AU2008202448A1

AU2008202448A1 - Reinforced Beam

Info

Publication number: AU2008202448A1
Application number: AU2008202448A
Authority: AU
Inventors: Martin Holland
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-05-30
Filing date: 2008-05-30
Publication date: 2008-12-18

Description

P/00/011 28/5/91 Regulation 3.2 00

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AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventor Address for service is: Martin Holland Martin Holland

WRAYS

Ground Floor, 56 Ord Street West Perth WA 6005 Attorney code: WR Invention Title: Reinforced Beam The following statement is a full description of this invention, including the best method of performing it known to me:- 00 SReinforced Beam SField of the Invention

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The present invention generally relates to a structural beam. In particular the 00 invention relates to the strengthening of the beam. oo c 5 Background Art oo 00 Timber beams are a common structural component used extensively in the N residential and light commercial building industry.

Timber beams are frequently utilised to span across two or more support points to provide strength and fortification to ceilings, rooves or floors.

Timber is available in many standard sizes and can be easily modified into a variety of shapes i.e. curved, notched, channeled or connected.

Structural beams can also be used as an architectural feature i.e. exposed beams.

The strength and deflection capacity of individual timber beam sizes is well known in the industry. However, timber beams have limitations in terms of stiffness, strength and load capacity and are unsuitable where a long span is required.

Typically, an increase in the stiffness, strength and load capacity relates to an increase in the size of the beam. This creates difficulty in handling the beam as well as accommodating the beam in the desired position. Several approaches have been taken to increase the beam strength using metal members extending along the longitudinal length of the beam. One such approach is disclosed in US patent 4,586,550 to Kitipornchai, S. This patent discloses a beam reinforced using metal plates or strips secured to the side of the beam wherein the plates have a plurality of teeth formed therein which extend into the beam, holding the plates thereto. The patent suggests that the reinforcing plate is restricted to a -3- 00 thickness of between 0.5-3.0mm which will provide the beam with a 50-80% increase in stiffness.

Where the reinforced plates are formed from thicker sheets of metal, the size of the teeth increases as the thickness of the sheet increases. This is due in part to the limitations of die technology used to press the teeth from the plate. As a 00 result the possible number of teeth per square meter is reduced. As there are not as many teeth which can extend into the beam there is a reduction in the Sstrength of the beam. Furthermore, as the length of the teeth increase the 0 integrity of the beam is jeopardised as the over sized teeth may lead to timber splitting.

In relation to plates formed from a thinner sheet of metal a denser tooth pattern may be achieved. However, providing a denser tooth pattern to increase load capacity results in a reduction in plate stiffness. This occurs because as each tooth is punched out from the plates it reduces the second moment of inertia.

If the plate has a less dense tooth pattern, shear transfer is reduced and the probability of local buckling of the plate between the teeth is increased resulting in a reduction of beam strength.

Another problem with using plates having teeth punched therein occurs when the teeth are sharp ended. Inserting sharp ended teeth/nails forces the timber fibres to curve at the initial insertion of the teeth, pulling the fibres apart. This is exacerbated when a subsequent load is applied, creating a tendency for the beam to split.

The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application.

It is an object of this invention to provide a reinforced beam having an increased strength capacity.

-4- 00oo SUMMARY OF INVENTION tThe advantages of this invention are found in providing a reinforced timber beam suitable for a wide range of applications.

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The present invention provides a reinforced beam comprising a beam having at oO 00 5 least one strengthening member secured to the beam using securing means, the Ssecuring means being in the form of a bond means to bond the strengthening Smember to the beam.

00oo SThe present invention provides a reinforced beam comprising a beam having at least one strengthening member secured to the beam using a bond means to bond the strengthening member to the beam.

The bonding means may be provided by a glue.

The beam may be formed from a plurality of beam members. The beam members may be held in spaced arrangement by the at least one strengthening member. The beam members may be made from timber.

The strengthening member may be in the form of a steel plate or strip.

The at least one strengthening member may also be secured to the beam using a securing means. The securing means may comprise a plurality of teeth extending from a side of the strengthening member, the teeth extending into the beam when the strengthening member is secured thereto.

An end of each tooth remote from the strengthening member is shaped so as to reduce the likelihood of jeopardising the overall integrity of the beam.

Preferably there are 1-15 teeth per metre along the strengthening member. The length of each tooth may be between 10mm-50mm, depending on the individual structural requirements.

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In one aspect of the invention the teeth extend substantially in a single line along the longitudinal length of the supporting member.

In another aspect the teeth extend across and along the strengthening member.

The teeth may be arranged in a uniform repetitive pattern.

00 5 Preferably a plurality of strengthening members are secured to the beam.

00 Preferably the strengthening members are secured to opposed sides of the Obeam. The plurality of strengthening members may extend along 70-100% of the length of the beam.

The beam may be recessed to accommodate the thickness of the strengthening members such that when in position the strengthening members are flusb with the surface of the beam.

Preferably the strengthening members are secured to the top and bottom chords of the beam.

The plurality of teeth may extend from both sides of the strengthening member.

This will allow the strengthening member to be placed between two beam members.

The present invention further provides a reinforced beam having a length of cold or hot-formed steel flange extending longitudinally along each of a top chord and a bottom chord of a timber beam, wherein each flange is secured to the beam with glue. Each flange may include a plurality of fixing teeth in the form of nails, spikes or pins. The steel fixing teeth are preferably formed in the flange when manufactured.

According to another aspect of the invention the teeth may be welded onto the flange.

-6- 00 a A web section of the beam may be hardwood, softwood, glulams, laminated timber, finger jointed timber or other timber products.

Preferably the teeth are ordered in a single line along the flange numbering between 1-15 per metre.

00 5 In one aspect of the invention the teeth may be relatively blunt at a remote end from the flange to maintain the integrity of the beam. In another aspect of the invention the remote end of the teeth may be tapered with a twist and a sharp

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Preferably the glue used to bond the flange to the timber web section is a 2 part epoxy glue, which is spread evenly over the teeth and the surface of the flange from which the teeth extend.

Preferably when securing a toothless flange to a beam clamps are used to press and hold the flange in position until the glue has dried sufficiently. Where the flanges have teeth, clamping can be removed once assembled as the glued teeth have sufficient permanent adhesion.

This invention improves the stiffness of the timber beam by up to 10 fold, at the same time maintaining appropriate strength for the applied load. Several benefits of the current invention are outlined below: providing a substantially continuous epoxy bond between the steel flanges and the timber beam restrains local buckling between the fixing teeth reducing the number of fixing teeth required; by using blunt fixing teeth the teeth literally cut into or shear the timber fibres on insertion. The fibres therefore remain at right angles creating a compression to the load, thereby reducing the tendency to split. The cutting of the fibres may reduce the flexural capacity of the timber, but these loads are transferred to the steel flanges; 00 0applying epoxy glue around the fixing teeth reduces the incidence of the timber splitting as it holds the fibres in place; using fewer fixing teeth improves beam stiffness and strength due to the M increased percentage of steel resisting the applied loads; 0 simple assembly is maintained as the fixing teeth are pressed into the timber beam; and once pressed into position the clamping can be Sremoved as the fixing teeth will keep the steel flanges in the correct 00oO alignment while the epoxy glue is curing; thick steel flanges can be rapidly fixed onto the timber beam; increasing the load capacity of the beam; as the reinforced beam is considerably lighter in weight than beams of the same strength and stiffness which comprise solely of timber or steel, they are easier to handle and position at the construction site; the reinforced beam can be worked with existing standard carpenter's tools.

Brief Description of the Drawings The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings in which: FIG 1 is a sectional side view of a reinforced beam according to a first embodiment of the invention; FIG 2 is a sectional side view of a strengthening member having a plurality of teeth; FIG 3 is a sectional top view of figure 2; -8- 00oo FIG 4 is a cross sectional view of a reinforced beam according to a second embodiment of the invention; FIG 5 is a cross sectional view of a reinforced beam according to a third Sembodiment of the invention; 00oo 5 FIG 6 is a cross sectional view of a reinforced beam according to the first Sembodiment of the invention; 00 FIG 7 is a cross sectional view of a reinforced beam according to a fourth Sembodiment of the invention; FIG 8 is a cross sectional view of a reinforced beam according to a fifth embodiment of the invention; FIG 9 is a cross sectional view of a reinforced beam according to a sixth embodiment of the invention; FIG 10 is a cross sectional view of a reinforced beam according to a seventh embodiment of the invention; FIG 11 is a cross sectional view of a reinforced beam according to an eighth embodiment of the invention; FIG 12 is a cross sectional view of a reinforced beam according to a ninth embodiment of the invention; and FIG 13 is a sectional side view of a reinforced beam according to a tenth embodiment of the invention, showing a chamfered end.

Best Mode(s) for Carrying out the Invention Referring to figures 1 and 6, the invention according to the first embodiment is in the form of a reinforced beam 21. The reinforced beam 21 comprises a timber beam 23 having a timber web 6. The timber web 6 can be either hardwood, -9o00 softwood, glulams, laminated timber, finger jointed timber or other similar timber products. In this embodiment the timber beam 23 comprises of only one beam Smember t' The reinforced beam 21 further comprises a strengthening member in the form of a plurality of flanges 1 secured to opposed sides of the timber beam 23, being a oO 00 top chord 10 and a bottom chord 11. In this embodiment each steel flange 1 c extends along 70-100% of the length of the timber beam 23.

oo 0Each flange 1 is formed from cold-formed or hot-formed steel. As shown in Sfigures 2 and 3, each flange has a securing means in the form of a plurality of teeth 4 extending therefrom. The teeth 4 are formed when rolling the flange 1 so as to be ordered in a line along the underside of the flange 1. When the teeth 4 are formed holes 2 are created in the flange 1. The teeth 4 are aligned in equal distance to the adjacent teeth 4 and number between 1-15 per metre along the full length of the flange 1.

In alternative embodiments the teeth 4 may be welded onto the flanges 1.

The flanges 1 are positioned along the timber beam 23 to support the area where maximum deflection occurs i.e. centralised.

The flanges 1 are secured to the chords 10, 11 of the beam 23 using a bond means in the form of glue 5. A suitable type of two-part epoxy glue 5 is applied evenly to the underside of the flange 1, ensuring that the teeth 4 are also sufficiently covered by the epoxy glue The glued steel flanges 1 are pressed onto the top and bottom chords 10, 11 of the timber web 6 such that the teeth 4 extend into the web 6. As the teeth 4 have been coated with epoxy glue 5 clamping is only required during the initial application and pressing. Once each flange 1 is in position the reinforced beam 21 is ready for immediate use.

In an alternative embodiment (not shown) each flange 1 does not incorporate 00 teeth 4. The same fixing procedure is followed as above with the flanges 1 extending along 70-100% of the length of the timber beam 23. However, each Sflange 1 will need to remain clamped onto the timber beam 23 until the glue has set hard.

In a further embodiment (not shown) pre-drilling holes into the timber web 6 to 00 accommodate the teeth 4 ensures a more dense timber and larger fixing teeth 4 c can be selected.

oo 0In both the above embodiments it is assumed that the timber beam 23 will be laid Shorizontal for the purposes of the construction of the reinforced beam 21.

Steel cold-formed nail plates can also be attached to either end of the reinforced beam 21 to improve the structural performance or for aesthetic reasons.

In the embodiments shown in figures 4, 5 and 7 to 13 the fundamental geometry and load bearing capacity remains the same as for the embodiment shown in figures 1 and 6. These variables have been developed to improve the performance of the timber beam 23 for varying structural circumstances.

Figure 4 illustrates a reinforced beam 21 comprising a timber beam 23 formed from two beam members 25. In this embodiment each flange 1 has the teeth 4 arranged so as to provide two lines of teeth extending along the longitudinal length of the flange 1.

Figure 5 illustrates a reinforced beam 21 in the form of an I-beam. In this embodiment each side of each flange 1 extends beyond the width of the timber beam 23.

Figure 7 is similar to the embodiment shown in figure 4 with the exception that the beam members 25 are in spaced relation. Hence when the reinforced beam 21 is assembled a cavity 27 will be formed between the two beam members This will allow an increase in size of the reinforced beam 21 without unduly increasing its weight.

-11 00 Figure 8 is similar to the first embodiment with the addition of a beam member to the top chord 10 of the main beam member 25. This is achieved using a flange la having teeth 4 extending from each side of the flange 1a.

Cc Figure 9 is similar to the first embodiment. In this embodiment the top chord and bottom chord 11 each incorporate a recess 29 to accommodate the oo 00 thickness of the flange 1. This will allow each flange 1 to be relatively flush with C the respective chord 10, 11 when in place.

oo 0Figure 10 is similar to the first embodiment with the addition of a veneer 9 fixed N to each face of the timber beam 23, improving the aesthetics of the reinforced beam 21.

Figure 11 shows a reinforced beam 21 having a C cross section. To achieve this, one side of each flange 1 extends beyond the width of the timber beam 23.

Figure 12 shows a reinforced beam 21 formed by joining two beam members along their chords. In this embodiment the flange la has teeth 4 extending from each side.

Figure 13 shows a beam 23 having a chamfered end 13. In this embodiment, the flange lb extending along the top chord 10, has a bend 12 formed therein so as to accommodate the profile change of the chord The use of a combination of blunt fixing teeth, steel flanges and epoxy glue allows for a variety of high strength joint formations (see Figs 1 and 4 to 13), this in turn eliminates the requirement for the timber to be precisely machined to suit the flanges prior to installation.

A timber beam reinforced with steel flanges is an appropriate addition to the building industry in terms of strength, stiffness, durability and load carrying capacity.

-12- 00 SModifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.

0Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood oO 5 to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

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Claims

4. The reinforced beam according to claim 3 wherein the beam members are held in spaced arrangement by the at least one strengthening member. The reinforced beam according to claim 1, 2, 3 or 4 wherein the strengthening member is in the form of a steel plate or strip.
6. The reinforced beam according to any one of the preceding claims wherein the at least one strengthening member is secured to the beam using a securing means.
7. The reinforced beam according to claim 6 wherein the securing means comprises a plurality of teeth extending from a side of the strengthening member, the teeth extending into the beam when the strengthening member is secured thereto.
8. The reinforced beam according to claim 7 wherein an end of each tooth, remote from the strengthening member, is shaped so as to reduce the likelihood of jeopardising the overall integrity of the beam.
9. The reinforced beam according to claim 7 or 8 wherein there are 1-15 teeth per metre along the strengthening member. -14- o00
010.The reinforced beam according to claim 7, 8 or 9 wherein the length of each tooth is between 10mm-50mm.
11.The reinforced beam according to any one of claims 7 to 10 wherein the teeth Sextend substantially in a single line along the longitudinal length of the supporting member. 00oo
12.The reinforced beam according to any one of claims 7 to 10 wherein the teeth Sextend across and along the strengthening member. 00oo S13.The reinforced beam according to any one of claims 7 to 12 wherein the teeth are arranged in a uniform repetitive pattern.
14.The reinforced beam according to any one of the preceding claims wherein a plurality of strengthening members are secured to the beam, the strengthening members being secured to opposed sides of the beam. reinforced beam according to claim 14 wherein the plurality of strengthening members extends along 70-100% of the length of the beam.
16.The reinforced beam according to claim 14 or 15 wherein each strengthening member is secured to the top and bottom chords of the beam.
17.The reinforced beam according to any one of the preceding claims wherein the beam is recessed to accommodate the thickness of the at least one strengthening member such that when in position the strengthening members are flush with the surface of the beam.
18.The reinforced beam according to any one of claims 7 to 17 wherein the plurality of teeth extend from both sides of the strengthening member.
19.A reinforced beam having a length of cold or hot-formed steel flange extending longitudinally along each of a top chord and a bottom chord of a timber beam, wherein each flange is secured to the beam with glue. o00 reinforced beam according to claim 19 wherein each flange includes a plurality of fixing teeth in the form of nails, spikes or pins.
21.The reinforced beam according to claim 20 wherein the fixing teeth are Sformed in the flange during manufacture. 00oo 5 22.The reinforced beam according to claim 20 wherein the teeth are welded onto ,Ithe flange. 00 23.The reinforced beam according to claim 19, 20, 21 or 22 wherein a web section of the beam is hardwood, softwood, glulams, laminated timber, finger jointed timber or other timber products.
24.The reinforced beam according to any one of claims 20 to 23 wherein the teeth are ordered in a single line along the flange numbering between 1-15 per metre. reinforced beam according to any one of claims 20 to 24 wherein the remote end of each tooth is relatively blunt.
26.The reinforced beam according to any one of claims 20 to 24 wherein the remote end of each tooth is tapered with a twist and a sharp end.
27.The reinforced beam according to any one of claims 19 to 26 wherein the glue used to bond the flange to the timber web section is a 2 part epoxy glue, which is spread evenly over the teeth and the surface of the flange from which the teeth extend.
28.A reinforced beam comprising a beam having at least one strengthening member secured to the beam using securing means, the securing means being in the form of a bond means to bond the strengthening member to the beam. -16- 00 S29.A reinforced beam as substantially herein described with reference to the drawings. 00 00 ^l