AU2021101980A4

AU2021101980A4 - Further improvements in steel column assembly and installation

Info

Publication number: AU2021101980A4
Application number: AU2021101980A
Authority: AU
Inventors: Bradbury Golledge; Lyndon Golledge; Malcolm Golledge
Original assignee: Bfre Pty Ltd
Current assignee: Bfre Pty Ltd
Priority date: 2020-04-16
Filing date: 2021-04-16
Publication date: 2021-06-03
Anticipated expiration: 2029-04-16

Abstract

A column assembly comprising: a hollow column 9 having a base end, a top end, an internal surface, an external surface and a wall thickness therebetween, a base plate assembly 10 comprising a flat steel base plate 1 having a top surface 11 and a bottom surface 12, the base plate assembly further comprising at least one formation 2 at the top surface thereof to be received into the base end of the column for engaging the internal surface of the column at the base end thereof, and a top plate assembly 20 comprising a flat steel top plate 7 having a top surface 11 and a bottom surface 12, the top plate assembly further comprising at least one formation 2 at the bottom surface thereof to be received into the top end of the column for engaging the internal surface of the column at the top end thereof. 10 14 10 166 1 --- 14 114 14 11 16 12

Description

10 14 10

166

1 ---

14

114

14

11

16

FURTHER IMPROVEMENTS IN STEEL COLUMN ASSEMBLY AND INSTALLATION FIELD OF THE INVENTION

This invention relates to an improved building method and in particular to improvements in structural steel column design and installation in Low Rise Residential Buildings.

.0 BACKGROUND TO THE INVENTION

In residential building construction, a diverse range of structural steel beams are used to support roof, floor and brick wall loads. The beams are normally supported at each end by steel columns which are generally made from square hollow section .5 tubes of varying dimensions and wall thickness. The columns have metal plates with holes for bolts, welded to either end. The columns are generally supplied with the structural steel beams to the construction sites prefabricated and to the design length for ready installation by carpenters.

o0 The cross-sectional size of the column is generally designed to be less than the wall frame thickness, so when they are installed they are concealed within it. The more common column sizes are 75x75 mm and 89x89 mm in a number of different material thicknesses. The wall thickness is 90 mm in frame construction and 110 mm in brick construction.

The base plate welded to the bottom of the column comes in a number of shapes, with a minimum of 2 holes in each hold down location. The more common base plate is a rectangular plate the same width as the column with a length twice the column width. The column is centrally located on the plate and a hole is pre- punched through the plate at either end to receive the hold down connection bolt. A space as wide as the base plate is made in the wall frame and the post is bolted to the concrete slab, or bolted to the floor structure.

In another form, the base plate is 1.5 times the width of the column and only extends from one face, and is flush with the other three faces. Similar sized plates are welded to the top of the column however to cater for dimensional tolerances in the as built walls, the holes in the top plate used to connect to the beams are generally slotted. The premade and sized to length columns with top and bottom plates welded to each end are delivered to site and installed along with the steel beams.

The deficiency in the prior art is the variation in the concrete slab flatness, the obstruction to the top and bottom wall plates and brickwork because of the fixing .0 plates extending from one or both sides of the columns footprint, and variations in the average height of the slab due to screeding inaccuracies resulting in column packing or length rectification on site. Another major deficiency in the prior art is the obstructions caused by the bolts once installed, leaves the bolt heads proud of the top and bottom column plates causing further interference with the frame top and .5 bottom plates and brickwork, which results in additional labour for fitment on site.

Another deficiency is the current practice of welding top and bottom plates to the column and the difficulty and costs in rectification on site if the columns are made too long or too short. -O It is the object of the present invention to address the above deficiencies or at least provide a useful alternative.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a column assembly comprising:

a hollow column having a base end, a top end, an internal surface, an external surface and a wall thickness therebetween,

a base plate assembly comprising a flat steel base plate having a top surface and a bottom surface, the base plate assembly further comprising at least one formation at the top surface thereof to be received into the base end of the column for engaging the internal surface of the column at the base end thereof, and a top plate assembly comprising a flat steel top plate having a top surface and a bottom surface, the top plate assembly further comprising at least one formation at the bottom surface thereof to be received into the top end of the column for engaging the internal surface of the column at the top end thereof.

Preferably, the base plate and the top plate are dimensioned to have side faces substantially aligned with the external surface of the column when the respective formations are received in the ends of the column. .0 Preferably, the column has a square cross section, and the at least one formation comprises two substantially right angle formations for each of the base plate and the top plate, each substantially right angle formation being a flat rectangular plate bent at a mid-portion thereof to have side portions at about 900 to each other. Preferably, the two right angle formations are laid to have a side edge thereof laying .5 on the plate, with each side portion adjacent a respective side edge of the plate. Preferably, wherein each side portion is a uniform distance inward from the respective side face of the plate, the uniform distance being the wall thickness of the hollow square section column. Preferably, the right angle formations are welded to the plates along the inside o0 junctions only such that the respective top and bottom plates abuts against the respective end of the column. Preferably, the base plate comprises a central oval slot. Preferably, the slot extends to a side face of the base plate. Preferably, the hollow column has a square, rectangular or circular cross section. Preferably, the respective formations lock with the respective ends of the column and prevent the column from moving laterally relative to the respective top and bottom plates.

In another aspect, the present invention provides a timber wall frame comprising: the column assembly of the above with the base plate assembly mounted to a concrete base via a bolt inserted into the base plate slot, the top plate assembly mounted to the top end of the column and the column mounted to the base plate assembly, two timber bottom plates disposed to extend from opposite sides of the column assembly, two timber wall studs disposed on each side of the column assembly, with lower ends thereof mounted to a respective timber bottom plate, two timber top plates disposed to extend from upper ends of the wall studs.

In another aspect, the present invention provides a timber wall frame comprising: a timber bottom plate, the column assembly of claim 1 with the base plate assembly and the top plate .0 assembly mounted to the base end and the top end of the column, the base plate resting on the timber bottom plate, two timber wall studs disposed on each side of the column assembly, with lower ends thereof mounted to a respective timber bottom plate, a timber top plate extending across the upper ends of the wall studs and the column .s assembly.

Preferably, the timber wall frame further comprises an aperture in the timber bottom plate for a dowel, the aperture aligned with the base plate assembly, and a dowel received in the aperture. -o In another aspect, the present invention provides method of assembly of an off-site pre-assembled timber wall frame with load bearing steel columns, the method comprising the steps of: forming a pocket in a wall frame between two wall studs, inserting the column assembly of the above with the base plate assembly and the top plate assembly mounted to the base end and the top end of the column.

In another aspect, the present invention provides a method of construction with the frame built on site, the method comprising: mounting the base plate assembly of the above to a concrete slab via a hold down connection bolt extending through the base plate slot, mounting the top plate assembly to the top end of the column, mounting a base end of the column to the base plate assembly, attaching wall studs to opposite sides of the column via fasteners.

In another aspect, the invention provides end plate assemblies for a hollow column having a base end, a top end, an internal surface, an external surface and a wall thickness therebetween, the end plate assemblies comprising: a base plate assembly comprising a flat steel base plate having a top surface and a bottom surface, the base plate assembly further comprising at least one formation at the top surface thereof to be received into the base end of the column for engaging the internal surface of the column at the base end thereof, and .0 a top plate assembly comprising a flat steel top plate having a top surface and a bottom surface, the top plate assembly further comprising at least one formation at the bottom surface thereof to be received into the top end of the column for engaging the internal surface of the column at the top end thereof.

.5 Preferably, the base plate and the top plate are dimensioned to have side faces substantially aligned with the external surface of the column when the respective formations are received in the ends of the column.

Preferably, the at least one formation comprises two substantially right angle o0 formations for each of the base plate and the top plate, each substantially right angle formation being a flat rectangular plate bent at a mid-portion thereof to have side portions at about 900 to each other.

Preferably, the two right angle formations are laid to have a side edge thereof laying on the plate, with each side portion adjacent a respective side edge of the plate.

Preferably, each side portion is a uniform distance inward from the respective side face of the plate, the uniform distance being the wall thickness of the hollow square section column.

Preferably, the right angle formations are welded to the plates along the inside junctions only such that the respective top and bottom plates abuts against the respective end of the column.

Preferably, the base plate comprises a central oval slot.

Preferably, the slot extends to a side face of the base plate.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1is a plan view of a base plate assembly. Fig. 2 is a side elevation of the base plate assembly. Fig. 3 is an isometric view of the base plate assembly. .o Fig. 4 is a plan view of a top plate assembly. Fig. 5 is a side elevation of the top plate assembly. Fig. 6 is an isometric view of the top plate assembly. Fig. 7 is an elevation of a wall assembly comprising a steel column, the base plate assembly, top plate assembly, a steel beam section, and a timber wall frame. .5 Fig. 8 is a part elevation of the bottom of a steel square hollow section column showing a gap between them filled with epoxy compound to transfer bearing loads. Fig 9 is an elevation of a wall panel with a steel post assembly fitted into a frame pocket. Fig 10 is a plan view of the underside of the wall frame assembly in fig 9 without a o dowel. Fig 11 is a plan view of the underside of the wall frame assembly in Fig 9 with a dowel installed. Fig 12 is an isometric view of a timber dowel. Fig 13 shows (a) side elevation view, (b) top view and (c) perspective view of an alternative base plate assembly.

BEST MODE OF CARRYING OUT THE INVENTION

Figures 1 to 3 show a base plate assembly 10 comprising a flat rectangular steel base plate 1 having a top surface 11 and a bottom surface 12 and a nominal thickness 6 therebetween. The base plate 1 is dimensioned to have side faces 16 substantially corresponding to the external surfaces of a square hollow section column 9 (see Figure 7). In other words, the base plate 1 has a length and width substantially equal (or slightly larger) to the cross-section length and width of the square hollow section column 9.

The base plate assembly 10 further comprises two right angle formations 2 welded to the top surface 11. Each right angle formation 2 is generally a flat rectangular plate bent at a mid-portion thereof to have side portions 14 at about 900 to each other. The two right angle formations 2 are laid to have a side edge 15 thereof laying on the top surface 11, with each side portion 14 adjacent a respective side edge 16 of the base plate 1. In other words, the two right angle formations 2 mirror each other, with the four side portions 14 generally following the sides of a rectangle.

.0 The right angle formations 2 are welded to the top surface 11 of the base plate 1, with each side portion 14 being a uniform distance inward from the respective side edge 16 of the base plate 1. The uniform distance is designated as 'd'which corresponds to the nominal wall thickness of the square hollow section column 9.

The right angle formations 2 are welded 3 to the base plate 1 along the inside .5 junctions of the side edges 15 only, and not at the outside facing junctions thereof. In other words, no welds 3 are made facing the side faces 16.

The base plate 1 has a central oval slot 4 cut through it disposed between the two right angle formations 2. The slot 4 corresponds to a hold down bolt diameter fitment and the slot 4 provides lateral adjustment and maximal edge distance for the bolt. o0 Figure 3 shows an isometric view of the base plate assembly 10 with partially exposed slot 4, angle formations 2 and base plate 1.

Figures 4 to 6 shows a top plate assembly 20 which is substantially identical to the base plate assembly 10. The top plate assembly 20 includes a top plate 7 having a top surface 11 and a bottom surface 12 and a nominal thickness 8 therebetween. The thickness 8 is smaller than the thickness 6.

The top plate 7 is also dimensioned to have side faces 16 substantially corresponding to the external surfaces of a square hollow section column 9 (see Figure 7). In other words, the top plate 7 has a length and width substantially equal (or slightly larger) to the cross-section length and width of the square hollow section column 9.

The top plate assembly 20 also further comprises two right angle formations 2, which are welded to the bottom surface 12. The two right angle formations 2 are laid to have a side edge 15 thereof laying on the bottom surface 12, with each side portion 14 adjacent a respective side edge 16 of the top plate 7. In other words, the two right angle formations 2 mirror each other, with the four side portions 14 generally following the sides of a rectangle.

The right angle formations 2 are welded to the bottom surface 12 of the top plate 7, with each side portion 14 being a uniform distance inward from the respective side edge 16 of the plate 1. The uniform distance is designated as 'd'which corresponds .0 to the nominal wall thickness of the square hollow section column 9.

The right angle formations 2 are welded 3 to the top plate 7 along the inside junctions of the side edges 15 only, and not at the outside facing junctions thereof. In other words, no welds 3 are made facing the side faces 16.

The top plate 7 does not have the central oval slot 4. The isometric view in figure 6 .5 shows the top plate assembly 20 with the top plate 7, and the right angle formations 2 welded 3 to the top plate 7.

Fig 7 shows a part elevation of a timber wall frame 30 with timber top plates 113, timber bottom plates 114 fixed to a concrete slab 115, timber wall studs 110, and O square hollow section steel column 9. Two timber bottom plates 114 are disposed to extend from opposite sides of the column 9. Two timber wall studs 110 are disposed on each side of the column 9, with lower ends thereof mounted to a respective timber bottom plate 14. Two timber top plates 113 extend from upper ends of the wall studs 110.

The base plate 1 is to be mounted to the concrete slab 115 using a suitably sized hold down bolt extending through the slot 4. The right angle formations 2 of the top plate assembly 20 are fitted inside the top end of the column 9. The column 9 with the top plate assembly 20 is then mounted to the base assembly 10, with the right angle formations 2 of the base plate assembly 10 fitted inside the bottom end of the column 9. The top plate 7 is aligned with the top surface of the timber top plates 113.

A steel beam 12 is fixed to the top surface 11 of the top plate 7 through pre-drilled holes in the bottom flange of the beam 12, using self-drilling tek screws 116 into the top plate 7.

The column 9 is held in position by self-drilling tek screws 111 installed through the timber studs 110 on each side of the column 9, the screws 111 being equi-spaced along the column height.

.0 Referring to Figure 8, where the fitment of the base end of the steel column 9 is not aligned (17) with the plane of the base plate 1 and its right angle formations 2, an epoxy bearing filler 18 is used to fill the void and maximise bearing contact about the perimeter of the column 9.

.5 Figure 9 shows an alternative embodiment, where the column 9 is fitted into a pocket of the timber frame. This embodiment uses single top and bottom timber wall plates 113 and 114 extending across the ends of the column assembly 9 with top and bottom plate assemblies 20 and 10 fitted at each end. In other words, the base plate 1 rests on the bottom timber plate 114 and the top plate 7 engages the top timber o0 plate 113. The base plate 1 does not need the slot 4 in this embodiment.

The wall studs 120 are installed to each side of the column 9, in one configuration screw fixings 111 fix the wall studs to the column 9. The dotted lines in Figure 10 show the wall studs 120 on the other side of the timber bottom plate 114 and nails 119 through the timber bottom plate 14 into the ends of the wall stud 120.

As shown in Figure 11, in an alternative embodiment when additional load carrying capacity is required in this location, a hole 121 is cut in the timber bottom plate 14 for receiving a dowel 122. Figure 12 shows an isometric view of the timber dowel 122.

The invention in one aspect thus provides a steel column assembly comprising a hollow square section column having a base end, a top end, an internal surface, an external surface and a wall thickness therebetween, a base plate assembly comprising a flat steel base plate having a top surface and a bottom surface, the base plate assembly further comprising at least one formation at the top surface thereof for engaging the internal surface of the hollow square section at the base end thereof, and a top plate assembly comprising a flat steel top plate having a top surface and a bottom surface, the top plate assembly further comprising at least one formation at the bottom surface thereof for engaging the internal surface of the hollow square section at the top end thereof. .0

The formations in the base plate assembly and top plate assemblies are inserted into the respective base end and top end of the steel column such that the formations engage the internal surface of the steel column at the base end and the top end to retain the base plate assembly and top plate assemblies to the column, with the .5 base plate and the top plate respectively abutting and engaging the base end and the top end of the column.

In one aspect, the invention thus provides a base plate 1 which is substantially the size of the column 9 external cross section dimensions, being preferably a little o0 larger but not so much as to interfere with abutting wall frame components. The base plate 1 is preferably 10 mm thick and has two diametrically opposed angle formations 2 welded to the top surface of the plate 1, so that the external dimensions of the opposing angle faces substantially corresponds with the internal dimensions of the column 9.

A slot 4, substantially the width of the hold down bolt, is cut through the base plate 1 extending from approximately the plate centre and perpendicularly from a plate side to an edge distance from the opposing side which is preferably 20 mm.

Figure 13 shows an embodiment where the slot 4 extends to a side edge 16 of the base plate 1 to assist with bolt installation confirmation during inspections. The slot 4 in the bottom bracket plate 1 is extended to one side face 16 of the bracket so that on inspection of the single bolt installation, a piece or straightened wire may be poked into the slot 4 to confirm whether the bolt has been installed or not, simply by establishing the movement of the wire when it bottoms out, and moved across the slot, a concave movement means the wire is hitting the end of the slot, a convex arc, means the wire is following the outline of the installed bolt.

The base plate 1 is located in the position where the post is located on the plan, or abutting a wall, and a hole is drilled in the slot either in beginning of the slot at the centre of the plate for internal wall frames, or at the furthermost extent of the slot when edge distance requirements are to be satisfied for external walls abounding the .0 slab edge. The base plate 1 is fixed in position using a suitably sized hold down bolt,

A measuring tape is used to measure the wall height at the post location to the top of the base plate 1, and the standard column length is cut to length by subtracting the thickness of the top plate 7 connection from that measurement. .5

The top plate connector assembly 20 which is sized to the same overall shape and dimension as the bottom plate assembly 10 with the diametrically opposed angle formations 2 similarly welded in position, is without the slot 4 and comprising a thinner thickness, preferably 6 mm. -o The top plate 7 is tapped into the top of the column 7. Epoxy bearing compound may be applied around the edge of the base plate 1 abutting the angle formations 2 and the column 9 is installed over the base plate 1 so that the diametrically opposed angle formations 2 on the base plate 1 fit inside the column 9.

The column 9 is fixed into position using screws installed through the abutting wall stud 110 of the wall frame into the mating face of the column 9. When there is net uplift loading on the columns from the structure above it, then additional screw fixing is required between the column face and the diametrically opposed angles formations 2 welded to the base and top plate assemblies 10 and 20.

In the case of a double brick wall, wall ties may be fixed to the column face which abuts the brick wall, the columns 9 is installed with screws side fixed into the plate angle formations 2 to hold the column 9 vertical prior to the brick wall being built.

The steel beams or lintels are installed onto the posts 9 and tek screwed from the top and through the bottom flange of the beam, into the preferably 6 mm top plate 7.

In one embodiment, columns 9 are supplied in standard lengths slightly larger than the required post height to be trimmed to length on site to overcome the varying height issues caused by concrete slab level variations. This means the method of manufacture is simplified by incorporating pre-cut to length stock in the manufacturing facility rather than cut to length for each job from standard lengths, which also creates a great deal of unusable offcut. .0 So, with tube manufacturing lead times, standard column lengths can now be sourced without wastage, simply by specifying lengths that are multiples of the standard lengths required.

.5 In another embodiment, the steel columns 9 are cut to the required length to suit the framed wall height minus the thickness of the top and bottom bracket plates 1 and 7 fitted to them and delivered to site so they can be installed within the wall frame, or as separate components so the bottom bracket assemblies 10 and 20 can be fixed to the concrete and column installed onto it. -O In a further embodiment, the steel column assembly comprising a top bracket, a bottom bracket and a steel column is installed between the top and bottom plates 113 and 114 of the wall frame during the wall frame assembly process. One benefit of this is the top plate 113 remains continuous and straight, rather than discontinuous and poorly aligned when it is cut to receive a steel post. The steel column 9 assembly is generally fitted within a pocket 200 in the wall frame which is bordered by timber studs 120 each side of it, and top and bottom plates 113 and 114 above it. The size of the pocket 200 corresponds to the size of the steel column assy. The top and bottom bracket assemblies 10 and 20 are held in place each end of the column 9 by the top and bottom timber or steel wall frame plates 113 and 114.

When the steel column 9 is installed within the pocket 200, preferably so the outside and inside face of the column 9 corresponds to the outside and inside plane of the wall studs 120, however a smaller column 9 then the width of the bottom plate, may require the column face to be aligned with one face or in the centre, the column 9 is fixed in place by screws, installed through the adjacent wall stud, into the side of the column, in locations preferably, top, bottom and middle of the wall frame height.

Other abounding stud combinations may be used, and in some situations it may be preferable to install the column base directly onto the floor, such as in the case of corners posts, once the wall frame is delivered to site. In this case, the steel column may be delivered loose with the frame shipment. In all other instances the steel columns are delivered to site assembled within the pre-made wall frame assembly. .o What is claimed in this embodiment is a steel column assembly built into a wall frame assembly made from either timber or steel.

Another embodiment of the current invention is a providing a means within the top and bottom timber wall frames to provide more bearing capacity for the steel column .5 9 so that larger loadings can be applied to the columns 9 than what would be sustainable otherwise on the top and bottom wall plate 113 and 114. Generally, with timber wall frame assemblies, the top and bottom plates 113 and 114 are employed to hold the timber vertical studs 120 in place by nailing, to suit the wall frame design.

o0 The general construction loading applied along the top plate 113 is transferred through the top plate 113, into the vertical stud as generally compression loading, and sometimes tensile loadings, and the loading is transferred by bearing through the timber bottom plate into the floor structure. The timber in the vertical studs has a grain structure aligned with the direction of the loading on the stud, and the bottom plate 114 and top plate 113 has a grain structure aligned perpendicularly to the direction of the loading on it. The structural bearing capacity of timber is maximised when the timber grain is aligned to the direction of loading, and considerably reduced when the loading is at right angles to the grain. While there is substantial bearing capacity when the loading is applied perpendicular to the grain, and will sustain a range of load applications in the house structural design, it is not sufficient for all loading situations.

Another embodiment of the current invention is to increase the bearing capacity of the top and bottom plates 113 and 114 by employing timber inserts or plugs 122, preferably round, installed into the top and bottom plates 113 and 114. In this way the direction of the timber grain in the inserts is aligned with the direction of the loading applied onto it. The timber inserts 122 are installed by firstly drilling a hole in the centre of the bottom and top plate 113 and 114 corresponding to the diameter of the timber insert, preferably a dowel 122. The hole centre is aligned with the longitudinal axis of the steel column 9. The dowel 122, preferably hardwood for greater compressive strength, is cut to the thickness of the timber plates 113 and 114, preferably 45 mm, glue applied to the sides, and the dowel plug is installed into each hole at the top and bottom plate 113 and 114 after or before the steel column 9 .o is installed into the pocket made for it.

When the frame is installed on site, if there is any gaps between the location of the steel column and the floor, a metal or engineered plastic shim can be inserted between the bottom of the bottom plate 1 and the floor to ensure the loading in the .s steel column can be transferred into the floor without causing deflections or distortions in the wall frame assembly. The wall frame is bolted to the floor through the bottom plate each side of the wall pocket holding the steel column, which means there is no further need to fix the column base or the column itself directly to the floor. -o In another embodiment of the present invention the wall frame assembly is made on or off site and holes cut into the top and bottom plate 113 and 114 in the location of the steel column. After the frame is installed, the holes in the bottom plate 114 are filled with high compression grout, the post 9 and bracket assembly 10 is then installed within the frame pocket and secured into the frame. The hole in the top plate 113 is then filled with grout until level with the top surface of the top plate 113. After drying the other load bearing elements are installed onto the frame and onto the top plate 7 above the steel column 9, alternatively timber dowel plugs 122 can be deployed and installed on-site to provide a similar function.

In another embodiment, the two right angle formations 2 can be replaced by a single hollow square formation.

The present embodiments also overcome additional disadvantages of current systems. Currently all the cut to length posts manufactured for onsite construction have the top and bottom plates welded to the column, simply because they need to when using flat plates. It is physically impossible to install a column with a welded on base plate and fix it to the slab within the footprint of the column.

The present embodiments remove the need for welding because the base plate has projections inserted into the column base end that laterally restrains the column when the base plate by itself is fixed to the floor structure.

The present embodiments thus remove the need to weld, effectively replacing .0 welding of plates to columns by using plates with angles welded to them, this enables fast and efficient site fix up when the columns are too long (by cutting it back with a grinder) or if too short, for packing, reusing the top and bottom bracket assembly, on a longer post. In prior art systems, site welding/ repair of posts may attract a minimum 4 hrs charge from a welder, a specialised trade, since carpenters .5 are generally not welders.

In the embodiment of Figure 9 where the column is deployed within a pocket of a pre-assembled offsite wall frame, it is possible to tack weld the bracket assemblies to each end of the column. In this embodiment, a top plate with the overall post dimensions and without the angles can be welded to the top of the column posts as O part of the manufacturing process.

Technically, the top plate assembly could be welded to the top of the column, leaving the base assembly to be installed onto the floor structure, then fitting the column with the top plate welded to it, after the column is cut to length (if required). Alternatively, the base assembly can be fitted into the column prior to fitting the column assembly within the pocket of a pre-assembled wall frame.

In the embodiments shown, welding of the angle formations is only to the inside junctions of the top and bottom plates, so that the plates rest flat against the top and bottom end edges of the column.

It is to be noted the invention can also be used for columns of other hollow cross sections such as rectangular or circular cross-sections.

The invention design provides a bracket (bottom plate assembly) with a fixing to the concrete base which is within the footprint of the column combined with a means to restrain the column internally without the need, generally of installing fixings to the outside surface of the post, which would interfere with claddings, or abutting of the timber studs against it. Thus, no scarfing or cut-outs are needed for the bottom timber plates and studs abutting the column.

The top and bottom timber plates are not scarfed out to achieve the present result when the top and bottom post plate assemblies are the same cross section as the column post itself.

.0

Claims

1. A column assembly comprising:

a base plate assembly comprising a flat steel base plate having a top surface and a bottom surface, the base plate assembly further comprising at least one formation at the top surface thereof to be received into the base end of the .0 column for engaging the internal surface of the column at the base end thereof, and

a top plate assembly comprising a flat steel top plate having a top surface and a bottom surface, the top plate assembly further comprising at least one formation .5 at the bottom surface thereof to be received into the top end of the column for engaging the internal surface of the column at the top end thereof.

2. The column assembly of claim 1 wherein the base plate and the top plate are dimensioned to have side faces substantially aligned with the external surface of '0 the column when the respective formations are received in the ends of the column.

3. The column assembly of claim 2 wherein the column has a rectangular cross section, and the at least one formation comprises two substantially right angle formations for each of the base plate and the top plate, each substantially right angle formation being a flat rectangular plate bent at a mid-portion thereof to have side portions at about 900 to each other.

4. The column assembly of claim 3 wherein the two right angle formations are laid to have a side edge thereof laying on the plate, with each side portion adjacent a respective side edge of the plate.

5. The column assembly of claim 4 wherein each side portion is a uniform distance inward from the respective side face of the plate, the uniform distance being the wall thickness of the hollow square section column.

6. The column assembly of claim 3 wherein the right angle formations are welded to the plates along the inside junctions only such that the respective top and bottom plates abuts against the respective end of the column.

7. The column assembly of claim 1 wherein the base plate comprises a central oval slot.

8. The column assembly of claim 7 wherein the slot extends to a side face of the base plate.

9. The column assembly of claim 1 wherein the hollow column has a square, rectangular or circular cross section. .0

10. The column assembly of claim 1 wherein the respective formations lock with the respective ends of the column and prevent the column from moving laterally relative to the respective top and bottom plates.

11. A timber wall frame comprising: the column assembly of claim 7 with the base plate assembly mounted to a .5 concrete base via a bolt inserted into the base plate slot, the top plate assembly mounted to the top end of the column and the column mounted to the base plate assembly, two timber bottom plates disposed to extend from opposite sides of the column assembly, two timber wall studs disposed on each side of the column assembly, with lower ends thereof mounted to a respective timber bottom plate, two timber top plates disposed to extend from upper ends of the wall studs.

12. A timber wall frame comprising: a timber bottom plate, the column assembly of claim 1 with the base plate assembly and the top plate assembly mounted to the base end and the top end of the column, the base plate resting on the timber bottom plate, two timber wall studs disposed on each side of the column assembly, with lower ends thereof mounted to a respective timber bottom plate, a timber top plate extending across the upper ends of the wall studs and the column assembly.

13. The timber wall frame of claim 10 further comprising an aperture in the timber bottom plate for a dowel, the aperture aligned with the base plate assembly, and a dowel received in the aperture.

14. A method of assembly of an off-site pre-assembled timber wall frame with load bearing steel columns, the method comprising the steps of: forming a pocket in a wall frame between two wall studs, inserting the column assembly of claim 1 with the base plate assembly and the top plate assembly mounted to the base end and the top end of the column.

15. A method of construction with the frame built on site, the method comprising: mounting the base plate assembly of claim 7 to a concrete slab via a hold down connection bolt extending through the base plate slot, mounting the top plate assembly to the top end of the column, .0 mounting a base end of the column to the base plate assembly, attaching wall studs to opposite sides of the column via fasteners.

16. End plate assemblies for a hollow column having a base end, a top end, an internal surface, an external surface and a wall thickness therebetween, the end plate assemblies comprising: .5 a base plate assembly comprising a flat steel base plate having a top surface and a bottom surface, the base plate assembly further comprising at least one formation at the top surface thereof to be received into the base end of the column for engaging the internal surface of the column at the base end thereof, and '0 a top plate assembly comprising a flat steel top plate having a top surface and a bottom surface, the top plate assembly further comprising at least one formation at the bottom surface thereof to be received into the top end of the column for engaging the internal surface of the column at the top end thereof.

17. The end plate assemblies of claim 16 wherein the base plate and the top plate are dimensioned to have side faces substantially aligned with the external surface of the column when the respective formations are received in the ends of the column.

18. The end plate assemblies of claim 17 wherein the at least one formation comprises two substantially right angle formations for each of the base plate and the top plate, each substantially right angle formation being a flat rectangular plate bent at a mid-portion thereof to have side portions at about 900 to each other.

19. The end plate assemblies of claim 18 wherein the two right angle formations are laid to have a side edge thereof laying on the plate, with each side portion adjacent a respective side edge of the plate.

20. The end plate assemblies of claim 19 wherein each side portion is a uniform distance inward from the respective side face of the plate, the uniform distance being the wall thickness of the hollow square section column.

21. The end plate assemblies of claim 18 the right angle formations are welded to the plates along the inside junctions only such that the respective top and bottom plates abuts against the respective end of the column. o

22. The end plate assemblies of claim 16 wherein the base plate comprises a central oval slot.

23. The end plate assemblies of claim 16 wherein the slot extends to a side face of the base plate.