TECHNICAL FIELD

This disclosure generally relates to structural insulated panels and in particular to an improved method of connecting such panels.

BACKGROUND ART

Multi-storey residential blocks are constructed using a variety of building methods, including steel-frame, reinforced concrete and the structural insulated panel (SIP) building system. Multi-storey buildings are increasingly constructed using engineered timber build systems, often incorporating a variation of the structural insulated panel.

A SIP is a type of sandwich panel, comprising a core insulant between two structural skins. The skins may be typically oriented strand board (OSB). Alternatively the skins of the SIP may be comprised of any other suitable material such as engineered timber in the form of cross laminated timber (CLT) or laminated veneer lumber (LVL).The core insulation can be solid, granulated or foamed and is used as a thermal and/or acoustic isolator. SIPs are fabricated in a factory environment and are customised with apertures for a specific structure. The panels are then transported on-site and assembled together to form a tight, energy-efficient structural and thermal envelope. This panelised building system may be used for structures that are up to five storeys high. Typically oriented strand board (OSB) with a sheet thickness of between 18mm and 22mm may be used for such buildings (although in some applications they can be used for higher buildings, depending on regulations in a given jurisdiction). For medium rise or larger structures, for example those approximately 6 to 12 storeys high,, other materials may be used for the skins of the SIPs. For example, engineered timber in the form of cross laminated timber (CLT) or laminated veneer lumber (LVL) with a sheet thickness ranging from 20mm to 60mm may be used. Globally, a growing demand for inner-city accommodation has led to a requirement for a panelised building system that can be used in mid-rise structures ie up to 12 storeys high. A major limiting factor of the SIP building system is the weakness of the inter-SIP connection compared with the strength of the panel itself. A strong and durable inter- SIP connection is critical for mid-rise structures and it is especially critical in locations subject to seismic activity. To match the increasing structural demands on SIP-built structures, inter-SIP connections are being continually improved.

A major limiting factor of a building system that incorporates the structural insulated panel (SIP) component, applicable to both the low-rise, mid-rise and larger use cases, is the weakness of the inter-panel connection compared with the strength of the panel itself. A strong and durable inter-panel connection is critical for structural integrity and is especially critical in locations subject to seismic activity. To match the increasing demands for cost-effective structural design of buildings using structural insulated panels, the inter-panel connections are being continually improved. US Patent No. 2014250827 discloses a method of connecting in-plane SIPs using connecting splines. US patent No. 20060185305A1 discloses an improved joint structure for adjoining in plane SIPs using a grooved joint. Recent improvements include the use of self tapping screws as connectors, both in-plane and out-of-plane. However, such improvements do not eliminate timber failure in the connection area and there is a need for an inter panel connection that is largely independent of localised timber strength.

It is an objective of the technology disclosed to provide a high-strength reinforced SIP and a high-strength inter-panel connection system that overcomes the problems described above.

The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded as subject matter by which the scope of the disclosed embodiments is to be bound.

SUMMARY OF INVENTION

Aspects of the invention are set out in the independent claims. Optional features are set out in the dependent claims.

The technology disclosed herein is a reinforced SIP and a high-strength inter-panel connection system. Conventional fastener technology, underpinning the use of splines or nails or screws, relies on local frictional or mechanical resistance of fasteners and timber to resist axial, bending and shear forces. The technology disclosed herein provides a connection system that spreads the forces experienced by the inter-panel connections across the entire length, width and depth of the panel. This spreading of forces is achieved by adding an embedded lattice framework to the casing of the SIP. The framework can be fabricated from a set of light and strong materials, including fibre reinforced polymer (FRP). A high-strength inter- panel connection is then created by linking a series of straps between adjacent SIPs. The straps link directly between connectors that are attached to the lattice frameworks.

The dispersion of the inter-panel connection forces into the SIP casing causes additional stresses to be applied to the SIP casing. To resist these forces in the low- rise structures, internal bracing is added between the facesheets. To resist these forces in the mid-rise structures, the framework incorporates full-depth solid or hollow tubes.

According to a first aspect there is provided a lattice framework for structural insulated panels (SIPs), wherein the SIPs each comprise a first facesheet and a second facesheet, the lattice framework comprising (a) a plurality of surface struts configured to be external to the external surface of each facesheet, (b) a plurality of internal struts connected to the surface struts, (c) at least one connecting element for connecting the lattice framework with an adjacent lattice framework. The connecting element may be known as a connector. The connecting element may be formed for example by a connecting node. Such a node may be joined by a further element to a secondary node of a separate lattice framework. Alternatively a connection element may be formed by an element that directly connects the lattice framework to a further lattice framework. In this case the connection element may form a strap, or a mating element, or a further such element. Alternatively, the connection element may simply comprise a location on the surface struts that is configured to be attached to a location on the surface struts of another lattice framework. For example, the surface struts may be welded together. The first aspect may be advantageous as it enables the strength of the connections between the lattice frameworks to increase, and so makes buildings formed of structural insulated panels incorporating such lattice frameworks more safe. This also increases the ability to build larger buildings from such structural insulated panels incorporating such frameworks. Optionally, the connecting element is configured to be connected to a second structural insulated panel by a strap, for example the strap comprising fibre reinforced polymer, optionally wherein the connecting element comprises the strap.

Optionally, the lattice framework is configured to be connected to cladding, wherein said connection is between the surface struts of the lattice framework and the cladding.

Optionally, the lattice framework is configured to be connected to internal fixtures, wherein said connection is between the surface struts of the lattice framework and the internal fixtures, for example wherein the internal fixtures include sanitary ware.

Optionally, the lattice framework is configured to be connected with a second lattice framework so that they are connected in-plane with each other.

Optionally, the lattice framework is configured to be connected with a second lattice framework so that they are connected out-of-plane with each other.

Optionally, said lattice framework comprises a material selected from the group consisting of fibre reinforced polymer, metal, metal composite. According to a second aspect there is disclosed a method for connecting together a first lattice framework and a second lattice framework, wherein both the first and second lattice frameworks are in accordance with the first aspect described above, wherein the method comprises connecting the surface struts of the first lattice framework with the surface struts of the second lattice framework, wherein the connection is provided by the connection element of at least one of the first or second lattice frameworks. This may be by connecting the lattice frameworks together directly by an element that forms part of at least one of the lattice frameworks. Alternatively the lattice frameworks may be connected together via a third apparatus element. The connection may be based on friction, or bonding, or any other type of connection. The second aspect gives a simple method for securely connecting two lattice frameworks together. This enables quick repeatable use of the structural insulated panels incorporating the lattice framework in the building industry.

Optionally, the connection element is a strap, for example where the strap is a fibre reinforced polymer.

Optionally, the connection element is either a male or female element, or alternatively comprises a ring or loop of material, preferably where that material is one of a metal, an alloy, particularly stainless steel, fibre reinforced polymer or a bio-material.

Optionally, the connection of the connection element is provided by at least one of: ultrasonic welding, laser welding, male/female connection, or nut/bolt.

Optionally, the first lattice framework and the second lattice framework are connected out-of-plane, for example in a T-junction or right-angled corner junction.

Optionally, the first lattice framework and the second lattice framework are connected in-plane. Optionally, further comprising connecting the surface struts of the first lattice framework to cladding.

Optionally, further comprising connecting the surface struts of the first lattice framework to internal fixtures, for example sanitary ware.

According to a third aspect there is described a structural insulated panel, comprising a first facesheet and a second facesheet, characterised by and further comprising a lattice framework according to the first aspect. Optionally, further comprising a sustainably-sourced insulant core sandwiched between the first facesheet and the second facesheet. Sustainably sourced means that the insulant material is formed of a renewable material that can be grown, or can be created from organic matter. Optionally, further comprising top and bottom plates, and a pair of edge sheets. Optionally, further comprising a plurality of internal bracing elements, preferably wherein said internal bracing elements are of a type selected from the group consisting of hollow tubes, solid tubes, bars of varying hollow or solid cross-sections.

Optionally, said facesheets are of a material selected from the group consisting of Fibre Reinforced Polymer, Oriented Strand Board, Magnesium Oxide board, metal, Laminated Veneer Lumber, and Cross Laminated Timber, and/or wherein said facesheets are fibre reinforced polymer isogrid structures.

According to a third aspect there is disclosed a method of manufacturing a structural insulated panel, comprising the steps of:

embedding a first plurality of surface struts into an external surface of a first facesheet, and embedding a second plurality of surface struts into an external surface of a second facesheet;

connecting the first plurality of surface struts with the second plurality of struts by providing a plurality of internal struts between the first facesheet and the second facesheet;

providing at least one connection element for connection with the surface struts of an adjacent panel.

Similarly, another aspect is disclosed of a method of manufacturing a structural insulated panel comprising the steps of:

attaching a first plurality of surface struts into an external surface of a first facesheet, and attaching a second plurality of surface struts into an external surface of a second facesheet;

connecting the first plurality of surface struts with the second plurality of struts by providing a plurality of internal struts between the first facesheet and the second facesheet;

providing at least one connection element for connection with the surface struts of an adjacent panel.

Optionally, comprising the steps of:

(a) Dimensioning the facesheets and cutting out as required; (b) Inserting one or more side sheets and top and bottom plates between the facesheets;

(c) Positioning the connectors;

(d) Adding the lattice framework as set out in claim 21 , and incorporating aforesaid connectors;

(e) optionally, adding insulation (this may alternatively be done on site after manufacture)

(f) Connecting to an adjacent structural insulated panel.

Optionally, wherein adding the lattice framework includes fitting plugs to one or more bracing elements and inserting one or more bracing elements.

Optionally, wherein connecting adjacent structural insulated panels includes attaching straps, or connecting elements, to connectors on the adjoining structural insulated panels. Optionally, comprising the steps of:

(a) Fitting plugs to one or more bracing elements;

(b) Dimensioning the facesheets and cutting out as required;

(c) Inserting one or more bracing elements, side sheets and top and bottom plates between the facesheets;

(d) Positioning the connectors;

(e) Adding the lattice framework as set out in claim 21 , and incorporating aforesaid connectors;

(f) Connecting to an adjacent structural insulated panel.

Optionally, wherein connecting adjacent structural insulated panels includes attaching straps to connectors on the adjoining structural insulated panels.

According to a fifth aspect there is disclosed a method of connecting two or more reinforced structural insulated panels, comprising: (i) adding an exoskeleton to each said panel (ii) creating a connection between said exoskeletons. The advantages of this method, and of the second aspect are similar as both increase the efficiency of building using structural insulated panels based on the connection of structural insulated panels together. According to a sixth aspect there is disclosed a multi-storey building comprising a plurality of structural insulated panels according to the third aspect.

According to a further disclosed embodiment, the reinforced SIP comprises a pair of facesheets, top and bottom plates, a pair of edge sheets, internal bracing and a lattice framework. The lattice framework comprises: (i) a plurality of surface struts embedded into the external surface of each facesheet (ii) a plurality of internal struts connecting the surface struts, and (iii) a plurality of connectors. According to another disclosed embodiment, the reinforced SIP is identical to that described in the first disclosed embodiment, plus it is connected by a plurality of straps to an adjoining in-plane reinforced SIP.

According to another disclosed embodiment, the reinforced SIP is identical to that described in the first disclosed embodiment, plus it is connected by a plurality of straps to an adjoining in-plane reinforced SIP, plus the facesheets 24, 26 are triangular and incorporate an FRP isogrid structure.

According to another disclosed embodiment, the reinforced SIP is identical to that described in the first disclosed embodiment, plus the facesheets 24, 26 incorporate an aperture.

According to another disclosed embodiment, the reinforced SIP is identical to that described in the first disclosed embodiment, plus a plurality of straps provide a high- strength inter-SIP connection with an identical adjoining out-of-plane reinforced SIP.

According to another disclosed embodiment, the reinforced SIP is identical to that described in the first disclosed embodiment, plus a plurality of straps provide high- strength inter-SIP connections with adjoining in-plane and out-of-plane reinforced SIPs.

According to an additional disclosed embodiment, a method is provided of fabricating a reinforced SIP and connecting to an adjacent reinforced SIP. The method may include the preparation of a SIP casing, adding reinforcement and connecting to an adjacent reinforced SIP. The preparation of a SIP casing may include cutting the facesheets to size, creating apertures in the facesheets and adding edge plates. Adding reinforcement may include adding lattice framework, adding internal bracing and attaching connectors to the lattice. Connecting to an adjacent reinforced SIP may include the use of straps to link connectors.

Further embodiments of the reinforced SIP are possible. Other features, benefits and advantages of the disclosed embodiments will become apparent from the following description of embodiments, when viewed in accordance with the attached drawings and appended claims.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS Fig. 1 is a perspective view of a reinforced SIP.

Fig. 2 is a cutaway view of Fig. 1. revealing bracing tubes and a truss of the lattice framework.

Fig. 3 is an exploded view of the reinforced SIP, revealing the main components as the casing, the lattice framework and the bracing.

Fig. 3a is an exploded view of the reinforced SIP, revealing the main components as the casing and the lattice framework.

Fig. 4 is a perspective view of two adjoining reinforced SIPs, plus the insulant column and splines.

Fig. 5 is a detail top view of Fig.4, showing how the insulant column and splines join the reinforced SIPs.

Fig. 6 is a detail perspective view of Fig.4, showing the connectors visible on each side of the panel joint.

Fig. 7 is a detail X-Ray view of Fig.6, showing the straps linking the two reinforced SIPs

Fig. 8 is a perspective view of a reinforced SIP, configured as a triangular shape and connected to a similar-shaped reinforced SIP.

Fig. 9 is a perspective view of a reinforced SIP, configured with an aperture.

Fig. 10 is a perspective view of two adjoining reinforced SIPs, configured in a t- junction, identifying the section that is seen in Fig 11. Fig. 11 is a section detail for panels that are fabricated with relatively thin facesheets and internal bracing, showing two crossed straps that connect an abutting reinforced SIP to another reinforced SIP.

Fig. 11 a is a section detail for panels that are fabricated with relatively thick facesheets without internal bracing, showing two crossed straps that connect an abutting reinforced SIP to another reinforced SIP.

Fig. 11 b is a magnified element of Fig 11 a, showing the bonding of internal and surface struts at the node position plus a connecting element.

Fig. 12 is a perspective view of two adjoining reinforced SIPs, configured in a right- angled corner.

Fig. 13 is a perspective view of four adjoining reinforced SIPs.

Fig. 14 is a perspective detail view of the floor slab shown in Fig.13, detailing the channels cut in the external surface of the upward-facing facesheet

Fig. 15 is a perspective detail view of the floor slab shown in Fig. 14, detailing the channels cut in the external surface of the downward-facing facesheet

Fig. 16 is a cross-sectional illustration of the seating detail for a bracing tube within the casing.

Fig. 17 is a cross-sectional illustration showing tapes threaded through the facesheets and through connectors.

Fig 17a is a cross-sectional illustration showing internal struts inserted into the facesheets.

Fig. 18A is the first part of a flow diagram illustrating a method for fabricating a reinforced SIP and connecting to an adjacent reinforced SIP.

Fig. 18B is the second part of a flow diagram, continuing from Fig. 18A.

Fig. 18C is an alternative first part of a flow diagram illustrating a method for fabricating a reinforced SIP and connecting to an adjacent reinforced SIP.

Fig. 18D is an alternative second part of a flow diagram, continuing from Fig. 18C.

Fig. 19 is a flow diagram illustrating a design and construction method.

Fig. 19a is an alternative flow diagram illustrating a design and construction method,. Fig. 20 is a block diagram of a building constructed with reinforced SIPs.

DETAILED DESCRIPTION OF THE FIGURES

Embodiments of the claims will now be described. In particular these set out the features of the lattice framework, the structural insulated panel, a method of connecting lattice frameworks and two variants of a method of manufacturing the structural insulated panel. A building may be formed by attaching the panels together.

The first variant of the method of manufacture described is typical of build systems that incorporate structural insulated panels fabricated from OSB facesheets. This method, features internal bracing added to the casing, will be referred to as the low-rise use case. In some locations structural insulated panels fabricated from OSB may be more suitable to low-rise uses. However, in other locations OSB may be used for higher level structures, for example in jurisdictions where regulations allow this use. Where the figure described depicts structural insulated panels with a relatively thin facesheet, approximately 10% of the overall thickness of the panel, it may illustrate the low-rise use case.

The second variant of the method of manufacture described is suitable for build systems that incorporate structural insulated panels fabricated from mass timber. This method will be referred to as the mid-rise use case. Such panels may be used for lower level buildings, although it may not be economical to do so. Where the figure described depicts structural insulated panels with a relatively thick facesheet, approximately 30% of the overall thickness of the panel, it may illustrate the mid-rise use case.

The low-rise variant is described in detail. The mid-rise variant is only described where it differs from the low-rise variant. The reinforced SIP has internal bracing added to the casing. The high-strength inter panel connection system is achieved by creating links directly between adjoining embedded lattice frameworks.

The lattice framework and internal bracing may be fabricated from a range of materials that includes fibre reinforced polymer (FRP), metals etc. FRP composites are proven materials in the construction industry. High-performance FRP composites made with synthetic fibres such as carbon or glass embedded in polymeric matrices provide the advantages of high stiffness and strength-to-weight ratio. Such material advantages may be harnessed by their use in the reinforced SIP as disclosed herein. The reinforcement of a building structure can be achieved using an exoskeletal framework, whereby the primary structural members are external to the main body of the building and the secondary internal structural members connect with the walls, floors and roof. The exoskeletal framework is very efficient at dissipating applied loads across the structure. The Figures described below described examples of exoskeleton based embodiments. Other embodiments may incorporate the use of exoskeleton frameworks or lattice frameworks without internal struts, but these are not described below.

The improved reinforcement of the SIP as disclosed herein is achieved through the addition of an exoskeletal framework. Instead of relying on the local frictional or mechanical resistance of fasteners such as nails or screws to resist axial, bending and shear forces, the addition of a high-strength exoskeletal framework to a SIP absorbs such localised forces and dissipates them across the structure. The exoskeleton may be connected to a second exoskeleton in the same manner as the lattice framework set out above. Moreover, the exoskeleton may further incorporate an inter-panel seam into the overall structure of the SIP, thus minimising any imbalance between the strength of the seam and the strength of the facesheets/core combination. The seam may be formed through applying and curing epoxy to connectors and/or any straps in use.

Referring to Figs. 1 to 3, a first disclosed embodiment of the reinforced SIP 20 is generally indicated by the numeral 20 and broadly comprises a casing 34, internal bracing 35 and a lattice framework 36.

Referring to Fig. 3a, an alternative first disclosed embodiment of the reinforced SIP 20 is generally indicated by the numeral 20 and broadly comprises a casing 34 and a lattice framework 36.

The embodiment of the reinforced SIP 20 shown in Fig.1 does not include apertures and is not configured for connection to adjacent reinforced SIPs 20. Flowever, as will be discussed below, in further embodiments, the reinforced SIP 20 may be configured to include at least one aperture and may be configured for connections to in-plane and out-of-plane reinforced SIPs 20.

The casing 34 is fabricated from a pair of facesheets 24, 26, top and bottom plates 31 ,32 and a pair of side sheets 33. The casing 34 provides a cavity which may be filled with a thermal or acoustic insulant (not shown). The cavity in the casing 34 may also be used to carry mechanical, electrical and plumbing systems (not shown). The prime objective of the insulant is to reduce noise or heat transfer across the facesheets 24, 26.

The facesheets 24, 26 may be of material that includes FRP, OSB, MgO board, metal, Laminated Veneer Lumber, and Cross Laminated Timber (CLT). Each facesheet 24, 26 has four edges 21 , comprising a top edge, a bottom edge and two side edges. The 3-dimensional lattice framework 36 comprises: a plurality of surface struts 41 embedded into the external surface of each facesheet; a plurality of internal struts 42 connecting the surface struts 41 ; a plurality of connectors 50.

A major role of the internal bracing 35 is to provide resistance to compression and shear forces. The internal bracing 35 may be in the format of solid or hollow tubes 37 that are placed between the facesheets 24, 26. The tubes 37 may have a circular cross-section or any other type of symmetrical cross-section. The tubes 37 may be angled at between 0 degrees and 45 degrees from the perpendicular to the plane of the facesheets 24, 26. Where the tubes are angled from the perpendicular, they may be grouped in sets of at least 4 tubes 37. This may advantageously be used in low-rise situations.

Referring to Fig. 3a, an alternative first disclosed embodiment of the reinforced SIP 20 is generally indicated by the numeral 20 and broadly comprises a casing 34 and a lattice framework 36. This features the relatively thick facesheets 24,26 and the absence of internal bracing 35. This embodiment may be advantageously used in mid rise, and in some instances high-rise use, cases. It shows internal struts 42 that may be fabricated from a material and profile that is sufficient to provide resistance to said compression and shear forces, thus removing the need for the internal bracing 35. The internal struts 42 may be in the format of solid or hollow tubes and they may penetrate the facesheets 24, 26. The internal struts 42 may be fabricated from a range of materials that includes fibre reinforced polymer (FRP), metals etc. and they may have a circular cross-section or any other type of symmetrical cross-section. The internal struts 42 may be angled at between 0 degrees and 45 degrees from the perpendicular to the plane of the facesheets 24, 26. The internal struts 42 may be positioned so that each end of each internal strut 42 is bonded to the end of at least one other internal strut 42 or to a surface strut 41. The surface struts 41 may be regularly spaced across the external surfaces 28, 29 of the facesheets 24, 26 where an external surface 28, 29 may be defined as that surface of the facesheet 24, 26 which is not within the cavity of the casing 34. A node 40 is a location where an internal strut 42 may connect with at least one surface strut 41 or with at least one other internal strut 42.

An internal strut 42 may exist between a pair of nodes 40, where each node 40 is on different facesheets 24, 26. The internal struts 42 may be inclined between 0 and 45 degrees from an axis perpendicular to the plane of the facesheets 24, 26. The internal struts 42 and the surface struts 41 may be combined to form a plurality of trusses 39 whereby a first series of parallel trusses 39 may be embedded in the reinforced SIP 20 in one direction. A second series of parallel trusses 39 may be embedded in the reinforced SIP 20 at an angle to the first series. A third series of parallel trusses 39 may be embedded in the reinforced SIP 20 at an angle to the first series and at a different angle to the second series.

According to another disclosed embodiment which is illustrated in Figs. 4 to 7, the reinforced SIP 20 is identical to that described in the first disclosed embodiment, plus it is connected by a plurality of straps to an adjoining in-plane reinforced SIP 20. Two reinforced SIPs 20 may be positioned adjacent to each other where they are designated as wall panels and are positioned to form a larger wall. Typically, a permanent joint is created at the two edges 21 where the reinforced SIPs 20 meet, using the combined insulant column 30 and surface splines 68 as illustrated in Figs. 4 and 5, or using another type of joint. No claim is made in respect of the surface spline 68 or the insulant column 30. The inter-panel connection is created by linking two connectors 50.A connector 50 may be a ring that is attached to a node 40. A series of connectors 50 may be placed on each side of a joint line of two adjoining reinforced SIPs 20, on both sides of the panels.

Straps 52 are used on-site to link a series of connectors 50 on one reinforced SIP 20 to a series of connectors 50 on an adjacent reinforced SIP 20. The strap 52 may be a loop of FRP tape that threads through the connector 50 of one reinforced SIP 20, travels through a pre-drilled hole 46 to the other side of the reinforced SIP 20 and then threads through a connector 50 of the adjoining reinforced SIP 20, as shown in Figs. 6 and 7. The loop of FRP tape is created by jointing a length of FRP tape using a technique that is selected from a technique set that includes ultra-sonic welding, laser welding and other types of welding. Alternatively, a strap 52 may comprise a steel or metal alloy bolt that connects the two connectors 50 and is secured by adding a threaded nut. Alternatively, a strap 52 may be another type of linking device.

For illustrative purposes only, the disclosed embodiment as illustrated in Fig. 4 is described in reference to forming a reinforced SIP 20 for use as part of a wall in a building. Flowever, while a wall with a flat plane is shown, the disclosed embodiment is equally applicable to a reinforced SIP 20 having curvature along one dimension.

Furthermore, while a wall is shown, the disclosed embodiment is equally applicable to floors and roofs. Furthermore, while a wall of rectangular dimensions is shown, the disclosed embodiment is equally applicable to a reinforced SIP 20 that has three or more sides.

According to another disclosed embodiment which is illustrated in Fig. 8, the reinforced SIP 20 is identical to that described in the first disclosed embodiment, plus it is connected by a plurality of straps to an adjoining in-plane reinforced SIP, plus the facesheets 24, 26 are triangular and incorporate an FRP isogrid structure. The isogrid structure may comprise upstanding FRP ribs that are arranged as a series of substantially equilateral triangles. The lattice framework 36 may be optimised by considering the stresses experienced by the facesheets 24, 26 when an aperture 60 is introduced into the reinforced SIP 20 or when the facesheets 24, 26 are subject to asymmetric loading. The effect of an aperture 60 within the reinforced SIP 20 may be observed in the disclosed embodiment which is illustrated in Fig. 9. In this embodiment, the reinforced SIP 20 is identical to that described in the first disclosed embodiment, plus the facesheets 24, 26 incorporate an aperture 60. The trusses 39 and the tubes 37 are specified and positioned to provide the optimal level of structural support around the aperture 60.

Specifying the trusses 39 and tubes 37 includes selecting material composition, tube diameters and tube inclinations to achieve the optimal performance of the reinforced SIP. This performance can be enhanced by increasing the density of trusses 39 and tubes 37 around the aperture 60. By placing a sufficient density of trusses 39 and tubes 37 around each aperture 60, the perimeter of the aperture 60 may be transformed from an area of weakness to an area of structural strength. This permits any required timber framing of the aperture 60 to be minimised. The result is a more efficient structural design and greater design freedom to position and size the apertures 60.

Examples of asymmetric loading on the reinforced SIP 20 are observed in further disclosed embodiments, illustrated in Figs. 10 to 12, wherein the reinforced SIPs 20 are identical to that described in the first disclosed embodiment. In such disclosed embodiments, the lattice framework 36 includes connectors 50 that are placed to allow jointing with an adjacent out-of-plane reinforced SIP 20. Out-of-plane configurations may include a t-junction and a right-angled corner junction.

A t-junction configuration may be observed in the disclosed embodiment which is illustrated in Figs. 10 to 11 b.

Referring to Figs 10 and 11 , a facesheet 26 of a reinforced SIP 20 is abutted by another reinforced SIP 20. Straps 52 are used to connect pairs of connectors 50 across the joint between the abutting reinforced SIPs 20. The existence of the internal bracing 35 and the relatively thin facesheets 24, 26 is indicative of a manufacturing method conducive to the low-rise use case.

An alternative t-junction configuration may be observed in Figs 11 a and 11 b, where a facesheet 26 of a reinforced SIP 20 is abutted by another reinforced SIP 20. Straps 52 are used to connect pairs of connectors 50 across the joint between the abutting reinforced SIPs 20. The absence of the internal bracing 35 combined with the existence of the relatively thick facesheets 24,26 is indicative of a manufacturing method conducive to the mid-rise use case.

Fig 11 b details how the lattice framework 36 components are bonded at the node 40 and linked via a connector 50 to a connecting element 52. At the external surface of the facesheet 24,26, a node bonding agent 54 envelopes the external surfaces of the two internal struts 42, the surface strut 41 and the connector 50 at the confluence of these components. Outside the confluent area of the node 40, the surface strut 41 is positioned within a channel 66. The node bonding agent 54 may be selected from any of a set of materials, including structural adhesives such as but not limited to methyl methacrylate or toughened epoxy and including a polymer reinforced by short or long fibres. In this embodiment, the connecting element 52 is shown as a bolt and nut that engages with an aperture in the connector 50.

A right-angled corner junction configuration may be observed in the disclosed embodiment which is illustrated in Fig. 12. In this embodiment, one reinforced SIP 20 overlaps the two edges 21 of another reinforced SIP 20 to form a right-angled corner. Straps 52 are used to connect pairs of connectors 50 across the corner joint.

The reinforced SIP 20 may be connected simultaneously to a plurality of adjacent reinforced SIPs 20, both in-plane and out-of-plane, as observed in the disclosed embodiment which is illustrated in Fig. 13. In this embodiment, the reinforced SIP 20 incorporates an aperture 60, connects with an adjacent in-plane reinforced SIP 20 and also connects with two adjacent out-of-plane reinforced SIPs 20. Straps 52 are used to connect pairs of connectors 50 across each joint. Where a plurality of reinforced SIPs 20 are jointed, the resulting network of connected lattice frameworks 36 provides an overall structural strength that is greater than the sum of its parts. In all disclosed embodiments describing the jointing of reinforced SIPs 20, the raised stress levels in the vicinity of a junction between two reinforced SIPs 20 may be relieved by adjusting the specification or by increasing the density of trusses 39 and tubes 37 in the stress-loaded areas of each reinforced SIP 20.

The reinforced SIP 20 may be connected to other reinforced SIPs 20 in various other configurations in other embodiments not detailed herein. The following information is applicable to all disclosed embodiments.

In order to enhance the adhesion of the lattice framework 36 to the external surface 28 of the reinforced SIP 20, channels 66 may be cut into the external surface 28 as illustrated in Fig. 14. In order to enhance the adhesion of the lattice framework 36 to the external surface 29 of the reinforced SIP 20, channels 67 may be cut into the external surface 29, as illustrated in Fig. 15. The pattern of channels 66,67 cut into the external surface 28,29 may vary according to the design of the lattice framework 36. The channels 66, 67 may have a depth of between about 0.05mm and about 10mm. For example, the depth may be about 0.05mm to about 1 mm, or about 0.05mm to about 2mm, or about 0.1 mm to about 2mm, or about 0.3mm to about 2mm, or about 1 mm to about 10mm. The channels 66, 67 may have a width of between about 0.05mm and about 20mm. For example, the width may be about 0.05mm to about 1 mm, or about 0.05mm to about 2mm, or about 0.1 mm to about 2mm, or about 0.3mm to about 20mm, or about 1 mm to about 20mm.

The surface struts 41 may be bonded into the channels 66, 67 by the addition of a bonding agent that includes epoxy resin. By surface-embedding the surface struts 41 into the channels 66, 67, the reinforced SIP 20 increases its capacity to resist axial loads, bending moments and shear forces.

The ability to assign the density and orientation of trusses and internal bracing according to the forces acting on the reinforced SIP 20 results in a very efficient structural design. This optimisation of the structural design minimises the requirement for timber blocking or bracing at junctions and apertures 60. One advantage is the reduction of cold bridging, which is the unwanted transfer of heat across the facesheets 24, 26. Another advantage of reduced timber blocking and bracing is that the strength-to-weight ratio is improved, permitting longer spans or greater live loads to be applied to the timber-reduced structure.

The lattice framework 36 of the reinforced SIP 20 may be designed so that its surface struts 41 largely align with the surface struts 41 of lattice frameworks 36 of adjoining reinforced SIPs 20. The result is the formation of a largely coherent lattice framework 36 across a connected assembly of reinforced SIPs 20. The alignment of surface struts 41 in this way promotes an efficient transfer of stresses across the adjoining reinforced SIPs 20. With the lattice frameworks 36 of adjoining reinforced SIPs 20 thus aligned, it is a simple process to then adjust the length and width dimensions of any reinforced SIPs 20 so that the channels 66, 67 are ideally positioned and do not coincide with the edges 21 of the reinforced SIPs 20.

The lattice framework may be used to provide secure connections for external cladding panels and internal fixtures. The connector 50 may be used to attach battens to the reinforced SIP; the battens then allow easy fixing of external cladding panels. The connector 50 may also be used to directly attach internal panels and internal fixtures such as sanitaryware.

The off-site manufacture of the reinforced SIP 20 starts with the assembly of the casing 34 and the internal bracing 35. This is followed by the addition of the lattice framework 36, incorporating the attachment of connectors 50.

The components of the SIP casing 34 are a pair of facesheets 24,26, top and bottom plates 31 ,32 and a pair of side sheets 33. The top and bottom plates 31 ,32 are typically timber beams fitted within the facesheets 24,26, flush with the top and bottom edges 21. The side sheets 33 are non-structural elements, fitted within the facesheets 24,26, flush with the side edges 21. Their primary function is to help form the cavity that holds the insulation material (not shown). The internal bracing 35 requires preparation before installation into the casing 34. Referring to Fig 16, seating plugs 38 are fitted to both ends of the tubes 37 to reduce eccentric loading of the tube ends. A plug 38 may have a central protruding spring 43 - loaded lug 45 that will be located into a seating recess 44 on a facesheet 24,26. The pair of facesheets 24,26 are positioned with the seating recesses 44 facing each other and the tubes 37 are clicked into position in the seating recesses 44.

Top and bottom plates 31 ,32 are added, plus the two side sheets 33. With the casing 34 assembled, the lattice framework 36 can be embedded. This involves the addition of surface struts 41 , internal struts 42 and connectors 50.

Fabrication of the surface struts 41 and internal struts 42 may involve the use of FRP thermoplastic tape. Surface struts 41 of the truss 39 may be created by spooling a first tape 70 into channels 66 that runs across the external surface 28 of the upper facesheet 24 and into channels 67 that runs across the external surface 29 of the lower facesheet 26. The lower channels 67 may be aligned with the upper channels 66. Both surface struts 41 and internal struts 42 may be created by threading a second tape 72 from one side of the reinforced SIP 20 to the other side and back again, repeatedly, as shown in Fig.17. The second tape 70 may be threaded at an optimal angle to the plane of the facesheets 24,26 in order to create the desired truss 39 design.

The threading of the tapes 70,72 to create the trusses 39 may be performed using equipment (not shown) that includes, without limitation, an automated toolhead operated by a programmed computer. Where a connector 50 is to be secured at a node 40, the connector 50 is pre-positioned at the node 40 so that it is ready to be threaded by the tape 70,72. The truss is completed by bonding tapes 70,72 at their intersections. The bonding can be achieved in a number of ways, including ultra-sonic welding and laser welding. The process may continue until the installation of all series of trusses 39 is complete for the entire reinforced SIP 20.

With the reinforced SIP 20 positioned in the horizontal plane, epoxy resin may then be added to the channels 66 of the upper facesheet 24 to bond the tapes 70,72 into the channels 66. After partial curing of the epoxy, the reinforced SIP 20 may be turned through 180 degrees so that the previously lower facesheet 26 is now uppermost. Epoxy resin may now be added to the channels 67 of the new upper facesheet 26 to bond the tapes 70,72 into the channels 67. Bonding between the tapes 70,72 and the facesheets 24, 26 contributes to the structural strength of the reinforced SIP 20.

The placement of the tapes 70, 72 in the channels 66, 67 has the following benefits: the bonding surface is maximised between the tapes 70, 72 and the facesheets 24, 26; the tapes 70, 72 are less susceptible to impact damage during subsequent transport and installation of the fabricated reinforced SIPs 20, and; the external surfaces 28, 29 of the facesheets 24, 26 are kept clear for any subsequent construction processes.

The off-site manufacturing method described above may be particularly useful for the low-rise use case which incorporates internal bracing 35 and seating plugs 38 to deliver the required bracing action. An alternative off-site manufacturing variant described below is relevant for the mid-rise use case which omits the internal bracing 35 and the seating plugs 38 and instead uses hollow or solid tubes extending from one external surface 28 to the other external surface 29as part of the lattice framework to provide the aforesaid bracing action, as shown in Fig.17a. The method starts with the assembly of the casing 34 and the internal struts 42.

The components of the SIP casing 34 are a pair of facesheets 24,26, top and bottom plates 31 ,32 and a pair of side sheets 33. The top and bottom plates 31 , 32 may be timber beams fitted within the facesheets 24,26, flush with the top and bottom edges 21. The side sheets 33 are non-structural elements, fitted within the facesheets 24,26, flush with the side edges 21. Their primary function is to help form the cavity that holds the insulation material (not shown).

The casing 34 is assembled by attaching the facesheets 24,26 to the top and bottom plates 31 ,32, plus the two side sheets 33. The internal struts 42 are threaded through the drilled holes 46 in the casing 34.

Fabrication of the surface struts 41 may involve the use of FRP thermoplastic rods, having a profile that may be consistently square or round or that may be fully or partly twisted or that may have an irregular profile for the purpose of achieving a greater bond with an applied bonding agent. The rods may have an overall diameter of between about 2mm to about 10mm. For example, the overall diameter may be about 2mm to about 4mm, or about 4mm to about 6mm, or about 2mm to about 8mm, or about 8mm to about 10mm. Surface struts 41 may be positioned into channels 66 that run across the external surface 28 of the upper facesheet 24 and into channels 67 that runs across the external surface 29 of the lower facesheet 26. The lower channels 67 may be aligned with the upper channels 66.

Where a connector 50 is to be secured at a node 40, the connector 50 is pre- positioned at the node 40. The truss 39 is completed by bonding the internal struts 42 and the surface struts 41 and the connectors 50 at their intersections. The bonding can be achieved in a number of ways, including (1 ) ultra-sonic or laser welding, (2) injection moulding of structural adhesive or fibre reinforced polymer after creating a moulding space around the intersected struts 41 ,42 and connector and (3)

overmoulding the intersected struts 41 ,42 and connector. The process may continue until the installation of all series of trusses 39 is complete for the entire reinforced SIP 20.

In both the Figure 17, and Figure 17a embodiments insulation material (not shown) may be added to the reinforced SIP via a fill-hole in a side sheet 33 when the reinforced SIP 20 is complete. Alternatively, it may be added on-site.

The reinforced SIP 20 is transported to site and installed in the usual way. The fabrication of the inter-panel joint is now described. The joint is created by linking a series of connectors 50 on the reinforced SIP 20 with a similar series of connectors 50 on an adjoining reinforced SIP 20. One or more straps 52 can be used to create the link between a pair of opposing connectors 50. This linkage occurs through a pre drilled hole 46 through both SIP casings 34.

The strap 52 may be created from any of a set of materials, including FRP tape and steel bolts. Where FRP tape is used, a loop is created between the pair of connectors 50. The loop is created at one of the connectors by welding the ends of the tape together. Where a bolt is used, it is threaded through one connector 50, pushed through a pre-drilled hole 46 to the other connector 50 where a securing nut is tightened.

Other types of strap 52 and connectors 50 may also be used to create the inter-panel joint. An alternative strap 52 may be one that is integral with a connector 50. The linking of strap 52 to connector 50 may include a method of bonding to or snapping onto or clipping into or screwing into each other, without limitation as to the method of attachment. The straps 52 and connectors 50 suggested above are just a few examples of the different methods of creating the inter-panel joint and other variations will occur to those of skill in the art.

The jointing of the reinforced SIPs 20 by a direct linkage between the embedded lattice frameworks 36 has the effect of eliminating connection failure arising from the traditional fastener/timber interaction. The technology described herein, specifically the method of linking the lattice frameworks 36, results in a structure-wide reinforcement net that provides an improved strength and durability to the building structure. This feature is not attainable by the traditional fasteners.

A connector 50 may be a ring fabricated from a set of materials that includes steel, aluminium, stainless steel, composites and metal alloys. A connector may also be fabricated by an additive manufacturing process using a set of materials that includes polymers, ceramics and metals. A connector 50 may have an overall ring diameter of between about 10mm to about 100mm. For example, the overall ring diameter may be about 10mm to about 20mm, or about 10mm to about 30mm, or about 20mm to about 50mm, or about 40mm to about 100mm. A connector 50 may have an annular diameter of between about 2mm to about 10mm. For example, the annular diameter may be about 2mm to about 4mm, or about 2mm to about 5mm, or about 3mm to about 5mm, or about 5mm to about 10mm. There can be several different versions of the connector 50, dependent on what will be linked to it. One version of the connector 50 is used to link adjacent reinforced SIPs 20 and it may be shaped to maximise bonding efficacy at the node 40 in addition to providing a suitable aperture for the connecting element 52. A different version of the connector 50 may be used to attach wall battens (not shown), upon which external cladding panels or internal fire-resistant panels or internal cupboards or shelving (not shown), are secured. Another version of the connector 50 may be used to attach directly to external cladding panels (not shown). Yet another version of the connector 50 may be used to attach directly to internal panels or sanitaryware (not shown).

A benefit of adding an externally-embedded lattice to the reinforced SIP 20 is that it helps to limit buckling of the casing 34 under eccentric axial loading. According to the technology disclosed, the facesheets 24, 26, are confined by the surface struts 41 , which are themselves held in place by the internal struts 42.

Referring now to Fig.18A, a method of fabricating a reinforced SIP 20 and connecting to an adjacent reinforced SIP 20 conducive with the construction of a low-rise multi storey building begins at step 100 by procuring the facesheets. At step 102, the facesheets 24, 26 are cut to size and apertures 60 are created as required. At step 104, the facesheets 24, 26 are processed further, with holes 46 drilled, channels 66,67 routed into the external surface of the facesheets 24, 26 and seating recesses 44 routed into the internal surfaces 28,29 of the facesheets 24, 26.

The facesheets 24, 26 are cut and drilled using joinery equipment (not shown) that includes, without limitation, an automated toolhead operated by a programmed computer. The joinery equipment may cut channels 66, 67, in a pattern dictated by the design of the lattice framework 36, into the external surfaces 28, 29 of the facesheets 24, 26. The channels 66, 67 may be sized to accommodate the surface struts 41 , the strap 52 and the connectors 50. The joinery equipment may drill a plurality of holes 46, at the desired angle from vertical, through the facesheets 24, 26 at the nodes 40.

At step 106, the facesheets 24, 26 are positioned opposite each other at the required distance apart. Separately, at step 108, FRP elements and plugs are procured. At step 110, the plugs are inserted into both ends of the tubes. One of the pairs of plugs 38 is spring 43 - loaded to assist positioning in the casing 34. At step 114, tubes 37 are installed between the facesheets 24, 26 by locating the lugs 45 of the spring 43 -loaded plugs 38 into the seating recesses 44. Separately, at step 116, the side sheets 33 and the top and bottom plates 31 ,32 are procured. At step 118, the side sheets 33 and the top and bottom plates 31 ,32 are added.

Referring now to Fig. 18B, continuing the method shown in Fig. 18A, step 120 is where the connectors 50 are procured. At step 124, the connectors 50 are positioned at lattice nodes 40, as required. At step 126, first tape 70 is placed in the channels 66, 67 on the external surfaces 28,29 of the facesheets 24, 26 and through any pre- positioned connectors 50. At step 128, second tape 72 is threaded through both the facesheets 24, 26 and through any pre-positioned connectors 50.

At Step 130, the tape intersections are welded. At Step 132, surface struts 41 may be bonded into channels 66,67 with epoxy. The reinforced SIP 20 may be positioned in the horizontal plane and epoxy resin then added to the channels 66 in the uppermost facesheet 24. The epoxy may then be part-cured. The reinforced SIP 20 may then be rotated through 180 degrees so that the previous downward-facing facesheet 26 is now uppermost. Epoxy resin may then be added to the channels 67 in facesheet 26 and part-cured.

Separately, at Step 134, battens may be procured. At step 136, battens are added.

At step 138, the reinforced SIP 20 is transported to site and positioned. An insulant column may be inserted at a side joint and another reinforced SIP 20 may be positioned in-plane onto the insulant column. Screws are added through the splines 68 to keep the reinforced SIPs 20 in position while straps 52 are linked to the connectors 50.

Referring now to Fig.18C, an alternative method of fabricating a reinforced SIP 20 and connecting to an adjacent reinforced SIP 20, conducive with the construction of a mid rise multi-storey building, begins at step 100 by procuring the facesheets. At step 102, the facesheets 24, 26 are cut to size and apertures are created as required. At step 104, the facesheets are processed further, with holes 46 drilled and channels 66,67 routed into the external surface of the facesheets 24, 26. The facesheets 24, 26 are cut and drilled using joinery equipment (not shown) that includes, without limitation, an automated toolhead operated by a programmed computer. The joinery equipment may cut channels 66, 67, in a pattern dictated by the design of the lattice framework 36, into the external surfaces 28, 29 of the facesheets 24, 26. The channels 66, 67 may be sized to accommodate the surface struts 41 and the connectors 50. The joinery equipment may drill a plurality of holes 46, at the desired angle from vertical, through the facesheets 24, 26 at the nodes 40.

Separately, at step 106, the side sheets 33 and the top and bottom plates 31 ,32 are procured. At step 108, the side sheets 33 and the top and bottom plates 31 ,32 are added to the facesheets 24,26 to complete the casing 34. At step 114, the internal struts 42 are inserted into the facesheets 24, 26. Separately, at step 120, the connectors 50 are procured. At step 124, the connectors 50 are positioned at lattice nodes 40, as required.

Referring now to Fig. 18D, continuing the method shown in Fig. 18C, step 126 is where the surface struts 41 are placed in the channels 66, 67 on the external surfaces 28,29 of the facesheets 24, 26.

At Step 128, the intersecting struts 41 , 42 and connectors 50 are bonded. Where the bonding method is injection moulding of a structural adhesive, polymer, or fibre reinforced polymer, this is achieved by placing a temporary surface plate (not shown) over the node 40 space and injecting the adhesive through the surface plate. At Step 132, the surface struts 41 may be bonded into channels 66,67 with epoxy. The reinforced SIP 20 may be positioned in the horizontal plane and epoxy resin then added to the channels 66 in the uppermost facesheet 24. The epoxy may then be part- cured. The reinforced SIP 20 may then be rotated through 180 degrees so that the previous downward-facing facesheet 26 is now uppermost. Epoxy resin may then be added to the channels 67 in facesheet 26 and part-cured.

At step 138, the reinforced SIP 20 is transported to site and positioned. An insulant column may be inserted at a side joint and another reinforced SIP 20 may be positioned in-plane onto the insulant column. At step 140, straps 52 are linked to the connectors 50.

INDUSTRIAL APPLICABILITY Embodiments of the disclosure may find use in a variety of new buildings constructed by participants in the construction industry, specifically in the context of a building design and construction method 220 as shown in Fig. 19 and a building 136 as shown in Fig. 20. Construction applications of the disclosed embodiments may include, for example, without limitation, reinforced SIPs 20 for use in wall systems, floor systems and roof systems or a combination of such systems, to name a few.

During design of the building 136, exemplary method 220 conducive with the low-rise use case may include a consideration of the stresses (222) acting at the junctions of an adjoining reinforced SIP and at each aperture, positioning of trusses (224) to accommodate the local forces, dimensioning of facesheets (226) and the assignment of connectors to nodes (228). During off-site fabrication, tubes are inserted between facesheets (230) and then struts and connectors are added (232). Following Transport and Installation on site (234), Linking of reinforced SIPs (236) takes place. An alternative building design and construction variant 320 conducive with the mid-rise use case may be used, as shown in Fig. 19a. During design of the building 136, exemplary method 320 may include a consideration of the stresses (322) acting at the junctions of an adjoining reinforced SIP and at each aperture, design of trusses (324) to accommodate the local forces, dimensioning of facesheets (326) and the

assignment of connectors to nodes (328). During off-site fabrication, struts and connectors are added to facesheets (330) and then struts and connectors are bonded (332). Following transport and Installation on site (334), linking of reinforced SIPs (336) takes place. The preferred methods 220, 320 of the disclosed embodiment are well suited for fabricating reinforced SIPs 20 that form part of a building system for residential, commercial, civic and other type of buildings. The construction method described and material selection used in the fabrication of the reinforced SIP 20 renders the reinforced SIP 20 suitable to be utilised in multi-level building construction, particularly in locations subject to seismic activity.

As shown in Fig. 20, the building 136 produced by exemplary methods 220, 320 may include a plurality of structures 138, systems 148 and fixtures 150. Examples of high- level structures 138 include one or more of a reinforced SIP 140, substructure 144 and other structures 146. Any number of other structures 138 may be included. Although a construction example is shown, the principles of the disclosed embodiment may be applied to other industries, such as the refrigeration industry.

Although the embodiments of this enclosure have been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art.