1、BS EN 338:2016Structural timber StrengthclassesBSI Standards PublicationBS EN 338:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 338:2016. Itsupersedes BS EN 338:2009 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalComm
2、ittee 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. The British Standards Institution
3、2016.Published by BSI Standards Limited 2016ISBN 978 0 580 83526 1 ICS 79.040 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 June 2016.Amendments/corrigenda i
4、ssued since publicationDate Text affectedBS EN 338:2016g3g3g3g8g24g21g18g19g8g4g17g3g22g23g4g17g7g4g21g7g3g17g18g21g16g8g3g8g24g21g18g19g50g8g17g17g8g3g8g24g21g18g19g34g12g22g6g11g8g3g17g18g21g16g3EN 338 g3 g3g3 g4g146g148g139g142g3g884g882g883g888g3g12g6g22g3g889g891g484g882g886g882g3 g22g151g146g1
5、35g148g149g135g134g135g149g3g8g17g3g885g885g890g483g884g882g882g891g8g144g137g142g139g149g138g3g25g135g148g149g139g145g144g3g3g22g150g148g151g133g150g151g148g131g142g3g150g139g143g132g135g148g3g486g3g22g150g148g135g144g137g150g138g3g133g142g131g149g149g135g149g3g5g145g139g149g3g134g135g3g149g150g148
6、g151g133g150g151g148g135g3g486g3g6g142g131g149g149g135g149g3g134g135g3g148g177g149g139g149g150g131g144g133g135g3 g3 g5g131g151g138g145g142g156g3g136g242g148g3g150g148g131g137g135g144g134g135g3g29g153g135g133g141g135g3g486g3g9g135g149g150g139g137g141g135g139g150g149g141g142g131g149g149g135g144g3g23g1
7、38g139g149g3g8g151g148g145g146g135g131g144g3g22g150g131g144g134g131g148g134g3g153g131g149g3g131g146g146g148g145g152g135g134g3g132g155g3g6g8g17g3g145g144g3g885g882g3g13g131g144g151g131g148g155g3g884g882g883g888g484g3g3g3g6g8g17g3g143g135g143g132g135g148g149g3g131g148g135g3g132g145g151g144g134g3g150g1
8、45g3g133g145g143g146g142g155g3g153g139g150g138g3g150g138g135g3g6g8g17g512g6g8g17g8g15g8g6g3g12g144g150g135g148g144g131g142g3g21g135g137g151g142g131g150g139g145g144g149g3g153g138g139g133g138g3g149g150g139g146g151g142g131g150g135g3g150g138g135g3g133g145g144g134g139g150g139g145g144g149g3g136g145g148g3g
9、137g139g152g139g144g137g3g150g138g139g149g3g8g151g148g145g146g135g131g144g3g22g150g131g144g134g131g148g134g3g150g138g135g3g149g150g131g150g151g149g3g145g136g3g131g3g144g131g150g139g145g144g131g142g3g149g150g131g144g134g131g148g134g3g153g139g150g138g145g151g150g3g131g144g155g3g131g142g150g135g148g131
10、g150g139g145g144g484g3g24g146g486g150g145g486g134g131g150g135g3g142g139g149g150g149g3g131g144g134g3g132g139g132g142g139g145g137g148g131g146g138g139g133g131g142g3g148g135g136g135g148g135g144g133g135g149g3g133g145g144g133g135g148g144g139g144g137g3g149g151g133g138g3g144g131g150g139g145g144g131g142g3g14
11、9g150g131g144g134g131g148g134g149g3g143g131g155g3g132g135g3g145g132g150g131g139g144g135g134g3g145g144g3g131g146g146g142g139g133g131g150g139g145g144g3g150g145g3g150g138g135g3g6g8g17g486g6g8g17g8g15g8g6g3g16g131g144g131g137g135g143g135g144g150g3g6g135g144g150g148g135g3g145g148g3g150g145g3g131g144g155g
12、3g6g8g17g3g143g135g143g132g135g148g484g3g3g23g138g139g149g3g8g151g148g145g146g135g131g144g3g22g150g131g144g134g131g148g134g3g135g154g139g149g150g149g3g139g144g3g150g138g148g135g135g3g145g136g136g139g133g139g131g142g3g152g135g148g149g139g145g144g149g3g523g8g144g137g142g139g149g138g481g3g9g148g135g144
13、g133g138g481g3g10g135g148g143g131g144g524g484g3g4g3g152g135g148g149g139g145g144g3g139g144g3g131g144g155g3g145g150g138g135g148g3g142g131g144g137g151g131g137g135g3g143g131g134g135g3g132g155g3g150g148g131g144g149g142g131g150g139g145g144g3g151g144g134g135g148g3g150g138g135g3g148g135g149g146g145g144g149g
14、139g132g139g142g139g150g155g3g145g136g3g131g3g6g8g17g3g143g135g143g132g135g148g3g139g144g150g145g3g139g150g149g3g145g153g144g3g142g131g144g137g151g131g137g135g3g131g144g134g3g144g145g150g139g136g139g135g134g3g150g145g3g150g138g135g3g6g8g17g486g6g8g17g8g15g8g6g3g16g131g144g131g137g135g143g135g144g150
15、g3g6g135g144g150g148g135g3g138g131g149g3g150g138g135g3g149g131g143g135g3g149g150g131g150g151g149g3g131g149g3g150g138g135g3g145g136g136g139g133g139g131g142g3g152g135g148g149g139g145g144g149g484g3g3g6g8g17g3g143g135g143g132g135g148g149g3g131g148g135g3g150g138g135g3g144g131g150g139g145g144g131g142g3g14
16、9g150g131g144g134g131g148g134g149g3g132g145g134g139g135g149g3g145g136g3g4g151g149g150g148g139g131g481g3g5g135g142g137g139g151g143g481g3g5g151g142g137g131g148g139g131g481g3g6g148g145g131g150g139g131g481g3g6g155g146g148g151g149g481g3g6g156g135g133g138g3g21g135g146g151g132g142g139g133g481g3g7g135g144g1
17、43g131g148g141g481g3g8g149g150g145g144g139g131g481g3g9g139g144g142g131g144g134g481g3g9g145g148g143g135g148g3g28g151g137g145g149g142g131g152g3g21g135g146g151g132g142g139g133g3g145g136g3g16g131g133g135g134g145g144g139g131g481g3g9g148g131g144g133g135g481g3g10g135g148g143g131g144g155g481g3g10g148g135g13
18、5g133g135g481g3g11g151g144g137g131g148g155g481g3g12g133g135g142g131g144g134g481g3g12g148g135g142g131g144g134g481g3g12g150g131g142g155g481g3g15g131g150g152g139g131g481g3g15g139g150g138g151g131g144g139g131g481g3g15g151g154g135g143g132g145g151g148g137g481g3g16g131g142g150g131g481g3g17g135g150g138g135g1
19、48g142g131g144g134g149g481g3g17g145g148g153g131g155g481g3g19g145g142g131g144g134g481g3g19g145g148g150g151g137g131g142g481g3g21g145g143g131g144g139g131g481g3g22g142g145g152g131g141g139g131g481g3g22g142g145g152g135g144g139g131g481g3g22g146g131g139g144g481g3g22g153g135g134g135g144g481g3g22g153g139g150g
20、156g135g148g142g131g144g134g481g3g23g151g148g141g135g155g3g131g144g134g3g24g144g139g150g135g134g3g14g139g144g137g134g145g143g484g3g3g3g3g3g8g24g21g18g19g8g4g17g3g6g18g16g16g12g23g23g8g8g3g9g18g21g3g22g23g4g17g7g4g21g7g12g29g4g23g12g18g17g3g6g18g16g12g23g50g3g8g24g21g18g19g50g8g17g3g7g8g3g17g18g21g16
21、g4g15g12g22g4g23g12g18g17g3g8g24g21g18g19g34g12g22g6g11g8g22g3g14g18g16g12g23g8g8g3g9g111g21g3g17g18g21g16g24g17g10g3g3g3g3CEN-CENELECg3Management Centre: Avenue Marnix 17, B-1000 Brussels g825g3g884g882g883g888g3g6g8g17g3 g4g142g142g3g148g139g137g138g150g149g3g145g136g3g135g154g146g142g145g139g150g
22、131g150g139g145g144g3g139g144g3g131g144g155g3g136g145g148g143g3g131g144g134g3g132g155g3g131g144g155g3g143g135g131g144g149g3g148g135g149g135g148g152g135g134g3g153g145g148g142g134g153g139g134g135g3g136g145g148g3g6g8g17g3g144g131g150g139g145g144g131g142g3g16g135g143g132g135g148g149g484g3g21g135g136g484
23、g3g17g145g484g3g8g17g3g885g885g890g483g884g882g883g888g3g8BS EN 338:2016EN 338:2016 (E) 2 Content Page European foreword 3 Introduction . 4 1 Scope . 5 2 Normative references . 5 3 Terms and definitions 5 4 Symbols and abbreviations 5 5 Classification of structural timber . 6 6 Allocation of a popul
24、ation to a strength class . 10 6.1 Grading 10 6.1.1 Visual graded timber . 10 6.1.2 Machine graded timber . 10 6.2 Classification . 10 6.2.1 Characteristic values 10 6.2.2 Allocation to a strength class 10 Bibliography 11 BS EN 338:2016g8g17g3g885g885g890g483g884g882g883g888g3g525g8g5262BS EN 338:20
25、16EN 338:2016 (E) 3 European foreword This document (EN 338:2016) 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
26、 by endorsement, at the latest by October 2016, and conflicting national standards shall be withdrawn at the latest by October 2016. 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
27、for identifying any or all such patent rights. This document supersedes EN 338:2009. Compared to EN 338:2009, the following modifications have been made: new table of strength classes for softwood species based on tension tests; extension with new classes in the table of strength classes for hardwoo
28、d species based on edgewise bending tests; modification of some characteristic values for strength, stiffness and density; equations to determine the characteristic values of other strength properties from the grade determining properties has been transferred to EN 384. According to the CEN/CENELEC
29、Internal Regulations, the national standards 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, Icelan
30、d, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 338:2016g8g17g3g885g885g890g483g884g882g883g888g3g525g8g5263BS EN 338:2016EN 338:2016 (E) 4 Introduction A str
31、ength class system groups together grades, species and sources with similar strength properties thus making them interchangeable. This then permits an engineer to specify a chosen strength class and use the characteristic strength values of that class in design calculations. BS EN 338:2016g8g17g3g88
32、5g885g890g483g884g882g883g888g3g525g8g5264BS EN 338:2016EN 338:2016 (E) 5 1 Scope This European Standard establishes a system of strength classes for general use in design codes. It gives characteristic strength and stiffness properties and density values for each class to which EN 14081-1 refers. T
33、his standard is applicable to all softwood and hardwood timber for structural use, within the scope of EN 14081-1. 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 th
34、e edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 384, Structural timber Determination of characteristic values of mechanical properties and density EN 14081 (all parts), Timber structures Strength graded structural
35、timber with rectangular cross section 3 Terms and definitions For the purposes of this document, the following term and definition apply. 3.1 population timber of one species or species combination and one source for which the strength, stiffness and density properties apply 4 Symbols and abbreviati
36、ons Em,0,meanmean characteristic value of modulus of elasticity in bending parallel to grain (in kN/mm2); Et,0,meanmean characteristic value of modulus of elasticity in tension parallel to grain (in kN/mm2); Em,0,k5-percentile characteristic value of modulus of elasticity in bending parallel to grai
37、n (in kN/mm2); Et,0,k5-percentile characteristic value of modulus of elasticity in tension parallel to grain (in kN/mm2); Em,90,meanmean characteristic value of modulus of elasticity in bending perpendicular to grain (in kN/mm2); Et,90,meanmean characteristic value of modulus of elasticity in tensio
38、n perpendicular to grain (in kN/mm2); fc,0,k5-percentile characteristic value of compressive strength parallel to grain (in N/mm2); fc,90,k5-percentile characteristic value of compressive strength perpendicular to grain (in N/mm2); fm,k5-percentile characteristic value of bending strength (in N/mm2)
39、; ft,0,k5-percentile characteristic value of tensile strength parallel to grain (in N/mm2); ft,90,k5-percentile characteristic value of tensile strength perpendicular to grain (in N/mm2); fv,k5-percentile characteristic value of shear strength (in N/mm2); BS EN 338:2016g8g17g3g885g885g890g483g884g88
40、2g883g888g3g525g8g5265BS EN 338:2016EN 338:2016 (E) 6 Gmeanmean characteristic value of shear modulus (in kN/mm2); g591k5-percentile characteristic value of density (in kg/m3); g591meanmean characteristic value of density (in kg/m3) 5 Classification of structural timber This standard provides for a
41、number of strength classes, each designated by a number indicating the value of the edgewise bending or tension strength in N/mm2. For softwood species based on edgewise bending tests, the characteristic values of strength, stiffness and density for the strength classes Cxx, where xx refers to the 5
42、-percentile characteristic bending strength value, are given in Table 1. For softwood species based on tension tests, the characteristic values of strength, stiffness and density for the strength classes Txx, where xx refers to the 5-percentile characteristic tension strength value, are given in Tab
43、le 2. NOTE 1 Timber belonging to T classes is mainly intended for glulam and other cases where tension is the dominating load. NOTE 2 The T classes correspond to classes L, LS or LD as in EN 140814 with some differences in tabulated properties and is also referred to in EN 14080. For hardwood specie
44、s based on edgewise bending tests, the characteristic values of strength, stiffness and density for the strength classes Dxx, where xx refers to the 5-percentile characteristic bending strength value, are given in Table 3. NOTE 3 C and T classes may also be used for hardwoods with similar strength a
45、nd density profiles such as e.g. poplar or chestnut. The most common used strength classes in Europe are printed in bold. BS EN 338:2016g8g17g3g885g885g890g483g884g882g883g888g3g525g8g5266BS EN 338:2016g8g17g3g885g885g890g483g884g882g883g888g3g525g8g5267Table1 Strengthclassesfor softwood based onedg
46、ewisebending tests strength, stiffness and density valuesClassC14C16 C18 C20C22C24 C27C30 C35C40C45C50StrengthpropertiesinN/mm2Bending fm,k14 161820 22 2427 3035 40 45 50 Tension parallelft,0,k7,28,51011,513 14,516,51922,526 30 33,5Tensionperpendicularft,90,k0,40,40,40,40,40,40,40,40,40,40,40,4Compr
47、ession parallelfc,0,k16 171819 20 2122 2425 27 29 30 Compression perpendicular fc,90,k2,02,22,22,32,42,52,52,72,72,82,93,0Shearfv,k3,03,23,43,63,84,04,04,04,04,04,04,0Stiffness properties in kN/mm2Mean modulusof elasticity parallel bendingEm,0,mean7,08,09,09,510,011,011,512,013,014,015,016,05 percen
48、tile modulus of elasticityparallel bending Em,0,k4,75,46,06,46,77,47,78,08,79,410,110,7Mean modulusof elasticityperpendicularEm,90,mean0,230,270,300,320,330,370,380,400,430,470,500,53Mean shear modulusGmean0,440,500,560,590,630,690,720,750,810,880,941,00Density inkg/m35 percentile densityg591k290310
49、320330340350360380390400410430Mean densityg591mean350370380400410420430460470480490520NOTE1 Values given above for tensionstrength,compression strength,shear strength,char.modulusof elasticityinbending,mean modulusof elasticityperpendicularto grain and mean shearmodulus have beencalculated usingtheequations givenin EN384.NOTE2 Thetension strengthvalues areconservativelyestimated sincegrading is done for bending strength.NOTE 3Thetabulatedpropertiesare compatiblewith timberat moisturecontentconsistentwith atemperatureof20 C andarelativehumidityof65%, which cor
