ISO 12122-1-2014 Timber structures - Determination of characteristic values - Part 1 Basic requirements《木结构 特性值的测定 第1部分 基本要求》.pdf

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1、 ISO 2014 Timber structures Determination of characteristic values Part 1: Basic requirements Structures en bois Dtermination des valeurs caractristiques Partie 1: Exigences de base INTERNATIONAL STANDARD ISO 12122-1 First edition 2014-03-01 Reference number ISO 12122-1:2014(E) ISO 12122-1:2014(E)ii

2、 ISO 2014 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2014 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an int

3、ranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org P

4、ublished in Switzerland ISO 12122-1:2014(E) ISO 2014 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Symbols and abbreviated terms . 2 5 Reference population 2 6 Sampling 3 6.1 Sampling method 3 6.2 Sample size . 3

5、7 Sample conditioning . 3 7.1 Sample moisture content . 4 7.2 Sample temperature . 4 8 Test data 4 8.1 Test method . 4 8.2 Test data compatible with product description . 4 9 Evaluation of characteristic values for structural properties . 4 9.1 Structural properties . 4 9.2 Characteristic value base

6、d on the mean . 5 9.3 Characteristic value based on the 5th percentile test value 5 10 Report 5 10.1 General . 5 10.2 Reference population 5 10.3 Sampling . 6 10.4 Test methods . 6 10.5 Analysis methods 6 10.6 Characteristic values 6 Annex A (normative) Analysis of data for characteristic values 7 A

7、nnex B (informative) Commentary 12 Annex C (informative) Examples 22 Bibliography .27 ISO 12122-1:2014(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is nor

8、mally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in

9、the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular t

10、he different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this doc

11、ument may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.o

12、rg/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO

13、 principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 165, Structural Timber. ISO 12122 consists of the following parts, under the general title Timber structures Determination of charact

14、eristic values: Part 1: Basic requirements Part 2: Sawn timberiv ISO 2014 All rights reserved ISO 12122-1:2014(E) Introduction This International Standard sets out a framework to establish characteristic values from test results on a sample drawn from a clearly defined reference population. The char

15、acteristic value is an estimate of the property of the reference population with a consistent level of confidence prescribed in this part of ISO 12122. It is the intention that this part of ISO 12122 can be used on any structural product including but not limited to: sawn timber, glulam, structural

16、composite lumber, I-beams, wood-based panels, poles, and round timber. Whenever it is used, this part of ISO 12122 alerts the user to the basic requirements for the determination of consistent characteristic values, but for some classes of products, additional requirements set out in other parts or

17、Annexes to this part give further mandatory detail and explanation. It permits the evaluation of characteristic values on testing of commercial sized specimens. In some cases, characteristic values determined in accordance with this part of ISO 12122 may be modified to become a design value. This pa

18、rt of ISO 12122 has the following Annexes: Annex A presents detail on a number of statistical methods that may be used in the evaluation of characteristic values. Annex B presents a commentary on the provisions in this part of ISO 12122. Annex C presents examples of the use of the statistical method

19、s. ISO 2014 All rights reserved v Timber structures Determination of characteristic values Part 1: Basic requirements 1 Scope This International Standard gives methods for the determination of characteristic values for a defined population of timber products, calculated from test values. It presents

20、 methods for the determination of a) characteristic value of mean-based properties, and b) characteristic value of 5th percentile-based properties. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its applicati

21、on. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. AS/NZS 4063.2, Characterisation of structural timber Part 2: Determination of characteristic values ASTM D2915, Sampling and data-analys

22、is for structural wood and wood-based products EN 14358, Timber structures Calculation of characteristic 5th percentile values and acceptance criteria for a sample 3 T erms a nd definiti ons For the purposes of this document, the following terms and definitions apply. 3.1 characteristic value value

23、of a property taken to represent the property of a designated population using a process of sampling, testing of specimens, and analysis 3.2 characteristic value of mean-based property two alternative presentations of characteristic value for mean-based properties are possible: a) the mean property

24、obtained from results of tests on the defined product; b) the mean property with 75 % confidence obtained from results of tests on the defined product 3.3 characteristic value of 5th percentile-based strength property 5th percentile value with 75 % confidence strength property obtained from results

25、of tests on the defined product INTERNATIONAL ST ANDARD ISO 12122-1:2014(E) ISO 2014 All rights reserved 1 ISO 12122-1:2014(E) 3.4 population all of the structural timber product that meets the description of the population Note 1 to entry: See Annex B for some examples of the use of the term popula

26、tion. 3.5 sample number of single members of the population, selected to represent the population Note 1 to entry: See Annex B for some examples of the use of the term sample. 3.6 specimen single element used in a test; the element may be a complete member, a member that has been trimmed to length,

27、or a part of a member fabricated for a specific test Note 1 to entry: See Annex B for some examples of the use of the term specimen. 4 Symbols and abbreviated terms Symbols defined in the relevant ISO product or test standard shall be used. In addition, the following apply: f m is the characteristic

28、 bending strength k mean, 0,75 is a multiplier to give the mean property with 75 % confidence and is given in Table A1 k 0,05, 0,75 is a multiplier to give the 5th percentile value with 75 % confidence for a 5th percen- tile-based property and is given in Table A2 M is the moment capacity n is the n

29、umber of specimens in the test data V is the coefficient of variation of the test data X is the target difference between the reported characteristic value and the test result 5th percentile X i is a generalized test value X mean is the average of the individual test values (X i ) X mean, 0,75 is th

30、e mean property with 75 % confidence X 0,05 is the 5th percentile value from the test data X 0,05, 0,75 is the 5th percentile value with 75 % confidence Z is the section modulus 5 Reference population The population to which the characteristic value applies shall be fully described. The description

31、shall reference all of the attributes that may affect either the strength or stiffness and restrict the pieces to the grouping for which the characteristic value is required. These include but are not limited to: a) reference to the relevant product standard or specification;2 ISO 2014 All rights re

32、served ISO 12122-1:2014(E) b) species or species grouping; c) designation of grade of the product; d) size or size range of the product; e) moisture condition of the product; f) treatment of the product; g) period in which the product was manufactured. The reference population shall be a grouping fr

33、om which it is possible to draw a representative sample, and on which it is possible to perform tests on specimens to characterize the required properties. 6 Sampling 6.1 Sampling method The sampling method shall aim to produce a sample that is representative of the variants in the defined reference

34、 population that may affect the tested properties. The sampling shall minimize selection bias, and shall be appropriate to the purpose of the characteristic value and the nature of the reference population. The sampling method shall be documented. The documentation shall include details of the steps

35、 taken to ensure that each of the variants listed in the population as described in Clause 5 is included in the representative sample. 6.2 Sample size The sample shall be large enough to cover variants of the product that impact on the tested properties, and give statistical significance to the resu

36、lt. NOTE 1 Materials with larger assumed or assigned population coefficient of variation, (V), of the tested properties should have a larger sample size. NOTE 2 Some product standards may define a minimum number of tests that must be undertaken to determine characteristic values to be used with desc

37、ribed products. NOTE 3 Annex B gives some guidance on selecting sample size. NOTE 4 For some populations, a number of different sub-groups within the population may need to be sampled (e.g. different cross-sectional sizes). In these cases, the size of each of the sub-groups may have to be sufficient

38、 to allow meaningful pooling of the results as indicated in Annex A. NOTE 5 Where characteristic values are to support limit states (or LRFD) design, the sample size should be appropriate for the statistical method selected to determine the 5th percentile value strength (full distribution or tail-fi

39、t). However, where the data are used to support a full reliability design method, the sample size should be appropriate to also enable the full statistical distribution of the property to be defined. 7 Sample conditioning Test data from the samples shall be compatible with the definition of the popu

40、lation by a) compliance with the specification of the reference population at the time of testing in accordance with 7.1 and 7.2, or b) adjustment of test data in accordance with 8.2 where compliance with 7.1 or 7.2 is not achieved. ISO 2014 All rights reserved 3 ISO 12122-1:2014(E) 7.1 Sample moist

41、ure content The sample shall be stored so that the moisture content at the time of test is appropriate to the description of the reference population as detailed in Clause 5. 7.2 Sample temperature The sample shall be stored and tested so that the temperature at the time of test is appropriate to th

42、e description of the reference population as detailed in Clause 5. 8 Test data 8.1 Test method The test data shall be derived in accordance with an appropriate test method for the properties and for the reference population. NOTE 1 For tests on some product types, discrimination of results on the ba

43、sis of failure mode may be required to ensure that the results are compatible with objectives of the test program and the property being determined. NOTE 2 Test methods involve many variables that may affect results including loading configuration and rates, specimen positioning and measurement meth

44、ods. The selection of these variables must be appropriate to the objectives of the testing, and may require some adjustments specified in 8.2. 8.2 Test data compatible with product description Where the characteristic value is applicable to a standard size or moisture content, adjustments to the raw

45、 test data may be required. Any adjustment shall be in accordance with appropriate behaviour models and shall be detailed in the report. NOTE Annex B gives examples of the types of adjustment that may be necessary in response to variation of the specimens from the description of the reference popula

46、tion. Where test data from a number of different data subsets are to be combined, the basis for the combination shall satisfy the following requirements: a) The data shall be derived from similar subsets that are standardized using the same adjustment models, and shall satisfy statistical tests for

47、combining the subsets into a single data set; b) Transformation methods shall be in accordance with appropriate behaviour models and shall be detailed in the report. NOTE Annex A gives requirements for combining or pooling of data from a number of different test programs. 9 Evaluation of characteris

48、tic values for structural properties 9.1 Structural properties Characteristic values for properties shall be reported in one of two ways according to the use of the product: a) Material properties where the determined property is multiplied by a geometric parameter to give a component capacity, or c

49、omponent stiffness; b) Component properties where the determined property is a component capacity or component stiffness. Characteristic values for structural properties shall be classified as those based on the mean of test results and those based on the 5th percentile of test results in accordance with 3.2 and 3.3.4 ISO 2014 All rights reserved ISO 12122-1:2014(E) 9.2 Characteristic value based on the mean The mean value of the test values shall be evaluated as either a) or b): a) the arithmetic average of the test values as