1、BRITISH STANDARD BS 476-23: 1987 Incorporating Amendment No.1 Fire tests on building materials and structures Part 23: Methods for determination of the contribution of components to the fire resistance of a structure ICS 13.220.50BS476-23:1987 This British Standard, having been prepared under the di
2、rection of the Fire Standards Committee, was published underthe authority of the BoardofBSI and comes into effect on 29 May1987 BSI 06-1999 The following BSI references relate to the work on this standard: Committee reference FSM/1 Draft for comment85/41321DC ISBN 0 580 15804 0 Committees responsibl
3、e for this British Standard The 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: The following bodies were also represented in the drafting of the standard, through subcommittees
4、 and panels: Association of British Roofing Felt Engineering Equipment and Materials Users Manufacturers Association Association of Building Component Eurisol (UK) Association of Manufacturers of Manufacturers Ltd. Mineral Insulation Fibres Association of Structural Fire Protection Fibre Building Bo
5、ard Organisation (FIDOR) Contractors and Manufacturers Fibre Cement Manufacturers Association British Coal Limited British Fire Services Association Fire Insurers Research and Testing British Floor Covering Manufacturers Organisation (FIRTO) Association Fire Offices Committee British Plastics Federa
6、tion Fire Protection Association British Railways Board Flat Glass Manufacturers Association British Rigid Urethane Foam Manufacturers Flat Roofing Contractors Advisory Board Association Gypsum Products Development Association British Wood Preserving Association Home Office Cement and Concrete Assoc
7、iation Institution of Fire Engineers Chemical Industries Association Mastic Asphalt Council and Employers Chief and Assistant Chief Fire Officers Federation Association National Council of Building Materials Concrete Society Producers Department of Education and Science National GRP Construction Fed
8、eration Department of the Environment for RAPRA Technology Ltd. Northern Ireland Royal Institute of British Architects Department of the Environment (Housing and Steel Construction Institute Construction Industries) Timber Research and Development Association Department of the Environment (Property
9、United Kingdom Antimony Oxide Services Agency) Manufacturers Association Department of Transport (Marine Directorate) United Kingdom Atomic Energy Authority Electricity Supply Industry in England and Warrington Fire Research Centre Wales Wood Wool Slab Manufacturers Association Yarsley Technical Cen
10、tre Ltd. Association of Builders Hardware Guild of Architectural Ironmongers Manufacturers Hevac Association British Steel Industry Intumescent Fire Seals Association Department of the Environment (Building National Association of Lift Makers Research Establishment, Fire Suspended Ceilings Associati
11、on Research Station) Thermal Insulation Manufacturers and Door and Shutter Association Suppliers Association (TIMSA) Electric Cable Makers Confederation Amendments issued since publication Amd. No. Date of issue Comments 9458 January1998 Indicated by a sideline in the marginBS476-23:1987 BSI 06-1999
12、 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Test conditions 1 4 Apparatus 1 5 Determination of the contribution of suspended ceilings to the fire resistance of steel beams 1 6 Determination of the contribution of intumescent seals to the fire re
13、sistance of timber door assemblies 4 Appendix A Guidance information 8 Figure 1 Non-loaded suspended ceiling test assembly 12 Figure 2 Supporting construction for a loadbearing test 13 Figure 3 Typical method applying test load to loadbearing test specimen 13 Figure 4 Thermocouple weight 14 Figure 5
14、 Apparatus for determining the contribution of intumescent seals to the fire resistance of door and shutter assemblies 15 Figure 6 Method of jointing the timber lippings 16 Figure 7 Thermocouple arrangements to be used when determining the contribution made by intumescent seals 17 Figure 8 Typical m
15、ethod for sealing joints between cover slabs 18 Publications referred to Inside back coverBS476-23:1987 ii BSI 06-1999 Foreword This Part of BS476 has been prepared under the direction of the Fire Standards Committee, and describes the specific equipment and procedures for determining the contributi
16、on made by components to the fire resistance of structures. These components need not have any fire resistance in their capacity as isolated components. This Part should be read in conjunction with BS476-20 which describes the general requirements for these methods. This Part has been prepared in su
17、ch a way as to allow reference to be made to the appropriate method of determining the contribution made by the designated component to the fire resistance of the structure by clause number only. Therefore clauses5 and6 are self-contained and cross refer to BS476-20 where necessary. Methods for dete
18、rmining the fire resistance of loadbearing and non-loadbearing elements of construction are described in BS476-21 and BS476-22 respectively. The general changes made to the method for suspended ceilings compared with BS476-8 are described in the foreword to BS476-20. The method for determining the c
19、ontribution of intumescent seals is a new test procedure developed as a quality control test by the intumescent sealants industry and has not previously been published. An appendix is included which gives guidance and background information which will assist the designer and the testing laboratory t
20、o select and evaluate specimens which are representative of “in use” situations. Attention is drawn to the Health and Safety at Work etc. Act1974, and the need to ensure that the methods specified in this standard are carried out under suitable environmental conditions to provide adequate protection
21、 to personnel against the risk of fire and/or inhalation of smoke and/or toxic products of combustion. CAUTION. The mechanical sawing of asbestos cement components attracts the provisions of the Asbestos Regulations1969. Adequate methods exist to control levels of dust during such operations and the
22、se are detailed in the Control and Safety Guides 1)issued by the Asbestos Research Council. This Part, together with BS476-20, BS476-21, BS476-22 and BS476-24 supersedes BS476-8:1972 which is withdrawn. However, the latter will still be made available on request since it is referred to in building r
23、egulations and other legislative documents. 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 obligation
24、s. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to18, 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 ins
25、ide front cover. 1) Available from Asbestors Information Centre, Sackville House,40 Piccadilly, LondonW1V9PA.BS476-23:1987 BSI 06-1999 1 1 Scope This Part of BS476 describes procedures for determining the contribution made by components to the total fire resistance of a structure or other elements u
26、sed in conjunction with them when subjected to the relevant heating and pressure conditions specified in BS476-20. This Part provides the requirements for specimen selection and/or its design and construction, the edge conditions, the equipment including any special apparatus or instrumentation, and
27、 the procedures and criteria as they apply to components which make a contribution to the fire resistance of a complete assembly. The methods are applicable to suspended ceilings protecting steel beams and intumescent seals for use in conjunction with single-acting, latched timber fire resisting doo
28、r assemblies. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this Part of BS476, the definitions given in BS476-20 and BS4422 apply, together with the following. 2.1 suspended ceiling a horizontal membrane and it
29、s associated suspension system which is provided below, and not in direct contact with, the structural, unprotected steel beams for the express purpose of protecting them from a fire environment, and which does not incorporate any loadbearing member of the structure 2.2 intumescent seal a seal compr
30、ising material or a combination of materials with the property of swelling or foaming when exposed to heat, intended to improve the fire performance of the element of construction in which it is incorporated 3 Test conditions The test conditions shall be as specified in BS476-20 except, when perform
31、ing tests in accordance with clause5, the pressure immediately below the suspended ceiling shall be neutral, i.e.in equilibrium with the laboratory. 4 Apparatus The apparatus for the test shall be as specified in BS476-20. Additional equipment will be required in order to evaluate the contribution t
32、o the fire resistance provided by these specified components and this equipment shall be as specified in5.4 and6.3. 5 Determination of the contribution of suspended ceilings to the fire resistance of steel beams 5.1 General 5.1.1 This clause describes a method for determining the effective, protecti
33、on that is provided by a suspended ceiling to a standard supporting construction of steel beams and specified concrete deck when exposed to specified conditions of heating and pressure from below. The method is applicable to ceilings used in situations where the cavity above the ceiling is entirely
34、surrounded by barriers which have the effect of restricting the transfer of hot gases (seeA.1.1). 5.1.2 The suspended ceiling is protecting loadbearing steel beams and the method described permits the test to be carried out in either of the following ways: a) without any load being applied to the st
35、ructural steel beams in which case only the maximum temperature of the beams is used to determine the limit of effective protection; or b) with the steel beams loaded, using one of the loading options given in A.4.2 of BS476-20:1987, in which case the degree or rate of deflection is used to determin
36、e the limit of effective protection. 5.1.3 The results obtained by this method are not directly applicable to all types of steel beam/concrete floor deck assemblies. The method provides for additional temperature measurements to be taken in order that the potential contribution of the suspended ceil
37、ing to the protection of other steel beam/concrete floor deck assemblies may be assessed. 5.1.4 When it is required to determine directly the fire resistance of a particular floor or flat roof assembly with a suspended ceiling, the methods described in this clause are not applicable (see clause 7 of
38、 BS476-21:1987). 5.2 Test specimen 5.2.1 Number of specimens. A single specimen shall be tested from its underside. NOTEWhilst a suspended ceiling is generally an asymmetrical construction, the fire protection is only required with respect to fire attacking its underside.BS 476-23:1987 2 BSI 06-1999
39、 5.2.2 Size of specimen. The specimen shall be of such dimensions that atleast4m3m is exposed to the furnace or full size if the element is smaller, and the specimen shall cover the full width and length of the furnace. 5.2.3 Design 5.2.3.1 The contribution to the fire resistance of steel beams, as
40、provided by a suspended ceiling, shall be determined by erecting the test specimen beneath either the specified form of construction described in5.2.5.2 or a suitable construction as described in5.2.5.3. The specimen shall be designed such that it is suspended from the supporting construction in a m
41、anner representative of that used in practice. In the case where the beams are loaded, however, the suspension system shall be such as to allow the ceiling to deflect in sympathy with the beams. The suspended ceiling shall normally be erected such that the ceiling is not closer than5mm nor further t
42、han400mm from the soffit of the steel beams. When the incorporation of other fittings, e.g.lighting units or duct entry grilles, requires a larger cavity the ceiling shall be fitted as close to the soffit of the steel beams as these items will allow (seeA.1.2.1). 5.2.3.2 The ceiling suspension syste
43、m shall be designed and erected such that the allowances for expansion do not exceed those provided in practice for the lengths of the members involved (seeA.1.2.2); where gaps are left at ends to provide additional expansion they shall be reported. 5.2.3.3 The size and types of ceiling panels or ti
44、les used shall not be mixed when designing the specimen (seeA.1.2.3). 5.2.3.4 In use, many suspended ceilings incorporate lighting fittings, speaker grilles, duct openings, etc. but these items shall not be incorporated in a test specimen that is intended to evaluate the basic performance of the mem
45、brane. The influence of these items shall be assessed or tested separately (seeA.1.2.4). 5.2.4 Specimen construction and condition. The construction of the specimen and the condition of the materials shall be in accordance with BS476-20. Whilst it may be convenient to install the panels or tiles fro
46、m above, the final closing of the cavity shall be performed from below as it would be in practice. 5.2.5 Supporting construction 5.2.5.1 The specimen shall be tested under either non-loadbearing or loadbearing conditions when the supporting construction shall be as described in5.2.5.2 or5.2.5.3 resp
47、ectively. 5.2.5.2 For a non-loadbearing test the construction shall consist of steel beams supporting concrete slabs as shown in Figure 1 (seeA.1.3). The steel beams shall be of solid rolled type having a perimeter to cross sectional area ratio (P/A ratio) larger than or equal to210m 1(three-sided e
48、xposure) (a nominal serial size of203mm 133mm 30kg/m). The ratio between the total exposed surface area of steel beams and the plan area of the suspended ceiling shall be less than0.8 : 1. The cover slabs shall be constructed from lightweight aggregate concrete (density1600 100kg/m 3 ) and shall be1
49、50mm thick. When more than one cover slab is used to cover the area of the cavity then all joints shall be substantially sealed. The perimeter wall of the cavity between the cover slabs and the suspended ceiling shall be manufactured from concrete with a density of1100kg/m 3or less with a thickness of not less than50mm, or where a higher density concrete is used then an insulating materials shall be applied to the cavity face in order to provide similar degrees of insulation. The joints between this perimeter frame and the cover slabs shall also be
