1、BRITISH STANDARD BS EN 14251:2003 Structural round timber Test methods The European Standard EN 14251:2003 has the status of a British Standard ICS 79.040; 91.080.20 BS EN 14251:2003 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 19 January
2、2005 BSI 19 January 2005 ISBN 0 580 45266 2 National foreword This British Standard is the official English language version of EN 14251:2003. The UK participation in its preparation was entrusted to Technical Committee B/518, Structural timber, which has the responsibility to: A list of organizatio
3、ns represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondenc
4、e Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itsel
5、f confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and pr
6、omulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 12, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since pu
7、blication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN14251 December2003 ICS79.040;91.080.20 Englishversion StructuralroundtimberTestmethods BoisdestructurerondMthodesdessai RundholzfrbaulicheZweckePrfverfahren ThisEuropeanStandardwasapprovedbyCENon1September2003. CENmembe
8、rsareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheCentralSecretariatortoanyCENmembe
9、r. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheCentralSecretariathasthesamestatusast heofficial versions. CENmembersarethenationalstandardsbodiesofAustria,Bel
10、gium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Hungary,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Slovakia,Spain,Sweden,SwitzerlandandUn ited Kingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruede
11、Stassart,36B1050Brussels 2003CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN14251:2003:EEN14251:2003(E) 2 Contents page Foreword3 1 Scope 4 2 Normativereferences 4 3 Termsanddefinitions . 4 4 Symbolsandabbreviations. .5 5 Determinationofthemoisture
12、contentoftestpieces .5 6 Determinationofdensityoftestpieces . .6 7 Determinationofdimensionsoftestpieces .6 8 Determinationofthemodulusofelasticityparalleltothegrain 6 8.1 Testprocedure 6 8.2 Expressionoftheresults. 7 9 Determinationofthebendingstrengthparalleltothegrain. 8 9.1 Testpiece 8 9.2 Testp
13、rocedure 8 9.3 Expressionoftheresults. 8 10 Determinationofthemodulusofelasticityincompressionparalleltothegrain.8 10.1 Testprocedure . .8 10.2 Expressionoftheresults .9 11 Compressivestrengthparalleltothegrain . .10 11.1 General10 11.2 Testprocedure . .10 11.3 Expressionoftheresults .10 12 Testrepo
14、rt 10 12.1 General10 12.2 Testpiece. .10 12.3 Testmethod .11 12.4 Testresults. .11 Bibliography 12 Page2 EN14251:2003EN14251:2003(E) 3 Foreword Thisdocument(EN14251:2003)hasbeenpreparedbyTechnicalCommitteeCEN/TC124,TimberStructures,the secretariatofwhichisheldbyDS. ThisEuropeanStandardshallbegiventh
15、estatusofanationalstandard,eitherbypublicationofanidenticaltextor byendorsement,atthelatestbyJune2004,andconflictingnationalstandardsshallbewithdrawnatthelatestby June2004. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthefollowing countriesareboundtoimplementthisEu
16、ropeanStandard:Austria,Belgium,CzechRepublic,Denmark,Finland, France,Germany,Greece,Hungary,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal, Slovakia,Spain,Sweden,SwitzerlandandtheUnitedKingdom. Page3 EN14251:2003EN14251:2003(E) 4 1Scope Thisstandardappliesforstructuralroundwoodti
17、mberotherthanspecifiedinEN12509. Thisteststandardspecifiestestmethodsfordeterminingthefollowingpropertiesofstructuralroundtimber;the bendingstrength,modulusofelasticityinbending;thecompressivestrengthparalleltothegrainandmodulusof elasticityincompressionparalleltothegrain. Inaddition,thedeterminatio
18、nofdimensions,moisturecontentanddensityisspecified.Themethodsapplyto debarkedroundtimber. Thisstandardisnotintendedforqualitycontroltestpurposes. 2 Normativereferences ThisEuropeanStandardincorporatesbydatedorundatedreference,provisionsfromotherpublications.These normativereferencesarecitedattheappr
19、opriateplacesinthetext,andthepublicationsarelistedhereafter.For datedreferences,subsequentamendmentstoorrevisionsofanyofthesepublicationsapplytothisEuropean Standardonlywhenincorporatedinitbyamendmentorrevision.Forundatedreferencesthelatesteditionofthe publicationreferredtoapplies(includingamendment
20、s). Notapplicable. 3 Termsanddefinitions ForthepurposesofthisEuropeanStandard,thefollowingtermsanddefinitionsapply: 3.1 minimumdiameter minimumdiameterofthepoleatthesectionofmeasurement 3.2 maximumdiameter maximumdiameterofthepoleatthesectionofmeasurement 3.3 apparentdiameter diameterofacirclewithth
21、esamecircumferenceastheactualcircumferenceatthesectionofmeasurement 3.4 nominaldiameter a) largestapparentdiameterforpoleswith5%orlessovality b) largestminimumdiameterforpoleswithmorethan5%ovality 3.5 ovality differencebetweenthemaximumandminimumdiameteratacrosssectionexpressedasapercentageofthe min
22、imumdiameter 3.6 sweep deviationofthelongitudinalaxisfromastraightline Page4 EN14251:2003EN14251:2003(E) 5 3.7 taper gradualchangeindiameteralongthelength 4 Symbolsandabbreviations A crosssectionalarea,insquaremillimetres a distancebetweenloadingpositionandnearestsupportinbendingtest,inmillimetres d
23、 nom nominaldiameterofroundtimberbeamateitherendgrainface,inmillimetres d h diameterofroundtimberperpendiculartothedirectionofloadatmidspan,inmillimetres d v diameterofroundtimberinthedirectionofloadatmidspan,inmillimetres E m,0 modulusofelasticityinbending,inNewtonpersquaremillimetre E c,0 moduluso
24、felasticityincompressionparalleltothegrain,inNewtonpersquaremillimetre F load,inNewton F max maximumload,inNewton f c,0 compressivestrengthparalleltothegrain,inNewtonpersquaremillimetre f m,0 bendingstrength,inNewtonpersquaremillimetre h heightofcompressionparalleltograintestpiece,inmillimetres h 0
25、gaugelengthofcompressionparalleltograintestpiece,inmillimetres I secondmomentofarea,inmillimetrestothefourthpower l spaninbending,inmillimetres l 1 gaugelengthforthedeterminationofmodulusofelasticityinbending,inmillimetres w deflectionordisplacementincompression,inmillimetres. 5 Determinationofthemo
26、isturecontentoftestpieces Thetestsshallbecarriedoutonpieceswhichareconditionedatthestandardenvironmentof(20 2) 0 Cand(65 5)%relativehumidity.Atestpieceisconditionedwhenitattainsconstantmass.Constantmassisconsideredtobe attainedwhentheresultsoftwosuccessiveweightings,carriedoutwithanintervalof6h,dono
27、tdifferbymore than0.1%ofthemassofthetestpiece. Whenotherconditionsapplytheyshallbereported. NOTE Besidesthatittakesalongtimetodrythesolidroundtimberastothestandardenvironmentthiswillalsoresultin substantialcracks . Whentestedinawetconditionthisaspectshouldbetakencareofinthederivationofcharacteristic
28、and designstrengthandstiffnessvalues. Page5 EN14251:2003EN14251:2003(E) 6 6 Determinationofdensityoftestpieces Thedensityismeasuredfromadisk(minimumthickness75mm),takenfromthetestspecimen.Thesectionshall beoffullcrosssection,freefromknotsandresinpockets Thedimensionsofthetestspecimenshallbemeasuredw
29、ithadevicewithanaccuracyof1%.Allmeasurements shallbemadewhenthetestpiecesareconditionedasspecifiedinClause5.Deviationsfromaconstantcross sectionalongthegraindirectionshallberecorded. 7 Determinationofdimensionsoftestpieces Thedimensionsofthetestspecimenshallbemeasuredwithadevicewithanaccuracyof1%.Al
30、lmeasurements shallbemadewhenthetestpiecesareconditionedasspecifiedinClause5.Deviationsfromaconstantcross sectionalongthegraindirectionshallberecorded. 8 Determinationofthemodulusofelasticityparalleltothegrain 8.1 Testprocedure Thetestpieceshallbesymmetricallyloadedinbendingattwopointsoveraspanof18t
31、imesthenominaldiameter oftheroundtimber.Theloadingheadsshallbeplacedatthethirdpointsofthespan.Thetestpieceshallbesimply supportedandthedirectionofthesweep,ifany,shouldbeinthedirectionoftheload. Ifthetestpieceortheequipmentdoesnotpermittheseconditionstobeachievedexactly,thedistancebetween theloadingp
32、ointsandsupportsmanybechangedbyanamountnotgreaterthan1,5timesthenominaldiameter measuredbetweenthespan.Thespanmaybechangedbyanamountnotgreaterthanthreetimesthenominal diameter,whilemaintainingthesymmetryofthetestsetup. Ashapedwoodenorwoodbasedblocktofittheroundtimber,oflengthnotgreaterthanthenominal
33、diameterof theroundtimbermaybeinsertedbetweenthetestpieceandtheloadingheadsorsupportstominimiselocal indentation. NOTE Theblocksundertheloadingheadsandthesupportsmaydifferinthicknessastotakeaccountofthetaperingofthe testpiece. Figure1Testarrangementforthedeterminationofthemodulusofelasticity Page6 E
34、N14251:2003EN14251:2003(E) 7 Thetestarrangementshallmaintaintheloadingforcesequal. Theloadshallbeappliedataconstantrate.Therateofmovementoftheloadingheadsisdeterminedfromthe resultsofpreliminarybendingstrengthtestsaccordingto9.2.Themeasuringdeviceusedshallbecapableof measuringtheloadtoanaccuracyof1%
35、oftheloadappliedtothetestpiece. Themaximumloadshallnotexceedtheproportionallimitloadorcausedamagetothepiece. Atmidspanthediameterinthedirectionoftheload d v andperpendiculartotheload d h arerecorded. Thedeformation w shallbetakenastheaverageofthemeasurementsonbothfacesattheneutralaxis,andshall bemea
36、suredatthecentreofthecentralgaugelengthoffivetimesthenominaldiameter, d nom atmidspaninthe directionoftheload,seeFigure1. Themeasurementsshallbedeterminedwithaccuracyof1%or,fordeformationslessthan2mm,withanaccuracy of0.02mm. 8.2 Expressionoftheresults Themodulusofelasticityinbendingparalleltothegrai
37、n E m,0 isdeterminedby: where M 1 M 2 istheincrementofbendingmomentonthestraightlineportionoftheloaddeformationcurve,in Newtonmillimetres w 1 w 2 istheincrementofdisplacement,inmillimetres d 1 isthesmallestapparentdiameteralongthegaugelength,inmillimetres d 2 isthebiggestapparentdiameteralongthegaug
38、elength,inmillimetres I 1 isthesmallestsecondmomentofareaalongthegaugelength,inmillimetrestothefourthpower l isthegaugelength,inmillimetres If E m,0 iscalculatedfromabendingmoment/deformationlinearregressionthesquareofthecorrelationcoefficient shouldbegreaterthan0.99. 4 12 m,0 22 121 1 11 22 21 1 ()
39、11 6( ) ( /2) 2 11 with and () () MMc D E wwI cl c ld cD dd ccl -=- + -+ = - -+ Page7 EN14251:2003EN14251:2003(E) 8 9 Determinationofthebendingstrengthparalleltothegrain 9.1 Testpiece Thetestpieceshallhaveaminimumlengthof18timesthenominaldiameter, d nom . 9.2 Testprocedure Theloadshallbeappliedataco
40、nstantrateandsoadjustedthatthemaximumloadisreachedwithin(300120)s. Thetimetofailureofeachtestpieceshallberecordedanditsaveragereported. Anysingletestpiecedivergingmorethan120sfromthetargetof300sshallbereported. Themodeoffractureandgrowthcharacteristicsatthefracturesectionofeachtestpieceshallbereport
41、ed. 9.3 Expressionoftheresults Thebendingstrength f m,0 isgivenbytheequation: where: F max themaximumtotalloadofbothloadingheads,inNewton a thedistancebetweentheloadingpositionandthesupport,inmillimetres d v thediameterinthedirectionoftheloadatmidspan,inmillimetres d h thediameterperpendiculartothel
42、oaddirectionatmidspan,inmillimetres 10 Determinationofthemodulusofelasticityincompressionparalleltothegrain Thetestpieceshallbeoffullcrosssection,andshallhavealengthofsixtimesthenominaldiameter, d nom .The endsurfacesshallbeaccuratelypreparedtoensurethattheyareplaneandparalleltoeachotherand perpendi
43、culartotheaxisofthetestpiece. 10.1 Testprocedure Thetestpieceshallbeloadedconcentrically.Thiscanbeachievedusingsphericallyseatedloadingheadsorother devices,whichpermittheapplicationofacompressiveloadwithoutinducingbending.Afteraninitialloadhasbeen appliedtheloadingheadsshallbelockedtopreventangularmovement. Thedeformationshallbemeasuredoveracentralgaugelength, h 0, equaltofourtimesthenominaldiameter, d nom ofthetestpiece.Thetransducer
