BS 4485-4-1996 Water cooling towers - Code of practice for structural design and construction《水冷却塔 第4部分 冷却塔结构设计和建造规程》.pdf
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1、BRITISH STANDARD BS4485-4: 1996 Water cooling towers Part 4: Code of practice for structural design and construction ICS 27.100:91.080BS4485-4:1996 This British Standard, havingbeen prepared under thedirection of the Engineering Sector Board, was published underthe authority of the Standards Board a
2、nd comes intoeffect on 15 August1996 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference B/525/15 Draft for comment92/17117 DC ISBN 0 580 25544 1 Committees responsible for this British Standard The preparation of this British Standard was entrusted to T
3、echnical Committee B/525/15, Cooling towers, upon which the following bodies were represented: Association of Consulting Engineers BEAMA Ltd. Concrete Society Electricity Association Engineering Employers Federation Federation of Civil Engineering Contractors Health and Safety Executive Hevac Associ
4、ation Industrial Water Society Institution of Chemical Engineers Institution of Civil Engineers Institution of Structural Engineers Process Plant Association Co-opted member Amendments issued since publication Amd. No. Date CommentsBS4485-4:1996 BSI 07-1999 i Contents Page Committees responsible Ins
5、ide front cover Foreword ii Section 1. General 1.1 Scope 1 1.2 References 1 1.3 Definitions 1 1.4 Symbols 3 1.5 Materials and workmanship 3 1.6 Packing support structures 6 1.7 Packings, water distribution systems, eliminators and cladding 8 1.8 Cooling tower fittings 9 1.9 Water retaining structure
6、s 9 1.10 Foundations and bases 10 Section 2. Hyperboloidal cooling towers (type1 towers) 2.1 Basis of design 11 2.2 Loading 11 2.3 Design considerations 12 2.4 Construction 18 Section 3. Mechanical draught towers (type2 towers) 3.1 Characteristic loads 20 3.2 Design considerations 20 Annex A (normat
7、ive) Recommendations for stress graded timber triangular section laths 21 Annex B (normative) Guidance on the use of plastics materials 23 Annex C (informative) Wind tunnel testing 24 Annex D (informative) Circumferential wind pressure distribution for hyperboloidal towers 24 Annex E (normative) Est
8、imation of resonant stresses 24 Annex F (informative) Derivation of natural frequencies of hyperboloidal towers 25 Figure 1 Pressure coefficient distribution for determination of wind loading 13 Figure 2 Arrangement of reinforcement trimming for openings in shells 17 Figure 3 Arrangement of reinforc
9、ement in the shell 18 Figure A.1 Splay knot 22 Figure A.2 Arris knot 22 Figure A.3 Face knot 22 Figure F.1 Typical finite element representation of cooling tower with column supports 26 Table 1 Dimensional deviations of precast components 4 Table 2 Coatings of metal components 7 Table 3 Determinatio
10、n of and 15 Table 4 Correction factors for stresses due to adjacent structures 16 Table 5 Minimum reinforcement in shell 16 Table A.1 Permissible knot size for a38mm 38mm lath 21 List of references 27BS4485-4:1996 ii BSI 07-1999 Foreword This Part of BS4485, which has been prepared by Subcommittee B
11、/525/15, Cooling towers, is concerned with the structural design and construction of natural draught and mechanical draught cooling towers. It is a revision of BS4485-4:1975, which is now withdrawn. As a code of practice, this British Standard takes the form of guidance and recommendations. It shoul
12、d not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading. This Part of BS4485 contains three sections: a general section relating to all towers and two separate sections covering hyperboloidal shell natural draught tower
13、s and mechanical draught towers. The method of design of concrete shells of natural draught towers has been the subject of extensive changes. This edition differs from the previous 1975 edition as follows. a) Wind loadings are based on hourly mean winds, as derived in BS6399-2. b) An amplification f
14、actor to the wind loading is introduced to take account of the fluctuations in incident wind on the tower, and the effect on resulting stresses of tower resonant response in the incident wind. The factor is derived by an empirical equation, related to design wind speed and the natural frequency of t
15、he tower. It is derived from wind tunnel test results. c) Serviceability limit states are defined more fully and include an additional equation for buckling of the shell, and limitations to which uplift of foundations may be permitted under factored wind loading. d) Design is related to BS8110, incl
16、uding the shell support system. 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 not of itself confer immunity from legal obligations. In partic
17、ular, attention is drawn to the Reservoirs Act 1975 1 and the need to ascertain at the time of the design of the cooling tower systems whether or not the cold water basin, especially if connected to other towers, comes within its scope. Summary of pages This document comprises a front cover, an insi
18、de front cover, pagesi andii, pages1 to28, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS4485-4:1996 BSI 07-1999 1 Section 1. General 1.1 S
19、cope This Part of BS4485 gives recommendations for the structural design and construction of water cooling towers of the following types: a) type1. Natural draught or assisted draught towers, in which the total air flow is wholly or partly induced by a reinforced concrete shell of hyperboloidal form
20、; b) type2. Mechanical draught towers, in which the total air flow is induced wholly by mechanical means within an enclosed structure. It applies only to those cooling towers constructed or erected on site and excludes factory assembled towers. In addition, matters relating to construction and workm
21、anship in concrete and other materials are dealt with only in so far as they are specific to cooling tower construction. Other items of construction are referred to in appropriate specifications. This code of practice covers the design of towers up to170m in height. However certain restrictions appl
22、y to formulae used for towers greater than120m in height. NOTEFor cooling towers of type1, shells similar in shape to the true hyperboloidal form may be considered. Where these other shapes are adopted then certain sections of this standard may not be strictly applicable. 1.2 References 1.2.1 Normat
23、ive references This Part of BS4485 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on pages27 and28. For dated references, only the edition cited applies:
24、any subsequent amendments to, or revisions of the cited publication apply to this Part of BS4485 only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 1.2.2 Informative references T
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