AU2011244956A1 - Corrugated shearwall - Google Patents

Abstract

OF THE INVENTION A prefabricated shearwall including a central diaphragm having a height generally defined by top and bottom edges, and a width generally defined by a pair of end sections. The diaphragm further includes at least one corrugation 5 extending in the height direction at least partially between the top and bottom edges. The corrugation increases the ductility and ability of the shearwall to withstand lateral forces such as those generated in earthquakes, high winds, floods and snow loads. The various components of the shearwall may be affixed to each other by welding, bolting, screwing and/or gluing. h - d0

Description

Australian Patents Act 1990 - Regulation 3.2A ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title "Corrugated shearwall" The following statement is a full description of this invention, including the best method of performing it known to me/us: P/00/00 1 C:\NRPortbl\DCCTZS959720_1.DOC - 3/11/11 -la 5 Inventors: Wiiiam F. Leek Jose L. Perez Jerry G. Gridley 10 Stephen B. Lamson 15 [0001] The disclosure of the complete specification of Australian Patent Application No. 20042378.48 as originally filed is incorporated herein by reference. 20 BACKGROUND OF THE INVENTION Field of the Invention [0002] The present invention relates to a shearwall for opposing lateral forces on building walls, and in particular to a prefabricated shearwall including a central 25 diaphragm having a corrugated or non-planar cross section to improve the ability of the shearwall to withstand lateral forces such as those generated in earthquakes, high winds, floods and snow loads. Description of the Related Art [0003] Shearwalls were developed to counteract the potentially -2 devastating effects of natural phenomena such as seismic activity, high winds, floods and snow loads on the structural integrity of light-framed constructions. Prior to shearwalls and lateral bracing systems, lateral forces generated during these natural phenomena often caused the top portion of a wall to move laterally 5 with respect to the bottom portion of the wall, which movement could result in structural failure of the wall and, in some instances, collapse of the building. Shearwalls within wall sections of light-framed constructions provide lateral stability and allow the lateral forces in the wall sections to be transmitted through the shearwalls between the upper portions of the wall and the floor diaphragm or 10 foundation of the building where they are dissipated without structural effect on the wall or building. [0004] In constructions such as residences and small buildings, a lateral bracing system typically includes vertical studs spaced from each other and affixed to horizontal top and bottom plates. The bottom plate is typically 15 anchored to the floor diaphragm or foundation. The bracing system typically further includes sheathing affixed to the studs, upper plate and/or lower plate to increase structural response to lateral forces. The sheathing used is generally oriented strand board (OSB) or plywood, but fiberboard, particleboard and drywall (gypsum board) are also used. Alternatively or additionally, light-frame 20 construction wall sections may include prefabricated shearwall sections, which can be positioned between the vertical studs and affixed to the studs and the top and bottom connecting plates. The sheathing or prefabricated panels can also be placed adjacent door and window frames to improve the response to lateral forces at these locations. 25 [0005] A conventional prefabricated shearwall 20 is shown in the perspective and cross-sectional views in Figs. 1 and 2. The shearwall includes an interior diaphragm 22 formed of thin gauge sheet steel which is affixed to an exterior wooden frame 24. The diaphragm is conventionally planar with the -3 edges along the length of the diaphragm being formed to respective lips 26 and 28. The lips 26, 28 allow the diaphragm to be affixed to the wooden frame. [0006] While a prefabricated shearwall of the construction shown in Figs. 1 and 2 provides lateral force response and resistance, it has limitations with 5 respect to its lateral load bearing capabilities. There is, therefore, a need for an improved shearwall capable of withstanding greater lateral loads. SUMMARY OF THE INVENTION [0007] It is therefore an advantage of the present invention to provide a shearwall having improved lateral load bearing characteristics relative to similarly 10 sized shearwalls. [0008] It is another advantage of the present invention to provide a shearwall having improved lateral load bearing characteristics without adding to the size or materials used relative to conventional shearwalls. [0009] It is another advantage of the present invention to provide a 15 shearwall having improved lateral load bearing characteristics which may be easily retrofit into existing structures. [0010] It is a still further advantage of the present invention to provide a variety of connecting methods for assembling the shearwall according to the present invention, including welding, bolting and gluing. 20 [0011] These and other advantages are provided by the present invention which in preferred embodiments relates to a prefabricated shearwall including a central diaphragm having a height generally defined by top and bottom edges, and a width generally defined by a pair of end sections. The diaphragm further includes at least one corrugation extending in the height direction at least 25 partially between the top and bottom edges. The corrugation increases the cross- -4 sectional area and ductility of the diaphragm in the lateral direction in comparison to conventional shearwalls, and further improves the resistance of the shearwall to lateral forces such as those generated in earthquakes, high winds, floods and snow loads. 5 [0012] In embodiments of the invention, the shearwall may further include a pair of reinforcing chords affixed to the end sections of the central diaphragm. The chords may be formed of 2 inch x 4 inch wooden studs having a height equal to that of the central diaphragm. The chords further improve the resistance of the shearwall to lateral forces. 10 [0013] In order to distribute the significant compressive forces exerted by the shearwall over a large surface area on the underlying support surface, the shearwall further includes a flat sill plate affixed to the bottom edge of the central diaphragm. In embodiments of the invention, the sill plate may have a footprint at least equal to that of the central diaphragm, the chords and any sheathing 15 affixed to the shearwall. The sill plate may be formed of a rigid material such as steel to evenly distribute any localized compressive forces from the shearwall. The sill plate may also underlie the chords to prevent any wetness or moisture from the underlying support surface from damaging the chords. [0014] While a preferred embodiment of the invention includes a central 20 diaphragm with a corrugation having a constant size and shape from the top edge to the bottom edge, the corrugation may be formed so that it is larger at the bottom edge of the central diaphragm and slopes inward to become smaller toward the top edge of the central diaphragm (or visa-versa). This results in a shearwall providing even greater lateral force resistance, as the sloped lines 25 defined by the bends at the intersection between the various diaphragm sections have lateral components that exhibit increased resistance to movement in the lateral direction.

-5 BRIEF DESCRIPTION OF THE DRAWINGS [0015] The present invention will now be described with reference to the drawings in which: [0016] FIGURE 1 is a perspective view of a prefabricated shearwall panel 5 according to the prior art; [0017] FIGURE 2 is a cross-sectional view through line 2-2 of Fig. 1 showing the prefabricated shearwall panel according to the prior art; [0018] FIGURE 3 is a perspective view of a prefabricated shearwall according to an embodiment of the present invention; 10 [0019] FIGURE 4 is a cross-sectional view through line 4-4 of Fig. 3 showing the prefabricated shearwall according to the present invention; [0020] FIGURE 5 is an exploded perspective view of the prefabricated shearwall according to the present invention; [0021] FIGURE 6 is a perspective view of a shearwall according to the 15 present invention mounted to an underlying support surface such as a building foundation; [0022] FIGURE 7 is a front view of a shearwall according to an alternative embodiment of the present invention where the size and shape of the corrugation changes from the top edge to the bottom edge of the shearwall; 20 [0023] FIGURE 8 is a cross-sectional view through line 8-8 of Fig. 7; [0024] FIGURE 9 is a cross-sectional view through line 9-9 of Fig. 7; [0025] FIGURE 10 is a cross-sectional view through line 10-10 of Fig. 7; -6 [0026] FIGURE 11 is a front view of a shearwall according to a further alternative embodiment of the present invention similar but inverted with respect to Fig. 7; [0027] FIGURE 12 is a front view of a shearwall according to a further 5 alternative embodiment of the present invention where the size and shape of the shearwall changes from the top edge to the bottom edge of the shearwall; [0028] FIGURE 13 is a front view of a shearwall according to a further alternative embodiment of the present invention where the size and shape of the corrugation changes from the top edge to the bottom edge of the shearwall; 10 [0029] FIGURE 14 is a cross-sectional view through line 14-14 of Fig. 13; [0030] FIGURE 15 is a cross-sectional view through line 15-15 of Fig. 13; [0031] FIGURE 16 is a cross-sectional view through line 16-16 of Fig. 13; [0032] FIGURE 17 is a front view of a shearwall according to a further alternative embodiment of the present invention where the shearwall has cutout 15 sections in the surface of the central diaphragm; [0033] FIGURE 18 is a cross-sectional view through line 18-18 of Fig. 17; [0034] FIGURE 19 is a cross-sectional view through line 19-19 of Fig. 17; [0035] FIGURES 20 through 24 are cross-sectional views of alternative embodiments of the central diaphragm which may be used in the present 20 invention; [0036] FIGURE 25 is a cross-sectional view from the same perspective as Figs. 20 through 24, further including an embossment; [0037] FIGURE 26 is a side view of an embossment shown in Fig. 25; -7 [0038] FIGURE 27 is a cross-sectional view from the same perspective as Figs. 20 through 24, further including an inwardly facing stiffening lip; [0039] FIGURE 28 is a cross-sectional view from the same perspective as Figs. 20 through 24, further including an outwardly facing stiffening lip; 5 [0040] FIGURES 29 and 30 are cross-sectional views of a further alternative embodiment of the present invention; and [0041] FIGURE 31 is a front view of the embodiment of the present invention shown in Figs. 29 or 30. DETAILED DESCRIPTION 10 [0042] The present invention will now be described with reference to Figs. 3 through 31, which in embodiments relate to a prefabricated shearwall panel including a central diaphragm having a non-planar cross-section to improve the lateral load bearing characteristics of the panel. It is understood that the present invention may be embodied in many different forms and should not be construed 15 as being limited to the embodiments set forth herein; rather these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the invention to those skilled in the art. Indeed, the invention is intended to cover alternatives, modifications and equivalents of these embodiments, which are included within the scope and spirit of the invention as defined by the 20 appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be clear to those of ordinary skill in the art that the present invention may be practiced without such specific details. 25 [0043] Referring now to Figs. 3 through 4, there is shown a prefabricated shearwall 100 according to the present invention. The shearwall 100 includes a central diaphragm 102 having a height, width, and depth, each perpendicular to each other and denoted as h, w and d, respectively, in Fig. 4. In embodiments of the present invention, the central diaphragm 102 includes a top edge 101 and a bottom edge 103 generally defining the height of the central diaphragm, and a 5 pair of end sections 104 and 106 generally defining the width of the central diaphragm. The diaphragm 102 further includes a corrugation 108 defined by rear planar sections 110 and 112, angled sections 114 and 116, and front planar section 118. While the corrugation 108 is shown comprised of planar sections joined at angles with respect to each other, it is understood that the corrugation 10 108 may have different configurations in alternative embodiments. As used herein, a corrugation may be any ridge, groove or angle formed in central diaphragm 102 extending in the height direction at least partially between the top edge 101 and the bottom edge 103. The ridge, groove or angle lies in between the end sections 104, 106 in a plane different from that of an adjacent section 15 which also extends in the height direction between the top and bottom edges 101, 103 in between the end sections 104,106. [0044] Some alternative embodiments of the central diaphragm are shown in Figs. 7 through 28 and discussed hereinafter. In addition to adding increased resistance to compressive loads (i.e., those parallel to the diaphragm height), the 20 corrugation 108 increases the cross-sectional area and its ability to withstand lateral forces (i.e., those parallel to the diaphragm width). Moreover, the corrugation 108 provides increased ductility to the shearwall in the lateral direction. [0045] In embodiments of the present invention, the central diaphragm may 25 have an overall height of 93% inches, an overall width of 12 inches, and a depth of 2% inches. It is understood that each of these dimensions may be varied in alternative embodiments, both proportionately and disproportionately with respect to each other. For example, in one alternative embodiment, the central -9 diaphragm may have an overall width of 18 inches. Each of the sections 104, 106 and 110 through 118 is preferably the same height. In embodiments where the overall width is 12 inches, end sections 104 and 106 may each be 2 1 % inches wide, rear planar sections 110 and 112 may each be 3 inches wide, the angled 5 sections 114 and 116 may each be 4% inches wide, and the front planar section 118 may be 1% inches wide. It is understood that each of these dimensions for the sections 104, 106 and 110 through 114 may vary in alternative embodiments, both proportionately and disproportionately with respect to each other. In embodiments of the present invention, the central diaphragm 102 may be formed 10 of 7-gauge sheet steel (0.1875 inches). Other gauges, such as for example 10 gauge sheet steel, and other materials of comparable strength and rigidity may be used in alternative embodiments. One such alternative material may be expanded metal. [0046] In a preferred embodiment, the rear planar sections 110, 112 may be 15 coplanar with a back edge of the diaphragm 102 and front planar section 118 may be coplanar with a front edge of the diaphragm 102 so that the corrugation 108 traverses the entire depth of the central diaphragm. As explained in greater detail below, the corrugation 108 need not traverse the entire depth of the central diaphragm in alternative embodiments. 20 [0047] Referring now to Figs. 5 and 6, when installed into a wall, the top and bottom edges 101 and 103 of the central diaphragm lie within U-shaped channels 119 and 121, respectively. In embodiments of the invention, both U-shaped channels may be formed of %A inch steel plate bent into a U shape. Each channel 119, 121 may be as long as the central diaphragm is wide. The uppermost 25 surface of channel 119 and the lowermost surface of channel 121 shown in Fig. 5 may be 3 inches wide. The front and back edges of the channels may extend a few inches over the top and bottom of the central diaphragm, and the front and back edges may include scallops to facilitate fastening of the bolts securing the -10 central diaphragm to the top plate and underlying surface as explained hereinafter. The channels 119 and 121 may be affixed in their respective positions on the central diaphragm by welding, bolting, gluing and other known affixation methods. As used here, gluing refers to the application of any of one or 5 more known compounds (including adhesives and epoxies) to at least portions of the interface between the channels 119/121 and central diaphragm which cause the channels and central diaphragm to stick to each other. The U-shaped channels 119, 121 may be omitted in alternative embodiments, in which case the top and bottom edges of the central diaphragm may attach directly to the top and 10 bottom plates of the wall. [0048] In embodiments of the present invention, the shearwall 100 may further include a pair of reinforcing chords 120 and 122 affixed to the end sections 104 and 106, respectively. The chords may be formed of wood, such as for example sawn lumber from lumber groups including spruce-pine-fir, Douglas 15 fir-larch, hem-fir and southem pine. The chords 120, 122 may alternatively be formed of engineered lumber, such as glulam and wood composites. Other types of wood are contemplated. The chords may have a height equal to that of the central diaphragm 102 and channels 119 and 121 together, and may be 4 inches wide by 2 inches deep. Various affixing mechanisms may be used to affix 20 the chords to the central diaphragm, such as for example a plurality of % inch x 1% inch Simpson Strong-Drive@ screws. Other types of screws and affixation methods are contemplated, such as for example gluing. As used in this regard, gluing refers to the application of any of one or more known compounds (including adhesives and epoxies) to at least portions of the interface between 25 the chords and central diaphragm which cause the chords and central diaphragm to stick to each other. In embodiments employing screws, the screws may be provided in each chord along a single column and spaced apart 6 to 12 inches from each other. It is understood that the screws may be provided in more than one column, or not aligned in a column, down the length of the chords 120, 122, -11 and may be spaced apart more or less than 6 to 12 inches in alternative embodiments. [0049] Affixation of the chords to the central diaphragm as described above further improves the resistance of shearwall 100 to lateral forces. While a single 5 chord is shown on each side of the central diaphragm, it is understood that more than one chord may be provided at each end. For example, 2 to 4 (or more) such chords may be affixed together and mounted to each side of the central diaphragm. It is also understood that chords of less than 2 inches deep and 4 inches wide may be used in alternative embodiments. Sheathing (not shown) 10 may be affixed over the front and back surface of the central diaphragm and chords, and affixed to the chords by a variety of affixing mechanisms including Simpson Strong-Drive@ screws and gluing. It is further understood that the chords 120,122 may be omitted in alternative embodiments. [0050] Shearwall 100 further includes a sill plate 124 affixed to the bottom of 15 the central diaphragm. This allows shearwall 100 to have a lower load bearing surface with a sufficient surface area to allow distribution of the shearwall compressive forces over a sufficiently large area on the underlying floor diaphragm or foundation. If the compressive forces from the shearwall are concentrated, for example in a situation where the bottom plate is small or is 20 shaped with channels so that only a portion of the bottom plate lies in contact with the underlying support surface, the resulting compressive forces can damage or cause failure in the underlying support surface. [0051] Accordingly, sill plate 124 is provided as a flat plate with a relatively large surface area. The plate 124 has a length which is preferably equal to that 25 of the central diaphragm and the chords 120 and 122 together, and a width that is equal to the width of the chords 120 and 122. This width dimension is greater than the width of the U-shaped channel 121 in embodiments of the present -12 invention. In such embodiments, this provides a sill plate which is 16 inches long and 4 inches wide. It is understood that the length and/or width of plate 124 may be larger in alternative embodiments. For example, in embodiments of the invention not including chords 120, 122 and/or channel 121, the footprint of the 5 sill plate may be the same size as the footprint of the central diaphragm. [0052] Sill plate is also rigid enough to allow even distribution of any localized compressive forces from the shearwall 100. In one embodiment of the present invention, the sill plate 124 is formed of %A inch thick steel. In embodiments of the invention, sill plate 124 may be affixed to channel 121 by affixation methods such 10 as welding, bolting or gluing. As used in this regard, gluing refers to the application of any of one or more known compounds (including adhesives and epoxies) to at least portions of the interface between the sill plate 124 and channel 121 which cause the sill plate and channel to stick to each other. The rigidity of the sill plate 124 as well as the rigid affixation of the sill plate 124 to the 15 channel 121 further prevents buckling of the shearwall under laterally applied loads. It is understood that sill plate 124 may have thicknesses other than %A inch in alternative embodiments. [0053] It is a further feature of the sill plate 124 to underlie the chords 120, 122, thereby preventing their contact with the underlying support surface. In 20 embodiments of the present invention where shearwall 100 is mounted on a foundation, the sill plate 124 isolates the chords from wetness and moisture from the foundation which may otherwise weaken and erode the chords. The provision of the sill plate 124 under the chords also allows the compressive forces exerted specifically by the chords to be evenly distributed over the sill 25 plate and onto the underlying support surface as described above. [0054] Referring now specifically to Fig. 6, there is shown a perspective view of the shearwall 100 mounted on an underlying support surface 150. In the -13 embodiment shown, underlying support surface 150 comprises a concrete building foundation, but it is understood that underlying support surface 150 may be any surface on which a conventional shearwall may be located, including for example a floor diaphragm on the building foundation or a floor diaphragm on a 5 top plate of a lower floor. The shearwall is fastened to the underlying support surface 150 by means of anchors 1:52 (partially shown in Fig. 6) protruding up through aligned holes formed in the sill plate 124, channel 121 and the bottom of the central diaphragm 102. The bolts are then fastened over threaded ends of anchors 152 to anchor the shearwall to the underlying support surface. It is 10 understood that shearwall 100 may be anchored to the underlying support surface by other anchoring mechanisms in alternative embodiments, such as for example by strap anchors, mudsill anchors, retrofit bolts, foundation plate holdowns, straps, ties, nails, screws, framing anchors, ties, plates, straps or a combination thereof. The shearwall may alternatively or additionally be fastened 15 to the underlying support surface 150 by gluing, which in this context refers to the application of any of one or more known compounds (including adhesives and epoxies) to at least portions of the interface between the shearwall and underlying surface which cause the shearwall and underlying surface to stick to each other. 20 [0055] Shearwall 100 may similarly include openings in the top edge of the central diaphragm 102 and channel 119 for affixation to a top plate of a wall as by welding, bolts and/or other anchoring mechanisms described above. The central diaphragm 102, channel 119 and top plate may additionally or alternatively be affixed to each other as by gluing, which refers to the application 25 of any of one or more known compounds (including adhesives and epoxies) to at least portions of the interface between the central diaphragm 102, channel 119 and/or top plate which cause the central diaphragm, channel and/or top plate to stick to each other. As also indicated above, shearwall 100 is prefabricated so that it may be easily located within a wall in any desired location simply by

-15 [0059] Fig. 11 is similar to Fig. 7 but inverted so that the intersection lines 220 and 222 between the rear planar sections and the angled sections slope outward from the bottom edge to the top edge. Similarly, the intersection lines 224 and 226 between the angled sections and the front planar section slope outward from 5 the bottom edge to the top edge. Fig. 12 is similar to Fig. 7 but rear planar sections 210 and 212 are omitted so that the size and shape of the shearwall changes from the top edge to the bottom edge of the shearwall. [0060] In addition to lateral force resisting characteristics of the shearwall 100 shown in Figs. 3-6, providing the bends between the various sections at angles 10 that slope inward or outward from bottom to top provides even greater lateral force resistance, as there is a lateral component to the various bends between the sections. The lateral component to the various bends further resists movement in the lateral direction, and further improves the resistance of the shearwall to lateral loads. 15 [0061] Although not shown in Figs. 7 through 12, the shearwall shown therein may include the channels 119, 121, the chords 120, 122 and the sill plate 124 described above. [0062] Figs. 13 through 16 are similar to Figs. 7 through 10, except that the corrugation 308 of Figs. 11 through 14 does not extend the entire length between 20 the top and bottom edges of the central diaphragm. Instead, the corrugation begins at the bottom edge and the intersection lines between the various sections 310, 314, 316 and 318 slope inward until the corrugation ends at a point 320 between the top and bottom edges. Again, the shearwall of Figs. 13 through 16 would preferably include the channels 119, 121, the chords 120, 122 and the 25 sill plate 124 described above. However, it is contemplated that the chords and/or the sill plate may be omitted in alternative embodiments.

-17 the front and back edge of the central diaphragm. The embodiments of Figs. 20 and 21 may also be combined with the embodiments of Figs. 7 through 19. [0065] As shown in Fig. 22, a further alternative embodiment of the central diaphragm may include a corrugation formed by a combination of straight and 5 rounded sections. As a further alternative shown in Fig. 23, the central diaphragm may include a plurality of rounded corrugations. Fig. 24 illustrates a further embodiment where the angled sections 114, 116 are formed at right angles to the rear planar sections 112, 114 and the front planar section 118. These embodiments may be combined with any of the embodiments shown in 10 Figs. 7 through 19. [0066] Figs. 25 and 26 show a further embodiment of the present invention including one or more embossments 270 formed in one or more surfaces of the central diaphragm to add strength to the diaphragm. While shown in end section 106, it is understood that the one or more embossments 270 may alternatively or 15 additionally be formed in opposite end section 104, or sections 112 through 118, in alternative embodiments. As shown in Fig. 26, when vertically oriented, the embossment(s) 270 may extend over a portion of sections 104, 106, and/or 112 through 118. Alternatively, the embossment(s) may extend substantially the entire length of the sections. While shown as being vertically oriented in Figs. 25 20 and 26, it is understood that the one or more embossments may be oriented differently in alternative embodiments. For example, the embossments may be provided horizontally or at an angle between the horizontal and vertical. Moreover, the embossments may be provided in a cross-hatched or herringbone configuration. The one or more embossments 270 may be used in any of the 25 embodiments shown in Figs. 7 through 24. [0067] Figs. 27 and 28 show a further embodiment of the present invention including stiffening lips 280 formed in the horizontally oriented edges of end

-19 the lengths of sections 406a and 406b may vary in alternative embodiments, both proportionately and disproportionately to each other. As above, the central sections may be affixed by welding, bolting, gluing or other known affixation methods. 5 [0070] The embodiment shown in Figs. 29 through 31 allows the overall width of the shearwall 100 to be easily provided to different widths in the field simply by using a central section of differing widths. A shorter width central section (Fig. 29) will provide one overall width, while a larger width central section (Fig. 30) will provide another overall width. Thus, a shearwall 100 of the precisely needed 10 width may be easily and quickly formed. The embodiment shown in Figs. 29-31 may be used in conjunction with the embodiments disclosed above with respect to Figs. 7 through 28. [0071] Although the invention has been described in detail herein, it should be understood that the invention is not limited to the embodiments herein disclosed. 15 Various changes, substitutions and modifications may be made thereto by those skilled in the art without departing from the spirit or scope of the invention as described and defined by the appended claims. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Claims (22)

1. A shearwall, comprising: a central diaphragm, including a top edge and a bottom edge generally defining a height of said central diaphragm, first and second ends, extending between the top and bottom edges, generally defining a width of said central diaphragm, and a corrugated section extending at least partially between said top edge and said bottom edge in between said first and second ends, said corrugated section forming at least one corrugation; and at least one of: a sill plate affixed at said bottom edge of the central diaphragm and having a footprint at least as large as the footprint of said central diaphragm, first and second chords affixed one each to said first and second ends, and a channel in which said central diaphragm is seated, at least two of the central diaphragm, sill plate, first and second chords and channel being affixed to each other by at least one of welding, bolting, screwing and gluing.

2. A shearwall as recited in claim 1, wherein said first and second chords are each formed of 2 inch x 4 inch wood.

3. A shearwall as recited in claim 1, the sill plate affixed at said bottom edge of the central diaphragm and having a footprint at least as large as the -21 combined footprint of said central diaphragm and said first and second chords together.

4. A shearwall as recited in claim 1, wherein said central diaphragm is formed of 7-guage steel.

5. A shearwall as recited in claim 1, said at least one corrugation being defined by a pair of angled sections extending along said height dimension from a first plane at a back edge of the central diaphragm and angling inward toward each other, said angled sections terminating in a second plane at a front edge of the central diaphragm, and said at least one corrugation further being defined by a front planar section in said second plate and extending between said pair of angled sections.

6. A shearwall as recited in claim 1, said at least one corrugation extending from said top edge to said bottom edge.

7. A shearwall as recited in claim 1, said at least one corrugation extending from said bottom edge and terminating at a position between said bottom edge and said top edge.

8. A shearwall as recited in claim 1, said at least one corrugation including two corrugations.

9. A shearwall as recited in claim 1, said central diaphragm including at least one aperture.

10. A shearwall as recited in claim 1, said central diaphragm including at least one embossment. -22

11. A shearwall as recited in claim 1, said central diaphragm including at least one stiffening lip.

12. A shearwall, comprising a central diaphragm having a height, width and depth, each being perpendicular to each other, and a corrugation extending in the direction of said height of said central diaphragm; first and second chords affixed to said central diaphragm at opposed edges of said central diaphragm and extending in the direction of said height of said central diaphragm; and a sill plate affixed to a bottom of the shearwall, said sill plate having a footprint at least as large as said central diaphragm and said first and second chords together; wherein at least two of the central diaphragm, the first chord, the second chord and sill plate are affixed to each other by at least one of welding, bolting, screwing and gluing.

13. A shearwall as recited in claim 12, further comprising a channel in which said central diaphragm resides.

14. A shearwall as recited in claim 13, said sill plate having a width greater than that of said channel.

15. A shearwall as recited in claim 13, said sill plate being formed of % inch thick steel.

16. A shearwall as recited in claim 13, said channel is affixed to the central diaphragm by at least one of welding, bolting, screwing and gluing. -23

17. A shearwall having a length between a top and bottom of the shearwall, comprising: a first member extending in the length direction between a top and bottom of the shearwall, the first member including at least a first corrugation; a second member extending in the length direction between the top and bottom of the shearwall, the second member including at least a second corrugation; and a central section of variable width in a direction transverse to the length of the shearwall for affixing the first member to the second member wherein the central section is affixed to the first and second members by at least one of welding, bolting, screwing and gluing.

18. A shearwall as recited in claim 17, where in the central section is a single unitary section extending at least partially between the top and bottom of the shearwall

19. A shearwall as recited in claim 17, where in the central section is comprised of a plurality of piece of sections positioned between the top and bottom of the shearwall.

20. A shearwall as recited in claim 17, where in the central section is welded to the first and second members. -24

21. A shearwall substantially as hereinbefore described with reference to the drawings and/or Examples.

22. The steps, features, compositions and compounds disclosed herein or referred to or indicated in the specification and/or claims of this application, individually or collectively, and any and all combinations of any two or more of said steps or features.