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Quantitative Analysis on Measure Results by Resistograh for Wood Decay of Ancient Architecture

By Beatrice Nichols,2014-02-17 19:07
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Quantitative Analysis on Measure Results by Resistograh for Wood Decay of Ancient Architecture

    Quantitative Analysis on Measure Results by Resistograh for Wood Decay of Ancient

    Architecture

    f,,

    CHINESEFORESTRYSCIENCEANDTECHNOLOGY

    QuantitativeAnalysisonMeasureResults

    byResistograhforWoodDecay

    ofAncientArchitecture

    !:22)

    WANGXiaohuanHUANGRongfengZHENGHongkuiLIHuaLIUXiuying

    seAcademvofForc~'trv,Beiiimz100091.P

    rMoneoliaAericulturalUniversitv.Hohhot.ojooj8

    Abstract:Theair-drieddensity,bendingstrength(MOR)andcompressivestrengthparalleltograinofdifferent

    gradesofrottenwoodweremeasuredwithtestspecimensof100-130year-oldlarch(

    sp.)collectedinWuYing

    Dian,theForbiddenCity.Inaddition,theMORofspecimenswasmeasuredbyResistographandthecorrelations

    wereanalyzedbetweenresistancevalueandmechanicalpropertiesofwood.Thecorrelationsaresignificantfor

    quantitativeevaluationofwoodstructuralconditionbyResistograph.Theresultsshowedthatwoodairdried

    density,strengthpropertiesandresistancevaluesdecreasedsignificantlywiththeincreaseofdecaydegree,andthere

    wereremarkabledifferencesamongvariousgradesofwood.Basedontherottendegree,theattenuationrateisinthe

followingorder:MOR>compressivestrengthparalleltograin>air

    driedwooddensity>resistancevalue,andthe

    above4indexeswere32%,53%,73%and74%ofthoseofintactwood,respectively,whenthedegreeofrottenwood

    reachedgrade3.Significantpositivecorrelationat0.01leve1wasshowedbetweenthewave~oughvaluesandwood

    air

    drieddensity,MOR,compressives~engthparalleltograin.Thecorrelationsbetweenthewavepeakvaluesand

    theaveragevalueandair-driedwooddensity,MORreached0.O1level,andthecorrelationsbetweenthewavepeak

    valuesandtheaveragevalueandcompressivestrengthparalleltograinreached0.05leve1.Basedonthecorrelation

    betweenresistancevalueandphysico

    mechanicalpropertiesofwood,thevaluescouldbeanalyzedquantitatively. Keywords:ancientarchitecture,Larixsp.,wooddecay,physico

    mechanicalproperties,Resistograph,quantitative

    analysis

    Themainbodyofancientarchitectureiswood

    constructioninChina,andthemainbearing

    componentsofthebuildingsusuallyusetimber,

    suchaspillar,beam,purlin,crossbeamandrafter.

    Timberisakindofbiomaterialandwillbedamaged

    byfungalattackorinsectsafterlongtimeuse,which

    willcausewoodframesdestroyedultimately.

    Timberdecaynotonlyexistsinitssurface,but

    alsousuallybegjnswiththeinnerofwood.Itis

    thereforeimperativetoconsiderusingalternative

    methodssuchasNonDestructiveEvaluation

    (NDE)duringroutineinspectionsforagedwood

    ofancientarchitecture.Atpresent,NDEmethods aredevelopedallovertheworld,suchassupersonic wave,stresswave,Xray,Yray,Pilodynand

    Resistograph.Thesupersonicwave,stresswave andResistographareincommon-use(WangLihai eta1.2001:Anthonyeta1.1989;Roberteta1.2002; ZhuYimineta1.1996;DuanXinfangeta1.2002). TheResistographisaqfiasiNDEinspectiondevice ThisworkwassupportedbyMinistryofScienceandTechnologyProject(No.2004DIB5J18

    7)andStateAdministrationofCulture

    HeritageProject(No.2003022)

    Correspondingauthors:HUANGRongfcng.Majorinwoodphysics.E-mail:huangrf@cafa

    c.cn

    16

    developedbyRinntechCompanyofGermanyfor1.2Methods wooddefectandwoodstructure.Itisusedtoassess theconditionofthewoodmaterialand1soneofthe mostoftenuseddevicesinEurope,America,Japan andTaiwan(P.R.China)(DuanXinfangeta1.2002; Laurenceeta1.1999:Lukaszkiewiczeta1.2005: Fikreteta1.2003;Gantzeta1.2002).Resistograph

    methodisbasedonmeasuringresistancevalueofa smalldiameterdrillbit(1.5mmdiameter)following penetrationintothetimber.Resistographdevice recordsresistancevalueintheprocessofstabbing intotimber,andtheresistancevaluewillchangewith differentdensity.Informationontheconditionof theoldtimberisacquiredaccordingtodetecting curveofresistancevalue,butitcannotbeusedto

eValuatePhYsicomechanicalproPerties

    quantitatively.

    Inthisstudy,theagedwoodsampiesfromthe ForbiddenCityareusedaccordingtothegradesof therottenwood,andtheirairdrieddensity,bending

    strength(MOR)andcompressivestrengthparallelto grainaredetectedafterclassificationbyeyes.The purposeofdetectingthesamples'MORby

    Resistographistodiscovertherelationsbetween resistancevalueandphysicomechanicalproperties

    andtorealizequantitativeanalysisonmeasureresults, andmeanwhiletoofferscientificfactsforquantitative evaluationofwoodenstructura1condjtion. 1ATERIALSANDMETHODS

    1.1Materials

    Thetestspecimenswereobtainedfromdemolished woodenframeworkaged50(135inWuYingDian,

    theForbiddenCity.Thesematerialswere confirmedaslarch(Larixsp.)speciesbythe anatomicmethod,andtheywereusedin1869or jn900.

    ,

    

    Vol5N.42006

    Thewoodspecimenswerepreparedfromrottenwood forairdrieddensity,MOR,compressivestrength paralleltograinandResistographtesting.Theblocks werecutaccordingtonationalstandardGB192991.

    andweredividedinto04fivegradesofdecay

accordingtonationalstandardGB/Tl3942.292fOr

    thedifferentextentofsampledecay.Grade0shows nonrottenwoodandgradesl4show4varOUS

    gradesofrottenwood,respectively.

    1,3Resistographmeasurements

    TheResistographincludesthemainpartsofadrilling needle,protectivedevice,computermemoryanda batterypack.TheResistographmeasuresthe resistancetothedrillingneedle(withadiameterof 1.5mm)whendrillingintothewoodatasteady speed,andtheresistancevalueisrecordedintothe storage,andtheresultisprintedoncollectionof illustrativeplatessimultaneously.Thedensityrange ofwood,thedensitychangesofearlywoodandlate woodandthedensitychangescausedbydecayare showndirectlyonamap.Duetohavingthesame decayextentwhendetectingphysicomechanical

    properties——airdrieddensity,MORandcompressive strengthparalleltograinofeachsample,onlythe sampleswhoseMORhadbeentestedweredetected byResistograph.Whendrillingintothetimber,the pointofdrillingshouldcoincidewithdecayextent. TheequipmentmodelisResistograph.3450P/S.The

    lengthofdrillingneedleis45cm.

    1.4Dataprocessingandanalysis

    PictureforResistographresultsisdrawnaccording tostoragedatatoanalyzeResistographresultsof rottenwood,usingExcelsoftware.Anexampleofa processeddrillingisshowninFigure1.Thereare threeranges,namely,trough,peakandaverageto

analyzethechangeofresistancevalue.

    17

CHINESEFORESTRYSCIENCEANDTECHNOLOGY

    678910111213

    DepthofdrillinIg/cm

    A-GraphofresistancevalueB.Mapona1:1scaleonthewaxpaperC.Timbertransversesectio

    n

    Figure1.PictureforcomparisonaRerprocessing Eachaveragevalueofwoodphysico.mechanical propertiesandresistancevalueofnon.rottenwood areconsideredas100%,afterwards,theattenuation ratesofdifferentgradesofrottenwoodarecalculated ,

    respectively.

    Therelationshipbetweenresistancevalueandphysico. mechanicalpropertiesofwoodisanalyzedby correlationanalysis.

    2~SULTSANDDISCUSSIONS

    2.1Physico.mechanicalpropertiesofeachgrade ofrottenwood

    Table1indicatestheresultsofphysico.mechanical propertiesofeachgraderottenwood.TherearenO resultsofphysicomechanicalpropertiesforgrade4 18

    rottenwoodbecauseitcannotbeprocessedintothe samples.Themeanair.drieddensityofnon.rotten part(grade0)intheoldtimberis0.597g.cm(,MOR

    is97.15MPa,andcompressivestrengthparallelto grainiS46.51MPa,whichareclosetothatofthe

    freshandhealthylarch(ChengJunqingeta1.1992). Whenreachingtograde1,thevalueofMOR

    decreasedto56.54MPa,andwhentograde3, itis

    31.37MPa,only32%ofthatofthenon.rotten wood(Figure2).Compressivestrengthparallelto graindecreasesobviouslywiththejncreaseofwood decay.Whenreachingtograde3,

    itdecreasesto

    24.58MPa,about53%ofthatofnon.rottenwood. Whenreachingtograde3,air.drieddensitydecreases to0.437g.cm(,about73%ofthatofnon.rotten

    wood.Theindexoftheabovethreephysico. mechanicalpropertiesreducesevidentlywiththe increaseofwooddecay,inwhichMORisthemost obvibus.

    0Il0ug?|s0

Vol5No42006/,-I-,

    Table1.indexonphysieo-mechanicalpropertiesofdifferentgradesofrottenwood

    Grade

    Figure2.Attenuationrateofair-drieddensityand strengthpropertiesofdifferentgradesofrottenwood 2.2Resictancevaluechangesofeachgradeof rottenwood

    Resistograph,whichhasbeendetectedfromphysico- mechanicalproperties.Theresistancevaluecanbe dividedintothreeranges,wavepeakisclosetolate wood,andtroughisclosetoearlywood.Table2 indicatestheresistancevalueofeachgradeofwood.

    Thedifferencebetweenwavepeakaverageand troughaverageofthesamegradeofrottenlarchis between45and100andthusiSsignificant.butthe differenceofattenuationrateiSnotobviousinwave peak,troughandweightedaverage(Figure3).The weightedaverageofthehealthywoodis231.83,and thetestingvaluedecreaseswiththeincreaseofwood decay.Especiallywhenincreasingfromgrade3to grade4,theweightedaverageis172.31and92.98, respectively,whichis74%and38%comparedto thenonrottenwood

    2.3Correlationanalysisbetweenresistancevalue andwoodphysicomechanicalproperties

    "Resi"isresistancevalue.Itsrangeisbetween0and 500.InordertoachievethequantitativeevaluationofCorrelationanalyseson43samples(n)ar

    edetected

    resistancevalue,thesamplesaredetectedbybetweenresistancevalueandairdrieddensity ,

    MOR

    Table2.Resistancevalueofdifferentgradesofrottenwood l10_lBrIl1

.

    

    CHINESEFORESTRYSCIENCEANDTECHNOLOGY

    andcompressivestrengthparalleltograin.Theresults arcshowninFigure4:Thereissignificantpositive correlationat0.011evelbetweenresistancevalue (trough)andairdrieddensityandMOR,andthereis

    positivecorrelationat0.05levelbetweenresistancevalue

(thepeakandaverage)andcompressivestrengthparallel

    tograin.Thecorrelationbetweenresistancevalueand

    airdrieddestinyisthelargest. 500

    400

    300

    200

    1o0

    0

    500

    4{)()

    300

    200

    lOO

    ()

    500

    400

    300

    200

    10O

    ()

    

    

    a

    

    Grade

    Figure3.Attenuationrateofresistancevalueofdifferent

    gradesofrottenwood

    v=2409x+49+36Iy=06032x+138+01 :f15(1na3500rr=039},n=43

().

    A|T

    400

    30()

    200

    l()O

    0

    00.20.40,60.80204060801()()12U14o

    driedDensity/(g?cm)MOR/MPa

    500

    400

    300

    200

    100

    0

    0204060

    Compressivestrength

    paralleltograin/MPa

    AAveragevaluerangeB-PeakrangeC-Troughange '

    Significanceat0.05level:Significanceat0.01level Figure4.Correlationanalysisbetweenphysico-mechanicalpropertiesandresistancevalue

    Theresistancevalueoftimberhasrelationswiththe distributionofearlywoodand1atewoodandtheir decay.Wavepeakappearedinlatewoodandwave troughinearlywoodorseriouslyrottenearlywood orlatewood.Fromtheaveragevalue,wavepeak andwavetrough,thereissignificantpositive correlationbetweentheaveragevalue,wavepeak

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