PORTAL FRAME AND METHOD OF ASSEMBLY

TECHNICAL FIELD

Described herein is a portal frame and method of assembly. More specifically, a wood composite portal frame and method of assembly is described.

BACKGROUND ART

A portal frame is used in construction to manufacture an engineered opening in a structure. The opening may be located on a building exterior and the opening filled with a window or doors. The portal frame may instead be located in a building interior and the portal frame used to provide strength to a void space. Portal frames may also be used in exterior locations e.g. for a car port. An aim of portal frames is to provide strength about an opening in a wider structure such as a wall.

Portal frames in the art are typically manufactured from steel or wood.

Steel is the most common material used for portal frames, usually using steel parallel flange channels (PFCs). Steel provides known high strength and stiffness hence is a useful material for portal frames. Steel however has the drawback of requiring alternative skills to the builder that normally constructs the wider building. Bringing in other skills can disrupt construction speed and provides less autonomy for the builder. Difficult to reach sites may also make prefabricated steel structures more difficult or even impossible to get to a site e.g. through a lack of crane access. Steel is also an increasingly expensive material to use and the manufacture of steel carries a significant environmental and carbon footprint.

Wood is a common material that builders are very familiar with and hence which builders will tend to work with if given the choice. Wood is durable and sustainable. Compared to steel, wood is generally lower cost and has a lower environmental and carbon footprint than steel. The use of wood for portal frames is however more limited since wood alone often does not meet the necessary bracing strength for many applications, mostly due to a low stiffness of wood relative to steel and due to movement post installation of wood unlike steel. Sometimes wood portal frames are used with added bracing features such as haunch and apex brackets or knee braces. These solutions may be useful but these detract from the portal frame aesthetics and introduce more parts and labour to assemble the portal frames. This bracing may also interfere with items installed in the portal blocking window and door movement.

Laminated wood beams offer greater strength and consistency over non-laminated wooden beams. Laminated wood beams are formed from a series of timber lamella adhered together in layers. The result is a higher and more consistent strength beam along the beam length particularly as measured in terms of stiffness or modulus of elasticity. Despite the improvement offered by laminated wood beams, steel in portal frames may still offer sufficient benefits to be preferable to laminated wood beams. Composite wood and steel beams have been described in the art but, in the applicant's experience, have not had wide acceptance at least in New Zealand. The applicant produces a laminated wood composite beam which uses steel bars located in a slot in the top and bottom shorter width sides of an elongated wood laminated beam. This beam has proven successful both for achieving higher strength levels and, also for doing so using timber that may otherwise have been downgraded to non-structural applications. Since composite wood and steel beams use far less steel than a pure steel beam, the drawbacks of steel use are reduced while the benefits of steel enhances the wood beam properties.

Other art composite timber and steel beam publications that the applicant is aware of have drawbacks in terms of strength or aesthetics. They also do not teach or describe use of the composite beams in portal frames and how to effect coupling of the composite beam to portal columns.

Problems in the art therefore relate securement of a composite beam to a column to form a structural portal frame. A further problem relates to reducing portal frame cost, particularly given the increasing cost of steel. A further problem relates to providing an alternative portal frame that avoids or minimises third party involvement on a build site beyond a builder. A further problem may be to improve on or overcome the limitations of wooden portal frames. A further problem may relate to the provision of lower environmental and lower carbon footprint materials to steel-only portal frames. A further problem may relate to minimising the number of parts necessary. A yet further problem may relate to providing an aesthetic finish to a portal frame that does not interfere with movement of a door or window installed within the portal frame.

Further aspects and advantages of the portal frame and method of assembly will become apparent from the ensuing description that is given by way of example only.

SUMMARY

Described herein is a portal frame comprising columns, a beam and couplers, the couplers configured to securely couple the beam ends to the columns and thereby define a portal frame and clear opening width and clear opening height therein. A method of assembling the portal frame is also described along with a related kit of parts.

In a first aspect, there is provided a portal frame, that, when assembled comprises: a first column and a second column, the first column and the second column defining a clear opening width between the first column and the second column, the first column and the second column having an upper end and a lower end; a beam, the beam having a first beam end and a second beam end, the first beam end coupled about the upper end of the first column and, the second beam end coupled about the upper end of the second column, wherein a distance between the beam and the lower end of the first column or lower end of the second column defines a clear opening height; wherein: the first column and the second column are substantially manufactured from wood; and the beam is a composite made from laminated wood and steel reinforcing; wherein the portal frame comprises a first coupler and a second coupler, the first coupler coupling the upper end of the first column to the first beam end; and, the second coupler coupling the upper end of the second column to the second beam end.

In a second aspect, there is provided a method of assembly a portal frame comprising: selecting a portal frame substantially as described above; and coupling the first coupler to the upper end of the first column and the first beam end; and coupling the second coupler to the upper end of the second column and the second beam end.

In a third aspect, there is provided a kit of parts comprising: the portal frame substantially as described above; and a set of instructions on assembly of the portal frame.

Advantages of the portal frame, method of assembly and kit of parts described above may include:

Providing a coupler to secure a beam to a column to form a structural portal frame;

Reducing portal frame cost, particularly given the increasing cost of steel;

Providing an alternative design of portal frame that avoids or minimises third party involvement on a build site beyond a builder;

Improving or overcoming the limitations of wooden portal frames, particularly around strength and stiffness;

Providing a lower environmental and lower carbon footprint portal frame to steel only portal frames;

Minimising the number of parts necessary to produce a portal frame;

Avoiding the need for nailing plates as used for steel portals to fix linings, claddings or trimming openings;

Providing an aesthetic finish to a portal frame that does not interfere with movement of a door or window installed within the portal frame.

Beam length and column height can be altered on site with a timber saw as there is no need to cut or weld steel;

A column can continue upward beyond the beam top if required to meet a top plate and replace/eliminate trimming studs;

The steel components used in the described portal frame are simple to fabricate and can easily be mass produced;

Any column dimension can be used and the column and beam do not need to match in width;

The portal frame described is easy to assemble on site with minimal work to a dependable standard (i.e., relative fool proof and inspections are straightforward if required);

No adhesive is needed to couple the columns and beam;

There is no interference with cladding or linings as the portal frame does not require side fixings;

There is minimal interference with framed opening or space above (~5mm plate thickness only).

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the portal frame and method of assembly will become apparent from the following description that is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 illustrates a perspective view from above of an example of an assembled portal frame;

Figure 2 illustrates a front elevation view of the assembled portal frame;

Figure 3 illustrates a plan elevation view of the assembled portal frame;

Figure 4 illustrates a detail perspective view from above of the connection detail for one side of the assembled portal frame between a column and a beam;

Figure 5 illustrates a detail perspective view from below of the connection detail for one side of the assembled portal frame between a column and the beam;

Figure 6 illustrates a detail perspective view from above of a coupler used about the connection detail of the portal frame between a column and the beam;

Figure 7 illustrates a detail perspective view from below of a coupler used about the connection detail of the portal frame between a column and the beam;

Figure 8 illustrates an exploded perspective view from above of the connection detail of the assembled portal frame between a column and the beam;

Figure 9 illustrates a detail plan view of the connection detail of the assembled portal frame between a column and the beam;

Figure 10 shows section A-A view of Figure 9 from a front elevation of the assembled portal frame between a column and the beam;

Figure 11 shows a detail front elevation view D from Figure 10 of the connection detail between the coupler and the beam;

Figure 12 shows a detail front elevation view B from Figure 10 of the connection detail between the coupler, column and the beam;

Figure 13 shows an alternative example of portal frame in a perspective exploded view from above and in front; Figure 14 shows a side elevation exploded view of the alternate example;

Figure 15 shows a perspective exploded view from above and behind of the alternate example;

Figure 16 shows a perspective assembled view from above and behind of the alternate example;

Figure 17 shows a rear elevation view in assembled form of the alternate example;

Figure 18 shows a side elevation view in assembled form of the alternate example;

Figure 19 shows a perspective exploded view from above and in front showing a further example using a foot for the column;

Figure 20 shows a perspective assembled view of the coupling assembly only with the beam and column removed and showing the foot for the column;

Figure 21 shows a perspective assembled view of the coupling assembly with the beam and column shown and showing the foot for the column;

Figure 22 shows an example of the portal used to form a single car garage portal opening;

Figure 23 shows an example of the portal used to form a small infill portal;

Figure 24 shows an example of the portal used to form a three storey apartment bracing portal;

Figure 25 shows an example of the portal used to form an alternative apartment bracing portal;

Figure 26 shows an alternative coupler assembly in a perspective view from above;

Figure 27 shows a plan view of the steel reinforcing, threaded bar and an alternative profiled anchor member;

Figure 28 shows a detail plan view of the steel reinforcing and profiled anchor member;

Figure 29 shows a perspective front view, plan elevation view and perspective side view of an alternative steel reinforcing profile to mate with the profiled anchor member;

Figure 30 shows a front elevation view of the assembled portal frame along with end elevations on either side and a plan elevation view;

Figure 31 shows the same front, side and plan elevations as Figure 30 but with the parts in a full assembly exploded view;

Figure 32 shows detail views 1, 2 and 3 indicated in Figures 30 and 31;

Figure 33 shows perspective views from above (left) and below (right) of the assembled beam and column joint;

Figure 34 shows a perspective view from underneath in a partly exploded form and Figure 34 shows Detail 4;

Figure 35 shows a section view of the beam to column image of Figure 33, in Figure 35 showing on the left an end view and on the right a section view along section line A-A;

Figure 36 shows the beam to column image of Figure 33 with the column and beam removed to expose the coupler and other parts;

Figure 37 shows a further example of the load bearing member steel bracket;

Figure 38 shows images of the second load bearing member steel bracket;

Figure 39 shows the footplate in more detail;

Figure 40 shows a detail view of the top corner of a column and the rebate inserted for the bracket; and

Figure 41 shows an end detail of the beam.

DETAILED DESCRIPTION

As noted above, described herein is a portal frame comprising columns, a beam and couplers, the couplers configured to securely couple the beam ends to the columns and thereby define a portal frame and clear opening width and clear opening height therein. A method of assembling the portal frame is also described along with a related kit of parts.

For the purposes of this specification, the term 'about' or 'approximately' and grammatical variations thereof mean a quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a reference quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length.

The term 'substantially' or grammatical variations thereof refers to at least about 50%, for example 75%, 85%, 95% or 98%.

The term 'comprise ¹ and grammatical variations thereof shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements.

Reference may be made in the singular to a connection or coupler but as may be appreciated, the portal frame comprises two couplers, one on each column. Reference to the singular or plural as used particularly in the context of the columns, beam ends and couplers should not be seen as limiting. One connection may be a mirror image of the other.

Terms including up, down, upper, lower and grammatical variations thereof refer to the portal frame in an assembled position defining a clear opening width and clear opening height therein. Portal Frame

In a first aspect, there is provided a portal frame, that, when assembled comprises: a first column and a second column, the first column and the second column defining a clear opening width between the first column and the second column, the first column and the second column having an upper end and a lower end; a beam, the beam having a first beam end and a second beam end, the first beam end coupled about the upper end of the first column and, the second beam end coupled about the upper end of the second column, wherein a distance between the beam and the lower end of the first column or lower end of the second column defines a clear opening height; wherein: the first column and the second column are substantially manufactured from wood; and the beam is a composite made from laminated wood and steel reinforcing; wherein the portal frame comprises a first coupler and a second coupler, the first coupler coupling the upper end of the first column to the first beam end; and, the second coupler coupling the upper end of the second column to the second beam end.

Clear Opening Width and Clear Opening Height

When defining clear opening height herein, this is described as being the distance between the beam and column lower end or ends for simplicity. In practice the lower ends of the columns will be fixed to a substrate such as ground, timber flooring or concrete. The ground or flooring then sets the lower level of the clear opening height which in turn may not be the absolute lower end of the column.

The clear opening width may be measured between an inner side of each of the columns.

The clear opening height may be measured between a lower side of the beam and the column lower end(s) or ground level.

Structural

The beam and portal frame as a whole may be structural. The term 'structural' in the context of this specification means the beam and portal frame as a whole may achieve SG8 standard in terms of strength and stiffness/elasticity. The beam and portal frame may achieve at least SG9, or SG10, or SG11, or SG12, or SG13, or SG14, or SG15, or SG16, or SG17, or SG18 standard. In the inventor's experience, it would be possible to achieve structural standards well in excess of SG18. For example SG50 could be achieved if desired.

Alternatively, the beam achieves SG8 or higher standard and uses wood for the beam that, without steel reinforcing would have a structural grade of less than SG8 or less than SG7, or less than SG6, or less than SG5.

A further aspect of the above described beam is that the overall beam has greater uniformity in strength and stiffness than a comparable wood only laminate beam. Wood inherently has varying properties being a natural material. The combination of steel reinforcing and wood laminate means that the final beam is very uniform along its length in terms of strength and elasticity or, at least more uniform than a usual range of averages for a batch of wood only laminate beams.

Further, the term structural also refers to modulus of elasticity about bending in a major or minor axis. As may be appreciated, bending of a beam may occur about one or both of a major (X-X) or minor (Y-Y) axis from a force. The extent of bending may be measured as a deflection.

The beam described herein increases the strength and stiffness in bending about both major X-X and minor Y-Y axes. The beam described herein increases strength and stiffness more efficiently than prior art sandwich style beams with a steel plate. This is understood to be because the steel reinforcing described herein is located away from a neutral axis in both bending modes than a central steel plate or layer thus experiences a greater amount of tension or compression in bending and hence reacts proportionately more to the tension or compression force. The beam design described however may mainly target bending about the major X-X axis.

Modulus of elasticity may be a useful comparison measure. The inventor has found that a beam manufactured from pure timber lamella that would normally achieve SG6 standard (hence have a modulus of elasticity of 6GPa) can be increased to a modulus of elasticity of 20GPa or higher about a major X-X axis by use of the design described herein and a modulus of elasticity about the minor Y-Y axis increased to around 8~10GPa. This is understood to be a higher gain than that seen for prior art wood and steel sandwich style beams. The described beam and wooden columns use less steel than prior art steel portal or steel sandwich style portal frames.

Columns

As noted above, the columns used to form the portal frame may be substantially formed from wood. The columns may be formed from wood only. The columns may be formed from a laminated wood.

Each column may have an oblong cross-section shape. A column may have an inner face or surface that is on the portal interior and faces the opposing column inner face or surface. A column may have an exterior or outer face or surface opposite the inner face or surface. The column may have front and rear surfaces as well off set by 90 degrees from the inner and exterior faces. The distance from the inner face to the outer face across the front or rear surface may define the column width. The front and rear faces may be in the same plane as the portal opening while the inner and exterior faces are off set 90 degrees from the portal frame opening. Other shapes may be used without departing form the scope herein. Each column may extend to the clear opening height and an added portion of height to end flush with the top of the beam once the portal frame is coupled. Alternatively, the column or columns may extend above the top of the beam so as to extend beyond the beam top.

During installation, if the column height needs to be reduced, the installer may easily cut the column length shorter using a wood saw. No special equipment or skills beyond the builder are required. With a steel only portal, a height adjustment may require substantial work through use of sub-tradespeople, steel cutting and re-welding or re-fastening and possible additional transport of the steel in the portal to and from the work site multiple times. These challenges are avoided if the column can be cut using tools and trade skills already on a build site.

Wood Type

Wood that may be used to manufacture the elongate beam and columns may be the same as those already used in the art such as those from the Pinus genus, Pseudotsuga genus, Picea genus and many others. Specific examples include Pinus radiata, Douglas fir, spruce, larch, gum and so on. The plant species from which the wood may be produced is not understood to be critical to the beam described herein although, as may be appreciated, some woods are preferred for structural applications over other woods.

The wood may be treated for longevity and for use above or in ground.

Laminate beams such as those produced already by the applicant may be used to form the wood laminate beam albeit, that they are modified in accordance with the above description.

Beam

The term 'beam' is used herein to refer to an elongated length of laminated wood used in construction to support a load thereon e.g. to define a clear opening height below the beam. The beam may support a structural lateral or orthogonal loading or end on loading.

Beam Shape

The beam may have a generally oblong cross-section shape. This shape description is provided for ease of reading. It should be appreciated that the beam may have varying cross-section shapes and may even be square, circular or semi-circular, three-sided or with five or more sides. These additional shapes are intended to be covered herein and the gist of the beam described comprising a cross-section shape with recesses and steel reinforcing does not change due a change in beam cross-sectional shape.

A beam end may have an oblong cross-section shape, with an end face and a longitudinal length. The cross-section shape may comprise relatively shorter width sides and longer depth sides. Lamella Adherent

The beam laminated wood may be formed from multiple lamella. The multiple lamella may be adhered together using adhesives. The adhesives may be epoxy glue, resorcinol glue, or other glues or glue combinations providing similar properties. The lamella may be adhered together to form the beam.

The beam may comprise timber lamella adhered together with a generally oblong cross-section shape with relatively shorter width sides and longer depth sides and a longitudinal length.

Recess and Stress Positioning

Recesses may be located at points experiencing greatest stress across the beam in the event of a bend loading in a major and/or minor axis being place on the beam. This may be so that the steel reinforcing may be located in the recess(es) at a point to provide the greatest degree of stiffening to the beam.

For example, at the exterior of the beam widest sides, steel reinforcing in a recess closest to a point lateral loading would undergo the greatest level of compression experienced across the beam length. On the opposing side, the steel reinforcing would experience the great tension loading experienced across the beam length. By having steel reinforcing located at both the highest compression and tension points, the extent of beam deflection may be minimised and the optimum amount of steel reinforcing may be utilised. By comparison, a steel layer located in the centre of the beam would need to be comparatively thicker to achieve the same level of stiffness as having steel at the outer edges described. A steel layer also would have considerable extra material relative to the steel reinforcing described herein and it is possible that at least some of the steel layer may well provide little if any benefit at all to the beam in a bend loading scenario. Discrete recessed steel reinforcing may therefore be tailored to where the strength is needed most to optimise strength and stiffness.

It was found that locating the recesses and steel reinforcing therein on the shorter width sides, i.e. minor Y-Y axis sides, was sufficient to provide the stiffening strength desired for the beam and portal frame.

No recesses and steel reinforcing may be required on the major axis sides to achieve a desired increase in strength and stiffness. This reduces manufacturing and material costs of the beam yet still achieves the desired designed for strength.

Recess Location and Size

A recess in the beam shorter side may be centred across the shorter side width.

A recess may comprise approximately 10-80% of a total width of the shorter width side.

The relatively shorter width sides of the beam may have at least one recess cut into and opening to a surface of the beam, the at least one recess extending along at least 80% of the longitudinal length of the beam and a smooth planar face on the longer depth sides of the beam.

By contrast, where multiple recesses are located in the shorter width side, the multiple recesses may also be centred, each of the multiple recesses located equidistant from each other across a total width of the beam shorter width side optionally, with one recess located on a central axis of the beam shorter width side.

For example, if a side comprises two recesses, each recess may be located on either side of the central axis of the beam, with an equal distance between the beam edges and central axis. If the beam has three recesses, one recess may be located along the beam centre and the other two recesses located equidistant on either side of the central recess.

Recess Quantity

Each beam may comprise 1-6, or 2-6, or 2-3 recesses and each recess may comprise 1-4, or 1-3, or 1-2, or a single steel reinforcing bar. The number of recesses used on one shorter width side of the beam may be matched on the opposing beam shorter width side by a complementary number and placement of recesses. The number of recesses used may be a function of beam width and design loadings required.

Recesses Distant to Long Sides

Recesses may remain distant to an outer edge of the beam and may not open to the wood laminate beam longer depth side or sides.

Recess Depth

Recesses may have a relatively small depth being approximately 2-10% of the longer depth side depth. The recesses may be designed to not impact or at least minimise impact on the structural strength of the beam. The depth of a recess may be complimentary to the depth of the steel reinforcing therein so that the steel reinforcing e.g. a steel bar sits flush within the recess once adhered into the recess.

The recess depth may be less than one, only one, or no more than two lamella deep into the wood of the beam.

A recess width may be the same or greater than the recess depth.

Recess Width

The recesses may have a width that is complimentary to the steel reinforcing width/diameter. As noted above, this width may be the same or greater than the recess depth corresponding to steel reinforcing with a width the same or greater than the recess depth. For example, if the steel reinforcing has a width or diameter of approximately 12mm, the recess may be approximately 12mm wide and 12mm deep. In another example, if the steel reinforcing has a width of 30mm and a depth of 12mm, the recess may have a width of approximately 30mm and a depth of 12mm as well.

The steel reinforcing may be nested into or fit snugly into the recess(es).

The steel reinforcing may not however be sized to significantly interfere with the recess width hence the two widths may be evenly matched and plastic deformation of the recess does not occur when the steel reinforcing is fitted to a recess.

Recess and Steel Reinforcing Length

The recess(es) and steel reinforcing in the recess(es) of the beam may extend along the beam length and terminate prior to each ends of the beam.

An end or ends of the steel reinforcing and recess that the steel reinforcing may be nested into may terminate prior to an end or ends of the beam.

For example, the stiffening element may terminate prior to the beam end by around 10% or less of the overall beam length. This may be the case at both ends of the beam. For example, if the beam is 5000mm long, then the steel reinforcing may terminate approximately 250mm or less from both ends of the beam (being 500mm or 10% of the overall beam length). Greater or lower overall beam lengths and greater or lower steel reinforcing termination points may be used and these dimensions are provided by way of example only.

One advantage of early termination of the steel reinforcing in the beam may be that the beam ends may be cut shorter at installation to suit an opening using a wood saw. No special tools or trade skills are required to shorten the beam length.

Steel Reinforcing and Properties

The steel reinforcing used may have a modulus of elasticity (Youngs Modulus) of at least 60, or 70, or 80, or 90, or 100 GPa. The modulus of elasticity may be over 180 GPa.

Steel Reinforcing Adherent

The steel reinforcing may be adhered into the recess(es) via at least one chemical or mechanical adherent. The chemical adherent may be an adhesive. For example, the adhesive may be selected from epoxy or resorcinol glues. The mechanical adherent may be in the form of plates, fasteners or other coupling shapes and devices to adhere the steel reinforcing into a recess. Combinations of both chemical and mechanical adherents may also be used. Steel Reinforcing Shape

The steel reinforcing may be shaped to conform and nest into the recess or recesses in the beam.

Each recess may have an oblong cross-section shape and the steel reinforcing may have a complementary oblong shape.

In one example, the steel reinforcing may be an oblong bar shaped steel extrusion, the oblong bar shaped steel extrusion having a cross-section shape complementary to the at least one recess in the beam.

Alternatively, the steel reinforcing may have a complementary width and varying cross-section shapes e.g. a circular or ovoid shape, the diameter corresponding to the recess width. In this embodiment, the steel reinforcing may be reinforcing bar (rebar) steel such as that used in concrete reinforcing and the rebar may have a width complementary to the recess width. The recess may be sized so that, once rebar in the above embodiment is adhered into a recess, the rebar outer diameter lies flush with the outer surface of the beam.

Relative Amounts

The beam described may be predominantly manufactured from wood hence may retain the inherent useful properties of wood but, may have a greater degree of strength and stiffness than wood-only beams. In one embodiment, less than 1.0, or 0.9, or 0.8, or 0.7, or 0.6, or 0.5, or 0.4, or 0.3% by crosssection area of the beam may comprise steel reinforcing. That is, 99% or greater of the cross-section area of the beam may be manufactured from wood therefore minimising expense due to the steel reinforcing.

Optional Covers

A cover plate or other aesthetic part may be placed over the shorter width side or sides to hide the steel reinforcing. This may be desired in some applications where the shorter width side is visible post construction and where, for aesthetic reasons, it would be useful to hide the steel reinforcing.

Coupler

The first or the second coupler may be identical. For brevity, only one coupler is described and, to construct the portal frame, two couplers as described above may be used, each coupler being a mirror image of the other, one coupler attaching a first beam end to a first column and the other coupler attaching a second beam end to a second column of the portal frame. The first coupler or the second coupler may comprise: at least one tension member, the at least one tension member having a first end and a second end and configured to tension the upper end of the first column or second column to either the first beam end or the second beam end; a coupling between the first end of the at least one tension member and the beam; a coupling between a second end of the at least one tension member and the first column or the second column; and at least one load bearing member, the at least one load bearing member configured to provide shear support between, the upper end of the first column or the first end of the upper end of the second column, and the first end of the beam or the second end of the beam.

Steel Coupler

The coupler may be substantially manufactured from steel or materials with similar structural properties to steel. The term 'coupler' refers to the various parts described above and all of the parts described may be manufactured from steel.

Tension Member

The at least one tension member may be at least one rod. The at least one rod may be at least one threaded rod.

Tensioning of the at least one tension member may be completed by tightening a nut on the at least one threaded rod, the nut located on a first end of the at least one threaded rod, and, a second end of the at least one threaded rod is fixed to the beam, and, as the nut is threaded onto the at least one threaded rod, the beam is drawn towards the first column or the second column, causing coupling of the beam and the first column or the second column.

Coupling to the Beam

The first end of the at least one tension member may be coupled to the steel reinforcing in the beam.

Coupling may be direct, for example by welding or fastening the tension member first end to the beam steel reinforcing.

Coupling of the at least one tension member to the steel reinforcing in the beam is indirect by coupling the first end of the at least one tension member to an anchor member and the anchor member is then coupled to the steel reinforcing in the beam. The anchor member may be welded to the steel reinforcing of the beam or may be fastened to the steel reinforcing of the beam. If a fastener is used, the fastener may be threaded from the beam exterior, through the steel reinforcing of the beam, through the anchor member and, into the timber lamella of the beam.

The anchor member may be formed as a threaded plug, one end of the threaded plug comprising a threaded opening configured to threadingly engage a threaded end of the at least one tension member. An opposing end of the threaded plug may comprise a tongue, the tongue configured to overlap with an end of the steel reinforcing of the beam. At least one fastener may link the tongue and the end of the steel reinforcing together.

The anchor member may be formed as a profiled section, one end that connects to an end of the at least one tension member and an opposing end that comprises a shaped profile that keys with a complementary profile on one end of the steel reinforcing in the beam.

The shape of the profile may be configured so that if a tension force is applied across the steel reinforcing and anchor member, the steel reinforcing and anchor member are prevented from detaching or at least the energy needed to pull apart the steel reinforcing and anchor member is increased compared to if no profile existed.

Upper and Lower Rods

The first coupler or the second coupler may comprise two tension members. The two tension members may be spaced apart vertically across a height of the beam so as to provide an upper tension member and a lower tension member.

Load Bearing Members

The at least one load bearing member may comprise a first bracket configured as a planar face with an upper end and a lower end, the planar face of the first bracket being sandwiched between a side of the upper end of the first column or second column and either the first beam end or the second beam end.

The first bracket may comprise a lip extending from the planar face of the lower end of the first bracket that is configured to support a downwards vertical load thereon from the first beam end or the second beam end. The lip may extend substantially orthogonally from the planar face of the bracket.

The first bracket may comprise a lip extending from the planar face of the first bracket upper end that may be configured to support an upwards vertical load thereon from the column upper end. The lip may extend substantially orthogonally from the planar face of the bracket.

The first bracket may comprise both of the above lips described above.

The at least one load bearing member may comprise a second bracket comprising a planar face with an upper end and a lower end that is located against a side of the upper end of the first column or the second column opposite either the first beam end or the second beam end.

The second bracket may comprise a lip extending from the planar face of the second bracket upper end that may be configured to support an upwards vertical load thereon from the column upper end. The lip may extend substantially orthogonally from the planar face of the bracket.

The second bracket may comprise a slightly bowed or rolled shape with the second bracket ends generally offset relative to a mid-section of the second bracket. The second bracket may for example be formed from a rectangular planar piece of steel and the steel rolled slightly to deflect the second brackets ends away from the plane of the rectangle.

The at least one tensioning member may pass through openings in the at least one load bearing member.

Axial Loading

The coupling may comprise a spring washer configured to urge an axial tension load along a longitudinal axis of the at least one tension member.

The spring washer may comprise a plate shape with a radius, the radius configured to be at least partly deformed elastically when the portal frame is assembled. For example, as a nut is threaded onto a tension member e.g. a threaded rod, to tension the beam and column together, the nut base bears on the spring washer and, as tightening occurs, the spring washer at least partly elastically deforms to flatten. The spring washer has a shape memory and urges an axial tension load to return to the original shape memory. A spring washer in this portal frame design was found to be useful as the tension load may change over time post installation as the timber used moves and adjusts. The spring washer through elastic movement may act to maintain a constant axial tension load through the tension member(s) despite timber movement during and after installation.

Bearing Fasteners

The coupling may further comprise bearing fasteners, the bearing fasteners inserted directly into the upper end or upper ends of the first column or the second column. The bearing fasteners may take the form of a threaded wood screw. Multiple bearing fasteners may be used.

The bearing fastener or fasteners may be inserted directly into the upper end or upper ends of the first column or second column. There may be no intervening plates or others items between the bearing fastener end or head and the column so that the bearing fasteners end or head when inserted into the column, sits flush with the column side.

Each column may have bearing fasteners inserted into the column generally about the upper end or the lower end of the load bearing members when the load bearing members are fitted to the column upper end. At least one, or two, or three, or four bearing fasteners may be inserted into the upper end of the column about an upper end of the load bearing member. At least one, or two, or three, or four bearing fasteners may be inserted into the upper end of the column about a lower end of the load bearing member. Where multiple bearing fasteners are used about each end of a load bearing member, the bearing fasteners may be spaced apart in both horizontal and vertical planes.

Each bearing fastener may have a length that may be between a quarter and a half of the column width. This is, the bearing fasteners are relatively long and protrude a significant distance into the column width. In one example, each bearing fastener may extend into the column once inserted into the column, substantially around a third of the column width. The bearing fasteners are inserted as noted above in the inner face or outer face of the column.

The inventor has found that inserting bearing fasteners of this nature about the upper end of the column significantly increases the strength of the assembled portal - in one trial completed by the inventors, the strength increase from use of four bearing screws at the upper end of the load bearing members and four bearing screws at the lower end of the load bearing members, inserted into either side of the column, resulted in a 47% increase in bracing units.

Footing

The portal frame columns may optionally comprise a footing or footings. The footing or footings may be configured to provide additional strength to the portal frame about the column base. The footing or footings may be used to link the portal frame to a substrate.

In one example, the first column and the second column may comprise a footing or footings, the footing or footings configured to provide additional strength to the portal frame about a base of the first column or the second column and configured to link the portal frame to a substrate.

The footing may comprise an oblong steel cross-section shape with openings to receive fasteners therethrough and top and bottom faces, the top face abutting or bearing on the column end and the bottom face abutting or bearing on a substrate when assembled.

The openings may either be in the top face or the bottom face of the footing.

Fasteners may extend from the top face of the footing, through the openings and into the column end. Fasteners may extend in the opposing direction from the footing, through the openings in the fitting base and into a substrate on which the footing and hence column base and portal frame generally may be fixed. The fasteners may provide a linking function and also strengthen the column base and overall portal strength.

In an alternative footing example, the footing may comprise a single plate and footing sides. The footing sides may extend from the single plate upwards so as to nest into recesses applied to sides of the column base. The recesses may be in the column base exterior sides. The footing sides and recesses in the column base may interlink and have complementary sizes.

Method of Assembly

In a second aspect, there is provided a method of assembly a portal frame comprising: selecting a portal frame substantially as described above; and coupling the first coupler to the upper end of the first column and the first beam end; and coupling the second coupler to the upper end of the second column and the second beam end.

Kit of Parts

In a third aspect, there is provided a kit of parts comprising: the portal frame substantially as described above; and a set of instructions on assembly of the portal frame.

Advantages of the portal frame, method of assembly and kit of parts described above may include:

Providing a coupler to secure a beam to a column to form a structural portal frame;

Reducing portal frame cost, particularly given the increasing cost of steel;

Providing an alternative design of portal frame that avoids or minimises third party involvement on a build site beyond a builder;

Improving or overcoming the limitations of wooden portal frames, particularly around strength and stiffness;

Providing a lower environmental and lower carbon footprint portal frame to steel only portal frames;

Minimising the number of parts necessary to produce a portal frame;

Avoiding the need for nailing plates as used for steel portals to fix linings, claddings or trimming openings;

Providing an aesthetic finish to a portal frame that does not interfere with movement of a door or window installed within the portal frame.

Beam length and column height can be altered on site with a timber saw as there is no need to cut or weld steel;

A column can continue upward beyond the beam top if required to meet a top plate and replace/eliminate trimming studs;

The steel components used in the described portal frame are simple to fabricate and can easily be mass produced; Any column dimension can be used and the column and beam do not need to match in width;

The portal frame described is easy to assemble on site with minimal work to a dependable standard (i.e., relative fool proof and inspections are straightforward if required);

No adhesive is needed to couple the columns and beam;

There is no interference with cladding or linings as the portal frame does not require side fixings;

There is minimal interference with framed opening or space above (~5mm plate thickness only).

The embodiments described above may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features.

Further, where specific integers are mentioned herein which have known equivalents in the art to which the embodiments relate, such known equivalents are deemed to be incorporated herein as if individually set forth.

WORKING EXAMPLES

The above described portal frame and method of assembly are now described by reference to specific examples and the following items and items numbers:

I Portal frame

X Clear opening width

Y Clear opening height

10 First column

10a First column upper end

10b First column lower end

II Second column

11a Second column upper end lib Second column lower end

12a First column internal side

12b Second column internal side

13 Column slot 14a First column external side

14b Second column external side

15 Recesses in the column base

20 Beam

20a First beam end

20b Second beam end

21 Steel reinforcing

22 Wood lamella

23 Beam shorter width sides

24 Beam longer width sides

25 Beam longitudinal length

26 Beam recess

27 Steel reinforcing termination point

28 Beam slot for coupler rods

40 Coupler

41a Upper threaded rod

41b Lower threaded rod

42 First load bearing member steel bracket

42a First steel bracket planar face

43 Second load bearing member steel bracket

43a Second steel bracket planar face

44a, 44b Lips from first steel bracket

44c Lip from second steel bracket

45 Openings in steel brackets for threaded rods

46 Tensioning nut

47 Coupling to beam steel reinforcing

48 Anchor plate 49 Fastener

50 Spring washer

60a Upper bearing fasteners

60b Lower bearing fasteners

70 Threaded plug

71 Threaded opening

72 Tongue

73 Plug fastener

80 Footing

81 Footing openings

82 Footing fasteners

83 Footing sides

84 Footing single plate

85 Top plate

86 Bottom plate

90 Intermediate beam

90a, 90b Intermediate beam ends

91 Ground floor

92 First floor

93 Second floor

100 Ground (dirt, steel, pile, wood etc)

110 Alternative anchor member

111 Profiled section 112 Connection anchor to threaded rod

113 Connection to steel reinforcing

114 Webbing

115 Steel reinforcing opening for profiled anchor member

120 Belleville washer

130 45 degree fastener

131 45 degree fastener opening in bracket leg

132 45 degree fastener opening in bracket body

140 Rebate in column

141 Rebate in beam

150 Bracket curve

EXAMPLE 1

Figures 1-12 illustrate a first example of the portal frame 1 described herein.

As shown in the Figures, the portal frame 1, when assembled comprises first 10 and second 11 columns, and a beam 20 coupled to the columns 10, 11. Each column 10, 11 has an upper end 10a, 11a and a lower end 10b, lib.

The beam 20 has a first beam end 20a and a second beam end 20b that bear on and are coupled to the column upper ends 10a, 11a, or more precisely an internal side 12a, 12b of the column upper ends 10a, 11a.

The distance between the first and second columns 10, 11 defines a clear opening width X and the height between the beam 20 and lower ends 10b, lib of the columns 10,11 (or ground surface) defines a clear opening height Y.

The beam 20 is a laminated wooden beam with steel reinforcing 21 to form a composite beam.

The columns 10,11 and beam 20 are coupled together via first and second couplers 40. One side of this connection is termed the connection detail in the drawing description above. The first coupler 40 couples the first column 10 upper end 10a to the beam 20 first end 20a and, a second coupler 40, couples the second column 11 upper end 11a to the beam 20 second end 20b.

The beam 20 comprises timber lamella 22 adhered together with a generally oblong cross-section shape and a longitudinal length 25, the cross-section shape comprising relatively shorter width sides 23 and longer depth sides 24.

Both of the beam 20 shorter width sides 23 have a recess 26 cut into and opening to a surface of the beam 20. Steel reinforcing 21 is located and adhered inside a recess 26 in the beam 20 . The steel reinforcing 21 substantially fills the recess 26 in which the steel reinforcing 21 is located and adhered to.

As shown, the steel reinforcing 21 is an oblong bar shaped steel extrusion with a cross-section shape complementary to the recess 26 oblong cross-section shape. Although other shapes of steel reinforcing 21 may be used, the applicant has found that this shape of steel reinforcing 21 provides optimum strength, modulus of elasticity, ease of manufacture and favoured aesthetics.

The steel reinforcing 21 and recess 26 in the beam 20 terminates at an end termination point 27 prior to the first beam end 20a and the second beam end 20b.

The coupler 40 used comprises at least one tension member, shown in the drawings as upper and lower threaded rods 41a, 41b. The upper rod 41a couples to steel reinforcing 21 of the beam 20, passes through a beam 20 slot 29, column slot 13 to a column external side 14a, 14b.

Each threaded rod 41a, 41b has a first end and a second end and the threaded rods 41a, 41b are configured to tension the column upper end 10a, 11a to either the first beam end 20a or the second beam end 20b.

A coupling 47 is located between a first end of the threaded rod 41a, 41b that couples the threaded rod 41a, 41b to the beam 20. The threaded rod 41a, 41b first end is coupled to the steel reinforcing 21 in the beam 20. Coupling 47 in this example is achieved via an anchor plate 48 that is welded to the threaded rod 41a, 41b at one end and the anchor plate 48 is fastened to the steel reinforcing 21 of the beam 20 via a fastener 49 such as a coach screw. The coach screw 49 threads through the steel reinforcing 21, the anchor plate 48 and into the timber of the beam 20. A pin (not shown) welded to the anchor plate 48 could also be used to form this coupling 47 and other configurations of coupling could be used as well.

A further coupling 46 is located between a second end of the threaded rod 41a, 41b and the column 10,11, in this example being a nut 46 threaded onto the rods 41a, 41b.

Tensioning of the threaded rods 41a, 41b is completed by threading the nut 46 onto the threaded rod 41a, 41b, the nut 46 located on a first end of the threaded rod 41a, 41b, and, a second end of the threaded rod 41a, 41b is fixed to the beam 20.

As the nut 46 threads onto the threaded rod 41a, 41b, the beam 20 is drawn towards the column 10,11 causing coupling of the beam 20 and column 10,11.

At least one load bearing member 42,43 is used as well configured to provide shear support between the column 10,11 upper end 10a, 11a and the first beam end 20a or second beam end 20b.

The load bearing members 42,43 in this example are first and second brackets 42,43. These may be steel brackets of a thickness sufficient to provide the desired degree of shear support. The thickness is envisaged at being from 1 to 10mm thick.

The first bracket 42 may have a planar face 42a that may be sandwiched between a side 12a, 12b of the column 10,11 upper end 10a, 11a and either the first beam end 20a or the second beam end 20b.

The first bracket 42may comprise a lip 44a extending orthogonally from a lower end of the planar face 42a of the first bracket 42 that is configured to support a downwards vertical load thereon from the beam 20 first beam end 20a or second beam end 20b.

The first bracket 42 may also comprise a lip 44b extending orthogonally from the planar face 42a of the first bracket 42 upper end that is configured to support an upwards vertical load thereon from the column 10,11 upper end 10a, 11a.

The second bracket 43 may be located against a side 12a, 12b of the column 10,11 upper end 10a, 11a opposite either the first beam end 20a or the second beam end 20b.

The second bracket 43 may comprise a lip 44c extending orthogonally from the planar face 43a of the second bracket 43 upper end that is configured to support an upwards vertical load thereon from the column 10,11 upper end 10a, 11a.

The threaded rods 41a, 41b may pass through openings 45 in the load bearing members 42,43.

The coupler 40 may further comprise a spring washer 50 configured to urge an axial tension load along a longitudinal axis of the threaded rod 41a, 41b longitudinal axis. The spring washer 50 as shown may be located between a nut 46 and outer face 12a, 12b of a column 10,11 upper end 10a, 11a. The spring washer 50 may have a plate shape with a radius, the radius configured to be at least partly deformed elastically when the portal frame 1 is assembled and the portal frame 1 tensioned together.

The above portal frame 1 shown in the drawings may be assembled by:

In-Factory

Beam steel reinforcing is pre-drilled at each end.

On site

A square slot 13 is routed in the top surface of the column 10,11 to house an upper rod 41a. A square slot 29 is routed along the centre of the beam 20 from the steel reinforcing 21 to the end (top and bottom) for rods 41a, 41b.

A hole is drilled through the centre of the column 10,11 for the lower rod 41b to pass through using the load bearing member brackets 42,43 as guides.

A hole is drilled into the timber lamella through the beam 20 steel reinforcing 21 pre-drilled hole above in preparation for insertion of a coach screws 49. Optionally, a lower corner of the beam 20 and upper corners of the columns 10,11 are chamfered.

The various components are assembled.

The nut 49 is tightened until the spring washer 50 is flat against the load bearing member 42,43 to a set a preload tension.

As may be appreciated, the portal frame described may be sold as a kit of parts comprising the parts described above along with a set of instructions for assembly.

EXAMPLE 2

Figures 13-18 show an alternate example of portal frame 1. As shown, the alternate portal frame 1 is similar to the portal frame 1 described in Example 1, however has differences as noted below relating to the brackets 42, 43, the use of bearing fasteners 60a, 60b and the use of threaded plugs 70.

In this alternate example, the load bearing members 42, 43 differ in shape. The first bracket 42 upper end has no lip 44b like that shown in Example 1. Further, the second bracket 43 upper end has no lip 44c as well. This example illustrates how the use of a lip 44b, 44c from the load bearing members 42, 43 may not be essential.

The load bearing member 43 on the exterior of the column 10 may also have a slight bow or roll included. This may be completed to tension the upper and lower tension rod 41a, 41b when the nuts 46 are tightened.

This alternate example also illustrates the use of bearing fasteners (upper 60a and lower 60b). Bearing fasteners (in this case, screws), are threaded directly into both sides 12a, 12b of the upper end 10a, 11a of the column 10, 11. A total of four screws 60a, 60b may be inserted generally about the upper and lower ends of the first and second brackets 42, 43. The bearing fasteners 60a, 60b may provide extra strength to the column 10, 11 about the column 10, 11 key stress points when incorporated into a portal frame 1. As shown, the bearing fasteners 60a, 60b are inserted directly into the column 10, 11 sides 12a, 12b and extend around a third of the way into the column width. The bearing fasteners 60a, 60b may be spaced in an array leaving a central area free of bearing fasteners 60a, 60b through which the brackets 42, 43 may be fixed to the column 10, 11 by a further fastener or fasteners.

This alternate example also shows the use of threaded plugs 70 that link the threaded rods 41a, 41b to steel reinforcing 21 in the beam 20.

Threaded plugs 70 may comprise a threaded opening 71 located at one end of the threaded plug 70. The threaded opening 71 may be configured to threadingly engage an end of the threaded rods 41a, 41b described in Example 1. At an opposing end of the threaded plug 70, the threaded plug 70 may comprise a tongue 72. When fitted to the beam 20, the tongue 72 may overlap an end of the steel reinforcing 21 of the beam 20. Plug fasteners 73 may be fitted through the steel reinforcing 21 and tongue 72 to link the threaded plugs 70 to the steel reinforcing 21 and hence, link the threaded rods 41a, 41b to the beam 20.

EXAMPLE 3

Figures 19-21 show a further design variation to the portal frame 1 described in Example 2 above. In this example, the column 10, 11 may comprise a footing 80. The footing 80 may be used to provide additional strength to the portal frame about the column 10, 11 base and may be used to link the columns 10, 11 to a substrate (not shown).

The footing 80 shown in Figure 20 and Figure 21 may comprise an oblong steel cross-section shape with openings 81 to receive fasteners 82. As shown in Figures 19-21, the openings 81 may be on either the top or bottom faces of the footing 80. Only the fasteners 82 linking the footing 80 to the column 10, 11 are shown in the figures however fasteners 82 may also extend in the opposing direction from the footing 80 to a substrate (not shown) on which the footing 80 may be fixed. The fasteners 82 as shown in these figures may provide a linking function and also strengthen the column 10, 11 base.

Figure 19 shows an alternative footing comprising a single plate 84 and footing sides 83 that interlink with complementary recesses 15 in the column 10, 11 base. Figure 20 and Figure 21 show the use of a footing 80 with no sides 83 or recesses 15.

EXAMPLE 4

Portal frames are widely used in building for many applications e.g. door frames, window frames, building sides and so on. To illustrate some example uses Figures 22-25 are provided.

Figure 22 shows a single car garage portal frame 1 as might be used to provide bracing about a garage door opening. The portal frame 1 in this example may have a height of 2.1 to 2.7m and opening width of 2.6 to 3.6m.

Figure 23 shows a portal frame 1 as used in a small infill to provide an architect or building designer with additional bracing units when required. The portal frame 1 in this example may have a height of 2.4 to 3.0m and opening width of 1.5 to 2.5m.

Note that the dimensions indicated in Figure 22 and Figure 23 are provided by way of example only.

Figure 24 shows how the portal frame 1 described may be extended vertically. Figure 24 shows the portal frame 1 having intermediate beams 90, the portal frame 1 as a whole defining a wall or side of a multi-storey building so that the portal frame 1 defines a ground floor 91, first floor 92 and second floor 93. The intermediate beams 90 may have the same characteristics as the top beam 20 e.g. with steel reinforcing 21 and a coupler 40 used to connect the intermediate beam 90 ends 90a, 90b to the columns 10, 11. Figure 25 shows another example of a multi-storey portal frame 1 in this example comprising steel reinforcing 21 also along the column 10, 11 exterior sides 14a, 14b and optionally also front sides that the top beam 20 and intermediate beam 90 couple to. The beams may also comprise steel reinforcing 21. The use of steel reinforcing 21 in this manner may provide an added level of strength to a taller portal frame 1 such as that illustrated in Figure 25.

EXAMPLE 5

In this example a further embodiment of coupler is shown with reference to Figure 26 showing the coupler assembly in a perspective view from above, Figure 27 showing a plan view of the steel reinforcing 21, threaded bar 41a, 41b and an alternative profiled anchor member 110; and Figure 28 showing a detail plan view of the steel reinforcing 21 and profiled anchor member 110.

In this example, the coupler uses a modified anchor member 110 which connects the steel reinforcing 21 to the threaded rod (tension member) 41a, 41b. This modified anchor member 110 comprises at one end an opening 112 to receive and connect to an end of the threaded rod 41a, 41b. The anchor member 110 at the opposing end 113 maybe formed with a profiled section 111, comprising a shaped profile 111 that keys with or mates with a complementary profile 111 on one end of the steel reinforcing 21 of the beam 20. The steel reinforcing 21 and profiled anchor member 110 maybe mated together by meshing the profiled sections 111 together in a plane orthogonal to the longitudinal axis of the steel reinforcing 21 and threaded rod 41a, 41b. The shape of the profile 111 may be configured so that if a tension force is applied across the steel reinforcing 21 and anchor member 110, the steel reinforcing 21 and anchor member 110 are prevented from detaching or at least the energy needed to pull apart the steel reinforcing 21 and anchor member 110 apart is increased compared to if no profile 111 existed. Various profiles 111 may be used however the one illustrated in Figures 26-28 was found to be beneficial to portal frame 1 strength. The anchor member 110 may further comprise an opening through which a fastener 49 may be inserted, the fastener 49 further linking the anchor member 110 directly to the beam 20.

Figure 29 shows an alternative end shape opening 115 to the steel reinforcing 21. In this example, the profiled section 111 still keys with the modified anchor member 110 but in this example, the opening in the end shape has webbing 114 remaining and the modified anchor member 110 sits within the opening 115 abutting or seating on the webbing 114. Webbing may be useful in high tension energy applications to help hold or draw together the keyed opening sides.

EXAMPLE 6

Figures 30 to 34 show a further example assembly of the portal frame 1.

Figure 30 shows a front elevation view of the assembled portal frame 1 along with end elevations on either side and a plan elevation view. Detail 5 is also shown in Figure 30. The beam 20 and columns 10, 11 are located in similar position to earlier examples. Detail 5 shows the use of a bolt and nut 46 arrangement with a Belleville washer 120 inserted. This washer 120 provides a sustained tension load on the beam 20 and column 10, 11 coupling 40.

Figure 31 shows the same front, side and plan elevations as Figure 30 but with the parts in a full assembly exploded view. The beam 20 is a composite steel and wood beam as described elsewhere. L- shaped brackets 42 are included. As shown, these may be rebated into the beam 20 via a rebate 140.

Curved plates 43 are used as part of the tensioning for the coupler 40. The beam 20 steel insert 21 may have profiled connections 110 welded to the flat bar or threaded rod to link the steel bar 21 and threaded rod 41a, 41b. Bearing screws may be used about the top 10a, 11a of each column 10, 11. Foot plate 80 screws 82 may be used to hold the foot plate 80 onto the column 10, 11 ends 10b, lib. In this example 45 degree angle screws 130 may be inserted about the bracket 42. As noted above a Belleville washer 120 may be used

In Figure 32, Detail views 1, 2 and 3 are shown indicated in Figures 30 and 31. Detail 1 shows the spring plate 43 and conical Belleville washer 120 more closely. These may be used as an indication of torque i.e. tightening ends once the plate 43 and washer 120 are flattened against the timber of the column 10, 11. Detail 2 shows the connection from above including the steel rod 21 to keyed feature connection 110 to threaded rod 41a, 41b , brackets 42 column 10, 11, screws and bolt 46 assembly of the coupler 40. Detail 3 shows the same view of Detail 1 but in an exploded view.

Figure 33 shows perspective views from above (left) and below (right) of the assembled beam 20 and column 10, 11 joint. Each column 10, 11 may have up to 600mm removed the column 10, 11 ends 10b, lib by cutting e.g. with a saw to adjust the overall column 10, 11 height. This may be useful to provide some degree of adjustment using simple tools. Similarly, the beam 20 ends 20a, 20b may be cut shorter by at least 150mm again using simple tools like a saw to adjust the beam 20 length. This is a key difference to welded steel portal frames where the portal dimensions cannot be adjusted quickly on site and may require specialist expertise with metals to make changes.

Figure 34 shows a perspective view from underneath in a partly exploded form and Figure 35 shows Detail 4. To assemble the parts as shown in Figure 35, the first step may be to install the L brackets 42 with 3mm nails to the column 10, 11 before any other parts. Step 2 may be to ensure the L bracket 42 is fully seated on to the rebate 141 of the beam 20. Step 3 may be to insert a lower rod 41b through the column 10, 11 first and connect both arrow dovetail sections 110 together. Step 4 may be to install keeper screws 130 through the L bracket openings 131, 132. Step 5 may be to slide the sprung plate 43 over threaded rods 41a, 41b ensuring that the centre of the plate 43 touches the column 10, 11 first and not the plate 43 ends. Step 6 may be to install the Belleville washers 120 so that the inside of the washer 120 faces the sprung plate 43. Lastly in step 7, tighten the nuts 46 until both Belleville washers 120 and sprung plate 43 are flattened. EXAMPLE 7

Referring to Figures 36 to 41, the general assembly of the portal 1 is shown in more detail.

Figure 36 shows a section view of the beam 20 to column 10, 11 image of Figure 33, in Figure 36 showing on the left an end view and on the right a section view along section line A-A. The rebate 140 in the column 10 is shown for the spring plate 43.

Figure 37 shows the beam 20 to column 10, 11 image of Figure 33 with the column 10, 11 and beam 20 removed to expose the coupler and other parts. As shown more clearly here, 45 degree fasteners 130 may be used that pass through openings 131, 132 in the L bracket 42.

Figure 38 shows a further example of the load bearing member steel bracket 42. This shows the 45 degree fastener 130 openings 131, 132 in more detail.

Figure 39 shows images of the second load bearing member steel bracket 43 in which the curved shape 150 can be more clearly seen. This may be a 5mm roll preload across the bracket 43 to give a slight concave shape 150 to the bracket 43 so that, when placed against a column, the bracket 43 ends are lifted slightly away from the column 10, 11 relative to the central section of the bracket 43.

Figure 40 shows the footplate 80 in more detail. In this example, the footplate 80 is manufactured from a top plate 85, a bottom plate 86 and spacing panels 83 that are welded together.

Figure 41 shows a detail view of the top end 10a of a first column 10 and the rebate 140 inserted for the bracket 43.

Figure 42 shows an end detail of the beam 20 illustrating further the beam 20 rebate 141 for an L bracket 42 and top and bottom recesses 26 for a steel rod.

Aspects of the portal frame and method of assembly have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the claims herein.