NZ711612A - Structural Building Element - Google Patents

Abstract

timber I-beam 701 has a top chord 702 and a bottom chord 704 forming the flanges of I-beam and a series of side by side timber blocks 706 each separated from the next by a gap 722, together forming a uniplanar, intermittent web. The blocks are aligned with the wood grain aligned transverse to the longitudinal axis of the beam, are adhesively connected to the top and bottom chords, and the adhesive provides the long term mechanical strength of the beam. Cables and pipes for a building may run transversely through the gaps. A method of making the I-beam is described. Such an arrangement is economical and versatile. The blocks also create gaps to allow cables/ducts to pass through joists longitudinal axis of the beam, are adhesively connected to the top and bottom chords, and the adhesive provides the long term mechanical strength of the beam. Cables and pipes for a building may run transversely through the gaps. A method of making the I-beam is described. Such an arrangement is economical and versatile. The blocks also create gaps to allow cables/ducts to pass through joists

Description

TITLE OF INVENTION Structural Building Element TECHNICAL FIELD This ion relates to a ural building element. More particularly, this invention relates to a comprising roof or ceiling frame supports. Still more ularly, this invention concerns beams for building construction and particularly timber beams for house construction.

BACKGROUND The following references to and descriptions ofprior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the following prior art discussion does not relate to what is ly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present invention of which the identification of pertinent prior art als is but one part.

It is known to build floor joists from a 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. Such a joist is described in US 156677 SUMNIARY OF INVENTION Technical Problem The steel joists leave no pathway for ducts, pipes and cables to cross the building through the joists. The earlier timber joists have great shear th but limited torsional strength. By trading off shear strength the inventor has achieved significant advantages.

The apparatus aspect of the invention provides a timber T or I-beam comprising a top plate and/or a bottom plate forming the flanges of an I—beam and a series of side by side timber blocks, each separated from the next by a gap, together forming a uniplanar intermittent web, the blocks oriented so that their grain extends transverse to the general udinal axis of the top plate.

In this document, in discussing the terms flange, chord or plate, the word “chord” generally refers to an elongate length of timber forming part of a truss, the word “flange” refers to an elongate length of timber forming part of a beam, whereas the word “plate” is used as a generic term. In discussing the words “board” or block”, these words are generally interchangeable and generally refer to a short span of timber extending from a plate or n a pair of plates. The pitch or rake of a roof surface, or the roof frame or truss s that support and/or form part of the roof structure, describes the angle of inclination achieved on the surface.

The I beam may be used as a building element of a roof truss or other roof frame. The top and bottom plates may extend parallel to one r. The blocks may be cut square.

The top and bottom plates may be set at an incline with respect to one another. The top plate may be set on an incline ve to the square bottom edge of each of the blocks or may extend parallel thereto. The rake of an ed plate may be minimal, for example around 30. The rake may vary to achieve roof pitches between 10 and 450. Where the T or I beam forms an A-frame, a double rake may be provided.

The top and bottom plates may be 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 t surface for other components and connect the upright parts of the beam.

The blocks may be of rectangular section, or trapezoid or other irregular shape to follow the desired inclined e of the plate. The face of the plate which contacts the web may be ed to include grooves or may be rough sawn.

Advantageously, the rake on the plate may be 10 to 30 and still require no modifications of the rectangular ned blocks. Greater raking will generally require planing or cutting of one end of the block to follow the incline of the plate.

The depth ofthe plate may be 25—110mm, the width 30-150mm.

The web may extend along at least the intermediate part of the beam. The ends of the I or T beam may be devoid of gaps in order to provide a beam which can be docked at one or both ends. So the blocks at one or both ends are greater lengthwise than the blocks separated by gaps.

The blocks are aligned so that their grain extends ersely relative to the T or I beams longitudinal axis. It is believed that significant gains in torsional strength are achieved whilst g off on shear lineal strength, which is still more than sufficient due to the nal strength of the plate and the blocks aligned with their grains generally erse to the longitudinal axis of the plates.

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

The width of the gaps may be equal along the length of the beam. The gaps width may be substantially equal to the length (the direction parallel to the longitudinal axis of the plate) of the blocks. 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 preferably 90- 500mm.

The beam may be made from structural pine for al use. For al use treated pine of structural grade containing arsenic is suitable. ted timber plates and blocks may be used instead but at higher cost. The type of material used to form such I- beams and T—beams as described herein in ance with the invention may be made from machine grade pine (MGP) or laminated veneer lumber (LVL), the latter being considered a generally higher grade material. Such materials may be used to achieve beams having short duration modulus elasticity (E values) of 6,100-21,500, preferably about 10,000, which pond to MGPlO. Most typically I—beams made according to the invention are required to conform to stress grade standards of F5-F27, but most typically will fall within the stress grade range of F8-Fl7, corresponding to E values of 9,100-14,000. For house construction, the plates may be 45—90mm and ably 70- 90mm in width and 35-45mm in depth. The blocks may be 70-190mm, preferably 90- l40mm in length (the direction parallel to the longitudinal axis of the plate), mm, and preferably 35—45mm in depth, noting that the height between the plates may vary depending on the application.

Polyurethane adhesives suffice for indoor work. Exterior polyurethane glues are preferable for joints which support balconies and outdoor structures.

Advantageous Effects of Invention l. The beam is versatile in the way it incorporates into existing building uction. 2. Its gaps allow transverse passage of pipes, ducts and cables. 3. It offers a useful range of spans. 4. It is economical in that it allows utilisation of short pieces of block which would otherwise be scrapped.

. It permits the economical tion of timber I and T construction beams. 6. By orienting the blocks ersally, it permits the tion of raked roof truss elements with minimal modification of component parts relative to beams with parallel plates. The narrower block width allows an inclined beam e to still rest stably on its end, even if minimally raked by an incline of, say, 10 — 30. 7. It allows efficient production of a range of raked roof truss elements through a range of inclinations by simple cutting of the angles of the respective blocks to length and inclination.

BRIEF DESCRIPTION OF DRAWINGS Various embodiments ofthe invention are now described with reference to the accompanying drawings, in which: Figure l is a perspective of a 6m beam.

Figure 2 is a side View of the beam when chamfered at the end support.

Figure 3 is a side View of the beam supported at one end in an alternative manner.

Figure 4 is a side view of two beams joined at 90 degrees.

Figure 5 is an end view of the beam supported on a conventional stud wall.

Figure 6 is a side View showing the beam ecting with a mid span/end span blocking lying in one of the gaps.

Figure 7 is a side view of part of a floor with the beam h projecting outside the first floor timber wall as a cantilever.

Figure 8 is the same as Figure 7 with alternative detail.

Figures 9, 10 and 11 are side views ofthe beam connected in ative ways to a steel 1— beam.

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

Figure 13 is a side View of a plano—convex beam.

Figure 14 is a side view of a biconcave beam.

Figure 15 is an end View of three I—beams braced by two bracing components.

Figure 16 is a side View of a plano convex beam of I-section.

Figure 17 is a side View of a biconcave beam of I-section.

Figure 18 is a side view of a slightly raked beam of I-section; Figure 19 is a side view of an A—frame beam of I—section, slightly raked from a centre high point; Figure 20 is a side View of a raked beam of I-section; Figure 21 is an amplified View of the centre point of the embodiment shown in Figure 19; Figure 22 is a perspective View of an I-beam in the process of being manufactured; Figure 23 is a perspective view of the I-beam of Figure 22 during manufacture; Figure 24 is an end tic View of a timber T—beam; Figure 25 is an end schematic View of a timber I—beam according to the invention; Figure 26 is a side art cross sectional View of a raked I-section beam according to the invention; Figure 27 is a side schematic part View of an I-beam with parallel chords; Figure 28 is an end schematic View of a wall and rooftruss frame ation sing a double raked A-frame roof structure; Figure 29 is an end view of a steeply pitched single raked building structure; Figure 30 is a perspective View of a block; and Figure 31 is a schematic end View of a plate.

DESCRIPTION OF EMBODIMENTS Referring now to Figure l, the beam is made of ural pine. Top chord 2 and bottom chord 4 are made of sawn 6000 X 90 X 35—45mm 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 ofthe chords with polyurethane. The grain of the boards lies parallel to the chords. The boards are separated from each other by a 0mm rectangular gap 10 which is large enough to admit 90mm PVC tubes or 300mm 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 l4, 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.

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

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, 34.

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 steel joist hanger 40 ly connects the beams. The top chords of both beams are united by skew nail 42.

Figure 5 shows an end View of a plurality of the bottom chords ofbeams 36 that are skew nailed to the top plate 44 and particle board flooring 46 is fixed to the top chords.

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.

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

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

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.

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

In Figure 11 the chords are cut back to allow the outermost board 16 to project between the steel I—beam flanges 76. The board is ed with bolts 78 to cleat plate 80.

In Figure 12 a jig for beam assembly is shown, wherein 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.

The chord plates 2, 4 are laid between the s and the clamps and the boards 6 are aligned with the spacers. Glue 94 is d from a gun and the clamps are tightened. In some beams the grain of the boards lie at 90 to the axis of the plates.

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.

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 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 a flat roof self draining. However, because the web boards 6 have substantial length the direction of the I—beam axis, they each must be individually cut, despite the shallow raked angle of 1— . However, it is not possible to cut them too short in their axial grain orientations.

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.

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 900 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.

Referring now to Figure 16, a top plate 2 is laminated to produce a convex shape as shown. A saw bench which docks the boards 6 is programmed to cut the boards 6 in a series to produce the shape shown. The jig is modified accordingly. se in Figure 17, the jig is further modified to produce the biconcave beam shown.

Turning to Figure 18, there is shown a raked I-beam comprising a lower chord 104 and an upper chord 102 interposed by equispaced blocks 106. The lower chord 104 extends fiat along a tabular jig 109, whereas the upper chord 102 declines at an angle (about 0.5- 300, preferably about 05-50, and most preferably 1.50 from an end point 115 to an outer end 116, Where the I-beam 101 is cut to suit outer roofing profiles, such as guttering and outer frame structures, and for this reason the ost block 106 comprises a board 118 that can be docked and cut to shape and size to suit the desired profile as shown in the drawing. It is noted that the description in relation to Figure 18 is with regard to an A—frame I—beam, but the relevant ption is applicable to single raked I—beams, such as those shown in Figure 20. g to Figure 19, a shallow A~frame 201 is shown having a high centre point 215 from which the raked upper chords 202a, b decline either side of the centre point 215.

The lower chord 204 lies flat on the planar jig 209 and interposed between the lower and upper chords 202, 204 are a plurality of aced blocks 206 advantageously cut square to minimize costs, each block 206 beam cut the length to support the upper chords 202a, b in raked position through to the outer most long board 218 a, b at either end.

In Figure 20, single raked I-beams are shown having a pair of upper and lower chords 302, 304 that are most likely spaced at a first end point 315 and converge at an angle of about 2-50 to a second end point 316. As with the embodiment shown in Figure 18, the single raked I-beam 301 comprises a plurality of blocks 306 each spaced to support and brace the upper and lower chords 302, 304. titial spaces 322 provide gaps to allow ducting, wiring and other building services to be passed through the I—beam 301 during the building phase, as well as once the building is erected. As shown in Figure 21, the titial spaces 222 ofA—frame I—beam 201 may be in registry with one another in situ to enable the passage of such building services. The blocks 206 may be cut square where the raking angle is shallow, such as 1—50, or may be cut at one end to conform to the angle of incline to ensure that the upper chord 202 rests stably on each block 206, as will be ned in more detail with reference to Figure 26.

With reference to Fig.22, during cture the upper and lower chords 402, 404 may be placed on a planar jig table 409 and braced in place using spacer blocks 413. Initially only one chord 404 is placed in position, glue is applied to predetermined regions on the chords internal surface 405 who correspond with the positioning of the end of face of each block 406, 418 that is to be placed in that glued region, the glue being a high strength semi-rigid external use polyurethane adhesive. The blocks 406, 418 are positioned in place and supported, spaced above the r jig 409 in a parallel horizontal plane by board spaces 484 positioned between the table 409 and the boards 406, 418, The second upper chord 402 is then placed with its wide face against the other end of the blocks 406, 418, but not before adhesive is similarly applied to corresponding regions along its inner face 407.

As shown in Figure 23, the upper and lower chords 404, 402 are then compressed together by clamps 490 and the , blocks 406, 418 are secured in position between the upper and lower chords 402, 404 by the application of nails through the outer surfaces of the chords 402, 404 into the ends ofthe blocks 406, 418 to secure the blocks 406, 418 until the adhesive can form a strong bond, noting that it is the adhesive that provides the long term mechanical strength or the I-beam 401. During cture, preferably a pair of nails 712 are inserted through the upper and lower chords 702, 704 into each block 706 at each end of the block 706 to prevent ng. To further secure the I—beam structure 701, screws 711 are inserted intermittently along the length of the I—beam 701 to hold or further clamp the boards or flanges 702, 704 in place against the adhesive 707 until the adhesive 707 sets, preferably at 500-1500mm intervals along the length of the I—beam 70 1 .

The I—beam 401 is then d from the jig 409 and the process is repeated to form a new I-beam 401.

The adhesive may be a high strength, semi-rigid polyurethane glue.

Turning to Figs 24, 25, 30 and 31, the I—beam may be substituted with a timber T—beam that may be defined with respect to the following dimensions: W = width of the chord, which may typically be 30—150mm, preferably 44- 120mm, and most preferably 70-90mm; D = depth of chord 502 which may be mm, more preferably 30-70mm, and most preferably 35-45mm; H = height of block 50-400mm, most preferably 70-290mm, noting that H can vary depending on the pitch of the truss I-beam or T—beam, the position of the block 506 along the length of the I-beam or T-beam 501 and the mechanical properties required of the block 506 for the particular application; t = thickness of the block 506 which may be 19-90mm, but more ably 35- 45mm.

Note: The web of the T-beam may or may not be continuous.

Similarly, with respect to the I—beam 601 shown in Figure 25 and more clearly shown in Figure 30, the block t value may be m and preferably 35—45mm, the latter using F grade or machine graded pine (MGP). The value w may be mm, preferably 70— 140mm, and most preferably 70-90mm. The raking angle may vary to odate different applications and may be between 040-450, with H being varied with the pitch angle.

As shown in Figure 26, the achievement of blocks 706 having a relatively small w value (for example 70mm, and in some ations, as low as 45mm), allows the block 706 to be cut square whilst still adequately supporting the inclined raking chord or flange 702.

A similarly formed I-beam 801 is shown in Figure 27 formed using similar principles to the I-beam 701 described with reference to Figure 26.

Referring to Figure 28, there is shown a combined wall frame and roof truss structure using parallel I-beams 801 made according to the invention. In Figure 29, there is shown a building structure with a single inclined I-beam span. It is noted that the parallel chords of the portal structure shown in Figures 28 and 29 can be replaced with dual raked roof truss structures (for the example shown in Figure 28) and with a single raked I-beam structure (see the example shown in Figure 29).

It is to be understood that the word “comprising” as used throughout the cation is to be interpreted in its inclusive form, ie. use of the word “comprising” does not exclude the addition of other elements.

It is to be understood that s 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 ations and/or additions are therefore considered to fall within the scope of the invention.

Claims (14)

1. A timber I-beam comprising a top chord and a bottom chord forming spaced flanges of an I~beam extending along a longitudinal axis, said flanges spaced from each other and supported by a series of at least two timber blocks lying in a single plane and each separated from the next by an interstitial gap adapted to receive ng es, the I-beam forming a uniplanar, intermittent web, wherein the blocks are oriented with their wood grains aligned transverse to the longitudinal axis.

A timber I-beam as claimed in Claim 1, wherein the top and bottom chords extend 10 parallel to one another.

A timber I—beam as claimed in Claim 1 or 2, wherein the blocks are of rectangular section.

A timber I-beam as claimed in any one of Claim 1-3, wherein the width, w, of the plate is about 90mm.

15 A timber I—beam as claimed in Claim 4, wherein the width of the block is about 45mm.

A timber I—beam as d in any one of Claims 1-5, wherein the top chord is raked relative to the bottom chord.

A timber I-beam as claimed in any one of Claims 1-6, wherein the width of the 20 gaps is equal along the length of the I—beam.

A timber I—beam as claimed in any one of Claims 1—7, wherein the width of the gaps is substantially r than the width of the blocks.

A timber I-beam as claimed in any one of Claims 1—6, wherein the Width of the gaps is at least twice the width of the blocks.

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 0.4 to 45 degrees in order to support a drainage surface.

11. A timber I-beam as claimed in Claim 10, wherein the raked inclination is about 1-

12. A timber I—beam as d in any one of Claims 1-11, wherein the I-beam is formed by first placing a chord on a table jig and applying ve to specific 10 regions where blocks will abut an internal face of the chord, positioning blocks at predetermined spaced intervals along the length of the chord, placing a second chord on the table jig to abut the free ends of the blocks but applying adhesive to corresponding regions of the second chord’s inner face to abut the blocks before fixing the second chord in position, ng clamps to hold the first and second 15 chords in spaced relationship against the interposed blocks, and applying a pair of nails to each end of each block through the outer surfaces of each respective chord.

13. A timber I—beam as claimed in Claim 1, wherein screws are applied to r hold the first and second chords to the blocks prior to the adhesive g. 20

14. A timber I-beam as claimed in claims 1-13, wherein the blocks are square cut and interposed between top and bottom chords raked to an angle of 20—50.