The present invention relates generally to cast in situ concrete beams for use in the building industry.

The present invention relates particularly, although by no means exclusively, to concrete beams that form part of cast in situ concrete floors, hereinafter referred to as "concrete floors", such as mezzanine floors and floors for multi-storey buildings, including multistorey carparks .

The present invention relates particularly, although by no means exclusively, to concrete floors that include concrete beams.

The present invention also relates more particularly, although by no means exclusively, to formwork elements for constructing concrete floors, particularly formwork elements for constructing beams of concrete floors, and to concrete floors made using the formwork elements .

In the context of the construction of floors , the term "concrete floor" is understood herein to include

(a) one or more than one concrete beam and (b) one or more than one a concrete slab section extending outwardly from the beam or beams as a part of the floor.

In the context of the construction of floors, the term "concrete floor" is understood herein to further include :

(a) a base of the floor that includes a formwork in the form of a plurality of profiled decking sheets positioned in side- by-side and/or end-to-end relationship as

required and other formwork elements as required to form the base; and

(b) a layer of concrete on the base.

Typically, in the context of the construction of floors, the term "concrete floor" is understood herein to include reinforcement embedded in the concrete layer. Such reinforcement may be in the concrete of the beam or beams and/or in the concrete of the slab section or sections .

The profiled decking sheets and other formwork elements of the concrete floor may contribute to. the mechanical performance of the concrete floor.

Specifically, the profiled decking sheets and other formwork elements may act compositely with the concrete via mechanical bonding and therefore contribute to the reinforcement of the concrete floor .

Notwithstanding the above, the present invention extends to arrangements in which the profiled decking sheets and other formwork elements do not make a contribution to the mechanical performance of the concrete floor and the profiled decking sheets and other formwork elements act as lost formwork only.

Typically, a concrete floor is formed in situ by:

(a) positioning a plurality of profiled decking sheets and other formwork elements onto a permanent support structure and forming a continuous base of the floor,

(b) positioning formwork that defines the outer side wall perimeter of the concrete floor,

(c) placing reinforcement, typically in the form of flat sheets of steel mesh or bars , or both mesh and bars , on or in relation to the profiled decking sheets and other fonnwork elements , and

(d) finally pouring concrete onto the assembly of the decking sheets and other formwork elements and reinforcement within the perimeter of the formwork and forming a layer of concrete.

Depending on a number of factors, including the shapes of the profiled decking sheets and other formwork elements, the weight of concrete required to form a concrete floor, the span between adjacent permanent support members, deflection limits, the concrete pour sequence , the number of spans , the means of fixing to the permanent support structure, and construction loads (other than wet concrete), the profiled decking sheets and other formwork elements may need to be propped temporarily between the permanent support members .

The term "profiled decking sheet" is understood herein to mean roll-formed sheets or brake pressed sheets "that, typically (although by no means exclusively) , include at least one pan and side edge formations that enable adjacent sheets to be positioned together in side- by-side relationship.

In situations in which a profiled decking sheet includes two or more than two pans, typically (although by no means exclusively) , the term "profiled decking sheet" is understood herein to include one or more than one upstanding rib separating adjacent pans.

The present invention provides an elongate formwork element that is particularly well suited for use as part of the formwork for concrete beams of a concrete floor.

According to the present invention there is provided an elongate formwork element for use in the construction of a concrete floor, which formwork element includes a base wall and a side wall extending from one side edge of the base wall so that the element is generally L-shaped in transverse section.

Preferably the formwork element is adapted to interlock, in use, with a horizontally disposed profiled decking sheet so that the side wall extends upwardly from a side edge of the profiled decking sheet.

The formwork element is particularly suitable for use as part of the formwork of a concrete beam of a concrete floor. In this application, the beam formwork is defined by:

(a) one or more than one profiled decking sheet that forms a base of the beam formwork, and

(b) one or more than one of the formwork element positioned on opposite sides of the profiled decking sheet or sheets and interlocked with the profiled decking sheet or sheets and forming the sides of the beam formwork .

The formwork element is also suitable for use as other parts of the formwork of a concrete floor .

In a' number of applications it is not necessary that the side wall of the formwork element be a load

bearing element. Therefore, the formwork element can be made, by way of example, form small gauge steel. The term "small" gauge steel is understood herein to mean steel that is less than 1 mm thickness .

Preferably the side wall of the formwork element includes a strengthening member. The strengthening member reduces lateral deflection (bulging) of the side wall when wet concrete is poured and bears against the side wall. The strengthening member also makes it possible to use lighter gauge steel to make the side wall than would otherwise be the case.

Preferably the strengthening member is in the form of a plurality of ribs in the side wall of the formwork element.

Preferably the ribs extend transversely to the length direction of the formwork element.

Preferably the ribs extend at least substantially between the base wall and a free end of the side wall. In a situation in which the formwork element is interlocked with a horizontally disposed profiled decking sheet so that the side wall extends upwardly from a side edge of the profiled decking sheet, the ribs extend upwardly at least substantially between the base wall and the free, i.e. upper, end of the side wall.

Preferably the ribs are in the form of deep embossments that make it possible for the side wall to act compositely with the concrete layer.

The term "deep" as used herein in the context of the embossments means that the depth of the embossments is at least 2 mm and more preferably at least 3 mm.

Preferably the base wall is shaped to interlock with the profiled decking sheet.

Preferably the base wall is shaped to interlock with the profiled decking sheet without the use of mechanical fasteners .

In a situation in which the profiled decking sheet includes at least one rib, preferably the base wall includes an upturned lip that is adapted to extend into a rib of the profiled decking sheet and the length of the base wall is selected so that, in use, the formwork element can be positioned so that the base wall is positioned against an undersurface of the profiled decking sheet at one side of the sheet and the lip extends into and engages the rib of the sheet .

Preferably an upper end of the side wall includes an end formation that defines a platform on which one or more than one profiled decking sheet can be located and secured, preferably by fasteners.

With the arrangement described in the preceding paragraph, it is possible to assemble together the formwork for an elongate concrete beam and sections of a concrete slab extending outwardly from one or both sides of the beam.

In particular, with this arrangement, it is possible to pre-assemble sections of the formwork for a concrete floor on the ground and thereafter lift the sections into a required location on a building under construction .

Preferably the end formation includes a lip that is adapted to contact edges, which are typically sharp edges, of the ends of profiled decking sheets positioned

on the end formation. The lip forms an end cap that prevents flow (and thereby loss) of concrete through deck voids , such as the ribs of profiled decking sheets . In addition, the lip covers sharp edges that may result in injury to workers assembling and/or installing the formwork .

According to the present invention there is also provided an assembly of a plurality of profiled decking sheets and a plurality of the above-described formwork element that form a formwork of a base of a part of a beam and slab sections of a concrete floor.

The above-described assembly can be put together on the ground and then lifted into a required position on a building under construction.

Preferably the assembly includes the formwork elements that form the sides of the beam formwork being interlocked with the profiled decking sheets that form the base of the beam formwork .

Preferably the upper ends of the formwork elements that form the sides of the beam formwork defining a support platform that supports the profiled decking sheets that form the base formwork of the slab sections .

Preferably the assembly includes a safety rail.

The safety rail is an important safety feature for persons constructing a concrete floor when the assembly is lifted into position.

In addition, the safety rail stiffens the assembly and contributes to maintaining the integrity of the assembly as it is lifted from the ground into a required position.

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According to the present invention there is also provided a concrete floor that includes one or more than one concrete beam and a concrete slab section extending outwardly from the beam as a part of the floor and further includes :

(a) a base that includes a formwork in the form of an assembly of a plurality of profiled decking sheets and a plurality of the above-described formwork element, and

(a) a layer of concrete on the base .

Preferably, the profiled decking sheets are pre- cambered along the length of the sheets .

Preferably the profiled decking sheets are pre- cambered along the length of the sheets so that the pans of the sheets form flat, horizontal surfaces when wet concrete is poured to form the concrete floor.

Preferably the concrete floor further includes reinforcement, such as steel mesh, embedded in the concrete .

The reinforcement may be pre- or post- tensioned.

The reinforcement may be welded or otherwise connected to the side edge formations and/or the ribs of the profiled decking sheets to increase the resistance to lateral deflection under load.

The present invention is described further by way of example with reference to the accompanying Figures, of which :

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Figure 1 is a vertical cross-section through a part of one embodiment of a concrete floor in accordance with the present invention; and

Figure 2 is a perspective view of one embodiment of a formwork element in accordance with the present invention that forms a part of the concrete floor shown in Figure 1.

The part of the concrete floor shown in Figure 1 includes an elongate concrete beam 3 (extending into the page) and a horizontal concrete slab section 5 extending outwardly from each side of the beam 3 , as shown in the Figure .

The part of the concrete floor shown in Figure 1 is formed from:

(a) a continuous base in the form of a formwork that includes an assembly of a plurality of horizontal steel profiled decking sheets 7 and vertical steel formwork elements 9,

(b) a layer of concrete 11 on the base/ and -

(c) reinforcement in the form of a steel mesh 13 embedded in the concrete layer 11.

The base is supported by a plurality of permanent support members (not shown) . By way of example, the permanent support members may be in the form of columns .

The profiled decking sheets 7 may be of any suitable configuration.

Moreover, it is not necessary that the same profiled decking sheets 7 be used to form the base of the beam 3 and the base of each slab section 5.

Figure 1 shows that the base of the beam 3 includes two profiled decking sheets 7 positioned side-by- side in overlapping relationship. Each profiled decking sheet 7 includes three pans 31 separated by parallel open ribs 33 and side edge formations 35.

Figure 1 shows two formwork elements 9 that form opposite sides of the beam 3.

Each formwork element 9 is made form small gauge steel having a thickness of 0.75 mm and includes a base wall 15 and a non-load bearing side wall 17 extending upwardly (as viewed in Figure 1) from one side edge of the base wall 15 so that the element 9 is generally L-shaped in transverse section .

Each formwork element 9 is formed so that it can interlock with an adjacent horizontal profiled decking sheet 7 of the base of the beam 3 , without the use of mechanical fasteners, so that the side wall 17 of the element 9 extends upwardly from a side edge of the sheet 7 and is held in that position. The interlocking of the formwork elements 9 and the profiled decking sheets 7 is advantageous because it assembles the components together and this simplifies construction of the concrete slab and allows the components and the concrete to act compositely.

The side wall 17 of each formwork element 9 includes a strengthening member in the form of a series of parallel ribs 21 of 3 mm depth that extend vertically at least substantially between the base wall 15 and an upper end of the side wall 17. The ribs 21 are deep ribs and consequently make it possible for the side walls 17 to act

compositely with the concrete layer. In addition, the ribs 21 make it possible to use lighter gauge steel to make the side wall 17 than would otherwise be the case.

The base wall 15 of each formwork element 9 is shaped to interlock with the profiled decking sheet 7.

Specifically, the base wall 15 of each formwork element 9 includes an upturned lip 37 that is adapted to extend into and engage the closest rib 33 to the formwork element 9. In addition, the length L (see Figure 2) of the base wall 15 of each formwork element 9 is selected so that, when the formwork element 9 is positioned with the base wall 15 against an undersurface of the profiled decking sheet 7 and with the lip 37 extending into and engaging the rib 35, the side wall 17 of the element 9 bears against the outer side edge formation 35 of the sheet 7, with the result that the formwork element 9 and the profiled decking sheet 7 are interlocked together .

The side wall 17 of each formwork element 9 includes an end formation 39 at an upper end thereof. The end formation 39 defines a platform on which one or more than one profiled decking sheet 7 for the base of the floor sections 5 are located and secured by fasteners 41,

The upper end formation 39 of the side wall 17 of each formwork element 9 includes a lip 43 that contacts the edges , which are typically sharp edges , of the ends of profiled decking sheets 7 of the base of the slab sections 5 that are on the end formation 39. The lip 43 is provided as a safety feature to minimize injury during construction of the concrete slab. Moreover, for safety reasons, the lip 43 has a small rounded return at the upper end so that it does not present a sharp edge. In addition, the lip 43 functions as an end cap for the ribs of the profiled decking sheets 7 of the base of the slab

sections 5 that prevent flow of wet concrete from the beam 3 via the ribs . Specifically, the ribs define openings below the profiled decking sheets 7 through which wet concrete could flow outwardly and downwardly from the beam 3.

The profiled decking sheets 7 and the formwork elements 9 can be readily manufactured and transported to a construction site and are adapted to be assembled together on the ground at the site and thereafter lifted by a crane into a required location for a building under construction.

One or more than one safety rail (not shown) may be positioned on the assembly for subsequent use as a safety measure after the assembly has been lifted into position and as a means of improving the rigidity of the assembly.

Many modifications may be made to the embodiment of the present invention described above without departing from the spirit and scope of the invention.

By way of example, whilst the description of the embodiment indicates that the profiled decking sheets 7 and the formwork elements 9 can be assembled together to form the formwork on the ground at a building site and thereafter lifted by a crane into a required location on a building under construction, the present invention is not so limited and extends to arrangements in which the profiled decking sheets 7 and the formwork elements 9 are separately lifted from the ground to a building and assembled together to form the forwoark on the building.

By way of further example, whilst the embodiment of the formwork shown in the drawings includes profiled decking sheet 7 that have three pans 31 separated by

parallel open ribs 33 and side edge formations 35, the present invention id not limited to this configuration of the profiled decking sheet.

By way of further example, whilst the embodiment of the formwork element 9 shown in the drawings is made form small gauge steel having a thickness of 0.75 mm, the present invention is not so limited and extends to formwork elements made from any suitable material of any suitable thickness and is not confined to small gauge steel of the stated thickness of 0.75 mm.