WO 98/59128 PCT/US97/11126 LOAD BEARING COMPONENTS AND A METHOD OF BUILDING FIELD OF THE INVENTION This invention relates to load bearing components mainly for use in industries such as the building and construction industries but which can also be 5 used in the aeronautical and other industries. It also relates to a method of building. BACKGROUND OF THE INVENTION The building industry is always seeking new components which have a ratio of weight to load bearing capacity that is superior to the components which it currently uses. Very simplistically the more a component weighs usually the 10 more it costs. A component which weighs less but can carry the same load clearly gives its user a substantial advantage when tendering for a contract. Another problem which the construction industry faces is that many load bearing components must be manufactured in a factory and shipped to site. Such components are often of open lattice work construction and occupy substantial 15 space. They are thus not cost effective to transport as, within their outside dimensions, there is a great deal of empty space. A load bearing component that can be fabricated on site from components which are in flat form when brought to site offers numerous advantages over a component which must be manufactured off-site and transported to site for erection. 20 OBJECTS OF THE INVENTION The present invention seeks to provide an improved load bearing component. The present invention also seeks to provide a load bearing component which can be fabricated on site from components that are transportable to site in flat form and bent to shape on site as necessary. It furthermore seeks to provide a novel 25 building method. BRIEF DESCRIPTION OF THE INVENTION According to one aspect of the present invention there is provided a method of fabricating an element for use in a load bearing component, the method comprising bending said strip along a series of curved lines each of which bounds 30 between itself and the edge of the strip a flange portion which is widest at the centre and tapers progressively towards its ends, the curved lines forming the boundaries of a web which varies in width, and bending the web to zig-zag form C!1TTDTr~r'TT'Tr 0~T1r'V'T 1 .... I '1 WO 98/59128 PCT/US97/11126 -2 along transverse bend lines which intersect said edges of the strip where each convex curve meets with the adjacent convex curve. A specific form of the method includes the step of bending each edge of the strip so as to leave straight edge portions between adjacent curved lines, and 5 the further step of bending the web transversely so that said transverse bend lines intersect said straight edge portions. In this form each straight edge can have a notch cut therein and the web can be bent so that the transverse bend lines intersect said notches. According to a further aspect of the present invention there is 10 provided an element for use in a load bearing component, the element comprising a web bent to zig-zag form along a plurality of transverse bend lines and further comprising a series of flanges on each side of the web, each flange having a free edge which is constituted by a curve and each being joined to said web along a curved line, each flange being widest at its centre and tapering progressively from 15 its centre towards both ends thereof, the web being bounded by said curved lines and having narrow portions where said flanges are widest and wide portions where said flanges are at their narrowest. In one embodiment said web is bounded by said curved lines and by straight edge portions which are between said curved lines. In this embodiment 20 notches can be cut in said straight edge portions, the transverse lines along which the web is bent to zig-zag form intersecting said notches. According to another aspect of the present invention there is provided a method of building comprising erecting a framework, the framework including inner and outer frames with a cavity therebetween, stacking bags filled with 25 aggregate in said cavity to form a wall core, attaching mesh material to the exposed faces of said inner and outer frames of said framework, and plastering over said exposed faces of said frames, over said mesh material and over said wall core to form a wall. To ensure that the mesh material is secure the method can further 30 include placing wire ties between the bags with the ends of the ties protruding beyond the bags and thereafter attaching the ties to the mesh material. To provide keying between walls which meet at right angles the T tT"r''TTT"'17 C'TTi'Y' i - \..
WO 98/59128 PCT/US97/11126 -3 method can include the step of using first bags and second bags, the second bags being double the length of the first bags, half the length of each second bag being in one wall and half the length of each second bag being in a wall at right angles to said one wall. 5 The bags are preferably filled through an open end thereof, and thereafter a flap of the bag is folded over to close-off said open end. To ensure that the wall is as regular as possible, each bag is tamped down after it has been stacked in the cavity so that each has a generally flat top surface for supporting a bag placed thereon. 10 BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figures 1 and 2 illustrate the production of a web element; 15 Figure 3 is an isometric view of a part of a load bearing component; Figure 4 is a side elevation of the component part illustrated in Figure 3; Figure 5 illustrates a modified horizontal for use in the components of Figures 3 and 4; 20 Figure 6 illustrates a modified web component; Figure 7 is a plan view of a sheet from which a bag can be produced; Figure 8 is a plan view of a first form of bag; Figure 9 is a plan view of a second form of bag; 25 Figure 10 is a plan view of a double size bag; Figure 11 is a plan view of a further form of double size bag; Figure 12 is a diagrammatic edge view of the bags of Figures 10 and 11; Figure 13 is a pictorial view of part of a building structure; 30 Figure 14 is a view of a wall; Figure 15 is a pictorial view of a wall; and Figure 16 is a detail of the wall. OYTT1'IrY~mTTTrIr C'TTrl' I' -.. I,- '% WO 98/59128 PCT/US97/11126 -4 DETAILED DESCRIPTION OF THE INVENTION The blank 10 shown in Figure 1 comprises an elongate strip of metal such as galvernised steel. The long edges of the strip are straight and the blank 10 is bent down along the series of curved lines shown at 12 to the condition shown in 5 Figure 2. It thus has a web 14 of varying width and a series of pairs of flanges 16 with curved edges 18. The flanges are best seen in Figures 3 and 4. The blank is bent in opposite directions about the lines 20, each bend being in the opposite direction to the adjacent bends. These bends are approximately 90 degree bends. The result is a zig-zag shaped web element 22 (see 10 Figures 3 and 4). The light weight load bearing component 24 of Figures 3 and 4 comprises, in addition to the web element 22 formed as described above, an upper horizontal 26 and a lower horizontal 28. The horizontals 26 and 28 are of wood and the web element 22 is nailed to them. The nails are shown at 30 and are driven 15 by a nail gun through the web 14. In Figures 3 and 4 the horizontals are constituted by wooden beams. In Figure 5 there is shown a construction in which the horizontal is a wooden beam 32 sheathed in a channel 34 fabricated by bending an elongate strip of galvernised iron through right angles along two parallel lines extending the length of the strip. 20 The beam 32 is, for the sake of illustration, shown protruding from the channel 34. In Figure 6 there is shown a modified version in which there are short straight edges 36 between the curved lines 12 with stress relieving notches 38 in the edges 36. The lines 20 intersect the notches 38. The sheet 110 shown in Figure 7 is of synthetic plastics material. It 25 is preferably woven using tapes or threads but could be of sheet material preferably with a rough surface. The sheet is folded twice (see Figure 8), one fold 112 providing a transverse end to the bag designated 114 and the other fold 116 forming a pillow case type flap 118. The bag is thereafter stitched or welded closed along the lines 120. 30 The bag 114 is filled with sand, soil or small stones or other material that can be packed into the bag 114. The term "aggregate" is used herein to designate such materials. The flap 118 is sufficient to prevent the aggregate in the TTDcTTTTVCT1 LT' rrT i ... u - I WO 98/59128 PCT/US97/11126 -5 bag 114 falling out. To enable small spaces to be filled during building it is possible to use a half size bag 114.1 as shown in Figure 9. In Figure 10 there is shown a double sized bag 122 which is divided 5 at the centre by means of a line of stitching or a weld designated 124. The bag is formed by stitching or welding two sheets 126, 128 (Figure 12) to one another along the edges 130 after folding the sheet to form two flaps 132. After the two halves of the bag have been filled through the openings designated 134, the openings 134 can be closed-off by folding back the flaps 132. 10 The bag 122 of Figure 11 differs from that of Figure 10 only in that the weld or stitch line, designated 124.1, is diagonal instead of transverse. It is possible to use tubular material welded or stitched closed across one end as bags. The bags are filled from a fixed volume container which is overfilled 15 and the excess then scrapped off using a straight edge. This ensures that each bag has substantially the same volume of aggregate as each other bag. The dividing lines 124, 124.1 inhibit deformation of a filled, double size bag. Mechanical fastening means such as clamps may be employed to close the bags. Such means can be instead of, or in addition to, the closing flaps 118, 132 described above. 20 The building structure of Figure 13 comprises a series of components 24 as shown in Figures 3 and 4. The components are arranged so as to form a series of inner frames 136 and a series of outer frames 138 with cavities 142 between the frames. As shown in Figure 14, the building construction of Figure 13 25 includes end columns 144, intermediate columns 146, upper and lower horizontals 148, 150 and intermediate horizontals 152. The intermediate horizontals 152 form parts of the window and door frames. All the columns and horizontals form part of the outer frame 138. The lower horizontals 150 can rest, in the simplest form, on a 30 levelled and tamped earth surface, marked with string or whitewash to indicate where the horizontals should be placed. Concrete or other foundations can, of course, be provided if desired but this adds to the cost. QrTT 'rFT'II"TT'Tr17r oTr'IrL-T / -.. 1- 14 It WO 98/59128 PCT/US97/11126 -6 Angle iron stanchions can be provided at the corners of the building if it is of rectangular shape. Filled bags 114 are placed in the cavities 142 as shown in Figures 14 and 15. The double sized bags 122 lie partly in one wall and partly in a wall at 5 right angles thereto thereby to key the two walls together. As each course of bags is positioned, the bags are flattened by tamping them with a paddle or an implement such as a cricket bat. The bags form the core of the wall. Galvanised wire ties 154 (see also Figure 16) are placed in the wall at intervals in both the vertical and horizontal directions. The ties 154 protrude 10 from the wall in both directions. It is also possible to incorporate piping 156 (Figure 15) into the walls. The piping 156 can be for inflammable gas or water or for receiving electrical wiring. Holes 158 (Figures 13 and 15) can be provided in the horizontals 24 to permit the piping 156 to pass through. The piping can be secured to the inner 15 frame 136 to ensure that it remains in place, and can be blanked-off if it is not to be used immediately. A board 160 (Figure 15) secured to the frame 136 can provide a mounting for a tap 162 and/or an electric socket 164. Once the cavity 142 has been filled up to the level of the upper 20 horizontals 148, mesh material designated 166 is stretched over and secured to the exposed faces of the inner frames 136 and the outer frames 138. The mesh material is tacked, stapled, nailed, or tied, or otherwise secured to the columns 144, 146 and the horizontals 148, 150 and 152. Chicken wire is the preferred mesh material. The wire ties 154 are used to pull the mesh material 166 against the 25 bags 114, 122 in the areas between the columns and horizontals. This is done by twisting the ends of the ties around the mesh material. A suitable plaster 168 is applied to both the inner surface and outer surface of the wall. The rough surfaces of the bags, and the mesh material, provide a base to which the plaster keys. Plaster enters the recesses between adjacent bags. 30 This plaster forms a waterproof skin that can then be painted. Roof trusses (not shown) supported by the upper horizontals 148 carry roofing sheets which can be of conventional corrugated steel or of the form rTT Q TT)TT 'rgTTTr-r " It '1T f .- ,I, 14 t WO 98/59128 PCT/US97/11126 -7 known as IBR. If a second door or further windows are to be fitted later, the appropriate openings are left in the wall and are not closed-off by means of filled bags. Temporary sheet material can be used to close up the openings until the 5 second door or further windows are to be fitted. The sheet material is then removed and a door or window frame inserted. The door or window frame is attached to the framework. cTTDc T'rT'T1T'T'r'I ' , .TTT'rT' I -.. 1- 4 1 WO 98/59128 PCT/US97/11126 -8 CLAIMS 1. A method of fabricating an element for use in a load bearing component, the method comprising bending a strip along a series of curved lines each of which bounds between itself and the adjacent edge of the strip a flange 5 portion which is widest at its centre and tapers progressively towards its ends, the curved lines forming the boundaries of a web which varies in width, and bending the web to zig-zag form along transverse bend lines which intersect said edges of the strip where said curved lines intersect said edges. 2. A method as claimed in claim 1, and including so forming said 10 curved lines as to leave straight edge portions of the element between the points at which adjacent curved lines intersect said edges, and bending the web transversely so that said transverse bend lines intersect said straight edge portions. 3. A method as claimed in claim 2, wherein each straight edge portion has a notch cut therein and the web is bent so that the transverse bend lines intersect 15 said notches. 4. A load bearing element as claimed in claim 1, wherein adjacent curved lines intersect the adjacent one of said edges at the same point and one of the transverse bend lines intersects that edge at the same point. 5. An element for use in a load bearing component, the element 20 comprising a web bent to zig-zag form along a plurality of transverse bend lines and further comprising a series of flanges on each side of the web, each flange having a free edge which is constituted by a curve and each being joined to said web along a curved line, each flange being widest at its centre and tapering progressively from its centre towards both ends thereof, the web being bounded by said curved lines 25 and having narrow portions where said flanges are widest and wide portions where said flanges are at their narrowest, said transverse bend lines being where said web is at its widest. 6. An element as claimed in claim 5, wherein each longitudinal edge of said web is bounded by a series of said curved lines and by straight edge portions 30 which are between adjacent curved lines. 7. An element as claimed in claim 6, wherein notches are cut in said straight edge portions, the transverse lines along which the web is bent to zig-zag CTT ' TT"Y'qm T TT I7' c 'ly Tf7'1 T -.. - 14