1、BRITISH STANDARDBS 476-21:1987Fire tests on building materials and structures Part 21: Methods for determination of the fire resistance of loadbearing elements of constructionUDC 614.841.332:620.1:69.01:699.81.071987Incorporating Corrigendum No. 1ICS 13.220.50BS 476-21:1987This British Standard, hav
2、ing been prepared under thedirection of the Fire Standards Committee, was published under the authority of the Board of BSI and comes into effect on 29 May 1987 BSI 01-1999The following BSI references relate to the work on this standard:Committee reference FSM/1Draft for comment 84/38798 DCISBN 0 58
3、0 15873 XCommittees responsible for this British StandardThe preparation of this British Standard was entrusted by the Fire Standards Committee (FSM/-) to Technical Committee FSM/1, upon which the following bodies were represented:Association of British Roofing Felt Eurisol (UK) Association of Manuf
4、acturers of Manufacturers Mineral Insulation FibresAssociation of Building Component Fibre Building Board Organisation (FIDOR)Manufacturers Ltd. Fibre Cement Manufacturers Association LimitedAssociation of Structural Fire Protection Contractors and Manufacturers Fire Insurers Research and Testing Br
5、itish Coal Organisation (FIRTO)British Fire Services Association Fire Offices CommitteeBritish Floor Covering Manufacturers AssociationFire Protection AssociationFlat Glass Manufacturers AssociationBritish Plastics Federation Flat Roofing Contractors Advisory BoardBritish Railways Board Gypsum Produ
6、cts Development AssociationBritish Rigid Urethane Foam Manufacturers Home OfficeAssociation Institution of Fire EngineersBritish Wood Preserving Association Mastic Asphalt Council and Employers Cement and Concrete Association FederationChemical Industries Association National Council of Building Mat
7、erials ProducersChief and Assistant Chief Fire Officers Association National GRP Construction FederationConcrete Society RAPRA Technology Ltd.Department of Education and Science Royal Institute of British ArchitectsDepartment of the Environment for Northern Steel Construction InstituteIreland Timber
8、 Research and Development Department of the Environment (Housing and AssociationConstruction Industries) United Kingdom Antimony Oxide Department of the Environment (Property Manufacturers AssociationServices Agency) United Kingdom Atomic Energy AuthorityDepartment of Transport (Marine Directorate)
9、Warrington Fire Research CentreElectricity Supply Industry in England and WalesWood Wool Slab Manufacturers AssociationYarsley Technical Centre Ltd.Engineering Equipment and Materials Users AssociationThe following bodies were also represented in the drafting of the standard, through subcommittees a
10、nd panels:Association of Builders Hardware Guild of Architectural IronmongersManufacturers Hevac AssociationBritish Steel Industry Intumescent Fire Seals AssociationDepartment of the Environment (Building National Association of Lift MakersResearch Establishment, Fire Research Station)Suspended Ceil
11、ing AssociationDoor and Shutter Association Thermal Insulation Manufacturers andElectric Cable Makers Confederation Suppliers Association (TIMSA)Amendments issued since publicationAmd. No. Date of issue CommentsBS 476-21:1987ISBN 978 0 580 85688 4Amendments/corrigenda issued since publicationAmd. No
12、. Date CommentsC1 April 2014 Information added to ForewordThis British Standard, having been prepared under the direction of the Fire Standards Committee, was published under the authority of the Board of BSI and comes into effect on 29 May 1987 The British Standards Institution 2014 Published by BS
13、I Standards Limited 2014The following BSI references relate to the work on this standard: Committee reference FSM/1 Draft for comment 84/38798 DCBS 476-21:1987 BSI 01-1999 iContentsPageCommittees responsible Inside front coverForeword ii1 Scope 12 Definitions 13 Test conditions 14 Apparatus 15 Deter
14、mination of the fire resistance of beams 16 Determination of the fire resistance of columns 37 Determination of the fire resistance of floors and flat roofs 58 Determination of the fire resistance of walls 5Appendix A Guidance information 11Figure 1 Calculation of test load for columns 4Publications
15、 referred to Inside back coveri The British Standards Institution 2014BS 476-21:1987ii BSI 01-1999ForewordThis Part of BS 476 has been prepared under the direction of the Fire Standards Committee, and describes the specific equipment and procedures for determining the fire resistance of loadbearing
16、elements of building construction. This Part should be read in conjunction with BS 476-20 which describes the general principles for these methods.This Part has been prepared in such a way as to allow reference to be made to the appropriate method of determining the fire resistance of the designated
17、 element by clause number only. Therefore clauses 5 to 8 are self-contained and cross refer to BS 476-20 where necessary.Methods for determining the fire resistance of non-loadbearing elements that have a finite fire resistance and of components that make a contribution to the fire resistance of a s
18、tructure are described in BS 476-22 and BS 476-23 respectively.Methods for determining the fire resistance of external beams and columns are under consideration in the International Organization for StandardizationISO/TC 92, Fire tests on building materials, components and structures.The general cha
19、nges made to the methods described in this Part compared with BS 476-8 are described in the foreword to BS 476-20. Appendix A gives guidance and background information that will assist the designer and the testing laboratory to select and evaluate specimens that are more representative of “in use” s
20、ituations.Attention is drawn to the Health and Safety at Work etc. Act 1974, and the need to ensure that the methods described in this standard are carried out under suitable environmental conditions to provide adequate protection to personnel against the risk of fire, and/or inhalation of smoke and
21、/or toxic products of combustion.CAUTION. The mechanical sawing of asbestos cement components attracts the provision of the Asbestos Regulations 1969. Adequate methods exist to control levels of dust during such operations and these are detailed in the Control and Safety Guides1)issued by the Asbest
22、os Research Council.This Part, together with BS 476-20, BS 476-22, BS 476-23 and BS 476-24, supersedes BS 476-8:1972, which is withdrawn. However, the latter will still be made available on request, since it is referred to in the building regulations and other legislative documents.A British Standar
23、d 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.Summary of pages This document comprises a front cover, an i
24、nside front cover, pages i and ii, pages 1 to 16, 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.1) Available from the Asbestos Information Cen
25、tre, Sackville House, 40 Piccadilly,London W1V 9PA.BS 476-21:1987ii BSI 01-1999ForewordThis Part of BS 476 has been prepared under the direction of the Fire Standards Committee, and describes the specific equipment and procedures for determining the fire resistance of loadbearing elements of buildin
26、g construction. This Part should be read in conjunction with BS 476-20 which describes the general principles for these methods.This Part has been prepared in such a way as to allow reference to be made to the appropriate method of determining the fire resistance of the designated element by clause
27、number only. Therefore clauses 5 to 8 are self-contained and cross refer to BS 476-20 where necessary.Methods for determining the fire resistance of non-loadbearing elements that have a finite fire resistance and of components that make a contribution to the fire resistance of a structure are descri
28、bed in BS 476-22 and BS 476-23 respectively.Methods for determining the fire resistance of external beams and columns are under consideration in the International Organization for StandardizationISO/TC 92, Fire tests on building materials, components and structures.The general changes made to the me
29、thods described in this Part compared with BS 476-8 are described in the foreword to BS 476-20. Appendix A gives guidance and background information that will assist the designer and the testing laboratory to select and evaluate specimens that are more representative of “in use” situations.Attention
30、 is drawn to the Health and Safety at Work etc. Act 1974, and the need to ensure that the methods described in this standard are carried out under suitable environmental conditions to provide adequate protection to personnel against the risk of fire, and/or inhalation of smoke and/or toxic products
31、of combustion.CAUTION. The mechanical sawing of asbestos cement components attracts the provision of the Asbestos Regulations 1969. Adequate methods exist to control levels of dust during such operations and these are detailed in the Control and Safety Guides1)issued by the Asbestos Research Council
32、.This Part, together with BS 476-20, BS 476-22, BS 476-23 and BS 476-24, supersedes BS 476-8:1972, which is withdrawn. However, the latter will still be made available on request, since it is referred to in the building regulations and other legislative documents.A British Standard does not purport
33、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.Summary of pages This document comprises a front cover, an inside front cover,
34、pages i and ii, pages 1 to 16, 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.1) Available from the Asbestos Information Centre, Sackville Hous
35、e, 40 Piccadilly,London W1V 9PA.BS 476-21:1987 The British Standards Institution 2014This part of BS 476 is published by BSI Standards Limited, under licence from The British Standards Institution.This standard has been superseded by the current BS EN 1365-1, BS EN 1365-2, BS EN 1365-3 and BS EN 136
36、5-4, but it has been retained based on legitimate need for the standards within non-EU markets.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from leg
37、al obligations.BS 476-21:1987 BSI 01-1999 11 ScopeThis Part of BS 476 describes procedures for determining the fire resistance of loadbearing elements of building construction when subjected to the heating and pressure conditions specified in BS 476-20. This Part provides requirements for specimen s
38、election and/or its design and construction, loading and restraint conditions, equipment, procedures and criteria as they apply to loadbearing specimens. The methods are applicable to beams, columns, floors, flat roofs and walls.The methods described are not applicable to suspended ceilings protecti
39、ng steel beams which are described in BS 476-23 (see A.1). Owing to limitations imposed by both the furnaces and their method of control, structures employing water cooling techniques are not capable of being evaluated realistically by these procedures.The methods described are not applicable to ass
40、emblies of elements, e.g. wall/floor combinations, although some guidance is provided in Appendix A for tests of this type (see A.1).NOTE The titles of the publications referred to in this standard are listed on the inside back cover.2 DefinitionsFor the purposes of this Part of BS 476, the definiti
41、ons given in BS 476-20 and BS 4422 apply.3 Test conditionsThe test conditions shall be as specified inBS 476-20 except that, in the case of vertical,non-separating elements, the neutral pressure axis may be at a height of up to 2 000 mm above the notional floor level.4 ApparatusThe apparatus for the
42、 test shall be as specified in BS 476-20.5 Determination of the fire resistance of beams5.1 General5.1.1 This clause describes a method for determining the fire resistance of beams with or without an applied fire protection insulation material and unventilated cavities.5.1.2 Beams that are incorpora
43、ted in, or which act in, a composite manner with either a floor or a roof construction are normally deemed to be a part of those elements of construction and shall be tested in accordance with clause 7 (see A.3.1).5.2 Test specimen5.2.1 Number of specimens. One specimen shall be tested.5.2.2 Size of
44、 specimen. The specimen shall be full size for beams with a span of up to 4 m. For elements that have a span in excess of 4 m, the minimum size of specimen exposed to the heating conditions of the furnace shall be not less than 4 m (see also 5.2.3).5.2.3 Design of specimen or test construction. When
45、 selecting a test specimen or designing a representative construction, the following points shall be considered.a) If the beam incorporates a mechanical joint along its length, this shall be incorporated as in practice or at mid-span. When joints occur in fire protective claddings, specimens incorpo
46、rating such protection shall include representative joints (see A.3.2.2).b) Where a beam in practice is only exposed to the effects of fire on three sides, e.g. where the top surface is supporting a floor construction, the specimen shall be provided with an associated construction as in practice. If
47、 the construction carried on the top surface of the beam is in continuous thermal contact with the beam, this shall be simulated by a dense aggregate concrete slab of 135 mm thickness. The topping construction shall extend at least 200 mm on each side of the beam.c) Any associated construction provi
48、ded to the top surface of the beam for the purpose of a test shall be designed and constructed such as not to provide any significant strength or stiffness to the beam. Any joints in the associated construction, or between the associated construction and any furnace closures, shall be sealed with a
49、resilient gasket of adequate fire performance.d) If fire protection material is applied or fixed to the beam, this shall be undertaken after the associated construction has been installed, unless in practice the protection is installed before installation of the supported construction. It shall extend over the length of the beam that is to be exposed to the heating conditions of the test, plus sufficient additional length at each end to terminate the protection outside the furnace. Where a void is created within the fire protection system (e.g. hollow box protection to
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