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PRIORITY CLAIM 
       [0001]    This application claims the benefit of the filing date of Australian Patent Application Serial No. 2015100133 A4, filed Feb. 6, 2015, for “Natural Ventilation Livestock Shed,” the disclosure of which is hereby incorporated herein in its entirety by this reference. 
       TECHNICAL FIELD 
       [0002]    This disclosure relates to large-scale buildings. More particularly, this disclosure relates to large-scale buildings with natural ventilation. Still more particularly, this disclosure relates to large-scale sheds with natural ventilation made especially for sheltering livestock, including ruminants such as cattle, sheep, camels and goats, and non-ruminants, such as equine and porcine animals, and bird livestock, such as chickens and turkeys. 
       BACKGROUND 
       [0003]    The following references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the following prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present disclosure of which the identification of pertinent prior art proposals is but one part. 
         [0004]    Stanchion type sheds should shed rain efficiently from the roof and promote ventilation. The passage of livestock, such as cattle, through the shed generates manure or other droppings, and while there may be equipment that disposes of this waste, the ammonia and hydrogen sulphide released by the waste may deleteriously affect both the livestock and the staff. The release of air from the shed and its replacement by incoming air should be uninterrupted irrespective of the weather, which may otherwise act to interfere with the flow. 
         [0005]    Likewise, a shed roof may absorb large amounts of heat through solar radiation daily. The heat may radiate to the air above and below the roof While the air above the roof is free to convect heat into the ambient surroundings, it is desirable that the air beneath the roof in the interior spaces of the shed should not heat up unduly or the livestock&#39;s condition and the staff&#39;s productivity may be adversely affected. 
         [0006]    It is considered by some that shed roof design should be restricted for the efficient drainage of rainwater to a gradient for which the optimal inclination is between 23 and 30 degrees. If a wide shed is required where the pitch extends a relatively long distance from a ridge, the height of the shed may exceed permissible limits in farm surroundings or may present excessive wind resistance, as well as attendant cost factors. By corollary, if the shed roof is too low, there may be a problem of an undesirable heat build-up in the shed&#39;s interior when the ambient temperature is high. 
         [0007]    An object of this disclosure is to ameliorate the aforementioned disadvantages of the prior art or to at least provide a useful alternative thereto. 
       BRIEF SUMMARY 
       [0008]    The disclosure according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the disclosure are defined in the dependent claims. 
         [0009]    Accordingly, in one aspect of the disclosure there is provided a shed with a roof supported by columns or stanchions and covering an interior, wherein the roof comprises at least two roof sections, including a first section and a second section, the roof sections extending between a central region outwardly toward a perimeter region, the central region having a ridge portion including at least one gap that allows ventilation for the interior, each roof section being substantially concave from above and increasing in height from the perimeter region to the central region. 
         [0010]    Stanchion sheds are advantageously employed to tightly but comfortably restrain livestock by use of the stanchions as structures to contain livestock, such as cattle. The stanchions may be closely spaced and arranged in rows under and supporting the roof. The stanchions may comprise at least two spaced rows extending along the perimeter region of each side of the shed. The stanchions may include one or more central rows of stanchions, to provide additional support and controlled accommodation for the livestock. The stanchions may be in the form of vertical posts. The stanchions may be supported by foundations. The stanchions may be supported by a base plate. The rows of stanchions may be supported by one or more piers. The foundations may comprise concrete set below ground level. 
         [0011]    The shed may be a structure for housing or protecting livestock. The shed may include enclosing walls or may be an open structure with partially or fully open sides and/or ends. For the purposes of this specification, the walls mean the peripheral sides and ends of the shed, whether they are open, partially open, or closed. Open or partially open walls may comprise a series of substantially vertical posts optionally braced with lateral horizontal or inclined beams. Closed or partially closed walls may comprise panels or other wall barriers extending across or between the posts. For ventilation purposes, the walls are preferably at least partially open to draw air in from the sides and/or ends of the shed. 
         [0012]    The walls may be inclined to the vertical. The walls may be outwardly inclined to provide a counter-supporting force for the peripheral portion of each roof section. Alternatively, the exterior walls may be inwardly inclined from their respective bases to their upper extent. Preferably, the walls are aligned substantially vertically, for example, being aligned in a substantially vertical plane. The walls may terminate and join the roof directly or indirectly. The walls may stand at a height substantially between about one-third to about one-half of the height of the inner stanchions, and preferably between about 40% and 45% of the height of the inner stanchions. Accordingly, the disclosure may achieve a shed height profile that is low to minimize exposure to wind gusts and achieve a smaller interior space, relative to a flat or convex profiled roof. 
         [0013]    Preferably, the gap is covered by a roof cap spaced from the roof to allow ventilation and exclude precipitation. It is feasible, however, to exclude the cap, so that is merely an optional, if desirable, feature. If the shed has no cap, for example, to reduce wind resistance, rain falls through the gap into the shed&#39;s interior, but a flushing drain may be sited or positioned directly beneath the gap to capture fallen precipitation so that the ingress of rain is not a problem. 
         [0014]    The perimeter of the arcuate or curved roof may adjoin a roof extension along one edge of the roof. The roof extension may be curved in profile. The roof extension may be cantilevered and supported from centrally located or perimeter-located rows of stanchions. 
         [0015]    The roof extension may be flat. The roof extension may be inclined. The roof extension may extend outwardly from the curved roof area from an extremity of the roof, including a side or end. The roof extension may extend inwardly. The roof extension may provide a bridge or span between the inner periphery of the curved roof structure and the gap. The roof extension may provide a corridor along one side edge of the shed. The roof extension may cover a central area of the shed. The shed may have a pair of side roof extensions, each extending along a side edge of the shed. 
         [0016]    The side roof extensions may each correspond to a proportion of about 5%-15%, more preferably about 8%-13%, and most preferably about 10%-12%, of the width of the shed. The central roof extension may comprise a pair of central roof extensions. The central roof extensions may be supported by cantilevered beams. The central roof extensions may comprise a pair of parallel and adjacent roof extensions, each extending from the curved roof section and joining at a central portion. The central portion may correspond to the location of the gap. The central roof extension may correspond to a proportion of about 5%-25%, more preferably about 12%-22%, still more preferably about 15%-20%, and most preferably about 17%-18%, of the width of the shed. 
         [0017]    The roof covering may include sheet metal. The sheet metal may be corrosion resistant. The sheet metal may have a corrugated or channel profile. The sheet metal may be galvanized iron, or zinc-coated steel. 
         [0018]    The gap is preferably about 1%-4%, preferably about 2%-3%, and most preferably about 2.2%-2.6%, of the shed width. The sizing of the gap width is advantageously large enough to promote draft of air flow through the shed interior. The gap width is preferably sized to present a small enough gap to be adequately covered by the cap or to present a small opening through which minimal weather ingress, such as by dust, debris and precipitation, can occur. 
         [0019]    The concavity of the curved roof section may be such that the width-to-rise ratio is about 1000:100-1000:400, and preferably about 1000:200-1000:300. 
         [0020]    The concavity of the roof is preferably such that the width-to-rise ratio is 1000:200-1000:300. 
       Advantageous Effects of Disclosure 
       [0021]    1. Sun protection combined with ventilation and adequate roof slope for run off. 
         [0022]    2. Economy of structure. 
         [0023]    3. Freedom of floor planning. 
         [0024]    4. Low overall height for a given floor area. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The disclosure is now described in the following non-limiting description of preferred embodiments with reference to the accompanying drawings, in which: 
           [0026]      FIG. 1  is an end elevation of a shed made according to a first embodiment of the disclosure; 
           [0027]      FIGS. 2 a  and 2 b    are, respectively, full and partial inner perspective views of the shed shown in  FIG. 1 ; 
           [0028]      FIGS. 3 a  and 3 b    are upper perspective views of the shed shown in  FIG. 1 ; 
           [0029]      FIGS. 4 a  and 4 b    are side perspective views of the shed shown in  FIG. 1 ; 
           [0030]      FIG. 5  is a perspective view of a fragment of the end of a shed according to a second embodiment showing a central row of stanchions and a ventilation cap. 
           [0031]      FIG. 6  is a side elevation of a third embodiment of a shed made according to the disclosure; 
           [0032]      FIGS. 7 a -7 c    are partial sectional side elevations of various components of the roof of the shed shown in  FIG. 6 ; 
           [0033]      FIG. 7 d    is a partial sectional side elevation of a stanchion footing of the shed shown in  FIG. 6 ; 
           [0034]      FIG. 8  is a sectional side elevation of a fourth embodiment of shed made according to the disclosure, including the structure of the shed of the second embodiment with additional cantilevered side roof extensions; and 
           [0035]      FIG. 9  is a sectional side elevation of a fifth embodiment of shed made according to the disclosure, including the structure of the shed of the second embodiment with additional side corridor extensions. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    Preferred features of the present disclosure will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the disclosure, except as may be recited in the claims accompanying this specification. 
         [0037]    Referring to the  FIGS. 1-4 , a shed  1  is shown in end elevation and includes a shed base or ground surface  2 , a roof  3 , sides  7   a  and ends  7   b , all defining an internal space  29 . 
         [0038]    The base  2  is laid out to accommodate the stalls, equipment, communicating pathways and travel pathways for livestock such as cows, personnel and vehicles. Inner pairs of rows of stanchions  4 ,  6  are erected in central axial rows. These stanchions  4 ,  6  are about 15-20 m apart across the width of the shed. 
         [0039]    Outer pairs of rows of stanchions  10 ,  12  are erected in two outer rows about 25-30 m from the central inner rows of stanchions  4 ,  6 . The inner stanchions  4 ,  6  are about 10-15 m, and preferably about 12-13 m, in height from the base  2 . The outer stanchions  10 ,  12  are about 4.5-6.5 m, and preferably about 5-6 m, in height from the base or ground surface  2 . 
         [0040]    The outer and inner rows of stanchions  4 ,  6 ,  10 ,  12  are spanned by curved steel beams  14 ,  16  that are about 25-30 m long and formed from upper and lower chords  13   a ,  13   b  spanned by interposing braces  15  arranged in z-formation. The curved steel beams  14 ,  16  are concave in order to support a roof profile across the roof span  40  in which the pitch increases or deepens from its side periphery  21  toward the shed&#39;s  1  center extending along the mid axis  35 . 
         [0041]    A perimeter row of stanchions  18  run parallel to the outer row  10  and a like perimeter row of stanchions  20  runs parallel to the outer row  12  along the side length of the shed  1 . 
         [0042]    The outer stanchion rows  10 ,  12  and perimeter stanchion rows  18 ,  20  are separated or spaced laterally across the shed&#39;s  1  width by a distance of about 10 m-12 m, and these outer strips  38  of the shed roof  3  are spanned by straight beams  22   a ,  22   b . The purpose of these portions of the roof  3  comprising the outer strips  38  is to form side eaves  23 , which include gutters  26  and down pipes (not shown) and to provide a covered lane or corridor  11  lined with feed mangers  25 . 
         [0043]    The central area  28  between the pairs of rows of inner stanchions  4 ,  6  is about 15 m-12 m wide and this space  28  is spanned by cantilever beams  24   a ,  24   b  projecting inwardly from the concave or curved beams  14 ,  16  to which they are bolted. The cantilever beams  24   a ,  24   b  intersect along the mid axis  35  of the roof  3  and support a ventilation gap  30  covered by a convex (from above) sheet metal roof cap  32  and having open sides  34 . 
         [0044]    The cap  32  is vertically spaced from the central beams  24   a ,  24   b  by a pair of rows of posts  31   a ,  31   b  mounted to a central upper portion of each central cantilever beam  24   a ,  24   b  as shown in  FIG. 2 , noting that only the first pair of posts  31   a ,  31   b  is shown for clarity. As shown in  FIG. 2 , the central straight cantilever beams  24   a ,  24   b  are advantageously formed from a pair of upper and lower chords supported and spaced from each other by interposed braces in Z-formation to provide relatively lightweight beams  24   a ,  24   b  extending over the central area  28 . 
         [0045]    The roof  3  begins at the open sides  34  and is made of overlapping sheets of zinc coated corrugated steel sheets  33   a ,  33   b  of a roof portion  36 . The opposing central roof sheets  33   a ,  33   b  do not join but define the gap  30 , which is intermittently crossed by the cantilevered beams  24   a ,  24   b . The central roof portions  36  meeting the concave mid-section  40  and overlying the cantilever beams  24   a ,  24   b , and the outer beams  22   a ,  22   b  supporting a peripheral roof portion  38  foaming the shed eaves  23 , are straight or linear. Accordingly, the inner and outer roof sections  36 ,  38  are substantially flat or substantially planar. 
         [0046]    The roof cap  32  is optimally set at a height of about 16 m from the base  2  and is raised about 1 m-1.5 m, and preferably about 1.2 m-1.3 m, and most optimally about 1220mm, above the peak of the central cantilever beams  24   a ,  24   b . The gap  30  between the roof portions  36  covered by the central roof sheets  33   a ,  33   b  is about 2 m-3 m, and more preferably about 2.3 m-2.6 m, and most optimally about 2.4 m wide. How quickly the convex curve of a roof truss rises or how “tight” the curve is will be expressed in terms of radius. The concave mid-section  40  of the roof  3  has a radius of curvature that exhibits a rise of about 100 mm-300 mm per meter, more preferably about 140 mm-260 mm per meter, still more preferably about 200 mm-250 mm per meter and most preferably about 248 mm per meter. 
         [0047]    In  FIG. 5 , a shed  301  according to a second embodiment of the disclosure is shown having a row of central stanchions  305  that support the centrally joined purlins  324   a ,  324   b  abutting the location of a ventilation gap  330 ,  334 . The shed  301  has a central cap  332  above the gap  330 ,  334  that is supported by a pair of rows of vertical posts  331   a ,  331   b  extending substantially the length of the shed&#39;s  301  roof  303 . 
         [0048]    In the remaining drawings, like features will be referred to using like reference numerals in the  100 &#39;s relative to the first embodiment and the other embodiments described in this specification. Where appropriate, dimensions have been indicated in the drawings to best exemplify the dimensions and ratios of the preferred embodiments. 
         [0049]    Referring to  FIGS. 6-7   d , a third embodiment of the disclosure is shown in the form of a shed  101 . The shed  101  comprises a shed having a lineal horizontal span of a roof  103  of about 30 m-35 m covering an interior space  129 . 
         [0050]    The shed  101  structure is supported by a pair of side rows of columns or stanchions  110 ,  112  made of H.D. galvanized steel and about 4 m in height and about 350 mm-410 mm in square section. The stanchions  110 ,  112  may be founded in a variety of ways depending on the constraints of the site and the particular loads and soil/ground types, such as rock, clay, sand, loam, etc. For structures having a high load through the stanchions and unstable soil/ground types, the stanchions  110 ,  112  may be founded in deep foundations  150  best shown in  FIG. 7 d    about 750 mm square and 1200 mm deep packed with concrete packed at 20 mPa. The base of the stanchions  110 ,  112  may be mounted to a horizontal square base plate  152  with tapered edges  153  through bolts  151  to a reinforcing pier frame  154  about 300 mm in width depending vertically about 1 m into the concrete foundation  150 . 
         [0051]    As best shown in  FIG. 7 a   , each stanchion&#39;s  110 ,  112  upper terminal end  160  is slightly inclined to follow the tangent  103   a  of about 3 degrees to the horizontal of the outer extent of the roof  103 . Attached to the internal side wall  165  of the upper end  160  is an eave and gutter outrigger bracket  161  that has an upstanding bracket  162  spaced outwardly from the stanchion  110 ,  112  to support the outer extremity of the roof  103 . Attached to the upstanding bracket to catch run-off is a gutter  163 . 
         [0052]    Internal to the stanchion  110 ,  112  is a second upstanding bracket  164   a  mounted to a first curved purlin  114 . Similar upstanding brackets  164   b  space zinc-plated roof cladding  133   a ,  133   b  from the purlins  114 ,  116  along their respective lengths. The first curved purlin  114  is mounted to the upper internal wall  165  by a pair of vertically spaced haunch plates  166   a ,  166   b . The stanchion  110 ,  112  is internally reinforced at the heights corresponding to the placement of haunch plates  166   a ,  166   b  by substantially horizontal column stiffener plates, bars or braces  167   a ,  167   b.    
         [0053]    The curved purlin  114  extends laterally inwardly and upwardly in a concave contour from above to a peak height H of about 8 m-9 m, where each inner end is joined to its opposed member purlin  116  of its pair to support each other and permit the structure to define an interior space  129  completely free of the need for vertical supports. Optionally, for large purlin  114 ,  116  spans as shown in this embodiment, each of the purlins  114 ,  116  may be formed from two or more curved lengths  114   a ,  114   b ,  116   a ,  116   b , preferably having substantially the same radius of about 4 m-6 m, preferably about 5 m, and following the same contour of curvature. The radius of curvature of the large purlins  114 ,  116  may correspond to a rise of about 200 mm-250 mm per meter and most preferably about 250 mm per meter. 
         [0054]    As best shown in  FIG. 7 b   , the purlin sections  114   a ,  114   b ,  116   a ,  116   b  are joined together intermediate their lengths by opposed pairs of splice plates  142   a - 142   d  welded to the ends of upper and lower chords  113   b ,  113   a  of mid-sections  144   a ,  144   b  of the purlins  114 ,  116 , respectively. Otherwise, along their respective lengths, the purlins  114 ,  116  are of similar design and construction as the purlins  14 ,  16  of the first embodiment. 
         [0055]    The purlins  114 ,  116  are joined at their respective inner ends, as best shown in  FIG. 7 c   , by a central pair of upper and lower splice places  143   a ,  143   b , so that the purlin pairings  114 ,  116  are supported above the base  102  by the resistance to outward displacement of the side stanchions  110 ,  112  to form a bridging purlin structure. The peak or ridge of the shed  101  includes a central ventilation gap  130  defined by the inner edges  134   a ,  134   b  of the spaced roof cladding  133   a ,  133   b . The shed&#39;s interior space  129  is protected from the ingress of weather and debris by a lightweight convex (from above) cap  132  extending substantially the full length of the roof  103  and comprises a shallow reinforcing frame  135  having lower rigid curved bars  136  spaced from the convex cap  132  and having substantially the same contour as the cap  132 . The cap  132  sheeting may be curved to have a similar radius as the purlins  114 ,  116 . 
         [0056]    The rigid bars  136  may be spaced from the underside of the cap  132  by two to five, preferably three, substantially interposed upstanding brackets  137 . Ideally, for the purposes of simplification of parts, the upstanding brackets  164   a ,  164   b ,  137  are identical in construction. Side edges  132   a ,  132   b  of the cap  132 , therefore, curve shallowly downwardly and the outer lateral extent of the side edges  132   a ,  132   b  at rest is set at an angle of overhang of about 40 degrees to about 50 degrees, preferably 45 degrees, relative to the inner edges  134   a ,  134   b  of the roof sheets  133   a ,  133   b . This overhang restricts or resists all but the most severe weather incursions while permitting adequate ventilation from the interior  129 . 
         [0057]    At each of the plurality of spaced purlin  114 ,  116  sites along the length of the roof ridge at its apex  141 , the cap  132  and the supporting frame  135  are supported by a pair of ribbon bars  139  mounted to the upper central splice plate  143   a  and each respectively curving outwardly to form a substantially flat upper surface to be welded to the underside of the rigid bar  136 . The fanning ribbon bars  139  are capable of some flexion with a view to withstanding metal fatigue and failure caused by wind gusts and other like forces. 
         [0058]    Turning to  FIG. 8 , a fourth embodiment of the disclosure is shown in the form of a shed  201  similar in structure to the second embodiment of the shed  301  and the third embodiment in the form of the shed  101 . However, there are some significant differences between the sheds  101 ,  201 . 
         [0059]    The shed  201  includes side lanes  211   a ,  211   b  provided with the overhead protection of a veranda roof  238  that is supported by cantilevered extension beams  222   a ,  222   b . The beams  222   a ,  222   b  continue the tangential curve of the main span of inner purlins  214 ,  216  and have cantilevered beams  222   a ,  222   b  with upper and lower chords  213   b ,  213   a  that converge from an inner end  221  in which the chords are spaced, to an outer end supporting eaves  223  at which the chords meet or converge to a spacing close to one another. The lanes  211   a ,  211   b  provide flush lanes adjacent the stanchions  210 ,  212  and feed lanes for livestock immediately under and within the cover of the eaves  223 . The animals may each be tethered or secured to, or indirectly by use of the outer stanchions  210 ,  212 , if desirable to restrain them. 
         [0060]    Central to the shed  201  structure is a central row of stanchions  205  vertically supporting the shed roof  203  at its ridge or apex  241 . Either side of the stanchions  205 , loafing areas or pads  202   a ,  202   b  are provided within the line of stanchion rows  210 ,  212 . The central row of stanchions  205  also supports a sub-frame  235  to, in turn, support an elongate cap  232  extending substantially the full length of the shed  201 . 
         [0061]    In  FIG. 9  there is shown a loafing shelter shed  401  having a similar floor  402  layout to the shed  1 , but a central apex  441  structure similar to the shed  101 . Inner rows of stanchions  404 ,  406  are positioned to support the roof purlins  414 ,  416  intermediate their length and preferably support the purlins at spliced joints  444 , if present in arrangements where the purlin span is large, such as purlin lineal spans greater than 15 m or where, prior to assembly, transport constraints require shorter length purlin components. 
         [0062]    As with the shed  1 , corridors  411  are provided by the attachment to the sides of the central shed structure of flat, low roof extensions  422  extending between outer rows of stanchions  410 ,  412  and perimeter rows of stanchions  420 . Livestock treatment and feeding structures  460  are provided in the corridors  411  and the central loafing area  428 . 
         [0063]    It is to be understood that the word “comprising” as used throughout the specification is to be interpreted in its inclusive form, i.e., use of the word “comprising” does not exclude the addition of other elements. 
         [0064]    In the present specification, terms such as “apparatus,” “means,” “device” and “member” may refer to singular or plural items and are terms intended to refer to a set of properties, functions or characteristics performed by one or more items or components having one or more parts. It is envisaged that where an “apparatus,” “means,” “device” or “member” or similar term is described as being a unitary object, then a functionally equivalent object having multiple components is considered to fall within the scope of the term, and similarly, where an “apparatus,” “assembly,” “means,” “device” or “member” is described as having multiple components, a functionally equivalent but unitary object is also considered to fall within the scope of the term, unless the contrary is expressly stated or the context requires otherwise. 
         [0065]    Orientational terms used in the specification and claims such as vertical, horizontal, top, bottom, upper and lower are to be interpreted as relational and are based on the premise that the component, item, article, apparatus, device or instrument will usually be considered in a particular orientation, typically with the convex cap  32  uppermost. The shed  1  is a large elongate structure as illustrated in  FIGS. 2 a   - 4 , and is generally longer than it is wide, in this embodiment having  25  stanchions  10 ,  12  in each row. However, its length is variable as it is substantially of consistent cross-section throughout its length and each set of lateral supporting and roofing components can be added to extend the shed  1  in the longitudinal direction parallel to the gap  30 . In  FIGS. 1, 6, 8 and 9 , the sheds  1 ,  101 ,  201 ,  401  are shown in end elevation. Orientation of the sheds  1 ,  101 ,  201 ,  301 ,  401  is site specific and depends on the terrain and may be determined by specific engineering considerations in each case, but the sheds may be oriented in situ side on to the prevailing winds of a particular geographical landscape to achieve optimum ventilation. 
         [0066]    It is to be understood that various modifications of and/or additions to the disclosure can be made without departing from the basic nature of the disclosure. These modifications and/or additions are, therefore, considered to fall within the scope of the disclosure.

Summary:
The livestock shed has parallel rows of stanchions rising from a concrete base and a metal roof that is built in two halves that are separated by a central air gap. Each roof half has an inclined center strip defining one half of the gap edge. The roof portion is generally concave. The resulting shed is of correspondingly low profile while still exerting good ventilation. In capped versions, the gap is surmounted by a convex roof cap spaced above the gap in order to allow ventilation while excluding precipitation.