BS EN 384-2016 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测定》.pdf

1、BS EN 384:2016Structural timber Determination of characteristicvalues of mechanical propertiesand densityBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN 384:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 384:2016.It s

2、upersedes BS EN 384:2010 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee B/518, Structural timber.A list of organizations represented on this committee can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 neces

3、saryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 83528 5ICS 79.040Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was publ

4、ished under the authority of theStandards Policy and Strategy Committee on 30 September 2016.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS EN 384:2016EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 384 August 2016 ICS 79.040 Supersedes EN 384:2010English Version S

5、tructural timber - Determination of characteristic values of mechanical properties and density Bois de structure - Dtermination des valeurs caractristiques des proprits mcaniques et de la masse volumique Bauholz fr tragende Zwecke - Bestimmung charakteristischer Werte fr mechanische Eigenschaften un

6、d Rohdichte This European Standard was approved by CEN on 30 January 2016. 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 bibliog

7、raphical references concerning such national standards may be obtained on application to the CEN-CENELEC 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 responsib

8、ility of a CEN member into its own language and notified to the CEN-CENELEC 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, Former Yugoslav Republi

9、c of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey andUnited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISA

10、TION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 384:2016 EBS EN 384:2016EN 384:2016 (E) 2 Contents Page European foreword . 3

11、 Introduction 4 1 Scope 5 2 Normative references 5 3 Terms and definitions . 5 4 Symbols and abbreviations . 6 5 Mechanical properties determined from full-size specimens 8 5.1 Sampling . 8 5.2 Testing . 8 5.3 Reference conditions . 8 5.3.1 Moisture content . 8 5.3.2 Bending strength . 8 5.3.3 Tensi

12、on strength . 8 5.3.4 Density 8 5.4 Adjustment factors . 9 5.4.1 General 9 5.4.2 Moisture content . 9 5.4.3 Timber size and test length . 9 5.4.4 Modulus of elasticity . 10 5.4.5 Other adjustments . 10 5.5 Analysis of data . 10 5.5.1 Sub-sample analysis 10 5.5.2 Characteristic values . 11 6 Bending

13、strength and modulus of elasticity determined from small, clear hardwood specimens . 13 7 Other mechanical properties for hardwoods and softwoods 13 8 Report . 15 Annex A (normative) Requirements for reports for visual grading assignment . 16 Bibliography . 19 BS EN 384:2016EN 384:2016 (E) 3 Europea

14、n foreword This document (EN 384:2016) has been prepared by Technical Committee CEN/TC 124 “Timber structures”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the lat

15、est by February 2017, and conflicting national standards shall be withdrawn at the latest by February 2017. Attention is drawn to the possibility that some 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 al

16、l such patent rights. This document supersedes EN 384:2010. Compared to EN 384:2010, the following modifications have been made: the definitions have been revised; the adjustments of test results to the reference moisture content are presented as equations; the equations for determining other proper

17、ties from properties derived by testing have been changed; regarding the determination of 5 %-percentiles the standard has been adopted to the revised EN 14358; the procedure for verification of a lot has been transferred to EN 14358. According to the CEN/CENELEC Internal Regulations, the national s

18、tandards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania

19、, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 384:2016EN 384:2016 (E) 4 Introduction Structural design codes can only function effectively if standard methods of determining the mechanical and

20、 physical properties exist. The aim of the procedures given in this standard is to derive characteristic values that are comparable in terms of the populations they represent. The standard permits the use of as much existing test data as possible from various sampling and testing techniques. Where m

21、ethods are given to permit characteristic values to be determined from a less than ideal amount of structural size test data, reduction factors to reflect a lower degree of confidence are employed. BS EN 384:2016EN 384:2016 (E) 5 1 Scope This European Standard gives a method for determining characte

22、ristic values of mechanical properties and density, for defined populations of visual grades and/or strength classes of machine graded structural timber. Additionally it covers the stages of sampling, testing, analysis and presentation of the data. The standard provides methods to derive strength, s

23、tiffness and density properties for structural timber from tests with defect-free specimen. The values determined in accordance with this standard for mechanical properties and density are suitable for assigning grades and species to the strength classes of EN 338. NOTE 1 For assigning grades and sp

24、ecies to the strength classes in EN 338 only three properties, i.e. bending or tension strength, modulus of elasticity parallel to grain in bending or tension and density need to be determined from test data, other properties can be calculated according to Table 2. NOTE 2 EN 1912 gives examples of e

25、stablished visual grades assigned to strength classes. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest

26、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 properties EN 13183-2, Moisture content of a piece of sawn timber Par

27、t 2: Estimation by electrical resistance method EN 13183-3, Moisture content of a piece of sawn timber Part 3: Estimation by capacitance method EN 14081-1:2016, Timber structures Strength graded structural timber with rectangular cross section Part 1: General requirements EN 14081-2, Timber structur

28、es Strength graded structural timber with rectangular cross section Part 2: Machine grading; additional requirements for initial type testing EN 14081-3, Timber structures Strength graded structural timber with rectangular cross section Part 3: Machine grading; additional requirements for factory pr

29、oduction control EN 14358:2016, Timber structures Calculation and verification of characteristic values 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 characteristic value representative value of a material property used for design, which is

30、 based either on 5-percentile values (e.g. strength properties and density) or mean values (e.g. modulus of elasticity) BS EN 384:2016EN 384:2016 (E) 6 3.2 p-percentile value for which the probability of getting lower values is p % 3.3 population timber for which the characteristic values are releva

31、nt 3.4 timber source identifiable geographical origin of a species or species combination from which timber is, or is intended to be, strength graded 3.5 sample a number of ungraded specimens of one timber species or species combination, one source, with sizes and quality representative of the timbe

32、r population (see 5.1) 3.6 sub-sample part of one or more samples consisting of specimens of one grade 3.7 small clear test test to determine mechanical properties of small defect-free specimens 3.8 specimen piece of timber from which the test piece is taken 3.9 thickness lesser dimension perpendicu

33、lar to the longitudinal axis of a piece of timber 3.10 width larger dimension perpendicular to the longitudinal axis of a piece of timber 3.11 depth in the case of bending, cross-sectional dimension parallel to the direction of loading; in the case of tension, the width 4 Symbols and abbreviations a

34、fdistance between the inner load points of the bending test (in mm) E0modulus of elasticity parallel to grain (in N/mm2) E0,meanmean characteristic value of modulus of elasticity parallel to grain (in N/mm2) E0,k 5-percentile characteristic value of modulus of elasticity parallel to grain (in N/mm2)

35、 E90,meanmean characteristic value of modulus of elasticity perpendicular to grain (in N/mm2) E i mean modulus of elasticity for one sub-sample (in N/mm2) BS EN 384:2016EN 384:2016 (E) 7 Ei,min lowest mean modulus of elasticity of all sub-samples (in N/mm2) Em,globalglobal modulus of elasticity in b

36、ending (in N/mm2) Em,locallocal modulus of elasticity in bending (in N/mm2) f strength property fc,0,k5- percentile characteristic value of compression strength parallel to grain (in N/mm2) fc,90,k5- percentile characteristic value of compression strength perpendicular to grain (in N/mm2) fk5- perce

37、ntile characteristic value of strength (in N/mm2) fm,k5- percentile characteristic value of bending strength (in N/mm2) ft,0,k5- percentile characteristic value of tension strength parallel to grain (in N/mm2) ft,90,k5- percentile characteristic value of tension strength perpendicular to grain (in N

38、/mm2) f05,i5-percentile value for each sub-sample (in N/mm2) f05,i,minlowest 5-percentile value of all sub-samples (in N/mm2) fv,k5- percentile characteristic value of shear strength (in N/mm2) Gmeanmean characteristic value of shear modulus (in N/mm2) h depth (in mm) khfactor for adjusting f when h

39、 is not 150 mm klfactor for adjusting f when test span is not 18 h knfactor to adjust for the number of sub-samples kvfactor to allow for the lower variability of f05values between sub-samples for machine grades in comparison with visual grades span (in mm) eteffective length for the test (in mm) n

40、total number of specimens ninumber of specimens in a sub-sample ns number of sub-samples u moisture content (in %) u ref reference moisture content, normally at 12 % density (in kg/m3) mean mean density (in kg/m3) kcharacteristic density (5-percentile) (in kg/m3) 05,i5-percentile density for a sub-s

41、ample (in kg/m3) 05,i,minlowest 5-percentile density of all sub-samples (in kg/m3) BS EN 384:2016EN 384:2016 (E) 8 5 Mechanical properties determined from full-size specimens 5.1 Sampling The sampling shall be representative of the population. Any known or suspected difference in the mechanical prop

42、erties of the population due to e.g. sawmills, tree size, countries or silviculture shall be represented within the sampling by a similar proportion to their frequency in the population. This shall be the major influence in determining the number and size of samples. Samples shall be selected from o

43、ne source of timber and shall be graded visually or by machine to sub-samples according to the requirements given in EN 14081-1. For visual grading, each sub-sample shall consist of at least 40 specimens and be of one source. For bending and tension parallel to grain tests, specimens shall have a su

44、fficient length so that critical defects can be located in the critical test zone (see 5.2). A length of at least 30 times the depth or 3.6 m whichever is the lesser meets this requirement. For the determination of strengths perpendicular to the grain and shear strength clear specimens shall be samp

45、led. 5.2 Testing Testing shall be carried out in accordance with EN 408 for strength, modulus of elasticity, density and moisture content. For bending parallel to grain, tension parallel to grain or modulus of elasticity, a critical section shall be selected in each piece of timber. This section is

46、the position at which failure is expected to occur and therefore determines the grade for that piece. For bending the tension edge shall be selected at random. Whenever possible the critical section shall be placed inside the inner load points in a bending test or between the jaws in a tension test

47、(centrally if possible). If this is not possible, the second most critical section shall be tested and determines the grade for that piece. Existing historical data (before 1995) from different test methods or moisture conditions are acceptable provided sufficient information exists to adjust the re

48、sults to the reference conditions given in 5.3. 5.3 Reference conditions 5.3.1 Moisture content The reference moisture content shall be consistent with a temperature of 20 C and 65 % relative humidity. NOTE For most timber species this corresponds to a moisture content of about 12 %. For specimens n

49、ot tested to failure, the moisture content of each specimen is permitted to be determined from EN 13183-2 or EN 13183-3. 5.3.2 Bending strength The reference condition corresponds to bending to a depth of 150 mm and to the standard test set-up proportions of third point loading with an overall span of 18 times the specimen depth. 5.3.3 Tension strength The reference condition corresponds to a depth of 150 mm. 5.3.4 Density Density is determined on small defect-free prisms according EN 408. BS EN 384:2016EN 384:2016 (E) 9 For spec