be appreciated, however, that in other embodiments, the grout may be introduced by any other suitable arrangements consistent with the spirit of the present invention. [0080] In existing arrangements, one or more external systems (not shown) are typically required to be fixed to the concrete structure (not shown) after the tensioning operation. These one or more external systems (not shown) may include, but not limited to, any one of the following: curtain walls, green walls, masonry walls, secondary steel frames, 20 cladding systems, temporary protection, balustrades, or signage. Referring to Fig. 3, in a preferred embodiment, the combination assembly 10 further comprises an external load transfer element 50 being co-operable with the channel 30, the external load transfer element 50 being connected to the external system (not shown), in use. Advantageously, the external load transfer element 50 allows direct attachment of the external system (not shown) to the concrete structure (not shown) without the need for any additional modification of the concrete structure (not shown), such as drilling. This is beneficial, for example, since drilling into the concrete structure (not shown) may potentially penetrate and damage the one or more tendon units 20. Furthermore, as the channel 30 comprises the longitudinal cavity 32, the external system (not shown) is afforded a translational degree of freedom, along the longitudinal axis of the channel 30, for adjustment prior to being attached to the concrete structure (not shown). [0081] In use, the external load transfer element 50 is connected to the external system (not shown), such that an external load is transferred from the external system (not shown), via the external load transfer element 50, to the channel 30. The channel 30 is keyed into the concrete structure (not shown), such that the external load is in turn distributed from the channel 30 to the concrete structure (not shown), enabling the channel 30 and the composite structure (not shown) to act in composite action to resist the external load. In one embodiment, the external load transfer element 50 comprises, at an outer end, a tail portion 51 for attachment to the external system (not shown), and at an inner end, a head portion 52 being co-operable with the channel 30. In this embodiment, the head portion 52 is configured to be received in the longitudinal cavity 21 32 in a first orientation, and subsequently retained by the partial luminal wall 31 in a second orientation. In use, the head portion 52 is further retained by the partial luminal wall 31 in circumstances wherein, for example, the tail portion 51 is subject to a downward load, such as the downward gravitational load of the external system (not shown). It will be appreciated, however, that any other suitable external load transfer element 50 is possible within the spirit of the present invention. [0082] In this embodiment, the tail portion 51 is a pair of plates such that any relevant components, such as brackets, of the external system (not shown) can be attached to the pair of plates, for example, through suitable fixings such as bolts and nuts. It will be appreciated, however, that in other embodiments, the tail portion 51 may be of any suitable structure that facilitates attachment of the external system (not shown). For example, in one embodiment, the tail portion 51 is an upturned angle such that the external system (not shown) can be easily hooked on, in use. [0083] Referring also to Fig. 2b, in a preferred embodiment, the channel 30 is of a generally dovetail cross sectional geometry such that the channel 30 is keyed into the concrete structure (not shown) during the casting process. In use, the generally dovetail cross sectional geometry of the channel 30 allows the compression reaction on the anchor block 40 to be transferred to a larger portion of the concrete structure (not shown), when the one or more strands 21 are in the tensioned configuration. This is beneficial, in generating the compressive stress in the larger portion of the concrete structure which may be used to balance any tensile stress being generated, for 22 example, by application of an applied load in to the concrete structure, in use. It will be appreciated therefore, that in other embodiments, the channel 30 may be of any other suitable cross sectional geometry, consistent with the spirit of the present invention, such that the channel 30 is keyed into the concrete structure (not shown) during the casting process. [0084] In this embodiment, and as shown in Fig. 3, the anchor block 40 and the external load transfer element 50 can occupy dissimilar positions along the longitudinal axis of the channel 30. In another embodiment, and as shown in Fig. 4, the anchor block 40 is an integrated anchor block 40' being integrated with the external load transfer element 50. Advantageously, the integrated anchor block 40' and the external load transfer element 50 can alternatively occupy a similar position along the longitudinal axis of the channel. In use, the anchor block 40 and the integrated anchor block 40' are beneficial such that any potential clashes with the external system (not shown) can be avoided. [0085] In existing arrangements, one or more steps of manipulation are typically required to position the channel 30 prior to the casting process. In some arrangements, the channel 30 is fixed to a given continuous perimeter through methods such as fastening or welding. In other arrangements, the channel 30 is assembled with one or more sections such as steel sheets, angles, or plates, to form a subassembly, the subassembly being subsequently used to form a continuous perimeter. In a preferred embodiment, and as shown in Figs. 5 and 6, the combination assembly 10 further comprises an edge-formwork element 35 for use in casting of the concrete structure 23 (not shown), and the channel 30 is an integrated channel 30' being integrated with the edge-formwork element 35 such that the integrated channel 30' is externally opening and horizontally disposed, such that the one or more steps of manipulation are not required. [0086] In this embodiment, the edge-formwork element 35 comprises a horizontal base 36; a vertical wall 37 extending from a longitudinal edge of the horizontal base 36; and a return lip 38 extending from a top edge of the vertical wall 37. In use, the horizontal base 36 is adapted to receive one or more horizontal formwork sheets (not shown), such that a plurality of edge-formwork elements 35 and horizontal formwork sheets (not shown) being positioned, for example, in an edge to edge relationship, forms a continuous perimeter defining a base and one or more edges of the concrete structure (not shown). In a casting process, therefore, wet concrete (not shown) can be poured within the continuous perimeter forming the concrete structure (not shown). [0087] In this embodiment, the one or more horizontal formwork sheets (not shown) are profiled steel sheets, and both the edge-formwork element 35 and the one or more horizontal formwork sheets (not shown) act as permanent formwork after the casting process. This is beneficial, since stripping of the edge-formwork element 35 and the one or more horizontal formwork sheets (not shown) is not required after the casting process, thereby saving time and relevant construction costs. In use, the edge-formwork element 35 and the one or more horizontal formwork sheets (not shown) may also contribute to the mechanical performance of the concrete structure (not shown), by 24 acting in composite action with the concrete structure (not shown), thereby reinforcing the concrete structure (not shown). It will be appreciated, however, that in other embodiments, the edge-formwork element 35 can be used with any other types of formwork elements consistent with the spirit of the present invention. For example, the horizontal base 36 of the edge-formwork element 35 may instead be received on temporary formwork elements, such as wooden formwork (not shown), such that only the edge-formwork element 35 act as permanent formwork after the casting process, while the temporary formwork elements are stripped off the concrete structure (not shown). [0088] In a preferred embodiment, the concrete structure (not shown) is a composite floor slab, for example, in a multi storey building. In use, the one or more horizontal formwork sheets (not shown) define the floor slab base, the edge-formwork element 35 defines the floor slab edge, and the height of the vertical wall 37 defines the floor slab thickness. It will be appreciated therefore, that various edge-formwork elements 35 having, for example, vertical walls 37 of various heights may be provided such that, in use, floor slabs of various corresponding thicknesses can be formed. It will be further appreciated that, in other embodiments, the edge-formwork element 35 may be used in casting of any other concrete structure (not shown) consistent with the spirit of the present invention, including, but not limited to, any one of the following: a concrete beam, a concrete edge-beam, a concrete up-stand, a concrete wall, or a concrete column. Advantageously, a plurality of edge-formwork elements 35 having integrated channels 30' of various vertical positions can be provided such that, in use, the one or 25 more strands 21 can be received and locked at the various vertical positions. This is beneficial, for example, in circumstances wherein each of the one or more tendon units 20 has a tendon profile that is characterised by high points and low points, since the high points and low points can be located at the various vertical positions. [0089] In use, the return lip 38 is attached to one or more tension straps (not shown), the one or more tension straps (not shown) being in turn attached to the one or more horizontal formwork sheets (not shown). This is beneficial in preventing the vertical wall 37 from moving laterally, for example, when wet concrete (not shown) bears against the vertical wall 37 during the casting process. In this embodiment, the one or more tension straps (not shown) are steel flats being attached to the return lip 38 and to the one or more horizontal formwork sheets (not shown) by suitable fasteners such as pop rivets (not shown). It will be appreciated, however, that in other embodiments, the return lip 38 may be connected to the one or more horizontal formwork sheets (not shown) via any other tie members consistent with the spirit of the present invention, including, but not limited to, any one of the following: metal wires, or plastic tapes. [0090] Advantageously, the return lip 38 also increases the weak axis section moment capacity of the vertical wall 37 such that the vertical wall 37 is stiffened and prevented from warping. This is beneficial, for example, in maintaining the geometrical integrity of the edge-formwork element 35 during transport, or when wet concrete (not shown) bears against the vertical wall 37 during the casting process.

26 [0091] Referring again to Figs. 5 and 6, in a preferred embodiment, the horizontal base 36 comprises a continuous indentation 80 being longitudinally disposed. Advantageously, the continuous indentation 80 is keyed into the concrete structure (not shown) during the casting process. In use, a portion of the concrete structure (not shown) adjacent to the continuous indentation 80 is activated when the external load is transferred from the external load transfer element to the integrated channel 30', such that the edge-formwork element 35 redistributes at least a portion of the external load via the continuous indentation 80 to the concrete structure (not shown), enabling the edge-formwork element 35 and the concrete structure (not shown) to act in composite action to resist the load. In this embodiment, the edge-formwork element 35 further comprises an upturn portion 39 extending from a free edge of the return lip 38, such that the return lip 38 and the upturn portion 39 defines another continuous indentation 81, the another continuous indentation 81 being longitudinally disposed. Advantageously, the another continuous indentation 81 is also keyed into the concrete structure (not shown) during the casting process. In use, a portion of the concrete structure (not shown) adjacent to the another continuous indentation 81 is activated when the edge formwork element 35 receives the external load, such that the edge-formwork element 35 redistributes at least a portion of the external load via the another continuous indentation 81 to the concrete structure (not shown), further enabling the edge-formwork element 35 and the concrete structure (not shown) to act in composite action to resist the external load.

27 [0092] Referring now to Fig. 7, in a preferred embodiment, the vertical wall 37 further comprises one or more additional slots 33 adapted to receive the one or more strands 21 therein. This is beneficial, for example, in circumstances wherein the each of the one or more tendon units 20 has a tendon profile that is characterised by high points and low points, since the high points and low points can be located at the one or more additional slots 33 in the vertical wall 37. In this embodiment, the one or more additional slots 33 are one or more through bores adapted to receive the one or more strands 21 therein and permit sliding translation of the one or more strands 21 perpendicular to the longitudinal axis of the edge-formwork element 35, allowing the one or more strands 21 to be tensioned relative to the edge-formwork element 35. The one or more locks 41 are further adapted to lock the positions of the one or more strands 21 relative to the edge formwork element 35 in the tensioned configuration, and to allow tensioning of the one or more strands 21 in the released configuration. This is beneficial, since the one or more strands 21 can be locked relative to the edge-formwork element 35 without the need for an additional anchor block. In the tensioned configuration, the tension forces in the one or more strands 21 impart an equal and opposite compression reaction in the edge-formwork element 35, the compression reaction being distributed from the edge formwork element 35 into the concrete structure (not shown). This is beneficial, in generating a compressive stress in the concrete structure (not shown) which may be used to balance any tensile stress being generated, for example, by application of an applied load to the concrete structure (not shown), in use.

28 [0093] Referring to Fig. 8, in another embodiment, the combination assembly 10 further comprises an additional anchor block 42 having one or more through bores (not shown) adapted to receive the one or more strands 21 therein and permit sliding translation of the one or more strands 21 perpendicular to the longitudinal axis of the edge-formwork element 35, allowing the one or more strands 21 to be tensioned relative to the edge formwork element 35, the additional anchor block 42 being stiffer than the edge formwork element 35, in use. In this embodiment, the one or more locks 41 are further adapted to lock the positions of the one or more strands 21 relative to the additional anchor block 42 in the tensioned configuration, and to allow adjustment of the one or more strands 21 in the released configuration. In the tensioned configuration, the additional anchor block 42 stiffens the edge-formwork element 35 such that the compression reaction is transferred to a larger portion of the concrete structure (not shown). This is beneficial, in generating the compressive stress in the larger portion of the concrete structure (not shown) which may be used to balance any tensile stress being generated, for example, by application of an applied load in to the concrete structure (not shown), in use. [0094] Referring to Fig. 9, in a preferred embodiment, the additional anchor block 42 is an integrated additional anchor block 42' being integrated with the external load transfer element 50. This is beneficial as the integrated additional anchor block 42' and the external load transfer element 50 can occupy a similar position along the longitudinal axis of the integrated channel 30' such that any potential clashes between the external system 50 and the integrated additional anchor block 42' is avoided, in use.

29 [0095] Referring again to Fig. 6, in a preferred embodiment, the edge-formwork element 35 comprises one or more radiused corners 34 adapted to reduced stress concentrations in the edge-formwork element 35, in use. Preferably, the one or more radiused corners 34 are being radiused such that at least a portion of the edge formwork element 35 can be formed by bending of a sheet material in a bending operation. This is beneficial, since at least the portion of the edge-formwork element 35 can be formed in a relatively simple and cost effective process. In this embodiment, the edge-formwork element 35 is formed of one continuous sheet of material through the bending operation of cold roll forming. It will be appreciated however, that in other embodiments, the edge-formwork element 35 may be formed through any other types of bending operation consistent with the spirit of the present invention, including, but not limited to, any one of the following: hot roll-forming, press brake forming, or folding. In this embodiment, the continuous sheet of material is a high strength sheet steel. This is beneficial in reducing the gauge of the material being required, in use. It will be appreciated, however, that the edge-formwork element 35 may be formed of any other material consistent with the spirit of the present invention. [0096] In this embodiment, the edge-formwork element 35 is formed of steel comprising a corrosion resisting coating, for example, a zinc coating formed in a hot dipped process. This is beneficial such that the edge-form work element 35 is of a suitable corrosion resistance without requiring additional corrosion treatment after forming which may, for example, distort the geometry of the edge-formwork element 35, or increase manufacturing costs of the edge-formwork element 35. It will be appreciated, however, 30 that in other embodiments, the edge-formwork element 35 may be afforded a suitable corrosion performance through any other method consistent with the spirit of the present invention. For example, the edge-formwork element 35 may be formed of a material having inherent corrosion resistance, including, but not limited to, any one of the following: stainless steel, polymer. Embodiments [0097] The preceding description and accompanying figures illustrate the principles, and modes of operation of the present invention through the exemplary embodiments. It will be appreciated, however, that the present invention should not be construed as being limited to the particular embodiments discussed. [0098] References in the preceding description to "an embodiment" or "one embodiment" refer to a particular structure, feature or characteristic described herein as being included in at least one embodiment of the present invention. As a consequence of this, the phrases "in one embodiment" or "in a preferred embodiment" or "in an exemplary embodiment", if used in this specification, do not necessarily refer to the same embodiment. Additionally, it will be appreciated that the particular structures, features or characteristics may be combined in any suitable manner. [0099] In the preceding description, various structures, features or characteristics may be combined in a single embodiment, description, or figure thereof to facilitate the disclosure. It will be appreciated, however, that the method of disclosure is not to be 31 construed as implying that the claimed invention requires additional structures, features or characteristics than as recited in each claim. Rather, as the claims reflect, the inventive aspects lie in less than all features of a single preceding disclosed embodiment. [0100] Similarly, although some embodiments described herein include some, but not other, structures, features or characteristics included in other embodiments, combinations of the various embodiments described herein will be appreciated as being within the scope of the present invention, and form different embodiments, as would be appreciated by one of ordinary skill in the art. Specific details [0101] In the preceding description and accompanying figures, various specific details are described. However, it will be appreciated that the various embodiments of the present invention may be practiced without these specific details. Furthermore, well known methods, structures and techniques have not been shown in detail, so as not obscure an understanding of the present invention. Terminology [0102] The invention is not intended to be limited to the specific terms as selected throughout this specification. Further, it will be appreciated that each specific term includes all technical equivalents which operate in a similar manner or to accomplish a similar technical purpose.

32 [0103] Specific terms such as "upper", "lower", "transverse", "longitudinal", "inner", "outer" and the like are used as words of convenience to provide reference points, and are not to be construed as limiting terms. [0104] Specific use of the ordinal adjectives "first", "second", "third" and the like to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner, unless otherwise specified. [0105] Specific use of the term "comprise" or variations such as "comprising" or "comprises" are used in an inclusive sense, for example, to specify the presence of the stated features but not to preclude the presence of additional features in various embodiments of the present invention. [0106] Specific use of the term "include" or variations such as "including" or "includes" are used in an open sense, for example, to specify the inclusion of the stated features but not the exclusion of additional features in various embodiments of the present invention. Therefore, "including" is synonymous with, and means, "comprising". [0107] Specific use of the term "a" or "an" are defined as one, or more than one. [0108] Specific use of the term "plurality" is defined as two, or more than two.

33 Scope [0109] Although what is believed to be the preferred embodiments of the present invention has been described herein, it will be appreciated that other and further modifications may be made thereto without departing from the spirit of the present invention. It is therefore intended to claim all such other and further modifications as within the scope of the present invention. While the present invention has been described with reference to specific examples, it will be appreciated that the invention may be embodied in many other forms. Accordingly, it will be appreciated that variations to these embodiments can be made by those skilled in the art without departing from the scope of the invention as defined by the claims. Industrial applicability [0110] It is apparent from the above, that arrangements described are applicable to the industries involving concrete casting, and post-tensioning.

Claims (21)

1. A combination assembly for casting and post-tensioning of, and subsequent fixing of an external system to, a concrete structure, comprising: - one or more tendon units adapted for post-tensioning of the concrete structure, each of the one or more tendon units comprising one or more strands, and a sheath adapted to receive the one or more strands therein; - a channel adapted to be cast into an edge of the concrete structure, the channel comprising a partial luminal wall defining a longitudinal cavity within, and one or more slots adapted to receive the one or more strands therein; - an anchor block being co-operable with the channel, the anchor block having one or more through bores adapted to receive the one or more strands therein and permit sliding translation of the one or more strands perpendicular to the longitudinal axis of the channel, allowing the one or more strands to be tensioned relative to the channel; - one or more locks adapted to lock the positions of the one or more strands relative to the anchor block, and thus the channel, in a tensioned configuration, and to allow adjustment of the one or more strands in a released configuration; and - an external load transfer element being co-operable with the channel, the external load transfer element being connected to the external system, in use.

2. The combination assembly according to claim 1, wherein the anchor block is an integrated anchor block being integrated with the external load transfer element. 35

3. The combination assembly according to any one of the preceding claims, wherein the channel is of a generally dovetail cross sectional geometry.

4. The combination assembly according to claim any one of the preceding claims, wherein the combination assembly further comprises an edge-formwork element for use in casting of the concrete structure, and the channel is an integrated channel being integrated with the edge-formwork element such that the integrated channel is externally opening and horizontally disposed.

5. The combination assembly according to claim 4, wherein the edge-formwork element comprises a horizontal base.

6. The combination assembly according to any one of the preceding claims 4 or 5, wherein the edge-formwork element further comprises a vertical wall extending from a longitudinal edge of the horizontal base, such that the integrated channel is integrated with the vertical wall.

7. The combination assembly according to claim 6, wherein the edge-formwork element further comprises a return lip extending from a top edge of the vertical wall.

8. The combination assembly according to any one of the preceding claims 5 to 7, wherein the horizontal base comprises a continuous indentation being longitudinally disposed. 36

9. The combination assembly according to any one of the preceding claims 7 or 8, wherein the edge-formwork element further comprises a upturn portion extending from a free edge of the return lip, such that the return lip and the upturn portion defines another continuous indentation, the another continuous indentation being longitudinally disposed.

10. The combination assembly according to any one of the preceding claims 6 to 9, wherein the vertical wall further comprises one or more additional slots adapted to receive the one or more strands therein

11. The combination assembly according to claim 10, wherein the one or more additional slots are one or more through bores adapted to receive the one or more strands therein and permit sliding translation of the one or more strands perpendicular to the longitudinal axis of the edge-formwork element, allowing the one or more strands to be tensioned relative to the edge-formwork element.

12. The combination assembly according to claim 11, wherein the one or more locks are further adapted to lock the positions of the one or more strands relative to the edge-formwork element in the tensioned configuration, and to allow adjustment of the one or more strands in the released configuration.

13. The combination assembly according to any one of the preceding claims 10 to 12, wherein the combination assembly further comprises an additional anchor block having one or more through bores adapted to receive the one or more strands 37 therein and permit sliding translation of the one or more strands perpendicular to the longitudinal axis of the edge-formwork element, allowing the one or more strands to be tensioned relative to the edge-formwork element, the additional anchor block being stiffer than the edge-formwork element, in use.

14. The combination assembly according to claim 13, wherein the one or more locks are further adapted to lock the positions of the one or more strands relative to the additional anchor block in the tensioned configuration, and to allow adjustment of the one or more strands in the released configuration.

15. The combination assembly according to any one of the preceding claims 13 or 14, wherein the additional anchor block is an integrated additional anchor block being integrated with the external load transfer element.

16. The combination assembly according to any one of the preceding claims, wherein the combination assembly is formed of a corrosion resistant material.

17. The combination assembly according to any one of the preceding claims, wherein the combination assembly comprises one or more radiused corners adapted to reduced stress concentrations in the combination assembly, in use.

18. The combination assembly according to claim 17, wherein the one or more radiused corners are being radiused such that at least a portion of the combination assembly can be formed by bending of a sheet material in a bending operation. 38

19. The combination assembly according to claim 18, wherein the one or more radiused corners are being radiused such that at least the portion of the combination assembly can be formed by bending of a high strength sheet material, in the bending operation.

20. The combination assembly according to any one of the preceding claims 18 or 19, wherein the one or more radiused corners are being radiused such that at least the portion of the combination assembly can be formed by bending of a sheet material having a corrosion resisting coat, in the bending operation.

21. The combination assembly according to any one of the preceding claims, wherein the combination assembly is further adapted for pre-tensioning of the concrete structure.