WO2013091000A1

WO2013091000A1 - A building structure

Info

Publication number: WO2013091000A1
Application number: PCT/AU2012/001565
Authority: WO
Inventors: Epaminondas Katsalidis
Original assignee: Unitised Building Limited
Priority date: 2011-12-19
Filing date: 2012-12-19
Publication date: 2013-06-27

Abstract

A pre-fabricated formwork module for a building portion; the module including: a first wall being configured to provide tensile reinforcement of the building portion in use; a second wall being coupled to the first wall and being arranged with respect to the first wall such as to define a volume therebetween for receiving settable material to be formed. The second wall is formed from a plurality of panels; each panel having a boundary portion and one or more projections, the panels being arranged such that the boundary portions together form at least part of the second wall of the formwork module and the projection(s) extend into the void for receiving settable material; wherein at least one projection of at least one panel is coupled to the first wall and in use is embedded in settable material formed in the module, such that when the settable material is set, the projection of the panel provides a shear connection between the settable material formed by the module and the first wall.

Description

A Building Structure

Field of the invention

The present invention relates to the construction of concrete buildings as well as elements, structures and methods used in their construction. The invention will be described in relation to the construction of high rise buildings. However, single storey and low rise buildings can also be constructed using aspects of the present invention.

Background of the invention

Buildings having concrete elements are constructed using formwork to create a temporary or permanent cast into which the concrete to form the structure of the building is poured. Temporary formwork is removed after curing of the concrete, whilst permanent formwork remains as part of the structure of the building after the concrete has cured. Current methods of providing concrete formwork are very labour intensive and potentially dangerous for workers.

Traditionally, timber formwork has been used. Timber formwork is built on site by a carpenter who uses timber to create a mould into which concrete can be formed. Typically plywood boards are used to define the sides and bottom of the moulds, and more solid timber frames and bracing used to hold the plywood in place. The use of timber for formwork has certain disadvantages, e.g. timber formwork is only able to be re-used a very limited number of times, it also has the inherent dimensional and structural irregularities associated with a natural product. Moreover, because the formwork is manually installed on-site, tolerances for installation are relatively loose.

Conventional timber formwork for a vertical wall will typically consist of a pair of boards spaced apart by the thickness of the wall to be created. The boards define the opposite surfaces of the wall. The boards are supported and braced on their external sides by timber beams and other bracing to hold them in place. The boards are also tied to each other at intervals to hold the walls of the formwork from moving apart under the pressure of the concrete being poured into the formwork. The ties can be located along the edges of the board or be placed such that they project through the wall of the board to the opposite facing board.

For horizontal structures, such as a floor, the underside of the floor is defined by one or more sheets of timber (e.g. made from plywood) that are supported on timber beams. For elevated floors a temporary support structure needs to be erected before the floor of the formwork can be installed. Such installation is very time consuming and potentially hazardous, particularly when the workers are installing timber panels on the bottom of the formwork section for horizontally extending structures like floors or beams onto the support beams. Around the edges of the timber floor, walls are erected to define a volume into which concrete will be poured. Prior to pouring concrete however, many other elements need to be laid into the formwork so that they can be cast into the concrete. Chief among these are reinforcing bars and conduits for post tensioning tendons, apertures and connections for plumbing and other services. The placement of each of these additional elements is performed onsite after the formation of the formwork, with each additional job becoming progressively more difficult and hazardous for workers as the working area becomes more cluttered with other elements. For example, in order to install plumbing connections in a floor it may be necessary for the installer to place components between many layers of reinforcing steel or other elements of the building. These elements will also need to be carried or manoeuvred across a surface of the formwork that is criss-crossed by reinforcing bars, associated ligatures holding the steel together and other elements.

After the concrete has cured, the temporary formwork then needs to be removed. This is also time consuming and potentially dangerous. In this case workers are removing supports, and structures positioned above their heads.

More recently modular temporary formwork systems have been devised. These include panels which have a frame, typically of metal, for providing structural strength. The panel surface defines the inside of the concrete mould. These systems include, corner modules, flat panels etc and the desired formwork shape can be made by joining these together. These systems can be quicker to place than conventional timber formwork because they can be clipped or bolted together and are typically able to be used many times more than conventional timber formwork, but in other respects have similar drawbacks.

One way of partly avoiding work associated with temporary formwork is the use of permanent formwork. For example steel panels can replace the floor of the formwork on horizontal surfaces. These panels are positioned in a very similar manner to that of the timber floor panels of conventional timber formwork but need not be removed afterward as they are formed into the underside of the concrete which they have been used to create. However, in other respects these systems are similar to conventional timber formwork.

Another type of permanent formwork module can be used to create a metal-concrete composite wall or other structure. These modules include a pair of steel plates that are spaced from each other and connected by a multitude of bars. The bars connect at each of their ends to the plates and act as shear studs to bond the plate to the concrete and transmit shear loads to the steel plates. Because the external plates reinforce the concrete when under tension, structures made in this form may largely avoid the need for additional internal reinforcing steel. However these formwork systems tend to be complex to manufacture because of the difficulty in placing and affixing the multitude of bars between the plates.

There also exists framing systems used for creating vertical walls such as the AFS system, which comprises a series of vertically extending studs to which cement sheet is attached on each side to define a wall cavity. These wall structures can be used as-is or filled with concrete to create a structural wall. If they are used as formwork the panels are first erected on site and braced. If reinforcing is needed, reinforcing bars are then inserted into the internal cavity as required. Services can be inserted through the wall before the concrete is finally poured. They can then be finished as required. One way of ameliorating the complexity, cost and risk of using formwork as described above is to precast the concrete elements off site, but this is only viable in certain situations.

The inventor has realised that structures similar to those described in the applicant's previous patent applications can be used as permanent formwork in the construction of concrete structures. Moreover particular advantages in manufacturability can also be obtained if prefabricated formwork modules, e.g. formwork modules for walls and cores and the like, are manufactured from panel assemblies similar to that described in International patent application PCT/AU2011/000298. One example of such a system is described in an International Patent Application PCT7AU2011/000525. However further developments have now been made.

Accordingly, it is an object of the present invention to address one or more of the drawbacks of the prior art systems and/or provide a useful alternative to them.

It is not admitted that any of the information in this specification is common general knowledge, or that the person skilled in the art could be reasonably expected to have ascertained or understood it regarded it as relevant or combined it in any way at the priority date.

Summary of the invention

In one aspect, the present invention provides a formwork module for forming a portion of a building, the module having a first wall and a second wall, the first and second walls being spaced apart from each other to define a volume for forming a settable material therein; the first and second walls being coupled to each other by one or more shear connectors; wherein the first and second walls are of different thicknesses to each other. Advantageously, the first wall is a plate of steel having a thickness at least twice that of the second wall. The shear connectors may be integrally formed within one of the walls or may be a separate component affixed to one of the walls. Preferably, the shear connectors extend from the second wall, being the thinner of the two walls. Most preferably the second wall is assembled from panels, wherein at least some of the panels have projections extending there from which in use function as shear connectors.

In a second aspect, the present invention provides a pre-fabricated formwork module for a building portion; the module including: a first wall being configured to provide tensile reinforcement of the building portion in use; a second wall being coupled to the first wall and being arranged with respect to the first wall such as to define a volume therebetween for receiving settable material to be formed. The second wall is formed from a plurality of panels; each panel having a boundary portion and one or more projections, the panels being arranged such that the boundary portions together form at least part of the second wall of the formwork module and the projection(s) extend into the void for receiving settable material; wherein at least one projection of at least one panel is coupled to the first wall and in use is embedded in settable material formed in the module, such that when the settable material is set, the projection of the panel provides a shear connection between the settable material formed by the module and the first wall.

The one or more projections may be a plurality of individual spaced apart projections, or may be part of a projecting structure that is castellated such that it includes one or more projections separated by cut-outs that open outwardly from the boundary portion; and at least some of said projections are coupled to the first wall. The projections of adjacent panels together may define a plurality voids which are interconnected via the cut-outs so in use, settable material can flow through the cut-outs and the building portion can be formed from a continuous phase of settable material. Alternatively the projecting structures can be a web with one aperture formed therein. Other arrangements are possible.

The formwork module is asymmetrical in terms of only one of the walls are a primary reinforcing component, and therefore has a thickness greater than the thickness of the other wall. Preferably the first wall is a plate and has a first thickness. The second wall can be formed from panels having a second thickness. Preferably the second thickness is less than the first thickness. The walls are advantageously made from steel.

Advantageously, the thickness of the first wall will be at least twice the thickness of the second wall. The thickness of the first wall will typically be between 4 and 40mm. Preferably it is between 5mm and 12mm. In some cases the first wall will be greater than 6mm. The panels will typically have a thickness of between 1 and 3mm. Preferably the panels have a thickness of around 1.6mm.

It should be appreciated that other thickness material can be used to fabricate the first wall and panels, depending on the strength requirements for the project being undertaken. The thickness of the second wall is preferably such that it is the primary reinforcing for said building portion in use; no additional internal reinforcing running the length of the formwork module is required.

Each projecting structure may terminate in a hook formation by which it is connected to the first wall.

Preferably the building portion formed with the module comprises some or all of a building core.

The building portion can have a vertical open-ended tubular configuration, including at least one sidewall defined by the formwork module such that an outermost side of the sidewall is formed by the first wall of the formwork module. The building portion most preferably has an open-ended rectilinear configuration having four external sidewalls, being four first walls of the formwork module. It will be appreciated that a formwork module could be an individual wall, or could be an assembled structure including a number of walls to form, for example, a building core. Further aspects of the present invention include composite panels, walls or other portions of buildings formed using a formwork module as described herein. Brief description of the drawings

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings. In the drawings:

Figure 1 illustrates a formwork module according to a first embodiment of the present invention;

Figure 2 shows a panel and panel assembly and illustrates a first stage in the fabrication of the formwork module of Figure 1 ; Figure 3 illustrates a formwork module which may be used in its own right to form a portion of a building, such as a wall* or be incorporated into the formwork module of Figure 1 ;

Figure 4 illustrates the formwork module of Figure 1 with coupling attachments connected thereto for connecting the formwork module to a neighbouring formwork module;

Figure 5 shows detail of the coupling attachments of Figure 4;

Figure 6 illustrates a pair of formwork modules of the type shown in Figure 1 which have been connected together;

Figure 7 illustrates a preferred mechanism for connecting a lower formwork module with buildings foundations;

Figure 8 is a truncated illustration of a panel showing the affixing of a projection according to one embodiment;

Figure 9 is a perspective view of a projection according to a second embodiment; Figure 10 is an illustration of the flat steel components and once bent and affixed to make a panel;

Figure 11 shows the assembly process to make a sidewall, with a first wall laid flat and successive panels positioned and welded in place; Figure 12 shows the assembly process of Figure 11 with further panels positioned and welded in place;

Figure 13 shows an assembled sidewall without door apertures;

Figure 14 shows the assembled side-wall of Figures 11 and 12;

Figure 15 illustrated the method of joining two sidewall formwork modules according to the present invention to two internally reinforced sidewall formwork modules; and

Figure 16 shows the assembled core formwork module of Figure 15.

Detailed description of the embodiments

Figure 1 illustrates a formwork module 100 made in accordance with a first embodiment of the present invention. The formwork module 100 is intended to be used to form concrete to construct a core of a high rise building. The module 100 will form a single storey portion of the core. In general configuration, the formwork module 100 is a vertical open ended box shape having four sidewalls 102, 104, 106 and 108. Each of the sidewalls 102 to 108 of the module 100 is created from one or more formwork module sub-assemblies, each of which could be considered a formwork module in its own right.. The module 100 is hollow through its centre 126 and thereby can be viewed as being generally tubular in overall shape. As the formwork module 100 is intended to form part of a core of a building, which will house lifts or the like, the sidewall 104 includes three openings 110, 112 and 114 which provide doorways into the internal part of the core for access to lifts and the like. The present invention is directed to externally reinforced formwork modules, whereby internal reinforcing mesh is not required to be embedded within the poured concrete. Reinforcing mesh is a difficult element to handle and installation is labour intensive, difficult and dangerous, particularly in vertical orientations. The first wall 122 provides the tensile and shear load characteristics normally carried by the reinforcing mesh, removing the problems associated with installing internal reinforcing mesh. Each of the sidewalls 102 to 108 have first and second walls 122, 124 that are spaced from each other and between them define a volume 125 in which concrete is formed. In a general sense, each of the sidewalls 102 to 108 have a first, outer wall 122 comprised of generally plate like material and a second, inner wall 124 which is formed of a sheet like material. The outer wall 122 is configured to provide reinforcing for the concrete formed by the formwork module 100, whereas the inner wall 124 primarily operates to provide a boundary for forming the concrete within the formwork module 100.

Junctions between neighbouring walls (102, 106; 106, 104; 104, 108; 108, 102) of the module 100 are created on the outer side by welding the outer walls 122 of the module together at 120, and on the inside by welding an angle section e.g. angle 116 between the adjacent walls 124. The inside faces of the openings 110, 112 and 114 in sidewall 104 are lined with suitable panels e.g. panel 118 to define the openings and close the formwork void 125. In use, the formwork module 100 is placed in its intended position within a building and the void 125 is filled with concrete. As will be appreciated from the following description, which will reveal more about the structure of the formwork module 100, the concrete poured into the formwork module 100 is able to flow throughout the volume 125 within the formwork module and create a monolithic concrete structure which is reinforced against tensile stresses by the formwork module 100.

Turning now to Figure 2, which illustrates some details of the construction of the formwork module of Figure 1, and in particular, Figure 2 shows a panel assembly 130 which can be used to form the second wall 124 of a formwork module. In this example, the panel assembly 130 can be used to form a formwork module sub-assembly such as sidewall 102 of the formwork module 100 of Figure 1. The panel assembly 130 is formed from plurality of panels, 132, 134, etc, where panels 134 are of greater width than panel 132 and different combinations of widths and heights can be combined to provide flexibility and adaptability to the building design. Example panel 136 shows the general form of the panels 132, 134 and is one embodiment of how the panels may be formed. As can be seen, the panel 136 includes a generally planar wall portion 36A and a projecting structure 136B that is integral and extends from the wall portion 136A generally perpendicularly by folding. The projecting structure 136B is generally castellated in shape and includes a plurality of projections 136C which are separate from each other by a series of cut outs 136D. Each of the projections 136C terminates in a flange 136E that are generally perpendicular to the projections 136C and parallel to the wall portion 126A, the purpose of which will become apparent in further description.

Within the assembly 130 adjacent panels 134 are arranged such that there is a small overlap between them and are held in relative position e.g. by spot welding or clinching them along the overlapping portions. The panels 132, 134 and 136 are generally similar to the panels described in the applicant's earlier patent application PCT/AU 2011/000298 and the mechanisms for joining the panels into the panel assembly 130 as illustrated in Figure 2 are described therein and in the applicant's further patent application PCT/AU 2011/00525. The contents of these patent applications are incorporated herein by reference. In the next stage of construction of the formwork module 100, this panel assembly 130 which creates second inner wall 134 is connected to another wall, being first inner wall 122. This is illustrated in Figure 3.

Figure 3 shows the sidewall assembly 102 comprising the second wall assembly 130 attached to a first wall 122. The first wall 122 is a thick plate of steel and is generally planar. In the embodiment illustrated in Figure 3 the first wall 122 includes a series of apertures 138. The first wall 122 is aligned with the second wall assembly 130 such that the apertures 138 align with the flanges 136E of the projections . The first wall 122 is then welded to the second wall 130 via the apertures 138. This construction forms an overall structure which has a first wall 122 and a second wall 124 which is spaced from the first wall 122. The walls 122, 124 are coupled to each other via a series of connections 136C. In this case the connections are the projecting structures 136B of the panels 134 forming the panel assembly 130. In this example, all of the flanges 136E of the panels 134 are attached to the first wall 122, but this may not be the case in some embodiments. The walls 122 and 124 form a volume 125 between them, which can be filled with concrete, in use, and form a composite sidewall forming a portion of a building.

The castellated structure of the projecting portions 136B of the panels 134 advantageously provides flow paths through the cut outs 136D (between the projections 136C of each of the panels) through which concrete may pass, to fill the entire formwork module 100. Moreover, once the concrete in the formwork module 100 is set it forms a monolithic block which encases the projections 136C of the panels 134.

The advantages gained from eliminating internal reinforcing come with complexities in manufacturing. Prior art externally reinforced formwork modules provide two reinforcing plates spaced apart and joined by shear connectors. The difficulty comes from the placement and connection of the plurality of shear connectors between the heavy large plates. The present invention overcomes these issues with manufacturability be providing one of the walls as a series of thin panels that can be progressively joined, allowing easy access to the shear connectors for joining to the opposite wall plate. The first wall 122 is of a relatively higher strength than the second wall 124 and thereby performs the function of reinforcing the concrete formed within the formwork module 100. This is due to the thickness of the first wall 122. As shown in Figure 3, first wall 122 is a plate of steel, whereas second wall 124 is a sheet and simply forms the boundary wall for the concrete. In addition to defining the separation between the walls 122, 124 the projecting structures 136B that connect the second wall 124 to the first wall 122 function as shear connecters when concrete is set within the sidewall formwork module 102 and transfer shear loads from the concrete into the first wall 122. The first wall 122, providing the external reinforcing, transfers these loads down into the footings of the building. This asymmetrical reinforcing construction means that loads are only transferred to one side of the constructed wall. This is counter-intuitive, as by offsetting the reinforcing, additional loads are introduced, which make the concrete tend to bend. These loads are transferred from the concrete through the shear connectors 136C to the reinforcing first wall 122. The loads are then transferred down to the footings. The disadvantages of the asymmetrical loading are offset by the advantages gained in the manufacturability of the assembly.

The formwork module 100 illustrated in Figure 1 is formed of four sidewalls, each having the same general construction as the sidewall formwork module 102 of Figure 3, but having slightly different shapes. As noted above, each of the sidewalls is connected to its adjacent sidewalls. In the example Figure 1, the outer, first walls 122, which perform the reinforcing function are connected to each other by a weld along their abutting edges, which is illustrated at 120 in Figure 1, whereas the inner walls 124 are joined via an angle 116.

Since the external wall 122 of the module 100 performs the function of reinforcing the concrete building portion created in the formwork module 100, it is relatively easy to create continuity in the reinforcing around the entire formwork module 100 by connecting the external walls of each of the sidewall formwork module sub-assemblies to each other. Of course, in embodiments in which the inside wall 124 of the formwork module 100 is used as the reinforcing wall, continuity in reinforcing between each of the walls could still be achieved by connecting them however, access to the inside of the formwork module would be needed during construction. Advantageously continuity in reinforcing is only needed on one wall of the formwork module.

Turning now to Figure 4, it shows the formwork module 100 of Figure 1, but with the addition of a module connection assembly. The module connection assembly includes a series of connection plates 142, 144, 146 and 148 which are bolted (or otherwise connected) to the uppermost edge of each of the side walls 102-108 of the module 100. These connection plates 142-148 are used to bolt or weld the module 100 to the next module which is vertically stacked upon the module 100 in use. The module 100 is additionally provided with floor support brackets (e.g. 150, 152 and 154), that form a shelf to support an adjacent slab structure of the building, e.g. by supporting beams, band beams and floors of the building in which the formwork module 100 is used. Figure 5 illustrates details of the connection plates and floor support. As can be seen from Figure 5, a pair of sidewalls 104 and 108, which are formed of formwork module assemblies such as that illustrated in Figure 3. The sidewalls meet at a corner 156. The first, outer walls 122 are joined by a weld 120 and the inner, second walls 124 of the respective sidewalls 104, 108 are connected via an angle 116. As can be seen, each formwork module sidewall 104 and 108 is provided at its upper edge with a connector plate 142 and 148. The connector plates 142 and 148 are simply a strip of steel with a series of holes formed therein. The connector plate 142 is bolted to the wall 122 via a bottom row of holes 142A. A second row of holes 142B are arranged to be bolted to the bottom edge of a similar vertically stacked formwork module in use. It will be appreciated from our previous patent applications mentioned above, that a module 100 of the type shown in Figure 4 will be stacked on top of a like module and connected thereto for forming a respective level of core of a building. In a high rise building, many similar formwork modules 100 will be stacked to create the core. It will be appreciated that any suitable connection method could be utilised.

The floor support brackets 150 and 152 each comprise an elongate angle bracket which is attached to the outer first wall 122 of the formwork module assemblies 104 and 108. These can be connected by either bolting or welding to the external, first walls 122. The horizontally projecting arm of the brackets 150, 152 are provided with a series of studs 154 which, in use are embedded in the concrete of the floor, or beam structure which is supported on the support brackets 150, 152. This transmits load between the core and floor or beam and provides continuity of reinforcing between them. Alternatively shear connection can be provided by providing threaded holes in one or more of the elements, e.g. the plate 142, top edge of the panel 104 or bracket 150 (or use of ferrules or other fixtures cast into the concrete) into which threaded-end reinforcing bars can be screwed in use.

Figure 6 illustrates a pair of similar modules 100 which are joined adjacently together. The modules 100A and 100B are connected to each other at each end by a header beam^" 160 and 162. The ends of the header beams are bolted to each of the respective modules 100A and 100B. Header plates 164 and 166 are also provided. The header beams 160, 162 and header plates 164, 166 maintain correct spacing between the core formwork modules 100A, 100B when placed, and support the slab of the floor between the cores. As will be appreciated, the assembly of formwork modules 100A, 100B illustrated in Figure 6 represents the formwork structure of the core of a single storey of a building. The module 100A is adapted for forming a core in which three lift wells are located, whereas the module 100B is adapted for forming stairwells. In this regard, the module 100B is provided with two doorways 101 A and 101B for providing access to stairwells formed within the core.

The construction of a building using formwork modules 100. such as those described herein is generally similar to the process described in our previous application PCT/AU 200 1/000525 and generally follows the process of placing the formwork modules 100 one or more storeys at a time and filling the formwork modules 100 with concrete. The major departure from that description being that the preferred embodiments of the present invention eliminate the need for separate internal reinforcing steel to be used within the inventive formwork modules. Figure 7 illustrates a structure 170 which is used to attach the lower most core formwork module 100 to the foundations (not shown) of the building. The structure 170 includes a stiffening frame 172, on which is carried a generally rectangular core support structure 174. The stiffening frame 172 is bolted to the foundations by a series of bolts 176 that are embedded in the foundations. The bolts 176 surrounding the perimeter of the structure 170 are cast into the foundations and are attached to respective plates 178 at their lower ends. The bolts 176 may be pre-tensioned and de-bonded to prevent snapping of the bolts.

The stiffening frame 172 can be bolted to the foundation either outside or inside the support structure 174, or both inside and outside, as illustrated in this embodiment. The core support structure 174 is effectively a formwork module for casting a block at the base of the building. The support structure 174 is formed from a plurality of panels 180, 182, 184, 186, 188, 190, 192 and 194. These panels are welded together along their abutting edges 196. Along the top edges of the panels 180 to 194 are arranged a series of holes 198 to which connection plates 200, 202, 204, 206 (similar to that described above) are bolted in a similar manner to the connection plates described above. In use, the lowermost formwork module is bolted to the support structure 170 in a manner analogous to that described above.

After the structure 170 is bolted to the foundations the void 208 formed within the support structure 174 can be partially filled with concrete, e.g. to half way up the panels 180, 182, 184, 186, 188, 190, 192 and 194 prior to the attachment of the first layer of overlying formwork module being attached thereto. In this case, the rest of the void 208 in the support structure 174 is filled with concrete as its overlying formwork module 100 is filled. Alternatively the entire void 208 formed within the support structure 174 can be filled with concrete along with the next formwork module 100 that is attached on top of it.

As noted above, in most embodiments of the present invention the first wall 122 of the formwork module 100 will be thicker than the second wall 124 of the formwork module 100 in order for the first wall 122 to perform the function of reinforcing the portion of the building formed in the formwork. Manufacturing the panels used to form the second wall 124 of the formwork module is also made relatively easier by using thinner material. In this regard, the first wall 122 will typically be formed from a steel plate having a thickness of between 4 and 30mm. In most cases the plate thickness will be between 5 and 10mm. The panel wall portions 136A forming the second wall 124 of the formwork module 100 will typically be formed from material having a thickness of between say 1 and 3mm. Most typically the panel will be formed from steel having a thickness around 1.6mm. In most embodiments of the present invention the panels forming the second wall 124 will be arranged such that their projecting structures are set at a spacing of between 150 and 1000mm and most preferably the spacing will be around 300mm. This range of dimensions is believed to give suitable structural properties to the composite wall formed by the formwork module and the concrete formed within it once the concrete is set.

An alternative panel and second wall construction is shown in Figures 8 through 14. In this embodiment the panels 336 are formed from a planar wall portion 336A and a separate projection 336C, which is not part of an integral projecting structure (such as 136B), but are individually spaced apart projections 336C. As seen in Figure 10, the panels 336 are formed from a flat sheet of steel 336A and individual discrete sheets 336C that are also flat. The flat sheet 336A has one longitudinal edge bent or roll formed to create upturned lip 335 extending along the length of the wall portion 336A (best seen in Figure 8). The individual projections 336C start as flat rectangular sheets typically of 1 to 3mm thickness and 150 to 300mm width (as shown in the lower illustration of Figure 10) and are bent or roll formed to create a profile (see Figure 9) that adds stiffness. The length is typically in the range of 200 to 1000mm to suit the width of the wall being constructed. The projections or shear connectors 336C illustrated in Figure 9 include a central ridge 337 and upturned edges 339. In the embodiment illustrated in Figure 8, the projections 336C include a flange section 338 that extends further than the edges 339 for welding (or otherwise affixing) the projection 336C to the upturned lip 335 of the flat sheet 336A. Figure 8 also illustrated a stepped portion 341 that creates an area for the opposite edge 351 of an adjacent panel 336 to overlap for affixing at weld points 353. It will be appreciated that any appropriate connecting means may be used.

The projections 336C are spaced along the edge 335 of the planar wall portion 136A such that they project perpendicularly and create cut outs 136D to allow for the flow of concrete between panels. The advantage of individual discrete shear connectors 336C over integral ones 136C is that they can be made from a different thickness steel to the flat sheet 336A. Additionally, spacing and length can be easily adapted to the design requirements. The shear connectors 336C are spaced apart dependent on the design factors of the building, but may typically be spaced in the range of 300 to 600mm centres.

Figure 11 shows the construction of a sidewall formwork module of a preferred embodiment. The reinforcing first wall 322 is laid flat. As you can see, this wall is made from a single thick steel plate, of say 6mm. The thickness of the steel chosen for the reinforcing first wall 322 is dependent on a number of factors, including the overall thickness of the sidewalls, the height between floors, the numbers and positions of opening in the sidewalls, the overall height of the building, the size and shape of the building, the size of the core relative to the size and shape of the building, the design loading requirements, the wind and earthquake category region, and the structural standards between countries. The greater the strength required by the reinforcing wall, in terms of shear and tensile strength, the greater the thickness of the first wall sheet steel. In comparison, the sheet steel of the second wall is typically around 1.6mm. In effect, this makes the second wall 324 a skin for containing the concrete. The actual bond between the concrete and the second wall 324 provides some minor shear strength, but it does not provide the reinforcing for transferring loads through to the footings.

Turning back to Figure 11, a first full length panel 336 is positioned at a first end of the first wall 322 and one or more projections 336C are welded to the first wall 332 on its inner surface. A shorter panel 336 is then positioned next to the first panel, above the doorway 310, with overlapping edges 351 of adjacent panels being welded together. Figure 12 illustrated subsequent panels 336 successively positioned and welded to the first wall 322 and each other to form the sidewall formwork module 304.As will be appreciated from the foregoing, variations in the structure of the panels used to form the second wall 124 of the embodiments described herein can be made, and examples of these variations are described in the aforementioned patent specifications which are incorporated herein by reference. Other variations may also be made to the preferred embodiment described above. For example, instead of a single layer of sheet material being used for the first wall 122 of each module as illustrated in Figure 3, a plurality of plates can be used to create the first wall 122. An example of this is illustrated in Figure 14, which shows another sidewall formwork module 504, where the first wall 522 is made from a series of seven panels. Adjacent sheets are welded to each other to form continuity of reinforcing. Figure 13 shows an alternative sidewall formwork module 404, where no openings are formed therein. Because preferred embodiments of the present invention only include reinforcing structure on one side of the formed composite panel, the building portion formed in this way, can potentially be more easily protected from fire than prior art composite panels. This is because only reinforcing on one side of panel needs to be protected from the effects of heat. Typically this can be done by lining the reinforcing wall of the composite panel with a fire rated material, such as fire rated plasterboard or the like. Figures 15 and 16 illustrate two externally reinforced sidewali formwork modules 600 that are being connected to two internally reinforced sidewali formwork modules 611. Hairpin bars 6 3 are added to the ends of the sidewali modules 600 to provide ties to the hairpin bars 615 that are part of the internal reinforcing of the sidewali modules 611. The hairpin bars 613 only extend into the voids 625 a short distance, connecting to a shear connector 636C. The effect of this connection is that the loads from the internal reinforcing 617 are transferred through the hairpins 615 to hairpins 613, through shear connectors 636C into the reinforcing first walls 622, or vice versa. As shown in Figure 16, when connected the internal and external corners are connected with folded angles 616. Vertical reinforcing and splice bars 619 can also be added to the upper openings of the voids 625 for tying to an upper module.

As will be appreciated from the foregoing, each sidewali of the modules described in Figures 1, 4, 5 and 6 can be considered to be formwork modules according to embodiments of the present invention in their own right, as can an entire assembled core structure as illustrated in Figure 1. Moreover, formwork modules formed using the construction techniques described herein can be created with curves by using curved panels as required.

The illustrative embodiments are described in the context of filling steel formwork modules with concrete. However, the settable material used to form the panel may be a material other than conventional concrete, which can be used to fill the formwork module in a flowable form which later set to form a solid structure. Each module can be manufactured offsite, either in panel form or as assembled self-supporting boxes, before being transported to site, installed and then filled with concrete.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

1. A pre-fabricated formwork module for a building portion; the module including: a first wall being configured to provide tensile reinforcement of the building portion in use; a second wall being coupled to the first wall and being arranged with respect to the first wall such as to define a volume therebetween for receiving concrete to be formed; said second wall being formed from a plurality of panels; each panel having a boundary portion and one or more projections, the panels being arranged such that the boundary portions together form at least part of the second wall of the formwork module and the projection(s) extend into the void for receiving concrete; wherein at least one projection of at least one panel is coupled to the first wall and in use is embedded in concrete formed in the module, such that when the concrete is set, the projection of the panel provides a shear connection between the concrete formed by the module and the first wall.

2. The module of claim 1, wherein the first wall has a thickness greater than the second wall.

3. The module of claim 1 or 2, wherein the one or more projections may be a plurality of individual spaced apart projections that are affixed to the boundary portion.

4. The module of claim 1 or 2, wherein the one or more projections are part of a projecting structure that is castellated and includes one or more projections separated by cut-outs that open outwardly from the boundary portion; and at least some of said projections are coupled to the first wall.

5. The module of any one of the preceding claims, wherein the walls and the projections of adjacent panels together define a plurality voids which are interconnected so in use, concrete can flow through the voids and the building portion can be formed from a continuous phase of concrete.

6. The module of any one of the preceding claims, wherein the first wall is a plate and has a first thickness and the second wall is formed from panels having a second thickness that is less than the first thickness.

7. The module of claim 6, wherein the thickness of the first wall is between 4 and 40mm.

8. The module of either of claims 6 or 7, wherein the panels have a thickness of between 1 and 3mm.

9. The module of claim 7, wherein the first wall has a thickness between 5 and 10mm.

10. The module of claim 8, wherein the panels have a thickness of around 1.6mm.

11. The module of any one of the preceding claims, wherein the thickness of the first wall is at least twice the thickness of the second wall.

12. The module of any one of the preceding claims wherein each projecting structure terminates in a hook formation by which it is connected to the first wall.

13. The module of any one of the preceding claims wherein the building portion comprises some or all of a building core.

14. The module of any one of the preceding claims wherein the building portion has a vertical open ended tubular configuration including at least one sidewall defined by the formwork module such that an outermost side of the sidewall is formed by the first wall of the formwork module.

15. The module of claim 14 wherein the building portion has an open ended rectilinear configuration having four external sidewalls.

16. A formwork module for forming a portion of a building, the module having a first wall and a second wall, the first and second walls being spaced apart from each other to define a volume for forming a settable material therein; the first and second walls being coupled to each other by one or more shear connectors; wherein the first and second walls are of different thicknesses to each other.

17. A module according to claim 16, wherein the first wall is a plate of steel having a thickness at least twice that of the second wall .

18. A module according to claim 16 or 17, wherein the shear connectors are integrally formed within one of the walls.

19. A module according to claim 16 or 17, wherein the shear connectors are separate components affixed to one of the walls.

20. A module according to claim 19, wherein the shear connectors extend from the second wall, being the thinner of the two walls.

21. A module according to claim 20, wherein the second wall is assembled from panels, wherein at least some of the panels have projections extending there from which in use function as shear connectors.