EN 384-2010 2500 Structural timber - Determination of characteristic values of mechanical properties and density《结构木材 机械性能和密度的特征值的测定》.pdf

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1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 384:2010Structural timber Determination of characteristicvalues of mechanical propertiesand densityCopyright European Committee for Standardization Provided by IHS under li

2、cense with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 384:2010 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 384:2010. Itsupersedes BS EN 384:2004 which is withdrawn.The UK participation in its preparation was e

3、ntrusted to TechnicalCommittee B/518, Structural timber.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010I

4、SBN 978 0 580 58145 8ICS 79.040Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 July 2010Amendments issued since publicationDate Text affectedCopyright European

5、Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 384:2010EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 384 April 2010 ICS 79.040 Supersedes EN 384:2004English Version Structural timber

6、- Determination of characteristic values of mechanical properties and density Structures en bois - Dtermination des valeurs caractristiques des proprits mcaniques et de la masse volumique Bauholz fr tragende Zwecke - Bestimmung charakteristischer Werte fr mechanische Eigenschaften und Rohdichte This

7、 European Standard was approved by CEN on 4 March 2010. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

8、 concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into

9、its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,

10、 Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 B

11、russels 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 384:2010: ECopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license fr

12、om IHS-,-,-BS EN 384:2010EN 384:2010 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Normative references 53 Terms and definitions .54 Symbols and abbreviations 65 Mechanical properties determined from full-size specimens .75.1 Sampling .75.2 Testing 85.3 Analysis of data .85.3.1 Determinati

13、on of sample 5-percentile for strength 85.3.2 Determination of the sample mean of modulus of elasticity 95.3.3 Reference conditions 95.3.4 Adjustment factors 95.4 Strength properties. 105.5 Modulus of elasticity 116 Alternative methods of determining mechanical properties 126.1 Bending strength and

14、modulus of elasticity determined from small, clear hardwood specimens . 126.2 Other mechanical properties for hardwoods and softwoods 126.2.1 General . 126.2.2 Tension strength parallel to grain and compression strength parallel to grain and shear strength 126.2.3 Tension perpendicular to grain stre

15、ngth . 126.2.4 Compression perpendicular to grain strength 126.2.5 Characteristic fifth percentile modulus of elasticity parallel to grain . 136.2.6 Mean modulus of elasticity perpendicular to grain . 136.2.7 Shear modulus 137 Mechanical properties for other grades of hardwood and softwood 138 Densi

16、ty . 139 Acceptance procedure for verification of a lot 149.1 General . 149.2 Verification of mean values (e.g. mean modulus of elasticity) 149.2.1 Method keeping the consumers risk at 10 % 149.2.2 Alternative method limiting the sample size for large COVs . 149.3 Verification of 5-percentile values

17、 (e.g. characteristic strength) . 159.3.1 Method with consumers risk equal to 10 % . 159.3.2 Alternative method limiting the sample size for large COVs . 1510 Report 16Annex A (normative) Form for declaring characteristic values 17Bibliography . 19Copyright European Committee for Standardization Pro

18、vided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 384:2010EN 384:2010 (E) 3 Foreword This document (EN 384:2010) has been prepared by Technical Committee CEN/TC 124 “Timber structures”, the secretariat of which is held by SFS.

19、 This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2010, and conflicting national standards shall be withdrawn at the latest by October 2010. Attention is drawn to the possibility that some

20、of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 384:2004. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the f

21、ollowing countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, S

22、lovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 384:2010EN 384:2010 (E) 4 Introduction In this revised

23、 edition, changes have been made to the equations giving the relativities between properties in 6.2.1, and the method of calculating the 5-percentile density. Also, the verification requirements in Clause 9 have been rewritten. Structural codes can only function effectively if standard methods of de

24、termining the mechanical and physical properties exist. Whilst total accuracy of characteristic values for any defined population is an aim, it is recognized that this is not achievable. A major aim of the procedures given in this standard is to produce characteristic values that are comparable in t

25、erms of the populations they represent. It is also important that the standard permits the use of as much existing test data as possible from various sampling and testing techniques. Where methods are given to permit characteristic values to be determined from a less than ideal amount of structural

26、size test data or from small, clear, defect-free specimen test data, reduction factors to reflect a lower degree of confidence are employed. This standard covers the stages of population definition, sampling, testing and analysis and presentation of data in the determination of characteristic values

27、. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 384:2010EN 384:2010 (E) 5 1 Scope This European Standard gives a method for determining characteristic values of mechanica

28、l properties and density, for defined populations of visual and/or mechanical strength grades of sawn timber. A method is also given for checking the strength of a timber sample against its designated value. The values determined in accordance with this standard for mechanical properties and density

29、 are suitable for assigning grades and species to the strength classes of EN 338. NOTE 1 For assigning grades and species to the strength classes in EN 338 only three characteristic values, i.e. bending strength, mean modulus of elasticity parallel to grain and density, need to be determined, other

30、properties may be taken from the table in EN 338. NOTE 2 EN 1912 gives examples of assignment to strength classes of established national or regional visual grades. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references,

31、 only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 338, Structural timber Strength classes EN 408, Timber structures Structural timber and glued laminated timber Determination of some physical and mechanical p

32、roperties EN 1912, Structural timber Strength classes Assignment of visual grades and species EN 14081-1, Timber structures Strength graded structural timber with rectangular cross section Part 1: General requirements EN 14081-2, Timber structures Strength graded structural timber with rectangular c

33、ross section Part 2: Machine grading, additional requirements for initial type testing ISO 3131:1975, Wood Determination of density for physical and mechanical tests 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 characteristic value general

34、ly, value that corresponds to a fractile of the statistical distribution of a timber property NOTE For strength properties, modulus of elasticity and density the fractile is the 5-percentile. For modulus of elasticity, the mean value is also a characteristic value. 3.2 p-percentile value for which t

35、he probability of getting lower values is p % 3.3 population material for which the associated characteristic values are relevant Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-

36、BS EN 384:2010EN 384:2010 (E) 6 NOTE The population is defined by parameters such as species or species combination, source and strength grade. 3.4 sample number of specimens of one cross section size and from one population NOTE See 5.1. 3.5 small clear test test to determine mechanical properties

37、of small defect-free specimens 3.6 specimen piece of timber for testing 3.7 thickness lesser dimension perpendicular to the longitudinal axis of a piece of timber 3.8 width greater dimension perpendicular to the longitudinal axis of a piece of timber 3.9 depth dimension perpendicular to the longitud

38、inal axis of a timber beam, in the plane of the bending forces 4 Symbols and abbreviations afdistance between the inner load points of the bending test (in millimetres) COV coefficient of variation E mean modulus of elasticity for one sample (in newtons per square millimetre) E0,meanmean characteris

39、tic value of modulus of elasticity parallel to grain (in newtons per square millimetre) E0,055-percentile characteristic value of modulus of elasticity parallel to grain (in newtons per square millimetre) E90,meanmean characteristic value of modulus of elasticity perpendicular to grain (in newtons p

40、er square millimetre) Emean,accmean modulus of elasticity for an acceptable quality lot (in newtons per square millimetre) Emean,unaccmean modulus of elasticity for an unacceptable quality lot (in newtons per square millimetre) f strength property fc,0,kcharacteristic value of compression strength p

41、arallel to grain (in newtons per square millimetre) fc,90,kcharacteristic value of compression strength perpendicular to grain (in newtons per square millimetre) fkcharacteristic value of strength (in newtons per square millimetre) Copyright European Committee for Standardization Provided by IHS und

42、er license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 384:2010EN 384:2010 (E) 7 fm,kcharacteristic value of bending strength (in newtons per square millimetre) ft,0,kcharacteristic value of tensile strength parallel to grain (in newtons per squar

43、e millimetre) ft,90,kcharacteristic value of tensile strength perpendicular to grain (in newtons per square millimetre) f055-percentile value for each sample (in newtons per square millimetre) f05,acc5-percentile value for an acceptable quality lot (in newtons per square millimetre) f05,unacc5-perce

44、ntile value for an unacceptable quality lot (in newtons per square millimetre) f05the mean value of f05for several samples (in newtons per square millimetre) fv,kcharacteristic value of shear strength (in newtons per square millimetre) Gmeanmean characteristic value of shear modulus (in newtons per

45、square millimetre) h depth of a bending specimen or width of a tension specimen (in millimetres) khfactor for adjusting fkwhen h is different from 150 mm klfactor for adjusting length; kqfactor for use when checking the quality of a graded sample ksfactor for adjusting for the number and size of sam

46、ples kvfactor for adjusting for machine grading l span (in millimetres) leteffective length for the test (in millimetres) n number of specimens in a sample plimacceptable probability limit for strength producers risk consumers risk density (in kilograms per cubic metre) kcharacteristic density (5-pe

47、rcentile) (in kilograms per cubic metre) 055-percentile density for a sample (in kilograms per cubic metre) 5 Mechanical properties determined from full-size specimens 5.1 Sampling Samples shall be selected from the population of timber graded visually or by machine to the requirements given in EN 1

48、4081-1. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 384:2010EN 384:2010 (E) 8 The test material shall be representative of the population. It shall represent the timber source, sizes, and quality that will be graded in production. Each sample shall be from one source. NOTE 1 For the derivation of settings for grading machines additional sampling requirements are giv