1、BRITISH STANDARD BS 6954-3: 1988 ISO 3443-3: 1987 Tolerances for building Part 3: Recommendations for selecting target size and predicting fit UDC 624+69:691+69.032+“313”+624.078.3BS6954-3:1988 This British Standard, having been prepared under the directionof the Basic Data andPerformance Criteria f
2、orCivilEngineering and BuildingStructures StandardsCommittee, waspublished under the authorityof the Board of BSIand comes intoeffecton 29February1988 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference BDB/4 Draft for comment 84/12614 DC ISBN 0 580 1650
3、6 X Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Basic Data and Performance Criteria for Civil Engineering and Building Structures Standards Committee (BDB/-) to Technical Committee BDB/4, upon which the following bodies were represen
4、ted: Association of County Councils British Standards Society Building Employers Confederation Chartered Institution of Building Services Engineers Concrete Society Department of Education and Science Department of the Environment (Building Research Establishment) Department of the Environment (Prop
5、erty Services Agency) Incorporated Association of Architects and Surveyors Institute of Building Control Institute of Clerks of Works of Great Britain Inc. Institution of Civil Engineers Institution of Structural Engineers Institution of Water and Environmental Management (IWEM) National Council of
6、Building Materials Producers Royal Institute of British Architects Royal Institution of Chartered Surveyors Amendments issued since publication Amd. No. Date of issue CommentsBS6954-3:1988 BSI 08-1999 i Contents Page Committees responsible Inside front cover National foreword ii 0 Introduction 1 1 S
7、cope 1 2 Field of application 1 3 References 1 4 Definitions 2 5 Symbols 2 6 Basis of procedures 3 7 Procedures 4 Annex A Inherent deviations 9 Annex B Worked examples 9 Figure 1 Illustration of extension and deduction 3 Figure 2 Q and q relate to the probabilities of “joints too large” and “joints
8、too small” respectively 7 Figure 3 Plan of opening between columns for a window 10 Figure 4 Plan of opening between cross walls, for three panels 14 Publications referred to Inside back coverBS6954-3:1988 ii BSI 08-1999 National foreword This Part of BS6954 has been prepared under the direction of t
9、he Basic Data and Performance Criteria for Civil Engineering and Building Structures Standards Committee. This Part of BS6954 together with Parts1 and2 form a revision of DD22:1972. BS6954-1,BS6954-2 andBS6954-3 supersede DD22:1972, which is withdrawn. This Part of BS6954 is identical with ISO3443-3
10、:1987 “Tolerances for building Part3: Procedures for selecting target size and predicting fit”, published by the International Organization for Standardization (ISO). BS6954 comprises three Parts as follows: Part 1: Recommendations for basic principles for evaluation and specification; Part 2: Recom
11、mendations for statistical basis for predicting fit between components having a normal distribution of sizes; Part 3: Recommendations for selecting target size and predicting fit. BS6954 enables the nature of deviations from intended sizes to be taken into account when designing to achieve satisfact
12、ory fit. This Part of BS6954 enables a building designer, a component manufacturer or a builder to assess the probability of satisfactory fit of components and joints. InFigure 1 the symbol C sprefers to the coordinating size of a space which is to accept one or more components. This Part of BS6954
13、provides a calculation method to be used with the characteristic accuracy data given in terms of mean and standard deviations shown in BS5606 1) . Reference is made in the introduction to ISO3443-4, which provides an alternative calculation procedure and has not been adopted by the UK; this Part of
14、BS6954 is considered to be preferable and can be used without reference to ISO3443-4. Terminology and conventions. The text of the international standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical
15、with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to t
16、his standard, they should be read as “British Standard”. 1) BS 5606:1978 “Code of practice for accuracy in building” (under revision). Cross-references International standard Corresponding British Standard ISO 1791:1983 BS 6100 Glossary of building and civil engineering terms Subsection 1.5.1:1984:
17、Coordination of dimensions; tolerances and accuracy (Technically equivalent) BS 6954 Tolerances for building ISO 3443-1:1979 Part 1:1988 Recommendations for basic principles for evaluation and specification (Identical) ISO 3443-2:1979 Part 2:1988 Recommendations for statistical basis for predicting
18、fit between components having a normal distribution of sizes (Identical)BS6954-3:1988 BSI 08-1999 iii The Technical Committee has reviewed the provisions of ISO1803-1 and ISO1803-2, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this stan
19、dard. A related standard to ISO1803-1:1985 is BS6100 “Glossary of building and civil engineering terms” Subsection1.5.1:1984 “Coordination of dimensions; tolerances and accuracy”. See also paragraph six of the national foreword. A British Standard does not purport to include all the necessary provis
20、ions 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, pages i to iv, pages1 to 14, an i
21、nside 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 theinside front cover.iv blankBS6954-3:1988 BSI 08-1999 1 0 Introduction This part of ISO3443 forms one of a series concer
22、ning tolerances for building and building components. It should be read in conjunction with parts1 and2 of ISO3443, ISO1803-1 and ISO1803-2. Parts3 and4 of ISO3443 have been produced to meet the needs for internationally agreed methods of relating accuracy, tolerances and fit in the determination of
23、 sizes for components and construction (and, in part4, joints). Two distinct needs are identified, though both share common ground. There is thus a need to provide generally applicable expressions relating accuracy, tolerances and fit, that can be drawn upon either a) to identify optimum target size
24、s for standard components where each type of component has a variety of applications, or b) to identify appropriate limits of size for components, whether standard or not, for application in a specific building. Both needs can be met by expression of substantially the same relationships between the
25、factors affecting fit, and in principle either part might be pressed into service to meet either aim. In practice, however, each is structured to serve its particular purpose. Joints in more than one dimension are however only considered in part4 of ISO3443. This part of ISO3443 is structured primar
26、ily to meet the aims in a) above. It provides procedures for selecting target sizes (formerly “work sizes”) for components or in situ parts, such that joint clearances will be within their required limits with a known probability of success. 2)The procedures deal with the relationship between the fo
27、llowing factors: 1) accuracy of components and in situ work; 2) sizes of components and in situ work; 3) joint clearances; 4) probability of fit; and they can be used whether 2), 3) or 4) above is the unknown to be calculated. The procedures assume that values for 1) above have been established by m
28、easurement surveys and relate target sizes to coordinating sizes using the concepts of “extension” and “deduction”. See4.4 and4.5. The procedures also enable a target size to be calculated for any standard component, such that the component will have an optimal probability of fit in all its applicat
29、ions. Worked examples are given inAnnex B. Part 4 of ISO3343 is structured primarily to meet the needs in b) above. It is therefore concerned primarily with the design of buildings in which components (including standard components) are used, and is aimed primarily at building designers who, as engi
30、neers, can be expected to be mathematically and statistically competent. It is to meet these aims that part4 of ISO3443 deals with methods for predicting deviations and specifying tolerances to obtain a particular desired total accuracy in an assembly; the effect of specified tolerances on expected
31、size variability; the basis for optimization of tolerances for each particular assembly and its elements. Part4 of ISO3443 presupposes calculations only for assemblies with elements of one dimension, such as beams and columns, for the sake of simplicity. However, tables for common cases with element
32、s of two and three dimensions (panels, etc.) are given in the annex to part4. 1 Scope This part of ISO3443 provides a basis for relating joint clearances and target sizes and for the prediction of fit within the context of dimensional coordination, including modular coordination. 2 Field of applicat
33、ion This part of ISO3443 is for use by component manufacturers when determining target sizes for standard components; it is also for use by building designers when determining target sizes for construction on site, assessing the applicability of standard components or determining target sizes for no
34、n-standard components. The applicability of the procedures is further described in6.1 and6.2. 3 References ISO 1791, Modular co-ordination Vocabulary. ISO 1803-1, Tolerances for building Vocabulary Part 1: General terms. ISO 1803-2, Tolerances for building Vocabulary Part 2: Derived terms. 2) This p
35、art deals with accuracy in terms of target size and limits of size (e.g.upper and lower limits of component size). Alternatively, accuracy can be defined in terms of permitted deviations in relation to a reference size usually identical with the target size. See ISO1803-1.BS6954-3:1988 2 BSI 08-1999
36、 ISO 3443-1, Tolerances for building Part 1: Basic principles for evaluation and specification. ISO 3443-2, Tolerances for building Part2:Statistical basis for predicting fit between components having a normal distribution of sizes. ISO 3443-4, Tolerances for building Part4:Methods for predicting de
37、viations of assemblies and the allocation of tolerances. 4 Definitions For the purposes of this part of ISO3443, the definitions given in ISO1791 and ISO1803, and as follows, are applicable. 4.1 systematic deviation mean deviation of the type of space or component 3)considered (to be found by measur
38、ement of a representative sample of constructed spaces, or of components 3) , of the type considered) see ISO3443-2 4.2 standard deviation positive square root of the mean of the squares of the deviations 4.3 space target size intended size of an opening formed between two erected components 3) NOTE
39、The size is equal to the sum of the coordinating size of the space and its extension. 4.4 extension amount by which the target size of a space exceeds its coordinating size (seeFigure 1) 4.5 deduction amount by which the target size of a component 3)is less than its coordinating size (seeFigure 1) 5
40、 Symbols 3) In certain cases, in situ work may be considered as if it were a component. C sp Space coordinating size D Deduction E Extension E max Maximum extension E min Minimum extension J Joint clearance (required by a chosen jointing technique) J max Maximum joint clearance (required by a chosen
41、 jointing technique) J min Minimum joint clearance (required by a chosen jointing technique) j Predicted joint clearance j max Maximum predicted joint clearance j min Minimum predicted joint clearance Systematic deviation comp Systematic deviation of component a sp Systematic deviation of space n Th
42、e number of components occupying a constructed space Q Multiplier of the standard deviation corresponding to a selected probability of joint clearances being too large q Multiplier of the standard deviation corresponding to a selected probability of joint clearances being too small r The mean of cor
43、relation coefficients between the sizes of all possible pairs of components comp The standard deviation of the total bdimensional variability, induced in manufacture of a component, along the axis considered sp The standard deviation of the total bdimensional variability that is characteristic of th
44、e type of space, along the axis considered W comp Target size of component a W max Component size upper target size limit a W min Component size lower target size limit a a In certain cases, in situ work may be considered as if it were a component. b i.e., embracing all constituent variables such as
45、 bow, twist, etc.BS6954-3:1988 BSI 08-1999 3 6 Basis of procedures Induced and inherent deviations 4)(see ISO3443-1) potentially prevent the achievement, on site, of joint clearances that are within the working limits of a jointing technique. The procedures recommended in this part of ISO3443 enable
46、 selection of suitable target sizes for components and construction so that joints that are within their required clearance limits can be achieved. The procedures also enable selection of jointing techniques that have suitable clearance limits when some or all of the target sizes are predetermined (
47、as when standard components are used). In either application the procedures enable prediction of the probability that joints on site will be within their clearance limits. The procedures are designed to predict the chance of misfitting either the minimum or maximum joint clearance of which the chose
48、n jointing technique is capable. 6.1 Assumptions 6.1.1 Deviations Dimensional variability data are for the general case of each form of construction or component; that is, it is assumed that tolerances have not yet been applied and that deviations for both components and in situ work therefore follo
49、w normal distributions about a mean the value of which is influenced by systematic deviation. The values of mean and standard deviation which are required as a description of dimensional variability may be estimated from measurement surveys; alternatively, standard deviation may be estimated from tolerance specifications combined with acceptance criteria, it being then assumed that systematic deviation is zero. 6.1.2 Criteria for fit Two factors, acting in conjunction, determine whether or not fit will be achieved. These f
