AU2009200214A1

AU2009200214A1 - Composite Beam

Info

Publication number: AU2009200214A1
Application number: AU2009200214A
Authority: AU
Inventors: Martin Holland
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-01-18
Filing date: 2009-01-19
Publication date: 2009-08-06

Description

P/00/011 28/5/91 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Martin Holland Actual Inventor Martin Holland Address for service is: WRAYS Ground Floor, 56 Ord Street West Perth WA 6005 Attomey code: WR Invention Title: Composite Beam The following statement is a full description of this invention, including the best method of performing it known to me: 1 2 Composite Beam Field of the Invention 5 The present invention generally relates to a design to improve shear transfer for concrete slabs. In particular, the invention provides a composite section using serrated beams, reinforcement mechanisms and concrete to achieve increased strength capabilities. The invention also provides a method of achieving composite interaction using an assembly of serrated beams, 10 concrete components, reinforcement members and/or shear transfer mechanisms. Background Art 15 There are several methods available for builders requiring composite sections, the majority being for the construction of floors and walls. For the purposes of providing a structurally sound composite section existing techniques were examined and a number of limitations were identified in relation to each method (as described below), which formed the impetus for 20 researching and developing an alternative model. US patent 3,263,387 to Simpson, claims a non-symmetrical beam having a lineal edge and a serrated edge, with attached steel flanges to the upper and lower planes of the beam. 25 The disadvantages identified in this model include: " There being no provision for transferring shear loads from the concrete to the beam for composite interaction to occur. " Compression loads that are applied to the attached flat plate will cause buckling to occur between the web posts. 30 US patent 4,416,199 to Fiergolla describes a compound girder with separate web sections bolted to the base of the steel member with the top of the webs (serrated edge) embedded in concrete to form ceiling panels.

3 The disadvantages identified in this model include: * Bolting the webs together is a complicated process, is time consuming and resultantly expensive. * That bolts can impose limitations to the spanning capacity when 5 attempting to increase the strength of the section. . There is no mechanism for achieving the transfer of shear flow in this method. US patent 4,115,971 to Varga describes the concept of embedding a 10 castellated beam into concrete, with the webs embedded in the concrete. Horizontal round bars are used as a sole connector and are placed at 90 degrees to the web posts to provide an anchor to the concrete. The disadvantages identified in this method include: * The castellated webs are extremely flexible, limiting the ability of the 15 section to span between supports. To counteract this the weight of the section would need to be increased. * Difficulty in relocating or handling, as the section can be easily damaged due to the inherent flexibility of the design. * Requires a wide web post design to provide an adequate area to fix the 20 anchors, creating bending moments at the base of the web posts. US patents 5,207,045, 5,669,197 and 6,708,459 82 to Bodnar discloses a sheet metal member having a linear edge and a castellated edge with the webs cast into concrete. The disadvantages identified in this method include: 25 * Flexibility of castellated webs limit the weight of the section and its ability to span between supports. * Difficulty in relocating or handling, as the section can be easily damaged due to the inherent flexibility of the design. * The folded lip pressed along the webs of the beam to transfer shear 30 flow to the concrete cannot easily be modified in size, which in turn limits the amount of shear load that can be transferred. * No inclusion of a mechanism to transfer shear load to the concrete.

4 * That the area between the apices is not connected (to allow for thermal expansion and contraction) and may not be sufficiently rigid. * That providing a wide web post design of this ratio in order to provide adequate space to fix the anchors may result in inducing bending 5 moments at the base of the web posts. US patent 5,152,112 to Eustace describes a method of constructing a composite girder primarily for bridges, whereby steel plates have square shaped studs welded thereon. The steel plates are placed opposite one 10 another and a reinforced concrete web is cast in position between the plates embedding the shear connectors within. The steel plates are wider than the concrete web and the composite section is placed horizontally to form the base of the bridge. The disadvantages identified in this design include: " The use of a large number of shear studs which are both labour and 15 cost intensive to apply. " The Individual studs may bend when transferring shear loads. " The studs do not increase the stiffness of the section. " The individual shear studs are expensive to manufacture. 20 US patent 5,220,761 to Selby is a light weight flooring system comprising a composite section, with additional shear connection in the form of inverted U shaped steel blocks attached to the primary support beams and a channel bar welded on top for embedding in the concrete. The disadvantages identified in this method include: 25 * Requires a large number of U-shaped channels to adequately transfer shear add to the expense of purchasing and fitting. * The continuous bar can flex between the studs reducing the stiffness of the section. " The individual U channels can bend under load limiting their ability to 30 transfer shear load. " The individual reinforcing bars can buckle between the U channels when handling the member prior to casting into the concrete.

5 US patent 2,479,476 to Cueni describes a composite section having a steel girder with a rectangular serpentine shaped shear connector and additional angles welded to the beam and the shear connection devices. The disadvantages identified in this method include: 5 a The individual shear connectors will limit the shear transfer load by bending under the load. * The shear connectors do not increase the stiffness of the section. a That the complex shape of the connectors will see an increase in the costs of manufacturing. 10 0 That attachment is only possible at the intermittent points of contact where the sinusoidal shear connector attaches to the beam limiting the strength of the shear connection. The preceding discussion of the background of the invention is intended only 15 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. 20 SUMMARY OF THE INVENTION It is an object of this invention to provide a reliable composite section using serrated beams, reinforcement mechanisms and concrete to achieve increased strength capabilities. 25 The advantages of this invention are found in the provision of an improved design for composite sections using easily recognisable readily available materials, suitable for a wide range of applications, including but not restricted to rooves, interior and exterior walls, decorated or conventional ceilings, 30 floors, bridges, stairways and retaining walls. In an embodiment the present invention provides an improved shear transfer mechanism for concrete slabs using serrated beams the shear transfer means 6 being from the form of arrangement of beams, shear connectors and ratio of cut in the serrated beam edge shear flow transfer means to transfer shear flow loads through these sections to the concrete to create a composite section of increased strength and capacity. 5 A primary serrated beam with a continuously attached reinforcing member is an essential shear flow interface in the construction of a composite section. Structural integrity may be achieved via the interface of shear flow loads between the reinforcement member and the concrete mix. 10 The present invention provides an improved shear transfer mechanism for composite sections comprising a plurality of primary, and a plurality of secondary beams, a shear transfer mechanism being formed by the arrangement of beams, and a plurality of shear connectors, the shear flow 15 transfer mechanism transferring shear flow loads through to the concrete of the composite section to create a composite section of increased strength and capacity. Preferably the primary beam will be serrated having a plurality of web posts 20 and webs. The present invention provides an improved shear transfer mechanism for composite sections comprising a plurality of serrated primary beams having a plurality of web posts and webs, and a plurality of secondary beams, a shear 25 transfer mechanism being formed by the arrangement of beams, shear connectors and ratio of serrations in the serrated primary beam edge, the shear flow transfer mechanism transfers shear flow loads through to the concrete of the composite section to create a composite section of increased strength and capacity. 30 A reinforcement member may be welded along each secondary beam. A reinforcement member may be welded along each primary beam.

7 The secondary beam may be serrated. Preferably the ratio and shape of the serrated webs is such that the 5 intersection of shear flow transfer occurs inside the section body either between or inside the web posts. In one aspect of the invention each web post has an increased width at the top of each web with narrower spaces in-between to create an enhanced 10 shear transfer point and an improved base for the attachment of reinforcement members. The essential benefits of the wider web posts (top) include the delivery of significantly improved shear flow transfer to the reinforcement members, and 15 a reduction in the occurrence of buckling between the webs, as shear is transferred from the flange of the primary beam within the body to the top of the web posts and the reinforcement member. In another aspect the web posts may be narrower at the top with a wider 20 flange at the base (in circumstances where services (e.g. plumbing) do not need to be accommodated) and buckling will not occur due to the strength of the concrete. The strengthening member may be in the form of a steel bar, flat or hollow 25 strip. Preferably the reinforcement member is in the form of a rounded rod having a ribbed circumference. This is used to strengthen the primary beam, increase the transfer of shear load from the beam to the concrete, resist tensile loads in 30 the concrete and provide a counteraction to stress occurring around the member.

8 Preferably each serrated primary beam will comprise single or multiple reinforcement members secured along its longitudinal length. The reinforcing member may be secured along an apex of the primary beam. 5 In another aspect secondary beams may be strengthened with a reinforcing member secured along its longitudinal length. The reinforcing member may be secured along the top flange of the secondary beam. In one aspect the continuous reinforcing member may be attached along the 10 face of an L, Z, T, angle, top hat, lintel and flat bar section, to create a composite or structural beam. In another aspect a variety of other suitably shaped and ribbed reinforcement members may substitute the more conventional design to include, but not 15 restricted to triangular, tubular, flat and angle bars, to increase resistance to bending, provide a shear flow interface and improve the strength and rigidity of the section. Preferably a plurality of serrated beam members will be used to transfer 20 tensile load and compression (from the base of the beam). In another aspect bearing capacity is provided by the vertical edge of the beam at the web post locations. 25 The present invention further comprises a composite section having a plurality of serrated primary and serrated or non serrated secondary beam members that may be made from steel and may be manufactured from light gauge cold or hot rolled steel including but not restricted to I, Z, C, or channel sections. 30 In another aspect the primary and secondary beams may comprise a concrete composite beam and may have a multiplicity of reinforcement members welded along the continuous length thereof.

9 According to another aspect of the invention the secondary beams may be in the form of various timber sections. Preferably a notch may be cut into the secondary beam to allow the primary 5 beam to be neatly positioned in-situ, and to enable easier fixing for other components like ceiling panels. The serrated edge of the beam may be made using CNC cutters or punches. Cutting through the middle of the chosen section effectively doubles the 10 number of beams as they are actually cut into two lengths, one side having a linear edge and the opposing side having a serrated edge. In another aspect of the invention the tops and sides of the serrated edge of the webs may be either pressed or folded over. 15 In a further aspect web post buckling may also be substantially minimised by pressing a corrugated patten into the web. According to the invention a composite section comprising a plurality of 20 primary beams and secondary beams are arranged in either a one way or two way direction with the primary and secondary beams placed at an angle to one another. In this arrangement the secondary beams may stop at right angles or may be placed in a continuous fashion with the beams passing though the open part of the arrangement. 25 Preferably one or more of the primary beams are serrated. One or more of the secondary beams may be serrated. 30 Preferably the primary and secondary beams are placed at a 900 angle to one another.

10 According to the invention a composite section comprising a plurality of serrated primary beams and secondary beams are arranged in either a one way or two way direction with the serrated primary and serrated and non serrated secondary beams placed at an angle to one another. In this 5 arrangement the secondary beams may stop at right angles or may be placed in a continuous fashion with the beams passing though the open part of the arrangement. Preferably the primary and secondary beams are placed at a 90* angle to one 10 another. The composite section comprises a suitable concrete mix to transfer compression or tensile load. 15 Preferably the concrete used may be high strength self-compacting fibre reinforced concrete. Suitable fibres may include, but are not restricted to, basalt, polypropylene glass or steel, carbon or Kevlar. In another aspect the concrete mix may also be in the form of a lightweight 20 cellular combination aggregate or standard concrete. Preferably a shrinkage control mesh is welded or hooked onto the reinforcing members as additional reinforcement where a standard aggregate concrete mix is used. 25 Concrete thickening is increased at the locality of the primary beam site to increase load capacity of the beam and in turn strengthen the composite section. 30 The composite section may be utilised in a number of orientations once the concrete has cured.

11 According to one aspect of the invention the composite section can be used concrete side face up or steel beam side face up, in a horizontal or reverse horizontal position, a vertical or reverse vertical position, a pitched or reverse pitched or upside down pitched position, an upside down or right way up 5 position, with the serrated beam (steel) side face up or as the base, with the concrete side face up or as the base. According to another aspect the composite section may be used to construct, but is not restricted to floors, walls, rooves, bridges, retaining walls and 10 ceilings. Preferably as a way of lifting and positioning the cured composite section, hinges or a lift bar may be bolted or embedded into the beams or concrete in pre-determined locations for attaching by cable to a small crane, the slab may 15 then be lifted, inverted and deposited into position. The present invention provides a composite section for use in the building industry, the composite section comprises an arrangement of; a plurality of primary beams; 20 a plurality of secondary beams orientated in a criss cross manner with respect to the primary beams; a shear transfer mechanism secured to at least one of the beams; and concrete; 25 wherein the shear load of each beam is transferred to the concrete. The primary beam may be serrated. Preferably a reinforcing member extends along the length of each primary 30 beam. A reinforcing member may extend along the length of each secondary beam.

12 The reinforcing member may provide the shear transfer mechanism. In another aspect of the invention the shear transfer mechanism may be secured to the reinforcing member. 5 The secondary beam may be serrated. The present invention also provides a strengthened beam comprising a beam having a reinforcing member secured along the beams longitudinal length 10 This invention provides a method of achieving composite interaction between a reinforcing mechanism (serrated beams and shear connectors) and concrete components. The benefits are outlined below: the ratio of cut of the serrations reduces bending forces, prevents 15 web post buckling, guarantees shear flow is transferred from the base and channelled upward to the concrete, and provides adequate access for other services (plumbing etc); shear load is transferred from the base or support points of the web 20 posts, and is channelled through to the top of the webs for transfer of shear flow from the reinforcement bar to the concrete, creating composite action; reinforcement members secured along the apex of the serrated beam 25 improves handling of the section prior to assembly, as the stiffness of the beam and concrete section is substantially increased; reinforcement members provide a guarantee for the section to self span between two support points and to resist negative moments by 30 providing tensile capacity to the base slab and importantly, cantilevers; 13 transfer of shear forces to the concrete is specifically due to the ribbing pattern on the surface of the reinforcement members; the top flange of the reinforced secondary beam is cast in the 5 concrete and provides negative lateral restraint in the span, an increased beam and section stiffness and tensile capacity for cantilevers; the arrangement of secondary beams support the framework, 10 provides support for the ceiling panels, and can be notched for the neat in-situ positioning of the primary beams; secondary beams are cast in the low position resulting in a minimal slab thickness and the potential for an increased number of levels for 15 a given height, step ups, corrugations, stairways, windows and other architectural profiles; a multiplicity of reinforcing members are welded in the serrated section of the plane to increase stiffness while still maintaining a 20 common serrated profile, minimise lateral torsional buckling both prior to and after casting, and provision of designs with an increased span; substituting conventional style reinforcing members with rectangular, square or circular hollow sections will increase resistance to lateral 25 torsional buckling due to the substantial resistance to buckling for a given weight resulting in the potential for an increased span size; the invention uses materials that are both readily available and well known by those in the building industry; 30 the methodology uses building techniques that are clearly recognisable and well practised by those in the trade; the composite section can be utilised in any number of combinations 14 and / or orientations, for example in: a horizontal or reverse horizontal position a vertical or reverse vertical position a pitched or reverse pitched or upside down pitched position 5 an upside down or right way up position with the serrated beam (steel) side face up or as the base with the concrete side face up or as the base. The present invention is a valuable and novel introduction to the building 10 industry exceeding current construction methods in relation to the utilisation of existing materials and production techniques, cost benefits, providing architectural flexibility and importantly by demonstrating structural integrity through sound engineering principles. 15 Methods to resist the development of bending loads that can develop at the low (open) section of the serrated beam are essential. Bending occurs when loads are transferred at the base towards the supporting points. In composite sections these bending moments can be significant and result in tearing or crushing at the corners of the castellation. Therefore, careful configuration of 20 the load transfer throughout the low points of the castellation is essential. A further consideration of serrated / castellated beam design is the development of buckling at the web-posts (high point of the serration), resulting from a lack of appropriate stiffening. This is addressed by looking at 25 the thickness of the web, length of the web post, height of the unrestrained web and provision of a wide enough area at the top of the web posts to weld or attach suitable reinforcement onto. It should be noted that in a composite section the top of the web post is cast 30 into the slab, and is not subject to buckling once it is cast into the level of the concrete. That is, the support provided by the slab may change the design parameters and the size requirements for the top of the web posts. However, there is considerable potential for the posts to buckle and remain in this 15 skewed position both prior to and after casting, which may affect the overall strength and performance of the section. Web post buckling may also be substantially minimised by pressing a 5 corrugated pattern into the web, which has the effect of increasing the out-of plane stiffness in the webs, however, it is a costly way of achieving the desired outcome. In another aspect of the design as a consequence of the wider web posts, the 10 webs themselves are closer together. This spacing allows the shear loads to transfer directly inside the body of the member. Shear load is transferred from the base of the support point of the web posts and channelled through to the top of the webs, and transfer of shear load 15 occurs through the reinforcement bars to the concrete creating an enhanced form of composite action. Reinforcement members transfer shear flow from the beam to the concrete, and have the additional benefit of increasing the stiffness of the serrated 20 beam prior to casting, resulting in the provision of a wider span and improved handling. Reinforcement members also control the bonding of concrete and steel during periods of thermal contraction and expansion. The mechanical bond for any 25 given reinforcement member can be measured or calculated as load carrying capacity per metre. To calculate the load that is applied by the differential expansion and contraction of both the steel and concrete is to ensure that the bond remains secure during fluctuations in temperature. 30 In summary, the calculation of known loads in addition to thermal loads and utilisation of appropriate continuous reinforcement will result in a composite section with high strength capacity, which can be designed for use in a wide range of applications. That is, without an appropriate form of reinforcement it 16 is doubtful whether the integrity and strength required of the composite section is satisfactorily achieved. BRIEF DESCRIPTION OF THE DRAWINGS 5 The invention wil be better understood by reference to the following descriptions of several specific embodiments thereof as shown in the accompanying drawings in which: 10 FIG I is a sectional side view of a composite section comprising a primary beam and a secondary beam according to a first embodiment of the invention; FIG 2 is a cross sectional view of figure 1; 15 FIG 3 is a sectional side view of a composite section comprising a primary beam and a secondary beam according to a second embodiment of the invention; 20 FIG 4 is sectional top view of a composite section comprising a plurality of primary and secondary as shown in figure 1; FIG 5 is sectional top view of a composite section similar to figure 4 but in a different arrangement; 25 FIG 6 is a sectional view depicting a type of serrated beam; FIG 7 is a sectional view of figure 6 with a reinforced member; 30 FIG 8 to 13 are cross sectional views of different shear key mechanisms secured to an end of a beam; 17 FIG 14 is a side view of a composite section according to a third embodiment of the invention having lift bar locations; FIG 15 is a side view showing a method of lifting the composite 5 section shown in figure 14; FIG 16 is a side view of the composite section shown in figure 14 in the final position; 10 FIG 17 is a cross sectional side view of a composite section according to a fourth embodiment of the invention; FIG 18 is a sectional side view of a composite section having a serrated beam with an improved profile according to a fifth 15 embodiment of the invention; FIG 19 is a sectional side view of a serrated beam shown in figure 18; 20 FIG 20 is a sectional side view of the beam in figure 19 having a reinforced member extending therealong; FIG 21 is a sectional side view of the reinforcement member; 25 FIG 22 is a cross sectional view of a composite section according to a sixth embodiment of the invention; FIG 23 is a sectional side view of a composite section according to a seventh embodiment of the invention; 30 FIG 24 is a sectional side view of a secondary beam having a reinforced member extending therealong; 18 FIG 25 to 32 are cross sectional side views of several shear key mechanisms secured to different beams; FIG 33 is another variation of a cross sectional side view of a shear 5 key mechanism secured to an angle beam for window lintels; FIG 34 is a cross sectional view of a composite beam according to an eighth embodiment of the invention; 10 FIG 35 is a cross sectional view of a shear key mechanism for a composite box beam; FIG 36 is a cross sectional view of a shear key mechanism for a composite I beam; 15 FIG 37 is a sectional side view of a composite section according to a ninth embodiment of the invention; FIG 38 is a sectional side view of a composite section according to a 20 tenth embodiment of the invention; FIG 39 is a sectional side view of a composite T section according to an eleventh embodiment of the invention; 25 FIG 40 is a sectional side view of a further serrated beam; FIG 41 is a cross sectional side view of a composite section according to a twelfth embodiment of the invention; 30 FIG 42 is a cross sectional view of a composite section according to a thirteenth embodiment of the invention. Best mode(s) for carrying out the Invention 19 Referring to figures 1 and 2 the invention according to the first embodiment is in the form of a composite section 9. The composite section 9 comprises a suitable concrete mix 25 poured into pre-prepared formwork 31 (not shown) 5 comprising a plurality of primary serrated beams 13 and a plurality of secondary beams 15 arranged in a criss cross manner whereby each primary serrated beam 13 is strengthened by a continuous reinforcement member 11. Figure 1 shows one of the plurality of primary beams 13 with one of the plurality of the secondary beams 15 positioned at right angles thereto. 10 Preferably the primary beams 13 and secondary beams 15 are formed from hot-formed or cold-formed light gauge steel. In an alternative aspect various suitable timber sections, other materials or a combination of both can also be used. 15 In the first embodiment each primary beam 13 is serrated and each secondary beam 15 is in a notch profile, as can be seen in figure 2. In other aspects each secondary beam 15 may either be serrated or non-serrated. 20 In this first embodiment each primary beam 13 is strengthened by the reinforcement member 11 secured along the apex of the primary beam 13 by welding thereto. In specific situations the secondary beam 15 may also comprise a 25 reinforcement member 11 as per the primary beam. Shrinkage control mesh 19 is secured to at least the upper surface of the composite section 9 by welding thereto. The mesh 19 could also overlap adjacent composite sections 9a. 30 in an alternative embodiment a self-compacting fibre concrete mix can be used, negating the need for shrinkage control mesh 19.

20 Once the primary beams 13 and secondary beams 15 are set out in the required arrangement the selected mix of concrete 25 is poured into the prepared formwork 31 (not shown) to a predetermined depth of between 50mm - 100mm (or to suit requirements) Concrete thickening occurs at the 5 sites of the primary beams 13 and the operator will ensure that this site is adequately covered with the concrete to create a composite action. If the slab is to be moved to an alternative site / position lift bars 35 (as shown in figures 14 to 16) are embedded or bolted with respect to a pivot point 43 10 section of the cured slab or alternatively the primary beams 13 or secondary beams 15. Once the concrete has cured a crane cable 45 is hooked onto the composite section 9 (opposite the lift bar location) and secured to a small crane. 15 The crane lifts the entire composite section 9 by hoisting the crane cable 45 vertically. Once in a vertical position the composite section 9 can be either inverted / rotated over via the pivot point 43. 20 in an alternative embodiment the composite section 9 can be used in another position i.e. ceiling or reverse vertical etc. The lift bars 35 and pivot points 43 can be adjusted accordingly. The crane rotates I inverts the composite section 9 and lowers it onto 25 concrete pilings or other support at the appropriate pre-chosen height from the ground. The composite section 9 may be supported at regular intervals, and due to the specific geometry of the serrated beams, the pilings will be placed at any point. The slab base i.e. the beam side 29 may now be at the top and the slab face 27 will now be at the base. 30 Depending on structural requirements the formwork can easily be configured in an arrangement to shape other structures i.e. stairways, retaining walls, bridges or other.

21 Figure 3 depicts a second embodiment of the composite section 9 wherein each secondary beam 15 is serrated to strengthen the composite section 9, and follows the same concepts, components and principles as the first 5 embodiment described in figure 1. Figures 4 and 5 demonstrate alternative arrangements for the layout of the primary beams 13 and secondary beams 15 as they are positioned onto the base of the formwork 31 (not shown). According to these specific applications, 10 the secondary beams 15 are at 90* angles to the primary beams 13. In an alternative embodiment the secondary beams 15 can also be placed in a continuous fashion with the primary beams 13 passing through the open section of the slab area. These arrangements have been developed to provide high structural performance for a variety of building requirements. 15 Figure 4 also shows the option to create slab penetrations 11 for services i.e. plumbing and the like. Figure 5 further shows the lift bar locations 35. Figure 6 illustrates a profile for a serrated primary beam 13 whereby each 20 web 18 has a wide base but converges towards the apex of the beam 13. This essentially equates to needing a shorter cutting distance and results in an improved base for shear transfer within the body of each web 18. Shear flow is channelled from the flange 37 of the beam to the webs. This is then transferred to the reinforcement member and the concrete (when the primary 25 beam 13 is assembled in the composite section 9). The top of the narrow web posts 18 will reduce the incidence of buckling and thus improve strength. The profile of the primary beam 13 allows selection of bearing locations to be made at all points of the bottom flange 37 of the under chassis as bending will 30 not occur due to the inherent strength of the section and is particularly useful in situations where service accommodation does not need to be provided.

22 Figure 7 further shows the profile of the webs 18 of the serrated primary beam 13 shown in figure 6, incorporating a reinforcement member 11 welded continuously along the entire length of the primary beam 13 to increase the strength. 5 The embodiment shown in figure 8 illustrates a reinforcement member 11 pressed into the fold of a primary beam 13, as an alternative form of strengthening the beam. 10 Figure 9 is a cross sectional view of the continuous reinforcement member 11 secured longitudinally along the entire length of the primary beam 13 which is in the form of a T section 67. The strengthened T section 67 can be used as a stand-alone structural member or as part of a composite section 9. 15 Figure 10 depicts a flat bar 11 secured along the entire length of the apex of a primary beam 13 which is in the form of a T section 67 to strengthen. The strengthened T section 67 can be used as a stand-alone structural member or as part of a composite section 9. 20 Figure 11 illustrates a primary beam 13 which is in the form of a T section 67 strengthened with multiple rows of reinforcement members 21. The strengthened T section 67 can be used as a stand-alone structural member or as part of a composite section 9. 25 Figures 12 and 13 show square hollow sections 51 welded longitudinally along the side of a primary beam 13 which is in the form of an angled member 53 (figure 12) and a T-section 67 (figure 13). In other aspects circular, square or rectangular hollow sections can be welded 30 onto the serrated primary beams 13 or angled members 53 thereby creating high lateral torsional resistance along the beam.

23 Figures 14, 15 and 16 depict the mechanisms for lifting and rotating / inverting the cured composite section 9 into position using a crane cable 45 which is attached to the section 9. Lift bars 35 are bolted or embedded to the composite section 9 (beam or concrete) at the pivot point 43 locations, the 5 section 9 is then hoisted vertically and moved into desired position by a small crane. Packers 47 may be used to support the section 9 in its final position. The embodiment shown in Figure 17 illustrates the arrangement of the composite section 9 depicting the layout of the formwork 31 for the concrete 10 25. A notch 23 has been cut into the secondary beam 15 to neatly accommodate in-situ the primary beam 13 providing a level profile, and as a platform for the attachment of further components i.e. ceiling panels. The embodiment in figure 18 depicts the components of the composite 15 section 9 illustrating a serrated primary beam 13 having a web profile wherein each web 17 is wider along the top . The essential benefits of the wider web posts along the top include the delivery of significantly improved shear flow transfer to the reinforcement members 11, and a reduction in the occurrence of buckling between the webs 17, as shear is transferred from the flange 37 of 20 the primary beam 13 within the body to the top of the web posts and the reinforcement member 11. Figures 19 and 20 show the cutting profile of the serrated edge with a wide web post 17 and a narrow base to be used in the composite section 9, as 25 described in figure 18. Shear load will be transferred from the flange of the beam 37 and channelled from within the body of the web through to the top of each web post 17 to the reinforcement member 11. This web profile (having a wider web post along the top and narrow space 30 between the base of the webs) 17 does not diminish beam strength and does enable greater transfer of shear flow to the reinforcement mechanisms due to the extended length along the top of the web posts.

24 The components for the embodiment shown in figure 18 follow the same principle concepts as the embodiment shown in figure 1 in the design of a composite section 9 5 Figure 21 depicts the profile of a typical reinforcement member 11. The ribbing pattern around the circumference of the bar is an essential element from which shear is transferred to the concrete and beam. Figure 22 is a cross sectional view of a composite section 9 showing concrete 10 25 thickening around the top of the web posts and reinforcement member 11. Figure 23 depicts a composite section 9 with a reinforced serrated secondary beam 15. 15 Figure 24 shows an I beam 55 with a reinforcement member 11 secured longitudinally along the entire length to increase strength. This assembly can be used as a stand-alone structural beam or part of a composite section 9.. The illustration in figure 25 shows anI beam 55 with three reinforcement 20 members 11 welded along the top flange. This formation can be used in a composite section or for all typically standard structural purposes. In figure 26 two rows of adjacent reinforcement members 11 are welded along the lower leg of an angle beam 53. The reinforced angle beam 53 is a more 25 cost effective and lighter alternative for a lintel formation used to support windows and doors, simultaneously providing the strength and rigidity expected for this area. Figure 27 shows two rows of reinforcement members 11 welded along the 30 lower leg of a Z section, as a strengthening agent.

25 Figure 28 shows a multiplicity of reinforcement bars 11 welded along a flat bar 57. The number of reinforcement members 11 used will be dependent on the structural situation. For instance, figure 43 shows two flat bars 57 each having two reinforcement bars 11 welded thereto. The flat bars are arranged 5 in a grid like manner (there may be a plurality) as may be the case for a foundation. As shown in figure 29, a top hat section 51 strengthened with two rows of continuous reinforcement members 11 to be used as a structural column or 10 beam or other. The embodiment in figures 30, 31 and 32 illustrate a multiplicity of reinforcement members 21 secured continuously along an I beam 55 to increase strength. 15 Figure 33 depicts an angled member 53 strengthened with two rows of reinforcement members 11 positioned along the base of the angle 53 in a continuous fashion. The reinforced section is used to strengthen brickwork 61 and may be useful around window lintels. 20 Figure 34 illustrates an alternative form of composite section 9 fashioned as a beam. Shear is transferred from a flat bar 57 to the concrete 25 through the assemblage of reinforcement members 11 at the base of the section. Shrinkage control mesh 19 is positioned along the top of the section to ensure 25 a rigid surface. Figure 35 illustrates a concrete box beam 65 having reinforcement members 11 positioned at opposing sides under flat bars 57 at the top and bottom flanges and having a concrete web 25. This embodiment can be used as a 30 standalone structural or composite beam. Figure 36 shows a concrete I beam 63. A multiplicity of reinforcement members 21 are positioned under the opposing top and bottom flat bar 57 26 flanges. The web comprises a concrete mix 25 and the design is suitable for utilisation in situations where other conventional beams of this size are selected or as a composite section. 5 The embodiment in figure 37 shows a composite section 9 having an I beam 55 as the primary beam (as in figure 25). Reinforcement members 11 are used to strengthen the beam 55. The section 9 follows the same concepts and principles as described in the first embodiment with the inclusion of permanent formwork 31 remaining in situ. 10 The embodiment in figure 38 is essentially the same as figure 37 showing the inclusion of a notch 23 cut into the secondary beam 15 to create a neat positioning of, and an even profile for the reinforced I beam 55 (as shown in figure 25). The composite section 9 follows the same components and 15 principles as the first embodiment. As depicted in figure 39 the embodiment shows a concrete I beam 63 used to strengthen a composite section 9. The components and principles are the same as for the first embodiment showing the versatility of the beam design 20 that can be used for a wide range of building requirements. As shown in the embodiment in figure 37 the formwork 31 is left in situ. The embodiment in figure 40 illustrates the improved profile of the serrated primary beam 13 having a wide web post 17 along the top to enhance shear 25 flow transfer to a flat bar 51. This profile will guarantee a decrease in buckling due to the increased width along the top of the web posts 17 and the resultant shorter distance between the webs. This beam can be used as a standalone structural member or as part of a composite section 9. 30 Figures 41 and 42 show a serrated beam 13 having a wide web post 71 along the top of the webs, designed to strengthen brickwork 61. Depending on structural circumstances additional flat bars 51 or, rectangular, circular or hollow sections may be specifically positioned to ensure structurally rigidity.

27 This beam can be used as a stand-alone structural member or as part of a composite section 9. The development of a reinforced composite section utilising concrete, 5 serrated beams, reinforcement members and other shear key mechanisms is an appropriate addition to the building industry, in terms of providing a relatively light weight, low cost, demonstrably structurally sound, mobile system appropriate in a market concerned with careful use of resources and suitable for a wide range of construction applications. 10 Each serrated primary beam 13 and serrated secondary beam 15 can be manufactured by cuffing or punching a serrated edge along the centre of the entire length of the chosen steel section. This creates a beam with one linear edge and one serrated or zigzag edge. An important outcome of this method 15 is the reduction in resources and expense as two serrated beams are produced. Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention. 20 Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. 25

Claims

1. An improved shear transfer mechanism for composite sections comprising a plurality of serrated primary beams having a plurality of 5 web posts and webs, and a plurality of secondary beams, a shear transfer mechanism being formed by the arrangement of beams, shear connectors and ratio of serrations in the serrated primary beam edge, the shear flow transfer mechanism transfers shear flow loads through to the concrete of the composite section to create a composite section of 10 increased strength and capacity.

2. The improved shear transfer mechanism according to claim 1 wherein a reinforcement member is welded along each secondary beam. 15

3. The improved shear transfer mechanism according to claim 1 or 2 wherein a reinforcement member is welded along each primary beam.

4. The improved shear transfer mechanism according to claim 1, 2 or 3 wherein the secondary beam is serrated. 20

5. The improved shear transfer mechanism according to any one of the preceding claims wherein the ratio and shape of the serrated webs is such that the intersection of shear flow transfer occurs inside the section body either between or inside the web posts. 25

6. The improved shear transfer mechanism according to any one of the preceding claims wherein each web post has an increased width at the top of each web with narrower spaces in-between to create an enhanced shear transfer point and an improved base for the attachment 30 of reinforcement members. 29

7. The improved shear transfer mechanism according to any one claims 1 to 6 wherein each web post is narrower at the top with a wider flange at the base. 5

8. The improved shear transfer mechanism according to any one of the preceding claims wherein the strengthening member is in the form of a steel bar, flat or hollow strip.

9. The improved shear transfer mechanism according to any one of 10 claims 3 to 8 wherein the reinforcement member is in the form of a rounded rod having a ribbed circumference.

10. The improved shear transfer mechanism according to any one of claims 3 to 9 wherein each serrated primary beam will comprise single 15 or multiple reinforcement members secured along its longitudinal length.

11. The improved shear transfer mechanism according to any one of claims 3 to 10 wherein the reinforcing member is secured along an apex of the primary beam. 20

12. The improved shear transfer mechanism according to any one of the preceding claims wherein the secondary beams is strengthened with a reinforcing member secured along its longitudinal length. 25

13. The improved shear transfer mechanism according to claim 12 wherein the reinforcing member is secured along the top flange of the secondary beam.

14. The improved shear transfer mechanism according to any one of 30 claims 3 to 13 wherein the continuous reinforcing member is attached along the face of an L, Z, T, angle, top hat, lintel and flat bar section, to create a composite or structural beam. 30

15. The improved shear transfer mechanism according to any one of the preceding claims wherein a plurality of serrated beam members will be used to transfer tensile load and compression (from the base of the beam). 5

16. The improved shear transfer mechanism according to any one of the preceding claims wherein bearing capacity is provided by the vertical edge of the beam at the web post locations. 10

17. The improved shear transfer mechanism according to any one of the preceding claims further comprising a composite section having a plurality of serrated primary and serrated or non serrated secondary beam members that is made from steel and is manufactured from light gauge cold or hot rolled steel. 15

18. The improved shear transfer mechanism according to any one of the preceding claims wherein the primary and secondary beams comprise a concrete composite beam and may have a multiplicity of reinforcement members welded along the continuous length thereof. 20

19. The improved shear transfer mechanism according to any one of the preceding claims wherein the secondary beams is in the form of various timber sections. 25

20. The improved shear transfer mechanism according to any one of the preceding claims wherein a notch is cut into the secondary beam to allow the primary beam to be neatly positioned in-situ, and to enable easier fixing for other components like ceiling panels. 30

21. The improved shear transfer mechanism according to any one of the preceding claims wherein the tops and sides of the serrated edge of the webs is either pressed or folded over. 31

22. The improved shear transfer mechanism according to any one of the preceding claims wherein the web post buckling is substantially minimised by pressing a corrugated pattern into the web. 5

23. A composite section comprising a plurality of primary beams and secondary beams are arranged in either a one way or two way direction with the primary and secondary beams placed at an angle to one another. 10

24. The composite section according to claim 23 wherein one or more of the primary beams are serrated.

25. The composite section according to claim 23 or 24 wherein one or more of the secondary beams is serrated. 15

26. The composite section according to claim 25 wherein the primary and secondary beams are placed at a 90" angle to one another.

27. A composite section comprising a plurality of serrated primary beams 20 and secondary beams are arranged in either a one way or two way direction with the serrated primary and serrated and non-serrated secondary beams placed at an angle to one another.

28. The composite section according to claim 27 wherein the primary and 25 secondary beams are placed at a 90* angle to one another.

29. The composite section according to claim 27 or 28 comprising a suitable concrete mix to transfer compression or tensile load.

30 30. The composite section according to claim 29 wherein the concrete used is high strength self-compacting fibre reinforced concrete. 32

31. The composite section according to claim 29 wherein the concrete mix is in the form of a lightweight cellular combination aggregate or standard concrete. 5

32. The composite section according to any one of claims 27 to 31 wherein a shrinkage control mesh is welded or hooked onto the reinforcing members as additional reinforcement where a standard aggregate concrete mix is used. 10

33. The composite section according to any one of claims 27 to 32 wherein concrete thickening is increased at the locality of the primary beam site to increase load capacity of the beam and in turn strengthen the composite section. 15

34. The composite section according to any one of claims 27 to 33 wherein hinges or a lift bar is bolted or embedded into the beams or concrete in pre-determined locations allowing section to be lifted, inverted and placed into position. 20

35. An improved shear transfer mechanism for composite sections comprising a plurality of primary, and a plurality of secondary beams, a shear transfer mechanism being formed by the arrangement of beams, and a plurality of shear connectors, the shear flow transfer mechanism transferring shear flow loads through to the concrete of the composite 25 section to create a composite section of increased strength and capacity.

36. The improved shear transfer mechanism according to claim 35 wherein the primary beam will be serrated having a plurality of web posts and 30 webs.

37. A composite section for use in the building industry, the composite section comprises an arrangement of; 33 a. a plurality of primary beams; b. a plurality of secondary beams orientated in a criss cross manner with respect to the primary beams; c. a shear transfer mechanism secured to at least one of the 5 beams; and d. concrete; wherein the shear load of each beam is transferred to the concrete.

38. The composite section according to claim 37 wherein the primary beam 10 is serrated.

39. The composite section according to claim 37 or 38 wherein a reinforcing member extends along the length of each primary beam. 15

40. The composite section according to claim 37, 38 or 39 wherein a reinforcing member extends along the length of each secondary beam.

41. The composite section according to claim 37, 38, 39 or 40 wherein the reinforcing member provides the shear transfer mechanism. 20

42. The composite section according to claim 37, 38, 39 or 40 wherein the shear transfer mechanism is secured to the reinforcing member.

43. The composite section according to any one of claims 37 to 42 wherein 25 the secondary beam is serrated.

44. A strengthened beam comprising a beam having a reinforcing member secured along the beams longitudinal length 30

45. An improved shear transfer mechanism as substantially herein described with reference to the drawings.

46. A composite section as substantially herein described with reference to the drawings.