NZ592598B - Structural Improvements Relating To Building Panels - Google Patents

Abstract

Patent 592598 Disclosed is a structural building panel allowing lighter and stronger building panels. The panel is a stressed-skinned panel, serving as whole or part floor or roof or ceiling or wall panels of room spaces, in single or multi-storey buildings, and comprises a pair of skins, where each skin is a plurality of plywood sheets, and a core formed from an egg-crate structure of interlocking longitudinal and transverse web strips at an angle that is substantially 90° and an surrounding edge frame, where each web has notches at one half the depth of the web at their points of intersection, Partial or full infills of structured open or closed cell foam of a density of 16kg/m³ or more and a compressive strength greater than 85KPa is fitted within cells formed by the interlocking webs of the egg-crate structure. re each skin is a plurality of plywood sheets, and a core formed from an egg-crate structure of interlocking longitudinal and transverse web strips at an angle that is substantially 90° and an surrounding edge frame, where each web has notches at one half the depth of the web at their points of intersection, Partial or full infills of structured open or closed cell foam of a density of 16kg/m³ or more and a compressive strength greater than 85KPa is fitted within cells formed by the interlocking webs of the egg-crate structure.

Description

Recevied at IPONZ 23 August 2012 Post-dated under Section12(4) 23 August 2012 PATENT SPECIFICATION APPLICATION NUMBER 592598 LODGED COMPLETE SPECIFICATION URAL ENTITLED IMPROVEMENTS RELATING TO BUILDING PANELS APPLICANT KEITH ERIC HAY ACTUAL INVENTOR KEITH ERIC HAY Received 3 Aug 2012 The objective of the invention is to produce a range of stable, flat, structural building panels by using stressed skinned panels in combination with open or closed cell structured foam infills, where the risk of buckling of the stressed skinned panels’ skins and core webs is decreased, correspondingly increasing the panels tolerance to shear and other load forces.

The ion is for cost-effective componentry, primarily though not solely for use as whole or part floors or roof and ceiling panels of room spaces, as non-load or load-bearing walls, shear walls and el panels or as one or two-way spanning panels, each type of use having increased structural performance by post-tensioning individual or component combinations in both single and multi-storey timber buildings.

The panels are lightweight and economic in use, of mainly commonly available sustainable als, and low in energy use in their simplicity of manufacture using standard sized materials with minimum waste for m efficiency.

The panels can be constructed in a range of modular sizes allowing a wide range of layout urations.

These structural panels are ideally suited to where there is a propensity to standardised componentry such as in modular design of pre-fabricated single or storey timber buildings.

Received 3 Aug 2012 The panels’ components can be varied at specific points by thickening, increasing depths, ing density, tions or the use of different material reinforcements in order to take care of variable or concentrated loads at those points. rly where higher stiffness to g is required, it is achievable by the use of a variety of structured open or closed cell foam core cell infills and/or skin stiffening by increasing skin thickness or by the use of differing laminations such as metal sheet to plywood or cross- laminating.

The structural panel can act as a panel system to resist shear forces in the plane of the panel as in a braced wall and as shear walls of vertical elements of a horizontal force resisting system.

With the modular layouts within the panel cores and their overall dimensions, consistency of material choices and methods of assembly, future cost effectiveness and efficiencies could be achieved in volume tion by the use of robotics.

The invention comprises a pair of skins, an egg-crate core,edge members and s of structured open or closed cell foams in the cells formed by the egg-crate core. The skins are continuous and formed by a plurality of sheets bonded edge to edge. The core is a plurality of strips in at least two directions, usually at 90° to each other, cross-halved at their intersections to form an egg- crate Received 3 Aug 2012 structure. Edge members form a perimeter to core and skin edges.

The structured open or closed cell foam infills are l or full infills to the core cells.

Edges of core strips are adhesive bonded to each skin and to the inner face of edge members. Edge s are adhesive bonded to the skins and the structured open or closed cell foam infills may be unbonded or partially or fully bonded on contact faces to the core cells, skins and/or edge members.

If the structured open or closed cell foam is a l or full cell infill, not fixed to any contact face but friction fitted, it will partially restrain buckling of the core strip, increasing the stressed skinned panels resistance to shearforces. If the infill is a partial or full cell infill fixed to one skin only, it will reduce buckling of that skin and partially restrain ng of the core strips increasing panels resistance to shearforces and bending stress. If the infill is a full cell infill fixed to both skins, the panels capacity for resistance to shear and bending stress is increased as the s and the skins bonded to them become sandwich-structured composites within each of the core cells.

If the full cell infill is bonded on all six faces to the skins and the core strips then the panel becomes a stressed skinned sandwich structured composite.

Recevied at IPONZ 23 August 2012 The panels skins and the core web s can be comprised of plywood, veneer board, oriented strand board, hardboard, particle board, high or medium density fibre board, reinforced cementitious materials, carbon fibre, timber, metal sheets, plaster board laminates, glass, rced thermoplastics and thermoset polymers. However as with the core webs, plywood sheets remain the most efficient and cost-effective material for the skins at this time.

The core cell infills are of open or closed cell structured foams such as polyvinyl chloride, polyurethane, polyethylene, polystyrene or syntactic foams of a density of 16kg/m3 or more and a compressive strength greater than 85 KPA.

The panels uction is advantageous in that it allows large lightweight panel sizes to be assembled, the limitations being the press size and/or the method of transportation, and in being able to construct structural members of a building by a consistency of method.

It can be shown that core members are analysed as being the web of a simple beam, the flanges of which are the width of the skins to a point halfway n the core member and adjacent core members on either side.

Thinness of core s is limited both by the tendency to buckle due to the diagonal component of the shear force of the web and by the shear forces perpendicular to the plane of the web caused by stress in the structure which would cause the web to collapse sideways or shear at the junction of the web and flanges.

The tendency to buckle can be avoided if the ratio of the thickness of the web member to the diagonal ement of its height taken at 45° to the vertical is less than 50. It is therefore advantageous to be able to adjust the thickness of the web independently of any other element in the panel so that it is as close as possible to the ratio of 50 in order to achieve maximum y.

The shear forces dicular to the plane of the web have in other examples been taken care of by making the web thick at the flange junction by using solid rectangular timber webs. A thin web member can be stiffened against collapse by bracing it ersely with similar thin sections placed at right angles at frequent intervals by employing the well- known principle of interlocking egg-crate construction to brace the webs by a series of transverse webs placed at the same intervals as the primary webs. This stiffens webs in both directions before any adhesive set and permits the erse webs to absorb all of the secondary stress due to shear perpendicular to the primary webs and the primary shear stress. Hence such a stressed skinned panel can be viewed as acting according to the ‘plate’ theory where forces on the panel are considered to be acting in a multitude of directions.

Core members should be acting in at least two ions at a substantial angle to each other, such as 90 degrees, especially when the skins composing the flanges are plywood and are intrinsically capable of acting equal, or near equal strength in the two major directions of the panel plane. Therefore both sets of webs can be considered as stress ing members and the core can be analysed as a two-directional shear core. This is ed by the spacing of one set of webs to similar intervals as the other set and by ensuring that the two sets co-act at the ections. To co-act equally can only be achieved by forming a slot in one set of exactly half the web depth and a corresponding slot in the other set with both slot widths corresponding to the width of the intersecting web.

Maximum continuity is achieved when the intersection is glued together on assembly so that there is continuity of shear forces in any one web member through the erse web and the vertical component of the shear forces to shear the web member at the slot is overcome by erring the vertical shear stress via the glue line at the flange to the web of the transverse member.

Timber is known to have one of the highest strength to weight ratios, is commonly available, has low initial cost and is easily worked. ln laminated form such as plywood the strength-to—weight ratio is increased, more stable and more dependable in moisture content, dimensions and evenness of structural properties. Its advantage in stressed skinned panels is that each part of the elements is used to its m structural advantage with a minimum of urally redundant material.

The limiting shear stress in d is usually taken to be that determined by what is termed the ng shear’ which occurs when one part of the shear force acts in the plane of one veneer in the direction of its grain and the other opposing part of the shear force acts in the next corresponding veneer, causing the fibres of the intervening transverse veneer to separate from each other in a rolling manner. The allowable shear stress in such circumstances is y taken to be less than the allowable shear in solid timber sections of the same timber species.

However, when the shear forces acting in the plane of a plywood sheet can be said to be acting over the whole cross sectional area of the plywood, and not on individual veneers, the d is said to be acting in ‘panel’ shear for which the allowable stress is usually taken as being twice that of the allowable shear stress in solid timber of the same species and three times as great as the allowable rolling shear stress in the same plywood. The advantage is to use plywood in such a manner that it is subjected to panel shear and not limited by rolling shear.

Previous attempts to use the panel shear characteristic of plywood have been to use the plywood for the web members of beams by attaching the plywood members to the flange members of the beams by gluing the flange members to the sides of the plywood webs. This method of attachment causes rolling shear in the plywood web over the area of attachment, due to the horizontal component of the shear force in the web. In the current design, e the lateral stability of the web is assured by the ocking effect of the egg crate construction, it is le to glue the d webs to the flanges, or skins of panels, at their edges only, thus eliminating the possibility of rolling shear occurring in the webs.

Where the skin of the panel is made from plywood, rolling shear will occur in the plywood skin at the point of attachment to the webs, but this will not limit the shear stresses allowable in the whole construction as long as the flange width corresponding to each web is more than three times the thickness of the web member. This is because the allowable stress in the panel shear is three times greater than the allowable stress in rolling shear for the same plywood. Therefore web thicknesess for panels are to be considerably less than the flange width appropriate to each web.

The th of the design depends on the use of an adhesive at the junction of the web flange members which is as strong or stronger than the on of the wood fibres to each other. A further aspect of the design is that part of its particular th at the web flange junction is that plywood is always made of an unequal number of veneers. The two s on the outside are parallel in fibre, or grain direction and the next inner veneer or veneers have a fibre direction transverse to this. It follows that maximum adhesion of the plywood sheet is obtained when the edge being glued is parallel to the fibre direction or grain of the face veneers.

Therefore in the plywood webs the high bond strength of the web to the flange ary is in part obtained by maintaining the face grain of the plywood webs parallel to the length of the webs, and to the plane of the flanges. This ensures that no matter how many veneers are used to make up the plywood used in the webs, the greater number are glued with the sides of the fibres in contact with the flanges of the panel and that the shear stress is buted symmetrically over the width of the web.

Therefore the design web thicknesses of 9mm and upwards, while large enough to ensure good gluing area on the edges, are very thin compared with the cell size. Similarly the access holes for bolting of panels together, which have to be in the order of 100mm in diameter to enable a bolt, hand or tool to be inserted, are small relative to the cell size or the panel size and hence do not have a marked effect in weakening the construction. thening is re-established once connections are complete by gluing tapered caps into the edge d access holes using caps of the same ess and material as the panel skins. Given the area of cell size considered, extra strengthening can be inserted by using smaller cell-sized egg-crate into particular cells where local resistance to ng shear is required, or sely thickening of the skins by cross lamination at these points of additional stress. Similarly, where it is desired, web spacing or thickness of webs and angles of web intersections can be varied locally.

When comparing the use of d webs to those of sawn lumber for the construction, a simplification of analysis is that the glued contact area between the web and the skin is greater in the timber web than in the ply web, and hence the amount of ‘pull’ the timber web can exert on the inner skin veneer, causing it to roll on the other veneer, is greater than in the case of the plywood web where the contact area is very narrow. Therefore somewhat imately it can be said that the greater strength of the plywood web, plus the fact that it is narrow, compared to the flange widths, makes the construction in plywood webs much stronger than the construction in sawn lumber webs.

The question of how thin the webs can become is limited by the point at which the stress causes them to buckle. The limit is derived from the shear stress which acts both vertically and horizontally in the web and are the same in each direction resulting in a diagonal stress in the web plane at 45 degrees. If the rule is applied that a column or thin plane will buckle if the ratio of the thickness to the length is greater than 50, then for a 9mm thick web the limit is . 450mm, so the diagonal measurement of the web should not be greater than 450mm. That gives a web height of 300mm before buckling will occur under the diagonal compression induced by the two sets of opposing shear forces in the web. If ever required to exceed 300mm in depth the web can be thickened and a new limit applies or we can introduce a ite al into the cells so that each cell forms a sandwich, changing the construction into a stressed skinned/sandwich panel combination.

A problem is to what effect do the cross-ribs have on the construction and three points emerge. 3. Although not envisaged at this stage due to the difficulties of glue application and lay-ups, gluing of the intersection of the webs will greatly strengthen the construction. By doing this panel shear will p in the cross ribs as well which could be limited by rolling shear at the point of intersection and such gluing will overcome the weakness in the ribs caused by the slots. b. The cross webs take care of secondary stresses, minimising them, and allow the whole panel to be analysed as a ‘plate’ rather than in simple beam theory.

Received 3 Aug 2012 c. If the panel is analysed as a plate the stresses acting can be drastically reduced. Thus in the floor and ceiling panel analyses, if taken as a two-way slab, all stresses are halved.

When bending stresses are considered, if the plywood flange in compression has a length (L) of , width 400mm, thickness (t) of 9mm then L/t = 3600/9 = 400; the flange could buckle, but if the flange is supported at each 400mm by the cross web of the core, the unsupported flange length becomes 400mm and being continuous this reduces to (400)(9)/10 = 360 and L/t s 360/9 = 40, a factor which makes the flange safe against buckling.

When structured open or closed cell foams are layered, placed or foamed into the cell spaces formed by the webs, the structural analysis in conjunction with the plate theory regarding spans, tions, shear loadings and panel thickness to span ratios becomes a combination of stress-skinned panel and a ch structured composite.

The structured open or closed cell foams are of a density of 16kg/m3 or more and a compressive strength greater than 85KPA.

The foams can be either partial or full cell infill and where they are a l cell infill it is in the form of a thin layer or thickness, glue- fixed to one skin only with an adhesive of high bond strength.

Any bending moment shear in this skin being in compression or Received 3 Aug 2012 tension will be reduced by the increase in skin thickness and the web buckling is reduced where the l composite es a degree of lateral int to the webs.

Where the structured open or closed cell foams are a full cell infill glue-fixed to both skins with an adhesive of high bond strength it provides a high degree of lateral restraint to buckling of the webs and the thickness of the web member to the diagonal measurement of its height taken at 45° to vertical alters substantially the ratio of 50. This also applies where the cell infill is glue-fixed to all six faces of the cell.

Full cell infills of structured open or closed cell foams overcome the problem of web gluing at their intersections and provide high strengthening by spreading shear into the cross ribs and decreasing the effects of rolling shear . Where the structured open or closed cell foams of full cell inserts are bonded to each of the panel skins, each cell becomes a sandwich structured composite with a high shear stiffness to weight ratio for the composite and the linear ch theory becomes important to the design and analysis of each of these cell sandwich panels in combination with the stress-skinned panel as a whole. The composite has a high tensile strength to weight ratio and the higher the stiffness of the panel skins there will be a higher bending stiffness to weight ratio for the ite.

Higher stiffness in the skins can also be achieved by cross- lamination or thickening or the tion of other materials.

Received 3 Aug 2012 The behaviour of a panel with a sandwich cross-section under load differs from a panel with a constant elastic cross-section in that the radius of curvature during bending is small compared to the thickness of a sandwich composite and the strains in the component als are small. Deformation can be separated into two parts being bending deformation due to bending moments and shear deformation due to transverse .

The ch panel theories assume that the reference stress state is zero. In order to use this reference it es an absence of temperature differentials to ally the skin sheets during the pressing and curing of the panels, thereby ating induced cturing bending stress so that the reference stress state solutions when the problem is linear is provided by sandwich theory.

If manufacturing residual stress develops or is a design parameter such as camber, then the initial stress state has to be incorporated directly into the sandwich theory.

The introduction of structured open or closed cell foam infills to the panel cells affects the cross-ribs and the panels as follows:- a) Whether partial or full cell infill, they increase the strength of the construction at the web intersections by their allowing panel shear to develop in the cross ribs and rolling shear will be limited at the point of intersection caused by weakness in ed 3 Aug 2012 the ribs by the slots by the restraining action of the infills against all sides of the cells. b) The cross webs and the infills take care of secondary stresses, minimizing them and allow the whole panel to be analysed as a plate rather than in simple beam theory, with, in the case of partial infill, a strengthening of either top or bottom skins, or both, and similarly a strengthening of the skin joints. 0) When the panel is without infill and is analysed as a plate, the acting stresses can be drastically reduced thus halving all es when taken as a two-way slab. The stresses are further d with full cell infills which are analysed as plates using the linear sandwich theory in conjunction with a two way slab.

When bending stresses are considered, full cell infills will se the panel’ 3 limit for both tension and ssion bending stresses by forming a fully adhesive-bonded support backing of the flange across the panel’s entire section increasing the safety factor of the flange against buckling. Similarly when partial cell infills are fully adhesive-bonded to either the panel’s bottom or top or both flange skins, they will correspondingly, to those respective positions, increase the limit of tension or compression bending and decrease the ability of the flange to buckle.

These panels are able to be post-tensioned in either direction separately or in series using post-tensioned tendons. Plastic sleeves can be positioned in pre-selected lines within the panel before adhesive-bonding of the top skins, including stiffening of the anchor points. Tendons, using either high e cable or rod, are threaded through the sleeves and the panels are either factory or e post- ned by tendon stretching and clamping once the design loading is reached.

Post-tensioning produces compressive stress that es tensile stress that the panel would othenNise experience when imposed g loads are applied and allows the panel thickness to be decreased or increases it’s ability to span longer distances.

Post-tensioning can also be applied outside of the panel by g tendons against an underside skin face, strengthening the ribs along the tendon lines and reinforced anchor points at the perimeter beams, with the ability to adjust individual tendons and to de-stress them during repair or required installation adjustments.

One preferred form of the invention will now be described with reference to the accompanying drawings in which: Received 3 Aug 2012 Fig.1 is a plan of a typical structural building panel of a width r than 2400mm with the bottom skin partly removed and showing d pad reinforcement laminated to the outer face of the bottom skin at inset support points where a cantilever of the panel may be required.

Fig.2 is a plan of an alternative structural layout for a typical panel of width 2400mm or less, again with plywood pad reinforcement laminated to the outer face of the bottom skin where a cantilevered panel may be required.

Fig.3 is a sectional elevation of a typical panel on the line A-A as shown in Fig.1 and Fig.2.

Fig.4 is an exploded view of components of a structural building panel according to the invention shown in isometric projection.

Fig.5 is a part isometric view of a panel assembly according to the Fig.6 is a detailed cross-section of the edge of the panel of Fig.5 with low density insulation.

Fig.7 is an alternative cross-section of the edge of the panel of Figs. and 6 with part core infills of structured open or closed cell foams.

Fig.8 is an alternative section of the edge of the panel of Figs. , 6 and 7 with full core infills of structured open or closed cell foams.

Received 3 Aug 2012 Fig.9 is an alternative section of the edge of the panel of Figs. ,6,7 and 8 with either full or part core infills of structured open or closed cell foams.

Fig. 10 is a plan view of the intersection of unglued web joints and unglued edge faces of part or full infills of structured open or closed cell foams.

Fig. 11 is a plan view of the intersection of glued web joints and unglued edge faces of part or full infills of structured open or closed cell foams.

Fig.12 is a plan view of the intersection of glued web joints and glued edge faces of part or full s of structured open or closed cell foams.

Fig. 13 is a plan view of the intersection of unglued web joints and glued edge faces of part or full infills of structured open or closed cell foams.

Fig. 14 is an ed view of components shown in Fig.6.

Fig. 15 is an exploded view of components shown in Fig.7.

Fig. 16 is an exploded view of components shown in Fig.8.

Fig. 17 is an exploded view of components shown in Fig.7 with glued edge faces of part infills of structured open or closed cell foams.

Received 3 Aug 2012 Fig. 18 is an exploded view of components shown in Fig.9 with glued edge faces of full infills of structured open or closed cell foams.

Fig.19 is a detail of an assembled joint between panel edges.

Fig. 20 shows alternative construction of outer edge members.

Fig. 21 is a plan of assembled panels showing a typical location of jointing means.

Fig.22 shows assembled components for connecting wall panels or other constructions to the panels’ outer edge Fig.23 shows led ents for ting wall panels or other constructions to the panels’ outer edges at a panel to panel butt joint Figs. 24, 25, 26 and 27 show means ofjointing facing skin and web materials.

Fig. 28 shows the location of material joints in relation to web g.

Fig.29 is an isometric view of a method of panel assembly A reference key to the assembly componentry of the invention’s accompanying drawings is: 1. Panel 2. Panel upper skin 3. Panel lower skin 4 . Upper longitudinal skin joint Received 3 Aug 2012 SPF???“ Lower longitudinal skin joint Upper and lower transverse skin joint Intersecting core web members Part core infills of structured open or closed cell foams. 9. Full core infills of structured open or closed cell foams.

. Edge s 11.lnset t point of plywood reinforcement pads laminated to the outer face of the lower skin 12.Alternative internal panel t point of plywood reinforcement pads laminated to the internal face of the lower skin 13. Panel core transverse webs 14. Panel core longitudinal webs . Inner edge member 16.0uter edge member 17.Web notches 18.Assembled web joints 19.Tapered circular access hole .Tapered circular cap 21 .Glue joint 22. Rebate in outer edge member 23. Panel to panel tubularjoining member 24. Part or full core infills of low density insulation Received 3 Aug 2012 . d contact face of web 26. Unglued contact face of structured open or closed cell foams 27. Glued contact faces of webs 28.Transverse hole through tubularjointer 29.Jointing bolt . Rebated slot in full infill composite at panel to panel bolting point 31 .Wall panel edge member with rebate for glued plywood tongue 32.Continuous plywood tongue 33. ed washer head wood screw 34.Wall edge member .Jointing feather 36. Panel skin 37. Scarfed joint 38.Structural fingerjoint Referring to the drawings a preferred form of panel is constructed as follows: In Fig 1 the panel 1 has a typical size of 3600 x 7200mm with core web s at 400mm each way. The lower skin 3 has longitudinal joints 5 and transverse joints 6 and the upper skin 2 has Received 3 Aug 2012 corresponding joints 4. The core has intersecting web members 7 and in this described example they are 9mm plywood. The panel is provided with edge members 10. Where floor panels are evered, support points for the panel are provided by laminating plywood pads to the outer face of the lower skin. Between the intersecting web s part or full infill of low density insulation or part infill of structured open or closed cell foams, or full infill of structured open or closed cell foams, are on fitted with partial infill 8 glue bonded to one skin and full infill 9 glue bonded to both top and bottom skins. Inset support points may be additionally reinforced with plywood pads laminated to the internal face of the lower skin between the intersecting webs and edge members surrounding these load points.

In Fig 2 is an alternative preferred form of the invention of a panel with a typical panel size of 2400 x 7200mm using 2400 X 1200 mm sheets to form the top skins 2 and ponding bottom skins 3 with longitudinal joints 4 and no transverse joints. In all other respects the descriptions for Fig 1 apply. Where floor panels are cantilevered, support points for the panel are provided by laminating plywood pads to the outer face of the lower skin and as shown in Fig.3 Received 3 Aug 2012 In Fig 4 the exploded isometric projection shows ents of a panel, the upper skin being 2, transverse core webs 13, longitudinal core webs 14, inner edge member 15, outer edge member 16, the lower skin 3. Notches 17 are cut to half depth at the same intervals in each set of web s and infill 8 or 9 or 24 between the intersecting webs.

In Fig 5 the components in Fig 4 are assembled to form the egg crate core of web members with the range of infill 8, 9 or 24 friction fitted between the core and edge members, with each set of web members at right angles and the infill in ponding squares, although other angles may be used.

In Fig 6 a detailed cross-section of the panel edge is shown with the tapered insert access disc 20 removed from the upper skin 2, at points of panel to panel joining and the inserted disc is placed in the access hole 19 with its glue joint 21. The outer edge member 16 has a rebated edge 22 for panel to panel joining into which is placed a circular locating connector tube 23, and the infill 24 is part or full low density insulation. All glue lines within the assembly are shown as heavy lines referenced 21.

Received 3 Aug 2012 In Fig 7 it is a similar cross section to Fig 6 but with a part infill of structured open or closed cell foam 8 friction fitted between the intersecting webs and glue bonded 21 to the lower skin 3.

In Fig 8 it is a similar cross section to Fig 6 but with a full infill of a structured open or closed cell foam 9 friction fitted between the intersecting web and glue bonded 21 to both the upper skin 2 and the lower skin 3.

In Fig 9 it is a similar cross section to Fig 6 but with the part infill 8 delineated by the dotted line or the full infill 9 of a structured open or closed cell foam glue bonded 21 to not only the skins but on all four edges to the faces referenced 27 of the intersecting webs 7 and the face of the inner edge member 15.

In Fig 10 the contact faces of the intersecting webs are unglued 25 as are the edge faces 26 of all the core infill types in t with the webs.

In Fig 11 the contact faces of the intersecting webs are glued 21 shown as heavy lines along the glue line, while the edge faces 26 of all the core infill types in contact with the webs are not.

Received 3 Aug 2012 In Fig 12 both the contact faces of the intersecting webs are glued 21 and the edge faces of all the core infill types in t with the webs are glued 27.

In Fig 13 the contact faces of the intersecting webs are unglued 25 while all the edge faces of all the core infill types in contact with the webs are glued 27.

In Fig 14 ed components of the Fig 6 assembly are shown with edges which are surfaces always glued 21 and surfaces 27 which remain unglued but glued in the preferred form of the invention.

In Fig 15 are exploded components of Fig 7 assembly with glue line 21 to the surface of the face of the infill in contact with the skin.

In Fig 16 are ed components of Fig 8 assembly with glue lines 21 to both surfaces of the infill in contact with the upper and lower skins.

In Fig 17 are exploded components of Fig 9 for part infill with glue lines 27 to the surfaces of the infill in contact with the side faces of the web in a preferred form of the invention. ed at IPONZ 23 August 2012 In Fig 18 are exploded components of Fig 9 for full infill with glue lines 27 to the surfaces of the infill in contact with the side faces of the web in a preferred form of the invention.

In Fig 19 the joint between two assembled panels is shown in detail.

A circular hole 19 is cut into the skins for access to the jointing bolt 29 which passes h a transverse hole 28 in the tubularjointing member, a formed rebated slot 30 in the infill 9 is formed at the jointing access. Once jointing is ted the insert disc 20 is glued into place.

In Fig 20 alternative outer edge s are shown.

In Fig 203 the outer edge member 16 is timber, finger-jointed timber, laminated veneer lumber, oriented strand board, laminated strand lumber, or parallel strand lumber and profiled for the tubular panel to panel jointer.

Fig 20b. The edge member is of plywood Iaminations in a preferred form of the invention and profiled for the tubular panel to panel jointer.

Fig 200 The outer edge member is not profiled as it is for an outer panel face where there is no panel to panel jointing and is of the same al options as in 20a.

Fig 20d The panel orientation is that of 200 and the member is of laminated plywood in a preferred form of the invention.

Received 3 Aug 2012 In Fig 21 is a panel to panel plan showing a typical location ofjointing tubes 23 of short s although full lengths can be inserted into the profiled outer edge members 20a or 20b reference Fig.20 and the positions of the bolting access holes 19.

In Fig 22 there is shown means of connecting wall panels or framed walls to the panels by means of a continuous plywood tongue 32, the length of the walls glue bonded into a rebate in the bottom and top plates 31 of the walls and the tongue is then screw fixed into the panels outer edge member 16.

In Fig 23 there is shown means of connecting internal wall panels or frame walls at a panel to panel jointing by means of recessed case hardened washer head wood screws 33 into the top or bottom wall plates 34.

In Figs 24 to 27 there is shown means and methods ofjoining sheet facing materials in the skins 2 and 3 of the panels and the webs of the core.

In Figs 24 and 25 the skin 36 is ed with a v-shaped slot into which a feather 35 of plywood or other suitable material is assembled with a glue line 21 as shown. If the skin is of plywood of three veneers the feather is of three veneers to obtain m contact Received 3 Aug 2012 area between the parallel . In the preferred form of the invention this ng is for the long edges of the plywood sheets with the face s grain running parallel to the joint. The groove in the skin edges and the slopes of the feather is a double taper of 1 in 8 with the feather slightly undersized to allow for the glue. Where thicker skins are required a series of grooves and rs is possible.

In Fig 26 a scarfed joint 37 is used to join the ends of the plywood skin sheets and webs 36, the scarfed joint being 1 in 10 for up to 12mm thick d and 1 in 8 for thicker sheets.

In Fig 27 an alternative jointing for the webs only is to use a structural fingerjoint 38.

In Fig 28 there is shown the preferable position of the edge joints carried between transverse webs to decrease the risk of joint breaking over a web.

In Fig 29 a preferred method of assembly of the invention is where the upper and lower skins 2 and 3, depending on the panels configurations, are jointed, glued and pressed separately. The same applies to the edge members 10 and the core webs, again assembled and glued as a separate unit. Full infills have the option of inclusion at this stage or installation as with part infills at the final gluing and pressing together of all three components and the panel constructed as bed will maintain a very flat surface when erected in a horizontal or vertical plane even when fully loaded.

Received at IPONZ 13 September 2012

Claims (4)

What I Claim Is:
1. A structural building panel being a stressed-skinned panel, in combination with structured open or closed cell foams, of a density of 16kg/m3 or more and a compressive strength greater than 85KPA, serving as whole or part floor or roof or g or wall panels of room spaces, in single or multi-storey buildings, the stressed-skinned panel comprising a pair of skins, each skin is a plurality of plywood sheets, an egg-crate structure is formed by ocking web strips and an edge frame, a core between the skins is an egg-crate ure of longitudinal and transverse webs interlocking at an angle that is substantially 90°, with each web having notches at one half the depth of the web at their points of intersection, with partial or full infills of structured open or closed cell foam fitted within cells formed by the interlocking webs of the egg-crate structure.
2. A ural building panel as claimed in Claim 1 in which the l or full infills of structured open or closed cell foams are friction-fitted within the cells formed by the interlocking webs of the egg-crate structure. Recevied at IPONZ 23 August 2012
3. 3. A ural building panel as claimed in Claim 1 in which the partial or full infills of structured open or closed cell foams are friction- fitted within the cells formed by the interlocking webs of the egg-crate structure and adhesive bonded to either the upper or lower skin of the panel.
4. 4. A structural building panel as claimed in claim 1 in which full s of structured open or closed cell foams are friction-fitted within the cells formed by the interlocking webs of the egg-crate structure and adhesive bonded to both the upper and lower skins of the panel forming a sandwich-structured composite within the cells formed by the interlocking webs of the egg-crate ure. A structural building panel as claimed in claim 1 in which full infills of structured open or closed cell foams are foamed into place with a bonding or adhesive agent or are fitted and ve-bonded to all the faces of the cells formed by the interlocking webs of the egg- crate structure and adhesive bonded to both the upper and lower skins of the panel and each of the filled cells becomes an individual sandwich structured composite panel within the stress-skinned panel. Recevied at IPONZ 23 August 2012 A structural building panel substantially as herein described with reference to and as shown in the anying drawings. Dated this 23rd ...... day of ...August....2012 Applicant: Keith Eric Hay fig.3 sechon A'-A 1of11