AU2021200695B2

AU2021200695B2 - Composite Timber Components

Info

Publication number: AU2021200695B2
Application number: AU2021200695A
Authority: AU
Inventors: Darren Robert Hercus; David Jarratt
Original assignee: Australian Eng Solutions Pty Ltd
Current assignee: Australian Engineered Solutions Pty Ltd
Priority date: 2011-06-03
Filing date: 2021-02-03
Publication date: 2023-01-19
Anticipated expiration: 2032-05-23
Also published as: AU2017204527A1; AU2021201635A1; AU2022202595A1; AU2012203009A1; AU2021201635B2; AU2015218559A1; AU2019200815A1; AU2021200695A1; AU2017201396A1; AU2019203601A1

Abstract

A timber I-beam has a top plate and a bottom plate forming the flanges of I-beam and a series of side by side timber boards each separated from the next by a gap, together forming a uniplanar, intermittent web. The cables and pipes for the building run transversely through the gaps. A method of making the beam is described. Curved beams are also described. A bracing component built like the I-beam is insertable transversely between adjacent pairs of I-beams in order to stabilise an entire floor. Fig. 1 1/8 20 22 16 4 r 6 10 8 12 FIGURE I 14 22 22 242 26 4 28 FIGURE 2

Description

1/8

20

22 16

4 r

6 10 8 12

FIGURE I

14 22

22

242

26 4 28 FIGURE 2

TITLE OF INVENTION

Composite Timber Components

TECHNICAL FIELD

[0001] This invention concerns beams for building construction and particularly timber beams for house construction.

BACKGROUND

[0002a] It is known to build floor joists from top and bottom chords with an open web made of a pair of zigzag steel strips nailed to the sides of the timber chords. The chords may be spliced to each other with halving joists.

[0002b] Such a joist is described in US 2006/0156677 (the equivalent of AU2004245582 by Benton in respect of braced timber trusses). Benton describes the prior art at the time as including parallel chorded trusses that are used as long span floor joists among other applications. These generally comprise wooden horizontal members separated and connected by cross-bracing multi toothed nail plate connector members.

The advantage of such trusses is that they provide good access between the cross members for facilities such as plumbing, electrical services and air conditioning ducts and the like. A disadvantage, however, is in the quality of the wood required, as for long spans it may be necessary to use hard woods which are quite costly when compared with soft woods and laminates which are used in other truss type members. Therefore, it would be an advantage over the prior art to be able to utilise offcuts, and other otherwise discarded timber from building sites in the manufacture of load-bearing beams.

Benton describes the alternative as using laminated plywoods as the wooden horizontal members and there is a clear functional and commercial advantage in using timber offcuts available from building sites and manufacturing installations, rather than the less structurally sound plywood or fibreboard.

Benton describes prior trusses as involving the formation of grooves in the horizontal members on their inner faces to accept a longitudinal sheet of cheap fibreboard or the like, which passes between them to provide the intermediate web of the truss assembly. The use of such a truss prohibits the possibility of cabling or any other services being able to pass through the truss as it is not possible to pierce the longitudinal sheet without adversely affecting the structural integrity of the truss.

In Benton, the lateral chord members have cross bracing means in which the penetrable separating member is a particle board elongate sheet which is in sleeved engagement with each chord member. The substantially continuous sheet member is required to be sufficiently strong and easy to cut, but Benton further requires cross bracing material in the form of multi toothed nail plate connectors that are nailed at each end to each chord member.

US 5664393 A (VEILLEUX et al.) describes a structural woodenjoist comprising upper and lower chords joined by an openwork web structure made of spaced horizontally spaced trapezoidal laminated panels defining a series of triangular spacings therebetween. As shown in Fig. 4, each panel has opposite short and long sides 16c,d that are joined to the chords by finger scarfing in accordance with known timber joint methods.

CA 1130078 A (PETERS DIERK D) describes a beam truss structure comprising upper and lower chords, each of which has grooves 19 to receive a web made of sheet material, the latter being scalloped in accordance with traditional timber joining practice.

US 2002/0157329 Al (BERDAN, II) shows a construction beam having a sound-proofing resilient web 106 in the form of a unitary piece of material, not a plurality of web members, extending between chords 102,104, and optionally cut to adjustably orient the chords relative to each other. As shown in Fig. 2, web 106 has edge portions 106a that are embedded into the chords, necessitating the formation of grooves in the respective inner faces of the chords. By its very flexible nature, Berdan does not describe a load bearing beam of the type proposed in this invention.

US 2008/0250747 Al (JOHNSON et al.) discloses a truss comprising upper and lower chords joined by a plurality of web members. The webs include bulbous rabbets 16 to receive correspondingly bulbous tenons 17 in a self-locking connection.

EP 0939177 B1 (KAUFMANN HOLZ) shows a pair of opposed chords or flanges 8 interposed by a web 9 shown to be interconnecting in Fig. 4 in customary tongue and groove manner.

JP 2002371674 A (TOBISHIMA CONSTRUCT CO LTD) shows an arched steel frame truss for a roofing panel and JP 3709080 B2 (NIPPON STEEL CORP) shows another steel beam structure.

An object of the present invention is to ameliorate the disadvantages of the prior art in which timber truss beams comprised of opposed spaced chords interposed with timber webbing require that the components be joined by traditional tongue and groove or other mechanical interlocking methods

SUMMARY OF INVENTION

Technical Problem

[0003] The joists leave no pathway for ducts, pipes and cables to cross the building through the joists.

[0004] The apparatus aspect of the invention provides a timber I-beam comprising a top plate and a bottom plate forming the flanges of the I-beam and a series of side by side timber boards, each separated from the next by a gap, together forming a uniplanar intermittent web.

[0005] The top and bottom plates maybe made of timber of a width larger than the thickness of the boards forming the web. The term plates is used in the framing sense in that they are the horizontals which act as a contact surface for other components and connect the upright parts of the beam.

[0006] The plates may be of rectangular section. The face of the plate which contacts the web can be rough, sawn or grooved.

[0007] The depth of the plate may be 190-320mm, the width 198-290mm.

[0008] The web may extend along at least the intermediate part of the beam, the ends being devoid of gaps in order to provide a beam which can be docked at one or both ends. So the boards at one or both ends are greater lengthwise than the boards separated by gaps.

[0009] The boards may be incorporated into the beam with the grain parallel to the axis of the plates. The grain of boards may instead lie perpendicular to the axis of the plates.

[0010] The horizontal sides of the boards may also be planed and secured to the plates by adhesive. The sides of the boards may project slightly into a longitudinal shallow housing in the plates.

[0011] The width of the gaps maybe equal along the length of the beam. Thegapswidth may be substantially equal to the length of the boards. The gap width will normally be selected to allow plumbing pipes, airconditioning ducts and extractor ducts to pass through thereon, together with smaller components such as water pipes and cables. The gap range may be 190 360mm.

[0012] The beam may be made from structural pine for internal use. For external use treated pine of structural grade containing arsenic is suitable. Laminated timber plates and boards may be used instead but at higher cost. For house construction, the plates may be 90 x 35mm min and the boards 190 x 45mm min.

[0013] Polyurethane adhesives suffice for indoor work. Exterior polyurethane glues are preferable forjoints which support balconies and outdoor structures.

Advantageous Effects of Invention

[0014] 1. The beam is versatile in the way it incorporates into existing building construction.

[0015] 2. Its gaps allow transverse passage of pipes, ducts and cables.

[0016] 3. It offers a useful range of spans.

[0017] 4. It is economical in that it allows utilisation of short pieces of board which would otherwise be scrapped.

BRIEF DESCRIPTION OF DRAWINGS

[0018] One embodiment of the invention is now described with reference to the accompanying drawings, in which:

[0019] Figure 1 is a perspective of a 6m beam.

[0020] Figure 2 is a side view of the beam when chamfered at the end support.

[0021] Figure 3 is a side view of the beam supported at one end in an alternative manner.

[0022] Figure 4 is a side view of two beams joined at 90.

[0023] Figure 5 is a side view of the beam supported on a conventional stud wall.

[0024] Figure 6 is a side view showing the beam intersecting with a mid span/end span blocking lying in one of the gaps.

[0025] Figure 7 is aside view of part of a floor with the beam beneath projecting outside the first floor timber wall as a cantilever.

[0026] Figure 8 is the same as Figure 7 with alternative detail.

[0027] Figures 9, 10 and 11 are side views of the beam connected in alternative ways to a steel I-beam.

[0028] Figure 12 is a diagram of a jig in which the beam components are arranged prior to glueing.

[0029] Figure 13 is a side view of a plano-convex beam.

[0030] Figure 14 is a side view of a biconcave beam.

[0031] Figure 15 is an end view of three I-beams braced by two bracing components.

[0032] Figure 16 is a side view of a plano convex beam of I-section.

[0033] Figure 17 is a side view of a biconcave beam of I-section.

[0033a] Figure 18 is a side elevation view of the 6m beam shown in Fig. 1.

[0033b Figures 19A - 19E are, respectively, tables regarding Material Properties, Loading Data, Section Properties and Results, Critical Moment and Reactions and Glue Checks.

DESCRIPTION OF EMBODIMENTS

[0034] Referring now to Figure 1, a beam 1 is made of structural pine. Top chord 2 and bottom chord 4 are made of sawn 6000 x 90 x 35mm scantlings. Laser guided sawing is adequate surface finish. The web is made of nine boards, 198 x 240 x 45mm, the sides 8 of which are glued to the faces of the chords with polyurethane. The grain of the boards lies parallel to the chords. The boards are separated from each other by a 190-320mm rectangular gap 10 which is large enough to admit 90mm PVC tubes or 200mm duct. The chords 2, 4 create a 23mm wide step 12 where the board meets the chord. The nine web boards 6 are separated from each other by eight equal gaps. The two outer boards 14, 16 are separated from the outermost boards 18, 20, each a minimum 600mm long by gaps 22, each 198mm wide. These can be varied in gap width to suit the construction for which they are intended. The outermost boards are made intentionally about 2.5 times the length of the web boards 6 to allow onsite docking if necessary.

[0035] In Figure 2 outermost web board 18 and the overlying end of chord 2 are docked at incline 24 to allow the beam to rest on plate 26 within the thickness of stud wall 28.

[0036] In Figure 3 chords 2, 4 project into the walls top and bottom plates 32, whereafter the end blocking board 34 is fixed to the members 2, 4.

[0037] In Figure 4 beam 36 intersects beam 38 at 90. Both chords 2, 4 are cut back to allow outermost board 16 to project into the space between steps 10. A steeljoist hanger 40 mutually connects the beams. The top chords of both beams are united by skew nail 42.

[0038] In Figure 5 the bottom chords of beams 36 are skew nailed to the top plate 44 and particle board flooring 46 is fixed to the top chords.

[0039] In Figure 6, when the beams are arranged in a parallel series across a building they are stabilised by the insertion into gap 8 of a common structural board such as a strongback 48 which is skew nailed to the chords and the upright end of web board 6.

[0040] In Figure 7 ground floor timber supporting wall 50 supports the beam such that it acts as a cantilever. The projecting extension portion 52 supports exterior flooring 54. The end which is inside the building is connected by a joist hanger 40 to a twin beam 56 which abuts floor 58. Packers 60 lie between top chord 2 and inside floor sheets 58.

[0041] In Figure 8 the endmost board 62 is made of treated pine and covered with exterior flooring sheets 54.

[0042] In Figure 9 ceiling battens 64 are fixed to bottom chord 4 to take plaster board sheets 66. A steel I-beam 68 supports the timber beam 32. A 35mm timber packer 70 is secured to the web of the steel beam 68 by bolts 72 and angle bracket 74 joins outermost board 16 to the packer 70. The chord 2 is cut back to allow the appropriate insertion.

[0043] In Figure 10 the same arrangement is shown again with packer 70 resting on the flange 76 of the I-beam. Instead of bracket 74, steel joist hanger 40 connects outermost board 16 to the packer.

[0044] In Figure l Ithe chords are cutback to allow the outermost board 16 to project between the steel I-beam flanges 76. The board is fastened with bolts 78 to cleat plate 80.

[0045] In Figure 12 a jig for beam assembly, a first angle iron clamp 82 is positioned alongside a row of flat, horizontal spacer supports 84 intended to raise the web boards. An opposing angle iron clamp 86 is positioned alongside and parallel to the row of spacers 84. Posts 88 are welded to the clamps at mid point and the posts are joined by threaded rods 90. Nuts 92 impose the clamping force.

[0046] The chord plates 2, 4 are laid between the spacers and the clamps and the boards 6 are aligned with the spacers. Glue 94 is applied from a gun and the clamps are tightened. In some beams the grain of the boards lie at 900 to the axis of the plates.

[0047] The clamps have pairs of holes 96 for each board so that nails can be inserted through the clamps, the plates 2, 4 and into the boards 6 after gluing.

[0048] Referring now to Figure 13, the beam has a top plate 2 and a bottom plate 4 joined by web boards 6. The gaps 10 between boards are the same but the outermost board 20 has a cut out 82 measuring 345 x 120mm. The LH end of the beam is 405mm deep and though the beam length varies, the outermost end of the beam would typically be 300mm. The saw is programmed to modify the depth of the web boards to reduce the beam height from the inner end to the outer end. This achieves the pitch required to make the flat roof self draining.

[0049] In Figures 14 and 15 a pair of brace boards 84, 86, the same depth as web boards 6 in Figure 13, are glued and nailed to top plate 88 and bottom plate 90. The boards lie end to end in contact and project 22mm beyond the plates at both ends.

[0050] The purpose is to lead to installation as shown in Figure 15. Here the component is lowered into the gap between a pair of adjacent parallel I-beams 92, 94 and rotated to lie 90 to both. Alternatively, the bracing component may be installed as the I-beams are laid. The plates 88 and 90 are skew nailed to the top plates of the I-beam alongside using nails 96 and to the wall plate beneath using nails 98.

[0051] Referring now to Figure 16, the top plate is laminated to produce a convex shape as shown. The saw bench which docks the boards is programmed to cut the boards in a series to produce the shape shown. The jig is modified accordingly. Likewise in Figure 17 the jig is further modified to produce the biconcave beam shown.

[0052] The beam 1 shown in Fig. 1 is represented in Figure 18 in side elevation. The beam 1 is a linear structural joist member adapted to extend substantially horizontally and to support flooring or other building loads. The beam 1 can be used to form a truss. In the example, the beam 1 is supported between a pair of spaced and vertically upright stud members 28.

[0053] The beam 1 demonstrates the exceptional and surprising strength achieved by structural members made according to the invention and this is described with reference to beam extremity of location A at board 18a, mid-span at location B and intermediate the length of the span at location C.

[0054] At the beam extremity C, the vertical shear forces at the end of the truss beam 1 result in high tension forces between the chord faces 5 of chords 2,4 and ends 19 of the board 18, which can be understood to be glue tension force.

[0055] At the mid-beam location B, bending moment translates LAP shear forces between the chord face 5 and the ends 7 of the blocks 6, resulting in glue shear force. Lap shear strength testing measures the ability of a material to withstand stresses set in a plane, where the exerted shear force is moving the two substrates in opposite directions, as in the structural bonding applications described herein.

[0056] Combined glue shear force and tension forces exist at sections intermediate the length of the beam 1, exemplified at intermediate location C, where there are both beam bending and shear forces. The inventor developed glue calculations at the time of the invention that enabled the calculation of the glue strength capacity as a result of applied stresses from the combination of the bending and shear forces. In this regard, the inventor determined that the calculated combined stress index (CSI) must be less than 1.00 (<1). The attempt to rely solely on adhesive secured joins was totally against the prevailing thought in the building industry at the time. The inventor pursued the making of a truss in which the components were joined and held against load-bearing forces in structural applications solely by adhesive. The joining method is radical and controversial, being based on beam calculations, despite the prediction by industry experts that it would not work without interlocking mechanical joins or metal fasteners between the block and chord components. Nevertheless, the inventor persisted with calculations that required extensive trial and experimentation and the positive result was surprising, and still is despite many successful years of production and installation.

[0057] Referring to the tables in Figures 19A - 19E, Fig. 19E shows the results of glue checks for the Applicant's MegaJoist TM (MJ) beam products (Codes 250, 300, 350, 400 and 450). Columns V* and 4V(kN) are used to calculate critical glue shear forces, whereas columns T* (kN) and @t (kN) are used to calculate critical glue tension. The CSI column shows the result of the combined calculation, indicating that Applicant's product Nos. MJ 300, 350, 400 and 450 passed with a CSI value less than 1.00.

[0058] It is to be understood that the word "comprising" as used throughout the specification is to be interpreted in its inclusive form, ie. use of the word "comprising" does not exclude the addition of other elements.

[0059] It is to be understood that various modifications of and/or additions to the invention can be made without departing from the basic nature of the invention. Materials other than timber are suitable for making into boards. Polymeric timber substitutes are suitable if they have suitable strength. These modifications and/or additions are therefore considered to fall within the scope of the invention.

Claims

The claims defining the invention are as follows:

1. A timber I-beam adapted for load-bearing comprising: a top chord and a bottom chord forming the flanges of the I-beam; and

a web comprising a plurality of side by side timber web-forming boards, including boards forming a uniplanar intermittent web, and two respective outermost boards,

wherein: the boards forming the web are inner boards relative to the outermost boards; the outermost boards at one or both ends are greater lengthwise than the inner boards; and each of the inner boards: is in the shape of a rectangular block; are separated from adjacent inner boards by a rectangular-shaped gap that is large enough to admit ducting; have opposed side faces that are broad, flat and of the same dimensions as each other, such that the upper area of contact of each said block to the top chord is substantially the same as the lower area of contact of the same block to the bottom chord; and have sides that are joined to opposed faces of the chords by glue without the opposed faces comprising tongue and groove or other mechanical interlocking methods whereby to present the opposed chord face as broad and flat.

2. A timber I-beam as claimed in Claim 1, wherein the top and bottom chords are made of timber of a width larger than the thickness of the boards forming the web.

3. A timber I-beam as claimed in Claim 1 or 2, wherein the chords are of rectangular section.

4. A timber I-beam as claimed in any one of Claim 1-3, wherein the depth of the chords is between 190mm and 320mm.

5. A timber I-beam as claimed in any one of Claims 1 - 4, wherein the width of the chords is between 198mm and 290mm.

6. A timber I-beam as claimed in any one of Claims 1-5, wherein the web extends along at least an intermediate part of the beam, the ends being devoid of gaps in order to enable the I-beam to be docked at one or both ends.

7. A timber I-beam as claimed in any one of Claims 1-6, wherein the width of the gaps is equal along the length of the beam.

8. A timber I-beam as claimed in any one of Claims 1-7, wherein the width of the gaps is substantially equal to the length of the boards.

9. A timber I-beam as claimed in any one of Claims 1-6, wherein the inner boards are incorporated into the beam with inner board grain parallel to the axis of the chords.

10. A timber I-beam as claimed in any one of Claims 1-9, wherein the top chord is inclined in relation to the bottom chord by one or more degrees in order to support a drainage surface.

11. A timber I-beam as claimed in any one of Claims 1-9, wherein the top chord is curved and the length of the inner boards is adapted to support the curve of the top chord.

12. A timber I-beam as claimed in any one of Claims 1-9, wherein the top and bottom chords are curved and of equal distance from each other along their respective lengths.

13. A timber I-beam as claimed in any one of the previous claims, wherein the inner boards adjacent to the outermost boards are separated from the outermost boards by long gaps.

14. A pair of I-beams including two timber I-beams as claimed in any one of Claims 1-13, the I-beam forming one member of a pair of I-beams laid mutually parallel to each other and braced by a bracing component inserted at 900 to the webs of the pair of I-beams, wherein the bracing component comprises an upright bracing board which extends beyond the top and bottom chords, the chords being attached to the top and bottom of the bracing board, whereby the top and bottom chords abut the corresponding chords of both I-beams and the ends of the bracing board abut both webs.

15. A pair of I-beams as claimed in Claim 14, wherein the bracing board is made of two halves in the form of boards lying end to end.

16. A method for manufacture of a structural timber I-beam adapted for load bearing according to any one of Claims 1- 13, the method including the steps of:

providing the top chord and the bottom chord; cutting the plurality of rectangular web-forming inner boards; placing inner boards in alignment in a jig, the separation between adjacent inner boards being large enough to admit ducting; mechanically attaching the inner boards to the top and bottom chords with screws or nails such that the upper area of contact of each said board to the top chord is substantially the same as the lower area of contact of the same board to the bottom chord; and gluing the boards to the respective faces of the chords, wherein the glue solely provides structural integrity of the join.

17. The method of Claim 16 when dependent on Claim 10, further including the step of cutting the inner boards to achieve a pitch in a roof constructed using the I beam.

18. The method of Claim 16 or 17, further including the step of inserting nails through the chords and into the inner boards after the gluing step.

19. The method of any one of Claims 16 - 18, further including the step of making the outermost boards about 2.5 times larger in length than the inner boards, the outermost boards being devoid of gaps in order to provide a beam which can be docked at one or both ends.

20. The method of any one of Claims 16 - 19, further including the step of cutting the chords to a shape such that they are rectangular in section, an opposed face of each top and bottom chord facing the other of the top and bottom chords not being grooved whereby to present the opposed chord face as broad and flat.