土木外文翻译.docx

土木外文翻译.docx

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土木外文翻译

Introductiontoreinforcedconcreteandearthworks

Abstract

Asadesignermustfirstclearthebuildingstructureitselfwasdesignedandintensitylevels,aswellasrelatedissuesin-depthdiscussionandresearch,thispaperdescribesonthereinforcedconcrete,earthworkengineeringknowledge,letmorein-depthunderstandingofthisDiscussesthekey,andtherationalapplicationofknowledgetohelpusdesignmoreexcellentbuilding

Keywords:

concrete；earthwork；structuralsafety

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1ReinforcedConcrete

Plainconcreteisformedfromahardenedmixtureofcement,water,fineaggregate,coarseaggregate（crushedstoneorgravel）,air,andoftenotheradmixtures.Theplasticmixisplacedandconsolidatedintheformwork,thencuredtofacilitatetheaccelerationofthechemicalhydrationreactionlfthecement/watermix,resultinginhardenedconcrete.Thefinishedproducthashighcompressivestrength,andlowresistancetotension,suchthatitstensilestrengthisapproximatelyonetenthlfitscompressivestrength.Consequently,tensileandshearreinforcementinthetensileregionsofsectionshastobeprovidedtocompensatefortheweaktensionregionsinthereinforcedconcreteelement.

Itisthisdeviationinthecompositionofareinforcesconcretesectionfromthehomogeneityofstandardwoodorsteelsectionsthatrequiresamodifiedapproachtothebasicprinciplesofstructuraldesign.Thetwocomponentsoftheheterogeneousreinforcedconcretesectionaretobesoarrangedandproportionedthatoptimaluseismadeofthematerialsinvolved.Thisispossiblebecauseconcretecaneasilybegivenanydesiredshapebyplacingandcompactingthewetmixtureoftheconstituentingredientsareproperlyproportioned,thefinishedproductbecomesstrong,durable,and,incombinationwiththereinforcingbars,adaptableforuseasmainmembersofanystructuralsystem.

Thetechniquesnecessaryforplacingconcretedependonthetypeofmembertobecast:

thatis,whetheritisacolumn,abean,awall,aslab,afoundation.amasscolumns,oranextensionofpreviouslyplacedandhardenedconcrete.Forbeams,columns,andwalls,theformsshouldbewelloiledaftercleaningthem,andthereinforcementshouldbeclearedofrustandotherharmfulmaterials.Infoundations,theearthshouldbecompactedandthoroughlymoistenedtoabout6in.indepthtoavoidabsorptionofthemoisturepresentinthewetconcrete.Concreteshouldalwaysbeplacedinhorizontallayerswhicharecompactedbymeansofhighfrequencypower-drivenvibratorsofeithertheimmersionorexternaltype,asthecaserequires,unlessitisplacedbypumping.Itmustbekeptinmind,however,thatovervibrationcanbeharmfulsinceitcouldcausesegregationoftheaggregateandbleedingoftheconcrete.

Hydrationofthecementtakesplaceinthepresenceofmoistureattemperaturesabove50°F.Itisnecessarytomaintainsuchaconditioninorderthatthechemicalhydrationreactioncantakeplace.Ifdryingistoorapid,surfacecrackingtakesplace.Thiswouldresultinreductionofconcretestrengthduetocrackingaswellasthefailuretoattainfullchemicalhydration.

Itisclearthatalargenumberofparametershavetobedealtwithinproportioningareinforcedconcreteelement,suchasgeometricalwidth,depth,areaofreinforcement,steelstrain,concretestrain,steelstress,andsoon.Consequently,trialandadjustmentisnecessaryinthechoiceofconcretesections,withassumptionsbasedonconditionsatsite,availabilityoftheconstituentmaterials,particulardemandsoftheowners,architecturalandheadroomrequirements,theapplicablecodes,andenvironmentalreinforcedconcreteisoftenasite-constructedcomposite,incontrasttothestandardmill-fabricatedbeamandcolumnsectionsinsteelstructures.

Atrialsectionhastobechosenforeachcriticallocationinastructuralsystem.Thetrialsectionhastobeanalyzedtodetermineifitsnominalresistingstrengthisadequatetocarrytheappliedfactoredload.Sincemorethanonetrialisoftennecessarytoarriveattherequiredsection,thefirstdesigninputstepgeneratesintoaseriesoftrial-and-adjustmentanalyses.

Thetrial-and–adjustmentproceduresforthechoiceofaconcretesectionleadtotheconvergenceofanalysisanddesign.Henceeverydesignisananalysisonceatrialsectionischosen.Theavailabilityofhandbooks,charts,andpersonalcomputersandprogramssupportsthisapproachasamoreefficient,compact,andspeedyinstructionalmethodcomparedwiththetraditionalapproachoftreatingtheanalysisofreinforcedconcreteseparatelyfrompuredesign.Concretestresstest

1TestIntroductionThetensilepropertiesofconcretecanbeenhancedsubstantiallybyincorporatinghighstrengthandsmalldiametershortsteelfibers.whichleadstothesteelfiberreincedconcrete（SFRC）.InconventionalSFRC,thesteelfibercontentisusuallywithintherangeofO.2%-2%byvolume.Atsuchalow6hercontent.thetensileresponseofSFRCwouldassumeanonhardeningtype.whichischaracterizedbythewideningofasinglecrack,similartoanunreinforcedconcrete.Thecontributionoffibersisapparentinthepost-crackingresponse,representedbyanincreaseinpost-crackingductilityduetotheworkassociatedwithpulloutoffibersbridgingafailurecrack.However,improvementsinsomeotherproptiesareinsignificant.Moreover,thesofteningsegmentofthestress-straincurveofSFRCwithsuchalowfibercontentunderuniaxialtensiondifficulttobegotwithnormal

experimentalmethods.Manyworkshavebeendonetofmdasuitableandrelativelyeasywaytoanalyzethetensilecharacteristics.Anditwasreportedthatthewholecurvecouldbegotonanonnaltestingmachinewithstiffeningcolponentsadded.Inthisarticle,thestress-strainbehaviorofSFRCunderuniaxialtensionWasanalyzedfordifferentopesoffiber.ThetensilecharacteristicsofSFRCinfluencedbythematrixstrengthandthesteelfibercontentwerestudiedalso.Inaddition,thestress-straincurvesofhighstrengthSFRCwithdifferentfactorswerewellacquired.Themechanismoffiberreinforcedconcretetoenhanceresearch,toobtainsteelfiberreinforcedconcreteintensioncurveofthewholeprocess,usingthemostappropriatemethodofaxialtension,buttomakeStethetestingmethodsimproved,andthetestingmachinemusthaveenoughstiffnesstoensurethetestingprocessstability.Iswellknowninengineeringpractice,process,technologyandeconomicconditionsduetoconstructionconstraints,SFRC-dopedfibervolumeintherateofgenerallynotmorethan2%,whilemostoftheengineeringexalllple,thefiberfractionareabout1%.InthispaperthedesignoftheaxialtensionSFRCmaterialtesting,fiberdosagetotake1%,andusingdifferentopesoffiber-reinforcedforms,wereanalyzed.2ExperimentalContentThespecimensweretestedona601duniversaltestingmachine.Fourhighsteelbarswereaddedtoenhancethestiffuessofthetestingmachine.Inaddition,spherichingeswereusedtoabatetheinitialaxialeccentricityofthespecimens..Itwasensuredthatspecimensshouldbepulledunderuniaxialtensionbyadjustingthefourhighstrengthboltswhichconnectthespecimenstothecrossbeam.Andthedifferencebetweenthetensilestrainsoftheoppositesidesofthespecimenshouldbelessthan15%oftheirmeanvalue.Whenthefibercontentwaslow（0and0.5%byvolume）,thecyclicquirethewholestress-strain.2.1MaterialsFour叩pesofsteelfibersshowninTablewerechosenforthistest.Threeofthesefibers（Fl,F2andF3）werehooked---endandtheotherone（F4）wassmooth.Threeconcretemixtures,showninTable2,wereinvestigated.WaterreducingagentswereusedinC60andC80mixes（DK-5madebyDalianStructureResearchInstituteandSikamadeinSwitzerlandrespectively）.ThecompressivestrengthsoftheseC30,C60,C80mixes28daysusing150mmx150mmx150mmcubes.Averagedresultsfor3specimensaregiveninTable2.OrdinaryPortlandcement（yieldedbyDalianHuanengOnodaCementCompany）of32.5and52.5（accordingtoChinastandard）werechosen.Riversand（modulusoffmenessis2.6）andcrushedlimestoneaggregates（5-20Bin）wereused.TableMatrixStrengthgradeCementuJcSandSandCrushedWaterCompressivecodeOfcementKg/m3rahrahoKg/m3StrnereducingSength（lSO）。

Kg/m3Mpa

C3032.54500.440.366671155----37.07

C6052.55000.350.336021223DK-567.59

C8052.56000.290.315351190Sika82.96

Specimen

ThetensileSpeCllenwasbondedtosteelpaddingplatesatbothendsbytygoweld.Atotalof110specimensweredividedinto22groupsaccordingtocertainparameters.TheparametersofthesespecimenseshowninTable3.2.3ItemsAttheageof28days.plainconcreteandsteelfiberconcretespeciInensweretestedfortensilestrength,respectively.Thetensilestress-straincveswereacquired.Manyothertensilecharactersofthehighstrengthsteelfiberconcretesuchastensilework,etcwerecalculateda1so.Enhancedclasssteelfiberreinforcedconcretetoughnesscategorythanthestrengthofsteelfiberreinforcedconcreteanaverageof13%;whilecrackingfromthebasictotheαackwidthof0.5mminterval（thecorrespondingstrainofabout2000με）showedtherenerrintegral:

tougheningclasssteelfiberreinforcedconcreteenhancedclassthanthefractureenergyofsteelfiberreinforcedconcreteanaverageof20%.omTable3alsoshowsthatmostoftheSFRCfrrstpeakcorrespondstothelimitoftensilestrainvalueandplainconαeterather,inthe100μεaround，indicatingalowrateoffiber-containingincorporationinimprovingtheroleofultiInatetensilestrainofconcretenoteverobvious.letougheningclassSFRCsecondpeakco