1、BRITISH STANDARDBS 5395-2: 1984Reprinted, incorporating Amendment No. 1 and Stairs, ladders and walkways Part 2: Code of practice for the design of helical and spiral stairsICS 91.060.30Corrigenda Nos. 1,2 and 3BS 5395-2:1984This British Standard, having been prepared under the direction of the Elem
2、ents and components (of Diverse materials) for Buildings Standards Committee, was published under the authority of the Board of BSI and comes into effect on 31 January 1984 The following BSI references relate to the work on this standard: Committee reference ECB/2 Draft for comment 82/12150 DCCommit
3、tees responsible for this British StandardThe preparation of this British Standard was entrusted by the Elements and Components (of Diverse Materials) for Buildings Standards Committee (ECB/-) to Technical Committee ECB/2 upon which the following bodies were represented:Aluminium FederationBritish W
4、oodworking FederationConcrete SocietyDepartment of Health and Social SecurityDepartment of the Environment, Building Research Establishment, Princes Risborough LaboratoryDepartment of the Environment, Housing and ConstructionEnergy Industries CouncilEngineering Equipment and Materials Users Associat
5、ionGreater London CouncilHealth and Safety ExecutiveIncorporated Association of Architects and SurveyorsInstitution of Mechanical EngineersInstitution of Structural EngineersJoinery Managers Association Ltd.London Transport ExecutiveRoyal Institute of British ArchitectsScottish Development Departmen
6、tSpiral Stair Manufacturers AssociationThe following bodies were also represented in the drafting of the standard, through subcommittees and panels:Institution of Building Control OfficersCo-opted membersAmendments issued since publicationAmd. No. Date of issue Comments6076 July 1989 Indicated by a
7、sideline in the marginJuly 2008 Corrigendum to replace poor quality figures BSI 2009ISBN 978 0 580 67560 7C2 Table 2: “Minimum outer going“ corrected to “Maximum outer going“ This corrigendum corrects an error that appears in some versions of this standard onlyMarch 2009.C3Corrigendum to replace inc
8、orrect figures including keys and to correct equation in 5. 2. June 2009BS 5395-2:1984iContentsPageCommittees responsible Inside front coverForeword ii1Scope 12 Definitions 13 Alternative materials, components and methods of design and construction 14 Materials 15Design 66 Fire protection and means
9、of escape 8Appendix A Load tests 9Appendix B Design geometry 10Figure 1 Typical layouts for stairs 2Figure 2 Relationship between rise and going 5Figure 3 Measurement of clear width and goings 7Figure 4 Landings 8Figure 5 Maximum gap between column and tread 8Figure 6 Calculation of going 9Figure 7
10、Calculation of clear headroom 11Table 1 Structural materials 3Table 2 Sizes of stairs 4Publications referred to 12 BSI 2009BS 5395-2:1984iiForewordThis standard has been prepared under the direction of the Elements and Components (of Diverse Materials) for Building Standards Committee. As a conseque
11、nce of the publication of this Part of this standard, the number of the existing BS 5395:1977 has been changed to BS 5395-1. BS 5395-3 covers industrial type stairs, ladders and walkways.This standard is based on accepted good practice by designers and manufacturers of helical and spiral stairs, It
12、should be borne in mind that helical and spiral stairs are not normally permitted for use as means of escape where large numbers of persons are involved.In drafting this standard the committee acknowledged the need for research into the structural behaviour of stairs.Appendix A describes a recommend
13、ed procedure for load tests on stairs. Further investigations are required to determine the appropriate loads for each stair category.The proper functioning and durability of a prefabricated stair designed in accordance with this standard depends on care in handling during transportation and on site
14、, as well as careful site storage, correct installation and temporary protection, and subsequent proper maintenance. Some general advice is given in BS 5395-1, but the manufacturer should inform the purchaser in writing of the precautions necessary.A British Standard does not purport to include all
15、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 pagesThis document comprises a front cover, an inside front cover, pages i and ii,
16、pages 1 to 12, 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. BSI 2009BS 5395-2:198411 ScopeThis Part of this standard gives recommendations f
17、or the design of helical and spiral stairs, to be used internally or externally in all types of building constructions. It covers only stairs which are circular on plan and does not deal with ramps.NOTE 1 Appendix B gives guidance on the geometry of helical and spiral stairs.NOTE 2 The titles of the
18、 publications referred to in this standard are listed on the inside back cover.2 DefinitionsFor the purposes of this standard the following definitions apply.2.1 spiral staira stair describing a helix around a central column see Figure 1(a)2.2 helical staira stair describing a helix around a central
19、 void see Figure 1(b)2.3 goingthe chord length on plan between two points on consecutive tread nosings at the same radius from the geometric centre of the stair, measured as described in 5.42.4 risethe vertical distance between two consecutive steps2.5 clear headroomthe distance measured vertically
20、from the pitch line of a stair or from a floor or landing to any obstruction overhead2.6 clear widththe unobstructed walking area throughout the stairs rise, measured as described in 5.62.7 outside diameterthe diameter of the outer edge of the handrail, strings or treads, whichever is the greater2.8
21、 pitch linea line drawn from the floor or landing below a stair to connect points on consecutive tread nosings at the same radius from the geometric centre of the stair2.9 nosingthe front edge of a tread2.10 riserthe part closing the front face of the step2.11 treadthe horizontal part or upper surfa
22、ce of the step3 Alternative materials, components and methods of design and constructionWhere materials, components and methods of design and construction are not covered by this standard or by any other British Standard, this is not necessarily to be regarded as discouraging their use. The designer
23、 should satisfy himself by reference to appropriate manufacturers literature and test evidence issued by competent, independent authorities that the materials and methods to be employed are such as to ensure a level of performance at least equal to that obtained by following the recommendations of t
24、his standard.4 MaterialsStructural materials should be selected from those listed in Table 1 and should be in accordance with the appropriate British Standard.Where stairs are constructed from two or more different materials, the materials should be compatible. For example, they should not give rise
25、 to electromagnetic or electrogalvanic action e.g. between different metals, chemical corrosion e.g. of metal fixings in timber, or differential movement e.g. between concrete and brickwork.For guidance on surface-finishing materials see clause 8 of BS 5395-1:1977. BSI 2009BS 5395-2:19842(a) Spiral
26、stair (b) Helical stairNOTE. Balusters are shown widely spaced for clarity. In areas frequented by children,the widest gap should not permit a sphere of 100 mm diameter to pass through.Figure 1 Typical layouts for stairs BSI 2009BS 5395-2:19843Table 1 Structural materialsMaterial British Standards O
27、ther recommendationsCode of practice SpecificationConcrete BS 8110Reinforced and granolithic terrazzo BS 4357Natural stone BS 5390 Not suitable for use in escape stairs (see clause 6)Cast stone BS 5628-3 BS 1217 Not suitable for use in escape stairs (see clause 6)Hopton stone and York stone are part
28、icularly suitable as aggregatesBrick and block BS 5628-3 BS 187BS 3921BS 6073-1Aluminium CP 118aNot suitable for use in escape stairs (see clause 6)Cast iron BS 1452Copper alloys BS 2870 Aluminium bronze (grades CA 101 to 106 inclusive) or phosphor bronze (grades PB 101 to 104 inclusive) should be u
29、sedBS 2872BS 2874See fire safety recommendations in clause 6Steel, including stainless steelBS 449BS 5950BS 1449 See fire safety recommendations in clause 6Austenitic stainless steel grade SS 16 316 should be used for external stairsPlastics materials BS 6180bNot suitable for use in escape stairs (s
30、ee clause 6)Hardwoods SoftwoodsBS 5268-2 BS 1186-1 and BS 1186-2Exterior grade plywood BS 5268-2 BS 6566-1 to BS 6566-8Marine plywood BS 5268-2 BS 1088 b) where there is no inner handrail, measure the radial distance between the centre column or the outside1)edge of the inner string and the inside f
31、ace of the outer handrail or the inside edge of the outer string, whichever is the nearer to the centre of the tread in each case see Figure 3(b).5.7 Landings. Landings at storey levels should subtend an angle of not less than 60 at the geometric centre on plan see Figure 4(a).Intermediate or rest l
32、andings should have a plan area of not less than two consecutive treads or subtend an angle of 45 at the geometric centre on plan, whichever is the greater see Figure 4(b).5.8 Guarding of stairs and landings. Protection against falling should follow the recommendations of 12.3 of BS 5395-1:1977. For
33、 safety reasons any gap between the end of a tread and the centre column of a stair should never exceed 100 mm (see Figure 5).Balustrades and handrails should follow the recommendations of BS 6180 provided that the definition of pitch line given in 2.8 of this standard is used. In areas frequented b
34、y children, the widest gap in a balustrade should not permit a sphere of 100 mm diameter to pass through.An inner handrail should be provided for semi-public and public stairs (categories C, D and E in Table 2).5.9 Passage of large objects. Designers should consider whether the minimum clearances re
35、commended in Table 2 are sufficient for the passage of large objects, such as furniture, coffins. The limiting factor in the size of the stairwell. However stairs may have balustrades and handrails that can be dismantled temporarily.r is the rise;g is the going.1) In all cases, the term “outside” re
36、fers to the edge or face furthest from the centre of the stair. BSI 2009 BS 5395-2:198475.10 Deflection. Helical and spiral stairs should be designed to be rigid enough to give confidence to the user, since they can be subject to oscillations. Stairs should be designed to limit deflections under wor
37、king conditions to the maximum values given in the appropriate standard (see Table 1).5.11 Accuracy. For general guidance on accuracy in building, see BS 5606. The maximum permissible deviation for any size should not exceed the appropriate value given in Table 2 of BS 5606:1978. For further guidanc
38、e see 11.2.3 of BS 5395-1:1977.Consistency of rise and going are of prime importance for user confidence and safety.5.12 Nosings. Nosings should be horizontal and straight between the pitch lines (see 2.8) corresponding to the inner and outer goings. BSI 2009(a) Spiral stair with inner handrail (b)
39、Spiral stair without inner handrailNOTE. Figure 3(a) shows a spiral stair only, but the same method of measurement applies to a helical stair. All dimensions are in millimetres.Figure 3 Measurement of clear width and goingsKey1 Clear width2 Inner handrail3 Outer handrail4 Centre column1334270270gigc
40、go412334270270gigcgo423 Outer handrail4 Centre columnBS 5395-2:198486 Fire protection and means of escapeStairs in most buildings form the main vertical escape routes and are often in the first protected areas reached by people escaping from a fire. The recommendations for planning, construction and
41、 protection of escape routes to prevent rapid spread of fire, given in CP 3: Chapter IV-12), or BS 5588-1,BS 5588-2, BS 5588-3 or BS 5588-8 as appropriate, should be followed.The minimum clear widths given in Table 2 may be insufficient for escape stairs, depending on the building use and the number
42、 of its occupants.The following materials should never be used to form the only escape stair in a building or a stair for fire fighting:a) materials having a low melting point, e.g. aluminium, owing to the likelihood of their early collapse when exposed to heat;b) stone, since when subjected to heat
43、 or cold water during fire-fighting operations it can collapse without warning;c) plastics materials not covered by (a), since these give off toxic fumes when subjected to heat.NOTE Further information may be obtained from Home Office, Scottish Home and Health Department “Guide to the Fire Precautio
44、n Act 1971” Nos. 1, 2 and 3, available from HMSO.2) To be revised as Part of BS 5588.(a) At storey level (b) Intermediate or rest landingFigure 4 LandingsDimension is in millimetres.Figure 5 Maximum gap between column and tread BSI 20096045100BS 5395-2:19849Appendix A Load testsThe following procedu
45、re may be used to test helical and spiral stairs.a) Apply a uniformly distributed lead of 3 kN/m2to 5 kN/m23)to each tread. Check deflections and displacements.b) Remove the lead from all treads forming the lower 180 segment of the stair. Check deflections and displacements.c) Remove the load from a
46、ll remaining treads except one tread at mid-height. Increase load on this tread to double the previous load. Check deflections and displacements.d) Check individual treads by placing on them two loads of 0.9 kN spaced 300 mm apart and placed symmetrically about the centre-line of the tread.3) This r
47、ange of uniformly distributed loads is taken from BS 6399-1. The actual value used should be chosen to suit the stair category and the intended function of the stair.Figure 6 Calculation of going BSI 2009NbRbgRsRhUoRs124356B2B17Key1 Centre from which tread radiates2 Centre column (if applicable)3 Tr
48、ead nosing4 Tread nosing above5 Geometric centre = centre of column or well6 Inner handrail (if applicable)7 Outer handrail(centre for s/b/h)R R RBS5395-2:198410Appendix B Design geometryNOTEFurther information may be obtained from “Specifying the geometry of helical and spiral stairs”, by Dr G.M.B.
49、 Webber, in Journal of the Institution of Building Control Officers, Spring/March 1983 Vol X no. 1 issue no. 37.B.1 Going. The going (in mm) on a spiral or helical stair can be determined at any point using the equation:whereHence inner going, gi (inmm), may be calculated from the equation:whereSimilarly the centre going, gc (in mm), is given by the equation:whereThe outer going, go (in mm), may likewise be obtained from the equation:The clear width, W (in mm), is given by the equation:The distance Nb (inmm), shown in
