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This is a continuation-in-part application of Ser. No. 723,312, filed Apr. 15, 1985, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an enclosed structure and has been devised particularly, though not solely, as a grain silo. 
     2. Description of the Prior Art 
     Most silos and containers or storage bins for large amounts of particulate solids, are made from reinforced concrete or heavy steel plate, or from a combination of heavy steel plate and lightweight steelwork. Such constructions require skilled engineering and manpower to erect and are also very costly to build. 
     Some silos are made entirely of lightweight steelwork but are in practice found to be susceptible to damage by wind when they are empty and to damage by grain pressures when they are being unloaded in a non-uniform way. Some of these structures are fabricated with corrugated sheeting disposed so that the ribs run horizontally that is circumferentially, around the silo. These structures are unhygienic since grain and grain dust tend to lodge on the corrugations and in laps and gaps in the sheeting so that they are prone to insect infestation. 
     It has been found in practice a desirable objective to dispose lightweight corrugated wall sheeting of grain silos in such a way that the ribs run vertically rather than circumferentially. This provides greater hygiene for storage of grain, since grain will then not readily adhere to wall. However it has been found in practice there are difficulties in this vertical arrangement of the wall sheeting corrugations. 
     Firstly there is a difficulty due to stiffness in the vertical direction which is caused by the phenomenon of the walls expanding outwards elastically as the silo is filled. In practice, this expansion causes a problem where the cladding is fastened to the floor or foundation which is unyielding. The vertical stiffness of the cladding material makes it unable to accommodate this movement above and the restraint below and this may lead to the sheeting being sheared open or cracked after a number of loadings. 
     There is also serious difficulty due to lack of stiffness in the horizontal direction which results in a weakness in resisting wind loads. So, in practice, wind girders have to be provided to safeguard the silo when it is empty. 
     A solution to the first of these difficulties has been proposed in U.S. Pat. No. 4,453,351 according to which a heavy steel plate is utilised for the bottom section of the wall. The plate is fixed the silo foundatios along its lower edge and to the cladding along its upper edge and has sufficient strength and flexibility to accomodate expansion of the silo. The steel plate arrangement is however, heavy and accordingly adds to the difficulty of assembly and cost of the silo. 
     U.S. Pat. No. 4,453,351 also describes a girt arrangement for stiffening the silo in which the girts comprise flat steel members joined by bolted steel angles welded to the girts. This arrangement can withstand the pressure of grain loads and the eccentric pressures due to wind loads and uneven grain loads, however the girts are heavy and significantly add to the cost of the silo. In addition, the flat steel girts do not provide significant strength against inwardly directed wind forces when the silo is empty so that additional strengthening is required to obtain sufficient resistance to wind damage. 
     The girts disclosed in U.S. Pat. No. 4,453,351 were joined using heavy steel plates and angle bars welded to the outside of the girts. This was due to the need to maintain a flush inside face in the girt members, because of the presence of the adjacent wall cladding, which inhibits the use of bolts passing through the girts. The connecting pieces in that invention were found in practice to be necessarily heavy and added significantly to the cost of the structure. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an enclosed structure suitable for containing particulate solids and a method of construction which will overcome, or at least ameliorate, the above disabilities. 
     Accordingly, this invention consists in an enclosed structure suitable for containing particulate solids comprising a plurality of posts set on foundations so as to define the external boundary of said structure, a plurality of rafters extending upwardly and inwardly from each said post to a central point or ridge, a plurality of circumferential girts extending substantially horizontally between said posts so as to define the line of a cornerless substantially circular wall, vertically corrugated sheet wall cladding extending the height of said wall and being fixed to the foundations at its lower edge, said sheet cladding being located within the wall defined by said girts and being fastened to said girts, the vertical edges of adjoining sheets of cladding being secured together in a structural manner, and roof cladding being placed over said rafters to form a roof, wherein the ratio of the height to diameter of said wall is less than or equal to 1.0 and each said girt is formed by a plurality of elongate channel elements joined substantially end to end, said girts being disposed at intervals along the full height of said wall within the number of girts per unit length increasing toward the bottom of said wall such that in a lower region of said wall the girt spacings are less than the calculated girt spacing for maximum desired cladding load at the corresponding part of said wall to control the deflected profile shape of the wall cladding between the fixed lower edge and the expanding upper region of said wall. 
     Preferably, the lower region is that portion of the wall disposed a distance from the lower edge of less than about 2.0 to 4.5 times the calculated girt spacing for maximum desired cladding load at the lower edge of the wall. 
     In one embodiment the edge flanges of the channel elements are at right angles to the band. In another embodiment the edge flanges project in outwardly diverging directions. 
     The channel elements are preferably formed from high strength steel manufactured by Lysaght Brown Built Industries and known as &#34;Hi-ten&#34;. This material is fully galvanised and has a strength which is much greater than that of ordinary structural grade steel. 
     In one embodiment, adjacent channel elements are joined by the elements overlapping and nesting one within the other. The elements are secured either by rivets or bolts through the overlapping band portions or bolts through overlapping edge flanges. 
     In another embodiment a plurality of channel elements are nested to form a composite girt of greater strength. Preferably, adjacent channel elements overlap so that joints in each element do not occur at the same circumferential point. 
     It will be apparent that in the nested or single channel element arrangement the edge flanges provide continuity of resistance to inwardly directed forces thus at least reducing the amount of additional wind stiffening required. 
     In some cases, additional wind stiffening may be eliminated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings: in which 
     FIG. 1 is a part cross sectional elevation of an enclosed structure according to the invention; 
     FIG. 2 is a schematic partially cut-away plan view of the structure shown in FIG. 1; 
     FIG. 3 is an enlargement of the part cross section shown in FIG. 1; 
     FIG. 4 is a cross section of a girt element according to the invention which has a steel angled bar attached; 
     FIG. 5 is a cross section of a girt element of multiple plies according to the invention attached to wall cladding; 
     FIG. 6 is an elevation showing the connection of two girt elements according to the invention joined at a post; 
     FIG. 7 is a plan view of the arrangement shown in FIG. 6; 
     FIG. 8 is a schematic planned view of a multiple ply girt arrangement according to another embodiment of the invention; 
     FIG. 9 is a cross sectional view along the line AA of FIG. 8; and 
     FIG. 10 is a plot of ratio of wall height to diameter against cost per cubic metre of storage. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Refering firstly to FIGS. 1 to 7 the preferred form of the invention provides an enclosed structure, particularly suitable for use as a grain silo, is constructed as follows. 
     A plurality of vertical posts 11 are provided set on foundations so as to define the line of a cornerless wall. In the preferred form of the invention shown in the accompanying drawings, 6, 8 or 12 vertical posts are provided set so as to define a circular wall. 
     The upperends of the posts are arranged to support roof rafters 13, which extend inwardly and upwardly from the posts to be a central receiving member point 14. 
     The vertical posts 11 are interconnected by a plurality of horizontal circumferential girts 15 which may for example be formed from &#34;C&#34; Section high strength steel sheet. The girts 15 form continuous circumferential hoops around the line of the posts 11. The girts may be attached to the posts 11 by bolting. 
     The roof framing of the embodiment shown in the accompanying drawings consist of a series of intersecting radial rafters which, in turn, support purlins 40. 
     The roof is covered with sheet cladding material shown at 17 in FIG. 2 which is joined on the line of the main rafters 13 by a ridge cap 18. The peak of the roof is provided with an opening 19 provided with a removable covering 10 to allow the silo to be filled with grain. 
     The walls of the silo are clad with corrugated sheet wall claddingn 20 extending the height of the wall and fastened to the girts 15, for example by rivetting or bolting. The vertical edges of adjoining sheets of cladding 20 are lapped, sealed and secured together in a structural manner, for example by applying a line of mastic compound, and fastening with heavy gauge rivets so that the sheet becomes one homogeneous structural and functional element. 
     There is also in the roof system a tie member near the eaves which attaches to the rafters 13 to act both in tension and compression. The tie member is connected structurally to the top of the girt of the wall and completes a structural system of exceptional strength and lightness since it embodies a skin membrane construction and provides a monolithic structure. 
     The girts 15 which support the wall cladding 20 are a sufficient strength to resist wind loads on the whole structure and keep the building stable and at the same time provide necessary strength to cater for both even and uneven internal pressures due to the contained load. 
     The lower part of the container wall is supported on the concrete foundation 12 with holding down bolts. 
     The girts 15 are disposed at intervals along the full height of the wall with the number of girts per unit length increasing toward the bottom of the wall. The girt strengths and girt spacings are calculated taking account of the strength of the wall sheeting in bending vertically between the girts and in compression due to frictional downdrag from the grain. That is, for a given girt strength spacings are calculated for maximum desired cladding load. 
     In the upper part of the silo wall not influenced by local effects at the base the girt spacing is arrived at substantially from these considerations. There are other factors such as wind resistance strength that are also checked. 
     In the lower region of the wall adjacent the foundation the deflected profile shape of the wall must be controlled to provide a transition between the fixed lower edge and the expandable upper portion of the wall. It has been found that by carefully selecting the girt spacings in the lower region of the wall the destructive bending effects in the cladding can be overcome and the stresses in the sheeting controlled. In designs to which the invention has been applied the following spacings have been found to achieve the desired result. The spacings are expressed in terms of S, the calculated spacing for maximum cladding load at the corresponding part of the wall. 
     
         ______________________________________GIRT                 SPACING______________________________________1st distance from foundation                200 to 300 mmto lst girt          about 0.4 to 0.65 SSpacing to 2nd girt  0.5 to 0.65 SSpacing to 3rd girt  0.55 to 0.85 SSpacing to 4th girt  0.6 to 0.85 SSpacing to 5th girt  0.8 to 1.05 S______________________________________ 
    
     Typically, the zone of wall, or &#34;lower region&#34; affected by this reduced spacing extends up the wall from the foundation a distance of 2.0 to 4.5 times the calculated gift spacing for maximum desired cladding load at the lower edge of the wall. This corresponds to an actual distance of from 1.0 to 2.5 meters. 
     The girts 15 are formed by a plurality of elongate channel elements 21 joined substantially end to end. The channel elements 21 comprise a band portion 22 having outwardly projecting edge flanges 23 extending along each longitudinal side. In the illustrated embodiment the flanges project at right angles to the band portion. Channel elements 21 are joined by adjacent elements 21 overlapping and nesting as best seen in FIGS. 5, 6 and 7. The overlapped band portions 22 as secured together by rivets 24. The heads 25 of rivets 24 are positioned on the inside of the girts 15 and the heads are sufficiently small to avoid interference with cladding 20. A sheet of fibrous material (not illustrated) can be placed between the cladding 20 and girts 15 to further avoid damage to the cladding 20 by rivet heads 25. 
     As shown in FIG. 4 the girts 15 can be additionally strengthened against inwardly directed forces by the addition of a wind bar 26 comprising a piece of angle steel to the elements 21 in the conventional manner. 
     FIGS. 8 and 9 illustrate an alternate embodiment of the girt elements according to the invention. In this arrangement the elements 51 are formed with flanges 52 both of which project. These girt elements 51 are primarily for use in larger silos where the girts can become too heavy for convenient hand placement. This difficulty is overcome by using a plurality of nested girt elements 51 to provide a sufficiently strong girt. The &#34;plies&#34; of girt elements 51 which make up the girt are arranged in an overlapping manner as illustrated in FIG. 8. This adds additional strength to the girt and provides a convenient method of joining the girt elements 51. A splice member 55 shaped to fit inside the girt completes the joining of the girt elements. 
     It has in practice been found that there is a significant economic benefit associated with silos according to this invention. In particular it has been found that the squat form of silo, that is where the ratio of height ot diameter is 1 or less, that can be built according to this invention has a lower unit storage cost than comparable silos. Additionally, it is possible to show that the cost of construction of silos according to this invention varies with the ratio of wall height to diameter (H/D) and that the optimum value is less than 1. Examples below detail the cost of silos of six different capacities and several H/D ratios and the values are plotted in FIG. 10. Although the H/D ratios show greater economy at the lower end of the range other factors such as availability of land and cost of conveying equipment must also be taken into account. In practice the following H/D ratios have been found to be the maximum required. 
     
         ______________________________________Silo CapacityTonnes (Wheat)       Volume (m.sup.3)                    H/D Ratio______________________________________500         641          1.02,000       2,564        0.755,000       6,410        0.6510,000      12,821       0.6020,000      25,641       0.6030,000      38,642       0.550,000      64,103       0.45______________________________________ 
    
     EXAMPLE 1 
     Silo Capacity 500 Tonnes of Wheat (641m 3 ) 
     
         __________________________________________________________________________RELATIVE COSTS BASED ON SILOS WITH CONCRETEFOUNDATION RING AND CONCRETE FLOOR.__________________________________________________________________________SILO NOM. CAP. TONNES WHEAT                 500.00                      500.00                           500.00                                500.00                                     500.00VOLUME CM @ 780 KG PER CM                 641.03                      641.03                           641.03                                641.03                                     641.03DIA                   12.00                      11.00                           10.00                                9.10 8.50WALL HT.              4.80 6.00 7.40 9.00 10.50RATIO WALL HT/DIA     .40  .55  .74  .99  1.24PLAN AREA SQ M.       113.10                      95.03                           78.54                                65.04                                     56.75EFF. HT               5.65 6.78 8.11 9.64 11.10ACTUAL VOLUME THESE DIMS.                 638.89                      644.16                           636.76                                627.22                                     629.95FLOOR BEAM WIDTH      .90  1.00 1.10 1.20 1.40FLOOR BEAM DEPTH      .28  .30  .33  .34  .40FLOOR BEAM VOL CONC   9.50 10.37                           11.40                                11.66                                     14.95FLOOR DIA I/S BEAM    11.10                      10.00                           8.90 7.90 7.10FLOOR SLAB VOL CONC   12.10                      9.82 7.78 6.13 4.95FLOOR VOL OF CONC. CU. M.                 21.60                      20.18                           19.18                                17.79                                     19.90FLOOR REINFORCEMENT SLAB                 .54  .44  .35  .27  .22FLOOR REINFORCEMENT BEAM                 .58  .64  .70  .72  .92FLOOR REINFT TOTAL TONNES                 1.13 1.08 1.05 .99  1.14WALL AREA             180.96                      207.35                           232.48                                257.30                                     280.39WT OF WALL SHEETING   .94  1.07 1.20 1.33 1.45WT OF GIRTS AND POSTS 3.32 3.81 4.27 4.73 5.15TOTAL WT OF WALL      4.26 4.88 5.47 6.06 6.60ROOF AREA             169.69                      143.77                           119.98                                100.41                                     88.33WT OF ROOF SHEETING   .80  .68  .57  .47  .42WT OF RAFTERS &amp; PURLINS ETC.                 1.09 .93  .77  .65  .57TOTAL WT OF ROOF      1.89 1.61 1.34 1.12 .99TOTAL WT STEELWK INC. SHTG                 6.15 6.49 6.81 7.18 7.59TOTAL WT OF SHEETING  1.74 1.75 1.77 1.81 1.87COST OF SHEETING @ $1450                 $2,520                      $2,540                           $2,566                                $2,617                                     $2,708TOTAL WT OF GIRTS, PURLINS,                 4.42 4.73 5.04 5.37 5.72COST OF GIRTS, PURLINS ETC                 $6,624                      $7,100                           $7,563                                $8,058                                     $8,578@ 1500/TONNETRANSPORT @ $40/TONNE $246 $259 $272 $287 $303TOTAL STRUCTURAL COST $9,390                      $9,900                           $10,401                                $10,963                                     $11,589ADJUST TO TODAY&#39;S RATES                 $11,550                      $12,177                           $12,794                                $13,484                                     $14,254(* 1.23)STRUCTURAL COST/TONNE STORAGE                 $23.10                      $24.35                           $25.59                                $26.97                                     $28.51FORMWORK, CONCRETE, PLACING                 $5,183                      $4,844                           $4,603                                $4,270                                     $4,777@ $240REINFORCEMENT @ $1000 $1,126                      $1,078                           $1,050                                $992 $1,142TOTAL COST SLAB       $6,310                      $5,922                           $5,653                                $5,262                                     $5,919ERECTION - 0.62* STRUCTURAL C                 $7,161                      $7,550                           $7,392                                $8,360                                     $8.838TOTAL COST SILOS ERECTED                 $25,020                      $25,649                           $26,379                                $27,106                                     $29,010File: DIM VS COST 500COST PER TONNE OF GRAIN                 $50.21                      $51.05                           $53.11                                $55.41                                     $59.04COST PER CU METER STORAGE                 39.16                      39.82                           41.43                                43.22                                     46.05__________________________________________________________________________ 
    
     EXAMPLE 2 
     Silo Capacity 2,000 Tonnes of Wheat (2564m 3 ) 
     
         __________________________________________________________________________RELATIVE COSTS BASED ON SILOS WITH CONCRETEFOUNDATION RING AND CONCRETE FLOOR.__________________________________________________________________________SILO NOM. CAP. TONNES WHEAT                 2.000                      2,000                           2,000                                2,000                                     2,000VOLUME @ 780 KG PER CU M.                 2,564                      2,564                           2,564                                2,564                                     2,564DIA                   20.90                      19.30                           17.80                                16.80                                     22.30WALL HT.              6.00 7.40 9.00 10.50                                     5.00RATIO WALL HT/DIA     .29  .38  .51  .62  .22AREA                  343.07                      292.55                           248.85                                221.67                                     390.57EFF. HT               7.48 8.77 10.26                                11.69                                     6.58ACTUAL VOLUME THESE DIMS.                 2,566                      2,564                           2,553                                2,591                                     2,569FLOOR BEAM WIDTH      1.00 1.10 1.20 1.40 .90FLOOR BEAM DEPTH      .30  .33  .34  .40  .30FLOOR BEAM VOL CONC   19.70                      22.01                           22.82                                29.56                                     18.92FLOOR DIA I/S BEAM    19.90                      18.20                           16.60                                15.40                                     21.40FLOOR SLAB VOL CONC   38.88                      32.52                           27.05                                23.28                                     44.96FLOOR VOL OF CONC. CU. M.                 58.58                      54.53                           49.87                                52.84                                     63.88FLOOR REINFORCEMENT SLAB                 1.74 1.46 1.21 1.04 2.01FLOOR REINFORCEMENT BEAM                 1.21 1.35 1.40 1.82 1.16FLOOR REINFT TOTAL TONNES                 2.95 2.81 2.62 2.86 3.18WALL AREA             393.96                      448.68                           503.28                                554.18                                     350.29WT OF SHEETING        2.04 2.32 2.60 2.87 1.81WT OF GIRTS AND POSTS 7.24 8.99 10.08                                11.57                                     7.60TOTAL WT OF WALL      9.27 11.31                           12.69                                14.43                                     9.41ROOF AREA             494.81                      423.85                           362.31                                323.66                                     561.41WT OF SHEETING        2.34 2.00 1.71 1.53 2.66WT OF RAFTERS &amp; PURLINS ETC.                 3.18 2.73 2.33 2.08 3.61TOTAL WT OF ROOF      5.52 4.73 4.05 3.62 6.27TOTAL WT STEELWK INC. SHTG                 14.80                      16.04                           16.73                                18.05                                     15.68TOTAL WT OF SHEETING  4.38 4.32 4.32 4.40 4.47COST OF SHEETING @ $1450                 $6,347                      $6,271                           $6,258                                $6,376                                     $6,476TOTAL WT OF GIRTS, PURLINS,                 10.42                      11.72                           12.42                                13.65                                     11.22COST OF GIRTS, PURLINS ETC                 $15,631                      $17,577                           $18,624                                $20,477                                     $16,825@ 1500/TONNETRANSPORT @ $40/TONNE $592 $642 $669 $722 $627TOTAL STRUCTURAL COST $22,569                      $24,489                           $25,551                                $27,576                                     $23,929ADJUST STRUC COST TO TO-DAYS                 $27,760                      $30,122                           $31,428                                $33,918                                     $29,432RATES (* 1.23)STRUCTURAL COST/TONNE STORAGE                 $13.88                      $15.06                           $15.71                                $16.96                                     $14.72FORMWORK, CONCRETE, PLACING                 $14,058                      $13,087                           $11,968                                $12,681                                     $15,330@ $240REINFORCEMENT @ $1000 $2,954                      $2,811                           $2,616                                $2,862                                     $3,178TOTAL COST SLAB       $17,012                      $15,898                           $14,584                                $15,543                                     $18,508ERECTION - 0.62* STRUC COST                 $17,211                      $18,676                           $19,485                                $21,029                                     $18,248File: DIM.COST 2000TOTAL COST SILOS ERECTED                 $61,984                      $64,696                           $65,497                                $70,490                                     $66,188COST PER TONNE OF GRAIN                 $30.97                      $32.34                           $32.89                                $34.88                                     $33.03COST PER METER OF STORAGE                 $24.16                      $25.23                           $25.66                                $27.21                                     $25.76__________________________________________________________________________ 
    
     EXAMPLE 3 
     Silo Capacity 5,000 Tonnes of Wheat (6410m 3 ) 
     
         __________________________________________________________________________RELATIVE COSTS BASED ON SILOS WITH CONCRETEFOUNDATION RING AND CONCRETE FLOOR.__________________________________________________________________________SILO NOM. CAP. TONNES WHEAT                 5,000                      5,000                           5,000                                5,000                                     5,000VOLUME @ 780 KG PER CU M.                 6,410                      6,410                           6,410                                6,410                                     6,410DIA                   33.30                      3l.50                           29.40                                27.30                                     25.70WALL HT.              5.00 6.00 7.40 9.00 10.50RATIO WALL HT/DIA     .15  .19  .25  .33  .41AREA                  870.92                      779.31                           678.87                                585.35                                     518.75EFF. HT               7.36 8.23 9.48 10.93                                     12.32ACTUAL VOLUME THESE DIMS.                 6,406                      6,413                           6,436                                6,399                                     6,390FLOOR BEAM WIDTH      .90  1.00 1.10 1.20 1.40FLOOR BEAM DEPTH      .30  .30  .33  .34  .40FLOOR BEAM VOL CONC   28.25                      29.69                           33.53                                34.99                                     45.21FLOOR DIA I/S BEAM    32.40                      30.50                           28.30                                26.10                                     24.30FLOOR SLAB VOL CONC   103.06                      91.33                           78.63                                66.88                                     57.97FLOOR VOL OF CONC. CU. M.                 131.31                      121.02                           112.15                                101.87                                     103.19FLOOR REINFORCEMENT SLAB                 4.62 4.09 3.52 3.00 2.60FLOOR REINFORCEMENT BEAM                 1.74 1.83 2.06 2.15 2.78FLOOR REINFT TOTAL TONNES                 6.35 5.92 5.59 5.15 5.38WALL AREA             523.08                      593.76                           683.48                                771.89                                     847.76WT OF SHEETING        2.70 3.07 3.53 3.99 4.38WT OF GIRTS AND POSTS 11.35                      10.91                           13.70                                15.47                                     17.69TOTAL WT OF WALL      14.06                      13.98                           17.23                                19.46                                     22.08ROOF AREA             1230.74                      1103.48                           963.77                                833.51                                     740.61WT OF SHEETING        5.82 5.22 4.56 3.94 3.50WT OF RAFTERS &amp; PURLINS ETC.                 7.92 7.10 6.20 5.36 4.77TOTAL WT OF ROOF      13.74                      12.32                           10.76                                9.31 8.27TOTAL WT STEELWK INC. SHTG                 27.80                      26.30                           27.99                                28.76                                     30.35TOTAL WT OF SHEETING  8.53 8.29 8.09 7.93 7.89COST OF SHEETING @ $1450                 $12,362                      $12,019                           $11,734                                $11,503                                     $11,435TOTAL WT OF GIRTS, PURLINS,                 19.27                      18.01                           19.90                                20.83                                     22.46COST OF GIRTS, PURLINS ETC                 $28,912                      $27,011                           $29,846                                $31,246                                     $33,691@ 1500/TONNETRANSP0RT @ $40/TONNE $1,112                      $1,052                           $1,120                                $1,151                                     $1,214TOTAL STRUCTURAL COST $42,387                      $40,082                           $42,700                                $43,900                                     $46,340ADJUST STRUC COST TO TO-DAYS                 $52,136                      $49,301                           $52,521                                $53,996                                     $56,988RATES (* 1.23)STRUCTURAL COST/TONNE STORAGE                 $10.43                      $9.86                           $10.50                                $10.80                                     $11.40FORMWORK, CONCRETE, PLACING                 $31,513                      $29,044                           $26,917                                $24,449                                     $24,764@ $240REINFORCEMENT @ $1000 $6,355                      $5,918                           $5,585                                $5,149                                     $5,379TOTAL COST SLAB       $37,868                      $34,961                           $32,502                                $29,598                                     $30,143ERECTION - 0.62* STRUC COST                 $32,324                      $30,567                           $32,563                                $33,478                                     $35,339TOTAL COST SILOS ERECTED                 $122,328                      $114,829                           $117,586                                $117,072                                     $122,480File: DIM V COST 5000COST PER TONNE OF GRAIN                 $24.48                      $22.96                           $23.42                                $23.46                                     $24.57COST PER CU. METER STORAGE                 $19.09                      $17.91                           $18.27                                $18.30                                     $19.17__________________________________________________________________________ 
    
     EXAMPLE 4 
     Silo Capacity 10,000 Tonnes of Wheat (12,821m 3 ) 
     
         __________________________________________________________________________RELATIVE COSTS BASED ON SILOS WITH CONCRETEFOUNDATION RING AND CONCRETE FLOOR.__________________________________________________________________________SILO NOM. CAP. TONNES WHEAT                 10,000                      10,000                           10,000                                10,000                                     10,000                                          10,000VOLUME CM @ 780 KG/CM 12,821                      12,821                           12,821                                12,821                                     12,821                                          12,821DIA                   42.60                      40.00                           37.50                                35.40                                     33.70                                          30.00WALL HT.              6.00 7.40 9.00 10.50                                     12.00                                          16.00RATIO WALL HT/DIA     .14  .18  .24  .30  .36  .53AREA                  1425.31                      1256.64                           1104.47                                984.23                                     891.97                                          706.86EFF. HT               9.01 10.23                           11.65                                13.00                                     14.38                                          18.12ACTUAL VOLUME THESE DIMS.                 12,848                      12,855                           12,871                                12,799                                     12,830                                          12,810FLOOR BEAM WIDTH      1.10 1.10 1.20 1.40 1.50 1.60FLOOR BEAM DEPTH      .33  .33  .34  .40  .42  .44FLOOR BEAM VOL CONC   48.58                      45.62                           48.07                                62.28                                     66.70                                          66.35FLOOR DIA I/S BEAM    41.50                      38.90                           36.30                                34.00                                     32.20                                          28.40FLOOR SLAB VOL CONC   169.08                      148.56                           129.36                                113.49                                     101.79                                          79.18FLOOR VOL OF CONC. CU. M.                 217.66                      194.17                           177.43                                175.77                                     168.49                                          145.53FLOOR REINFORCEMENT SLAB                 7.57 6.65 5.79 5.08 4.56 3.55FLOOR REINFORCEMENT BEAM                 2.99 2.81 2.96 3.83 4.l0 4.08FLOOR REINFT TOTAL TONNES                 10.56                      9.46 8.75 8.92 8.66 7.63WALL AREA             802.99                      929.91                           1060.29                                1167.73                                     1270.46                                          1507.96WT OF SHEETING        7.23 8.37 9.54 11.68                                     12.70                                          15.08WT OF GIRTS AND POSTS 21.42                      24.81                           28.28                                31.15                                     33.89                                          40.23TOTAL WT OF WALL      28.65                      33.18                           37.83                                42.83                                     46.59                                          55.31ROOF AREA             1998.89                      1765.47                           1554.70                                1388.00                                     1259.97                                          1002.72WT OF SHEETING        9.45 8.35 7.35 6.57 5.96 4.74WT OF RAFTERS &amp; PURLINS ETC.                 13.19                      11.36                           10.01                                8.93 8.11 6.45TOTAL WT OF ROOF      22.65                      19.71                           17.36                                15.50                                     14.07                                          11.20TOTAL WT STEELWK INC. SHTG                 51.30                      52.89                           55.19                                58.33                                     60.66                                          66.50TOTAL WT OF SHEETING  16.68                      16.72                           16.90                                18.24                                     18.66                                          19.82COST OF SHEETING @ $1450                 $24,188                      $24,244                           $24,500                                $26,452                                     $27,063                                          $28,743TOTAL WT OF GIRTS, PURLINS,                 34.61                      36.17                           38.29                                40.08                                     42.00                                          46.68COST OF GIRTS, PURLINS ETC                 $51,921                      $54,252                           $57,434                                $60,127                                     $62,999                                          $70,019@ 1500/TONNETRANSPORT @ $40/TONNE $2,052                      $2,116                           $2,207                                $2,333                                     $2,427                                          $2,660TOTAL STRUCTURAL COST $78,162                      $80,611                           $84,141                                $88,912                                     $92,488                                          $101,421ADJUST STRUC COST TO TO-DAYS                 $96,139                      $99,152                           $103,494                                $109,361                                     $113,761                                          $124,748RATES (* 1.23)STRUCTURAL COST/TONNE STORAGE                 $9.61                      $9.92                           $10.35                                $10.94                                     $11.38                                          $12.47FORMWORK, CONCRETE, PLACING                 $52,239                      $46,602                           $42,583                                $42,185                                     $40,438                                          $34,928@ $240REINFORCEMENT @ $1000 $10,563                      $9,462                           $8,753                                $8,916                                     $8,664                                          $7,630TOTAL COST SLAB       $62,802                      $56,064                           $51,336                                $51,101                                     $49,102                                          $42,558ERECTION - 0.62* STRUC COST                 $59,606                      $61,474                           $64,166                                $67,804                                     $70,532                                          $77,344File: DIM.COST 10000TOTAL COST SILOS ERECTED                 $218,547                      $216,690                           $218,996                                $228,266                                     $233,394                                          $244,651COST PER TONNE OF GRAIN                 $21.85                      $21.67                           $21.90                                $22.83                                     $23.34                                          $24.47COST PER CU. METER STORAGE                 $17.01                      $16.86                           $17.02                                $17.83                                     $18.19                                          $19.10__________________________________________________________________________ 
    
     EXAMPLE 5 
     Silo Capacity 20,000 Tonnes of Wheat (25,641m 3 ) 
     
         __________________________________________________________________________RELATIVE COSTS BASED ON SILOS WITH CONCRETE FOUNDATION RING AND CONCRETEFLOOR__________________________________________________________________________SILO NOM. CAP. TONNES WHEAT                  20,000                       20,000                            20,000                                 20,000                                      20,000                                           20,000                                                20,000                                                     20,000VOLUME CM @ 780 KG/CM  25,641                       25,641                            25,641                                 25,641                                      25,641                                           25,641                                                25,641                                                     25 641DIA                    57.00                       54.00                            51.00                                 48.50                                      46.20                                           41.50                                                38.00                                                     35.00WALL HT.               6.00 7.40 9.00 10.50                                      12.00                                           16.00                                                20.00                                                     24.00RATIO WALL HT/DIA      .11  .14  .18  .22  .26  .39  .53  .69AREA                   2551.76                       2290.23                            2042.83                                 1847.46                                      1676.39                                           1352.66                                                1134.12                                                     962.12EFF. HT                10.03                       11.22                            12.61                                 13.93                                      15.27                                           18.94                                                22.69                                                     26.48ACTUAL VOLUME THESE DIMS.                  25,601                       25,697                            25,756                                 25,738                                      25,596                                           25,614                                                25,731                                                     25,473FLOOR BEAM WIDTH       1.10 1.10 1.20 1.40 1.50 1.60 1.70 1.80FLOOR BEAM DEPTH       .33  .33  .34  .40  .42  .44  .45  .47FLOOR BEAM VOL CONC    65.00                       61.58                            65.37                                 85.33                                      91.44                                           91.78                                                91.33                                                     93.02FLOOR DIA I/S BEAM     55.90                       52.90                            49.80                                 47.10                                      44.70                                           39.90                                                36.30                                                     33.20FLOOR SLAB VOL CONC    306.78                       274.73                            243.48                                 217.79                                      196.16                                           156.30                                                129.36                                                     108.21FLOOR VOL OF CONC. CU. M.                  371.78                       336.31                            308.85                                 303.12                                      287.60                                           248.08                                                220.69                                                     201.23FLOOR REINFORCEMENT SLAB                  13.74                       12.31                            10.91                                 9.76 8.79 7.00 5.79 4.85FLOOR REINFORCEMENT BEAM                  4.00 3.79 4.02 5.25 5.63 5.65 5.62 5.72FLOOR REINFT TOTAL TONNES                  17.74                       16.10                            14.93                                 15.01                                      14.41                                           12.65                                                11.41                                                     10.57WALL AREA              1074.42                       1255.38                            1441.99                                 1599.86                                      1741.70                                           2086.02                                                2387.61                                                     2638.94WT OF wall SHEETING tonnes                  10.72                       12.52                            16.18                                 19.95                                      21.72                                           26.01                                                29.77                                                     32.91WT OF GIRTS AND POSTS  26.12                       30.52                            35.06                                 38.90                                      42.35                                           50.72                                                58.06                                                     64.17TOTAL WT OF WALL       36.84                       43.05                            51.25                                 58.85                                      64.07                                           76.73                                                87.83                                                     97.07.ROOF AREA              3553.87                       3193.28                            2851.97                                 2582.27                                      2345.98                                           1898.37                                                1595.78                                                     1357.32WT OF ROOF SHEETING tonnes                  16.81                       15.10                            13.49                                 12.21                                      11.10                                           8.98 7.55 6.42WT OF RAFTERS &amp; PURLINS ETC.                  23.46                       20.55                            18.35                                 16.62                                      15.10                                           12.22                                                10.27                                                     8.74TOTAL WT OF ROOF       40.27                       35.66                            31.84                                 28.83                                      26.19                                           21.20                                                17.82                                                     15.16TOTAL WT STEELWK INC. SHTG                  77.11                       78.70                            83.09                                 87.68                                      90.26                                           97.93                                                105.65                                                     112.23TOTAL WT OF SHEETING ROOF                  27.53                       27.63                            29.67                                 32.16                                      32.82                                           34.99                                                37.32                                                     39.33&amp; WALLCOST OF SHEETING @ $1450                  $39,916                       $40,060                            $43,026                                 $46,638                                      $47,582                                           $50,738                                                $54,116                                                     $57,025TOTAL WT OF GIRTS, PURLINS,                  49.58                       51.08                            53.42                                 55.52                                      57.45                                           62.94                                                68.33                                                     72.90COST OF GIRTS, PURLINS ETC                  $74,374                       76,614                            80,125                                 83,279                                      86,174                                           94,409                                                102,488                                                     109,353@ 1500/TONNETRANSPORT @ $40/TONNE  $3,084                       $3,148                            $3,324                                 $3,507                                      $3,611                                           $3,917                                                $4,226                                                     $4,489TOTAL STRUCTURAL COST $                  117,375                       119,822                            126,475                                 133,425                                      137,367                                           149,065                                                160,830                                                     170,867ADJUST STRUC COST TO TO-DAYS                  144,371                       147,381                            155,564                                 164,113                                      168,961                                           183,350                                                197,821                                                     210,166RATES (* 1.23)STRUCTURAL COST/TONNE STORAGE                  $7.22                       $7.37                            $7.78                                 $8.21                                      $8.45                                           $9.17                                                $9.89                                                     $10.51FORMWORK, CONCRETE, PLACING                  $89,227                       $80,716                            $74,123                                 $72,748                                      $69,024                                           $59,539                                                $52,966                                                     $48,296@ $240REINFORCEMENT @ $1000  $17,742                       $16,096                            $14,929                                 $15,006                                      $14,414                                           $12,649                                                $11,415                                                     $10,572TOTAL COST SLAB        106,969                       $96,811                            $89,052                                 $87,755                                      $83,438                                           $72,188                                                $64,380                                                     $58,868ERECTION - 0.62* STRUC COST                  89,510                       91,376                            96,450                                 101,750                                      104,756                                           113,677                                                122,649                                                     130,303File: DIM.COST 20000sTOTAL COST SILOS ERECTED                  $340,850                       335,569                            341,066                                 353,617                                      357,156                                           369,215                                                384,851                                                     399,338COST PER TONNE OF GRAIN                  $17.07                       $16.74                            $16.98                                 $17.61                                      $17.89                                           $18.48                                                $19.17                                                     $20.10COST PER CU. METER STORAGE                  $13.31                       $13.06                            $13.24                                 $13.74                                      $13.95                                           $14.41                                                $14.96                                                     $15.68__________________________________________________________________________ 
    
     EXAMPLE 6 
     Silo Capacity 30,000 Tonnes of Wheat (38,462m 3 ) 
     
         __________________________________________________________________________RELATIVE COSTS BASED ON SILOS WITH CONCRETE FOUNDATION RING AND CONCRETEFLOOR__________________________________________________________________________SILO NOM. CAP. TONNES WHEAT                  30,000                       30,000                            30,000                                 30,000                                      30,000                                           30,000                                                30,000                                                     30,000VOLUME CM @ 780 KG/CM  38,462                       38,462                            38,462                                 38,462                                      38,462                                           38,462                                                38,462                                                     38,462DIA                    67.50                       64.20                            60.70                                 58.00                                      55.50                                           50.10                                                46.00                                                     42.60WALL HT.               6.00 7.40 9.00 10.50                                      12.00                                           16.00                                                20.00                                                     24.00RATIO WALL HT/DIA      .09  .12  .15  .18  .22  .32  .43  .56AREA                   3578.48                       3237.14                            2893.80                                 2642.09                                      2419.23                                           1971.36                                                1661.91                                                     1425.31EFF. HT                10.78                       11.94                            13.29                                 14.60                                      15.93                                           19.54                                                23.25                                                     27.01ACTUAL VOLUME THESE DIMS.                  38,560                       38,658                            38,472                                 38,584                                      38,530                                           38,529                                                38,647                                                     38,503FLOOR BEAM WIDTH       1.10 1.10 1.20 1.40 1.50 1.60 1.70 1.80FLOOR BEAM DEPTH       .33  .33  .34  .40  .42  .44  .45  .47FLOOR BEAM VOL CONC    76.98                       73.21                            77.80                                 102.04                                      109.85                                           110.81                                                110.55                                                     113.22FLOOR DIA I/S BEAM     66.40                       63.10                            59.50                                 56.60                                      54.00                                           48.50                                                44.30                                                     40.80FLOOR SLAB VOL CONC    432.85                       390.89                            347.56                                 314.51                                      286.28                                           230.93                                                192.67                                                     163.43FLOOR VOL OF CONC. CU. M.                  509.83                       464.11                            425.37                                 416.55                                      396.12                                           341.74                                                303.22                                                     276.65FLOOR REINFORCEMENT SLAB                  19.39                       17.51                            15.57                                 14.09                                      12.82                                           10.34                                                8.63 7.32FLOOR REINFORCEMENT BEAM                  4.74 4.51 4.79 6.28 6.76 6.82 6.80 6.97FLOOR REINFT TOTAL TONNES                  24.13                       22.01                            20.36                                 20.37                                      19.58                                           17.16                                                15.43                                                     14.29WALL AREA              1272.35                       1492.51                            1716.25                                 1913.23                                      2092.30                                           2518.30                                                2890.27                                                     3211.96WT OF wall SHEETING tonnes                  15.27                       17.91                            23.17                                 28.70                                      31.38                                           37.77                                                43.35                                                     48.18WT OF GIRTS AND POSTS  30.94                       36.29                            41.74                                 46.53                                      50.88                                           61.24                                                70.28                                                     78.11TOTAL WT OF WALL       46.21                       54.20                            64.90                                 75.22                                      82.26                                           99.01                                                113.64                                                     126.29ROOF AREA              4967.81                       4497.98                            4025.16                                 3678.36                                      3371.17                                           2753.34                                                2325.97                                                     1998.99WT OF ROOF SHEETING tonnes                  23.50                       21.28                            19.04                                 17.40                                      15.95                                           13.02                                                11.00                                                     9.45WT OF RAFTERS &amp; PURLINS ETC.                  32.79                       28.95                            25.90                                 23.67                                      21.70                                           17.72                                                14.97                                                     12.86TOTAL WT OF ROOF       56.29                       50.22                            44.94                                 41.07                                      37.64                                           30.74                                                25.97                                                     22.32TOTAL WT STEELWK INC. SHTG                  102.50                       104.43                            109.85                                 116.30                                      119.90                                           129.76                                                139.61                                                     148.61TOTAL WT OF SHEETING ROOF                  38.77                       39.19                            42.21                                 46.10                                      47.33                                           50.80                                                54.36                                                     57.63&amp; WALLCOST OF SHEETING, @ 1450                  $56,211                       $56,819                            $61,202                                 $66,841                                      $68,629                                           $73,657                                                $78,816                                                     $83,570TOTAL WT OF GIRTS, PURLINS,                  63.73                       65.24                            67.64                                 70.20                                      72.57                                           78.96                                                85.25                                                     90.97COST OF GIRTS, PURLINS ETC                  $95,597                       97,863                            101,460                                 105,297                                      108,859                                           118,438                                                127,881                                                     136,458@ 1500/TONNETRANSPORT @ $40/TONNE  $4,100                       $4,177                            $4,394                                 $4,652                                      $4,796                                           $5,190                                                $5,584                                                     $5,944TOTAL STRUCTURAL COST $                  155,907                       158,859                            167,056                                 176,790                                      182,283                                           197,285                                                212,281                                                     225,972ADJUST STRUC COST TO TO-DAYS                  191,766                       195,396                            205,479                                 217,451                                      224,209                                           242,661                                                261,106                                                     277,945RATES (* 1.23)STRUCTURAL COST/TONNE STORAGE                  $6.39                       $6.51                            $6.85                                 $7.25                                      $7.47                                           $8.09                                                $8.70                                                     $9.26FORMWORK, CONCRETE, PLACING                  122,358                       111,386                            102,088                                 99,971                                      95,070                                           82,017                                                72,773                                                     66,395@ $240REINFORCEMENT @ $1000  $24,126                       $22,015                            $20,356                                 $20,367                                      $19,583                                           $17,163                                                $15,433                                                     $14,288TOTAL COST SLAB        146,484                       133,400                            122,444                                 120,339                                      114,653                                           99,180                                                88,206                                                     80,683ERECTION - 0.62* STRUC COST                  118,895                       121,146                            127,397                                 134,820                                      139,009                                           150,450                                                161,886                                                     172,326File: DIM.COST 30000TOTAL COST SILOS ERECTED                  457,145                       449,942                            455,320                                 472,610                                      477,870                                           492,291                                                511,197                                                     530,954COST PER TONNE OF GRAIN                  $15.20                       $14.92                            $15.17                                 $15.70                                      $15.90                                           $16.38                                                $16.96                                                     $17.68COST PER CU. METER STORAGE                  $11.86                       $11.64                            $11.84                                 $12.25                                      $12.40                                           $12.78                                                $13.23                                                     $13.79__________________________________________________________________________

Summary:
An enclosed structure for containing particulate solids includes a plurality of circumferentially disposed vertical posts. Circumferentially directed girts extending horizontally are affixed to the posts and corrugated metal cladding is attached to the girts. The vertical spacing of the girts varies and they are closer together near the bottom of the structure.