土木工程混凝土强度中英文对照外文翻译文献.docx

土木工程混凝土强度中英文对照外文翻译文献.docx

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土木工程混凝土强度中英文对照外文翻译文献

中英文对照外文翻译

（文档含英文原文和中文翻译）

原文:

StrengthofConcreteinSlabs,InvestigatesalongDirectionofConcreting

ABSTRACT

Intheoryofconcreteitisassumedthatconcretecompositesareisotropiconamacroscale.Forexample,itisassumedthatafloorslab’sorabeam’sstrengthisidenticalinalldirectionsanditsnonhomogeneityisrandom.Henceneithercalculationsoftheload-bearingcapacityofstructuralcomponentsnorthetechniquesofinvestigatingconcreteinstructureinsitutakeintoaccounttoasufficientdegreethefactthattheassumptionaboutconcreteisotropyisoverlyoptimistic.Thepresentresearchshowsthatvariationinconcretestrengthalongthedirectionofconcretinghasnotonlyaqualitativeeffect（asiscommonlybelieved）,butalsoasignificantquantitativeeffect.Thisindicatesthatconcreteisacompositewhichhasnotbeenfullyunderstoodyet.Thepaperpresentsevaluationsofordinaryconcrete（OC）homogeneityalongcomponentthicknessalongthedirectionofconcreting.Theultrasonicmethodandmodifiedexponentialheadswithapointcontactwithconcretewereusedintheinvestigations[1-3].

Keywords:

Concrete;CompressiveStrengthofConcrete;Non-Destructive

1.Introduction

Inabuildingstructuretherearecomponentswhichareexpectedtohavespecialpropertiesbutnotnecessarilyinthewholecrosssection.Componentsunderbending,suchasbeamsandfloorslabsaregenerallycompressedintheirupperzoneandtheconcrete’scompressivestrengthisvitalmainlyinthiszone.Thecomponentsareusuallymouldedinthesamepositioninwhichtheylaterremaininservice,i.e.withtheirupperzoneundercompression.Concreteintheupperzoneisexpectedtobeslightlyweakerthaninthelowerzone,butitisunclearhowmuchweaker[4,5].Alsoflooringslabsinproductionhallsaremostexposedtoabrasionandimpactloadsintheirupperzonewhichisnottheirstrongestpart.Itisknownfrompracticethatindustrialfloorsbelongtothemostoftendamagedbuildingcomponents.

Whenreinforcedconcretebeamsorfloorslabsaretobetestedtheycanbeaccessedonlyfromtheirundersidesandsoonlythebottompartsaretestedandonthisbasisconclusionsaredrawnaboutthestrengthoftheconcreteinthewholecrosssection,includinginthecompressedupperzone.Thusaquestionarises:

howlargearetheerrorscommittedinthiskindofinvestigations?

Inordertoanswertheaboveandotherquestions,testsofthestrengthofconcreteinvariousstructuralcomponents,especiallyinhorizontallyconcretedslabs,werecarriedout.Thevariationofstrengthalongthethicknessofthecomponentswasanalyzed.

2.ResearchSignificance

Theresearchresultspresentedinthepapershowthatthecompressivestrengthofconcreteinhorizontallyformedstructuralelementsvariesalongtheirthickness.Inthetopzonethestrengthisby25%-30%lowerthanthestrengthinthemiddlezone,anditcanbebyasmuchas100%lowerthanthestrengthinthebottomzone.Theobservationsarebasedontheresultsofnondestructivetestscarriedoutondrillcorestakenfromthestructure,andverifiedbyadestructivemethod.Itisinterestingtonotethatdespitethegreatadvancesinconcretetechnology,thevariationincompressivestrengthalongthethicknessofstructuralelementsischaracteristicofbothold（over60yearsold）concretesandcontemporaryordinaryconcretes.

3.TestMethodology

BeforeConcretestrengthwastestedbytheultrasonicmethodusingexponentialheadswithapointcontactwithconcrete.Thedetailedspecificationsoftheheadscanbefoundin[2,3].Theheads’frequencywas40and100kHzandthediameteroftheirconcentratorsamountedto1mm.

Inordertodeterminetherealstrengthdistributionsintheexistingstructures,cylindricalcores80mmor114mmdiameter（Figure2）weredrilledfromtheminthedirectionofconcreting.Thenspecimenswiththeirheightequaltotheirdiameterwerecutoutofthecores.

UltrasonicmeasurementswereperformedonthecoresaccordingtotheschemeshowninFigure3.Ultrasonicpulses（pings）werepassedthroughintwoperpendiculardirectionsIandIIinplanesspacedevery10mm.Inthiswayonecoulddeterminehowpingvelocityvariedalongthecore’sheight,i.e.alongthethicknessofthetestedcomponent.

InbothtestdirectionspingpasstimesweredeterminedandvelocitiesCLwerecalculated.Thevelocitiesfromthetwodirectionsinatestedmeasurementplanewereaveraged.Subsequently,specimenswiththeirheightequaltotheirdiameterof80mmwerecutoutofthecores.Aver-ageultrasonicpulsevelocityCLforthespecimen’scentralzonewascorrelatedwithfatiguestrengthfcdeterminedbydestructivetestscarriedoutinastrengthtester.Forthedifferentconcretesdifferentcorrelationcurveswithalinear,exponentialorpowerequationwereobtained.Exemplarycorrelationcurveequationsaregivenbelow:

where:

fc—thecompressivestrengthofconcreteMPa,

CL—pingvelocitykm/s.

Thedeterminedcorrelationcurvewasusedtocalculatethestrengthofconcreteineachtestedcorecrosssectionandtheresultsarepresentedintheformofgraphsillustratingconcretestrengthdistributionalongthethicknessofthetestedcomponent.

4.InvestigationofConcreteinIndustrialFloors

AfterFloorinsugarfactory’srawmaterialsstoragehallConcreteinanindustrialfloormusthaveparticularlygoodcharacteristicsinthetoplayer.Sinceitwastobeloadedwithwarehousetrucksandstoredsugarbeetsandfrequentlywashedtheinvestigatedconcretefloor（builtin1944）wasdesignedasconsistingofa150mmthickunderlayanda50mmthicksurfacelayerandmadeofconcretewithastrengthof20MPa（concreteA）.Aspartoftheinvestigationseightcores,each80mmindiameter,weredrilledfromthefloor.Theinvestigationsshowedsignificantdeparturesfromthedesign.Theconcretesubfloor’sthicknessvariedfrom40to150mm.Thesurfacelayerwasnotmadeofconcrete,butofcementmortarwithsandusedastheaggregate.Alsothethicknessofthislayerwasuneven,varyingfrom40to122mm.Aftertheultrasonictestsspecimenswiththeirheightequaltotheirdiameterof80mmwerecutoutofthecores.Twoscalingcurves:

oneforthesurfacelayerandtheotherforthebottomconcretelayerweredetermined.Acharacteristicconcretecompressivestrengthdistributionalongthefloor’sthicknessisshowninFigure4.Strengthintheupperzoneismuchlowerthaninthelowerzone:

rangingfrom4.7to9.8MPaforthemortarandfrom13.9to29.0MPafortheconcretelayer.Theverylowstrengthoftheupperlayerofmortaristheresultofstrongporositycausedbyairbubblesescapingupwardsduringthevibrationofconcrete.Figure5showsthespecimen’sporoustopsurface.FloorinwarehousehallwithforklifttrucktransportThefloorwasbuiltin1998.Cellularconcretewasusedasfortheunderlayandthe150mmthicksurfacelayerwasmadeofordinaryconcretewithfibre（steelwires）reinforcement（concreteB）.Cores80mmhighand80mmindiameterweredrilledfromthesurfacelayer.Ultrasonicmeasurementsanddestructivetestswereperformedasdescribedabove.Alsothetestresultswerehandledinasimilarway.Anexemplarystrengthdistributionalongthefloor’sthicknessisshowninFigure6.

5.Conclusions

Testsofordinaryconcretesshowunexpectedlygreatlyreducedstrengthintheupperzoneofhorizontallymouldedstructuralcomponents.Thisistoalargedegreeduetothevibrationofconcreteasaresultofwhichcoarseaggregatedisplacesdownwardsmakingthelowerlayersmorecompactwhileairmovesupwardsaeratingtheupperlayersandtherebyincreasingtheirporosity.Theincreaseintheconcrete’sporosityresultsinalargedropinitscompressivestrength.Thankstotheuseoftheultrasonicmethodandprobeswithexponentialconcentratorsitcouldbedemonstratedhowthecompressivestrengthofordinaryconcreteisdistributedalongthethicknessofstructuralcomponentsinbuildingstructures.Itbecameapparentthatthereductionincompressivestrengthinthecompressedzoneofstructuralcomponentsunderbendingandinindustrialconcretefloorscanbeverylarge（amountingtoasmuchas50%ofthestrengthoftheslab’slowerzone）.Thereforethisphenomenonshouldbetakenintoaccountatthestageofcalculatingslabs,reinforcedconcretebeamsandindustrialfloors[6].

Theresultsofthepresentedinvestigationsapplytoordinaryconcretes（OC）whichareincreasinglysupplantedbyself-compactingconcretes（SCC）andhigh-performanceconcretes（HPC）.Sincenointensivevibrationisrequiredtomouldstructuresfromsuchconcretesonecanexpectthattheyaremuchmorehomogenousalongtheirthickness[7].Thiswillbeknownoncetheongoingexperimentalresearchiscompleted.

BohdanStawiski

StrengthofConcreteinSlabs,InvestigatesalongDirectionofConcreting[D]

InstituteofBuildingEngineering,WroclawUniversityofTechnologyWybrzezeWyspianskiego,Wroclaw,Poland

ReceivedOctober15,2011;revisedNovember21,2011;acceptedNovember30,2011

译文:

混凝土强度与混凝土浇筑方向关系的研究

摘要

从理论上看，假设混凝土复合材料是各项同性的从宏观尺度上讲。

例如，假定在所有的方向楼板或梁的强度是相同并且它的非均匀性是随机的。

因此，倘若既不计算结构构件的承载能力，也不考虑结构中混凝土的技术，在考虑到足够程度的情况，关于混凝土各向同性的假设是过于乐观的。

目前的研究表明，在沿浇筑方向混凝土强度有变化不只是一个定性的影响（正如人们普遍认为的），但也有显著的定量效应。

这说明混凝土是一种尚未被完全认识的复合材料。

本文介绍了普通混凝土（OC）同质性构件厚度沿浇筑方向的评价。

超声波法和混凝土接触点修正指数头被用在研究[1-3]。

关键词：

混凝土；混凝土抗压强度；非破坏性

1.介绍

在一个建筑结构中，有一部分是具有特殊性质的，但不一定是在整个截面上的。

例如梁、楼板这样的弯曲部件，一般都是在其上部受压，而混凝土的抗压强度则主要是在这个区域内。

组件通常在一直被保养的位置压模，即在压缩下的上部区域。

在上部区域的混凝土被认为将略弱于在较低的区域，但目前尚不清楚有弱了多少[4,5]。

生产大厅的地板是最容易磨损和冲击载荷，在其上部区域不是他们最强的部分。

在实践是我们都知道工业地板属于最经常损坏的建筑组件。

他们只能从钢筋混凝土梁或楼板的底面进行试验，在此基础上得到整个截面的混凝土强度的结果，包括在压缩的上部区域。

因此而产生的一个问题：

在类似的这种试验中的错误有多少？

为了回答上述问题和其他问题，在各种结构构件混凝土