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1、BRITISH STANDARD BS 5061:1974 Incorporating Amendment Nos. 1 and 2 Specification for Cylindrical forage tower silos and recommendations for their use UDC 631.243.244 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 14:22:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5061:1974 This British S
2、tandard, having been approved by the Farm and Horticultural Buildings Industry Standards Committee, was published under the authority of the Executive Board on 11 April 1974 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference FHB/8 Draft for comment 71/1
3、0441 ISBN 0 580 08070 6 Co-operating organizations The Farm and Horticultural Buildings Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives of the following Government departments and scientific and industrial organizations: British P
4、recast Concrete Federation* British Constructional Steelwork Association* British Steel Industry* British Wood Preserving Association Cement and Concrete Association* Country Landowners Association Department of Agriculture and Fisheries for Scotland Farm Buildings Centre Ministry of Agriculture (Go
5、vernment of Northern Ireland) Ministry of Agriculture, Fisheries and Food* National Farmers Union* National Farmers Union of Scotland National Federation of Building Trades Employers National Union of Agricultural and Allied Workers* Royal Institute of British Architects Royal Institution of Charter
6、ed Surveyors Timber Research and Development Association* Transport and General Workers Union The Government department and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committees entrusted with the p
7、reparation of this British Standard: Agricultural Engineers Association Farm Building Association Home Office Institution of Civil Engineers Institution of Structural Engineers National Institute of Agricultural Engineering Amendments issued since publication Amd. No.Date of issueComments 1747May 19
8、75 6074September 1990 Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 14:22:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5061:1974 BSI 10-1999i Contents Page Co-operating organizationsInside front cover Forewordii 1General1 1.1Scope1 1.2Definitions1 1
9、.3Symbols2 2Silo dimensions2 3Foundations, anchorage and siting2 3.1Foundations2 3.2Anchorage2 3.3Siting2 4Loading2 4.1Silo for H.D.M. silage2 4.2General purpose forage silo4 5Design and materials4 5.1Silo wall4 5.2Steel hooping for concrete stave silos4 5.3Silo of concrete stave construction4 5.4Ti
10、mber5 6Construction5 6.1Dimensional accuracy5 6.2Fluid pressure relief5 6.3Fire5 6.4Access equipment6 7Notice Boards6 8Manufacturers handbook6 Appendix A Recommended list of British Standards for reference7 Appendix B Manufacturers handbook8 Appendix C Standard capacity of silo8 Appendix D Guidance
11、on the use of forage tower silos8 Appendix E Composition of silage effluent12 Appendix F Buckling coefficients for the silo wall12 Figure 1 Staggering of lugs13 Table 1 Recommended filling moisture contents for average maturity grass (C.P. 12 % M.A.D. fibre 28 %)9 Table 2 Recommended filling moistur
12、e contents for young leafy grass (C.P. 18 % M.A.D. fibre 24 %)9 Table 3 Recommended filling moisture contents for mature grass and mature arable silage (C.P. 8 % M.A.D. fibre 32 %)9 Table 4 Relationship between silo diameter and filling rate10 Table 5 Minimum unloading rate11 Publications referred t
13、o14 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 14:22:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5061:1974 ii BSI 10-1999 Foreword This British Standard has been prepared under the authority of the Farm and Horticultural Buildings Industry Standards Committee, to meet the requiremen
14、ts for the large outdoor silos which are currently being developed. It relates to cylindrical silos used for the conservation of crops as silage, and data is specified from which they may be designed. In preparing the standard, consideration has been given to research into silo pressures and investi
15、gation into the required properties of the silo components carried out recently, notably in the Civil Engineering Department of the University of Newcastle upon Tyne, to which acknowledgment is given. The silo structure should be designed not only to resist the pressures and loads to which it is sub
16、jected, but also to act as an integrated part of a farming system and as a means of controlling the fermentation of the silage and minimizing the loss of nutrients. For the purpose of structural design, it is important to define the limits of use; these determine the pressures to be used in calculat
17、ions. Two conditions of loading are dealt with in this standard; firstly, to cover the storage of high dry matter silage which enables a more efficient and economical design to be adopted, provided the farmer can generally fill and maintain the silo in accordance with Appendix D, and, secondly, to c
18、over the storage of all types of forage of high moisture content. Included in the appendices are recommendations for the determination of the silo capacity, rate of filling, preferred moisture contents and other points to be observed in the use of the silo. This specification is confirmed with the p
19、rimary intention of providing information for the maintenance of existing forage tower silos. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does n
20、ot of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 14, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This
21、 will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 14:22:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5061:1974 BSI 10-19991 1 General 1.1 Scope This British Standard sets out the basic data for the design of tower silos us
22、ed for the conservation of grasses as silage under UK farming conditions. From this data silos may be designed, provided the design is carried out in accordance with accepted structural engineering practice. Additional considerations need to be applied to the data when grasses contain additives, adm
23、ixtures or other herbages. The standard applies to cylindrical tower silos of all sizes with over 3 m effective depth of storage. NOTEThe titles of British Standards referred to in this standard are listed on page 14. 1.2 Definitions For the purpose of this standard, the following definitions apply:
24、 1.2.1 effective height (he) height in metres from floor level to top of the cylinder 1.2.2 utilized height (hu) maximum depth in metres of material, before settlement, that will be placed in the silo using intended filling machinery. This is used for the calculation of silo capacity 1.2.3 cylinder
25、height (hc) height in metres from top of foundations to top of silo cylinder 1.2.4 settled surface of silage the level 0.90 he above silo floor, the reference level for calculation of pressures; or the level 0.90 hu above silo floor, the reference level for calculation of silo capacity 1.2.5 depth o
26、f silage (hs) the distance in metres below settled surface of silage of the point under consideration 1.2.6 1.2.6.1 silo diameter (d) average internal diameter of silo in metres 1.2.6.2 silo diameter (de) Average external diameter of silo in metres 1.2.7 tower silo cylindrical structure for conservi
27、ng silage 1.2.8 general purpose forage silo a tower silo used for storing any forage of high moisture content 1.2.9 silage fibrous crops preserved by natural and/or artificial acidification in anaerobic conditions 1.2.10 high dry matter silage silage made from crops wilted in accordance with certain
28、 recommendations; abbreviated to H.D.M. silage NOTEThe recommendations are given in D.1. 1.2.11 dry matter (D.M.) dry fraction of the crop, i.e. that which would remain after the moisture had been driven off at 105 C for 16 h 1.2.12 percentage moisture content weight of moisture driven off, at 105 C
29、 for 16 h, divided by initial sample weight multiplied by 100 1.2.13 standard capacity (C) dry matter capacity of silo in tonnes under average conditions calculated in accordance with a standard method NOTEThe standard method of calculation is set out in Appendix C. 1.2.14 density () total weight (k
30、g) of silage per cubic metre 1.2.15 dry density (d) weight (kg) of dry matter in silage per cubic metre, i.e., 1.2.16 M.A.D. fibre percentage by weight of modified acid detergent fibre in dry matter of crop or silage NOTEThe M.A.D. fibre percentage of a crop is increased by between 4 % and 15 % duri
31、ng fermentation into silage in the tower, the exact amount depending on the type of fermentation. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 14:22:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5061:1974 2 BSI 10-1999 1.2.17 crude protein (C.P.) percentage by weight of crude protein in
32、 dry matter of crop or silage NOTEThe C.P. percentage of a crop is increased by between 4 % and 15 % during fermentation into silage in the tower, the exact amount depending on the type of fermentation. 1.3 Symbols The symbols used in this British Standard are as follows: See also 1.2 for symbols us
33、ed for the terms defined in that clause. 2 Silo dimensions Provided all structural requirements are met, the height is limited by the necessity of having to wilt consistently to moisture contents which avoid undue risk of fluid pressure developing and effluent being exuded (see D.1). The diameter of
34、 the silo is limited by the need to ensure that the required rate of consolidation of the grass can be achieved with the planned field machinery system and that the required rate of unloading can be maintained (see D.2). 3 Foundations, anchorage and siting 3.1 Foundations The foundations shall be co
35、nsidered as an integral part of the design and shall be constructed in accordance with the relevant recommendations of BS 8004. Due regard shall be given to differences in settlement between silo bases and adjacent structures. The foundation shall provide uniform contact pressure on the bearing sect
36、ions of the silo wall. Fluid pressure release drainage shall be provided in accordance with 6.2. Whether structural or non-structural, the concrete liable to come in contact with effluent shall be of not less than 150 mm vertical thickness and shall be of dense concrete of at least 30 N/mm2 compress
37、ive strength with a minimum cement content of 330 kg/m3. The cement used shall comply with BS 12. See Appendix E for composition of silage effluent. 3.2 Anchorage The silo cylinder shall be securely anchored to the foundation when its dead weight is insufficient to resist the upward forces of wind o
38、verturning combined with silage uplift calculated in accordance with 4.1.2 and 4.1.6.2. 3.3 Siting The wall of the silo shall not be sited within 1.25 he of domestic dwellings. 4 Loading The loading to be assumed in the design of the silo shall be calculated in accordance with 4.1 for H.D.M. silage,
39、 and with 4.2 for general purpose silos. For the purpose of calculation of loading, the unit weights of the materials shall be those specified in BS 648. 4.1 Silo for H.D.M. silage 4.1.1 Imposed roof load. Imposed roof load shall be calculated in accordance with BS 6399-1. 4.1.2 Wind load. The struc
40、ture, supporting framework, foundations, attachments such as chutes, ladders and ducts, together with their appropriate connections and fixings shall be designed to resist the wind pressure and loads calculated in accordance with Part 2 of CP 3:Chapter V. For the purpose of designing against overtur
41、ning, the design wind speed VS shall be based on a design life of 30 years. The silo shall be stiff enough to resist, without exceeding permissible stresses, the distortion due to the variation in pressure round the silo for a design wind speed of 0.8 VS based on a design life of 30 years. NOTECP 3:
42、Chapter V-2 is currently being revised as BS 6399-2. SSpacing of stiffening rings in metres. EYoungs modulus in N/m2. tThickness of the silo wall sheet in metres. rExternal radius of the silo wall or stiffening ring in metres. uPoissons ratio (0.3 for steel). IMoment of inertia of the stiffening rin
43、g in metres4. pPermissable depression of internal pressure in the silo below atmospheric to be used in calculating buckling under internal suction. fbAxial compressive stress in a cylinder which would produce elastic buckling instability. pcritDepression below atmospheric of the internal pressure in
44、 a cylinder which will cause elastic buckling instability of the cylinder wall. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 14:22:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5061:1974 BSI 10-19993 When considered in conjunction with the silage uplift forces, calculated in accordance
45、with 4.1.6.2, the uplift forces due to wind shall be based on a design wind speed of VS related to a design life of 2 years when anchorage rods are required and of 30 years when the dead load only of walls is considered. The area of the equivalent cylinder to be used for calculating wind loading on
46、a single silo with appendages, may be taken as (de + 0.6) (hc +0.3de). 4.1.3 Internal gas pressures. Where necessary (see D.2.2), the silo shall be vented to prevent large positive or negative gas pressures developing. The vents shall be of a size to prevent pressure exceeding 1.5 times the pressure
47、 at which the vent normally opens. The silo shall be designed to withstand a pressure difference of twice that at which the vent opens. The pressure that can occur when openings are situated in areas of high or low external pressure caused by the wind should also be considered. 4.1.4 Machinery loads
48、. The design of the silo shall take into account the static and dynamic loads imposed on the structure by the filling and unloading, machinery. Due regard should be given to the conditions of loading specified in 4.1.6.2. 4.1.5 Density of silage. The dry density of silage of average maturity at any
49、moisture content, provided its moisture content is not so high that it reaches the saturation density range of 1 000 to 1 100 kg/m3 shall be assumed for the purposes of design to be d= (140 + 14.4 hS) kg/m3, and the bulk density to be 4.1.6 Pressures exerted by silage. The silage pressures on the silo structure are: 1) Lateral pressure, which is the sum of the pressure due to the fibrous mass and the fluid pressure due to fluid squeezed out of the fibrous mass. 2) Vertical friction between the mass of settling or re-expanding silage and the silo wall
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