土木工程毕业设计外文翻译.docx

土木工程毕业设计外文翻译.docx

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土木工程毕业设计外文翻译

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毕业设计（论文）

外文翻译

设计（论文）题目：

宁波新城艺术宾馆2#楼

结构设计与预算

学院名称：

建筑工程

专业：

土木工程

学生姓名：

顾丽敏学号：

06404010101

指导教师：

袁坚敏

2010年01月10日

外文原文I：

Afundamentalexplanationofthebehaviourof

reinforcedconcretebeamsinflexurebased

onthepropertiesofconcreteundermultiaxialstress

M.D.Kotsovos

DepartmentofCivilEngineering

ImperialCollegeofScienceandTechnology

London（U.K.）

　　Thepaperquestionsthevalidityofthegenerallyacceptedviewthatforareinforcedconcretestructuretoexhibit"ductile"behaviourunderincreasingloaditisnecessaryforthestressstrainrelationshipsofconcretetohaveagraduallydescendingpost-ultimatebranch.Experimentaldataarepresentedforreinforcedconcretebeamsinbendingwhichindicatethepresenceoflongitudinalcompressivestrainsonthecompressivefaceinexcessof0.0035.Itisshownthatthesestrains

whichareessentialfor"ductile"behaviour

arecausedbyacomplexmultiaxialcompressivestateofstressbelowultimatestrengthratherthanpostultimatematerialcharacteristics.Thepresenceofacomplexstresssystemprovidesafundamentalexplanationforbeambehaviourwhichdoesnotaffectexistingdesignprocedures.

1.INTRODUCTION

　　The"planesections"theorynot

onlyisgenerallyconsideredtodescriberealisticallythedeformationresponseofreinforcedandprestressedconcretebeamsunderflexureandaxialload

butisalsoformulatedsothatitprovidesadesigntoolnotedforbothitseffectivenessandsimplicity[1].Thetheorydescribesanalyticallytherelationshipbetweenload-carryingcapacityandgeometriccharacteristicsofabeambyconsideringtheequilibriumconditionsatcriticalcross-sections.Compatibilityofdeformationissatisfiedbythe"planecross-sectionsremainplane"assumptionandthelongitudinalconcreteandsteelstressesareevaluatedbythematerialstress-straincharacteristics.Transversestressesandstrainsareignoredforthepurposesofsimplicity.

　　Thestress-straincharacteristicsofconcreteincompressionareconsideredtobeadequatelydescribedbythedeformationalresponseofconcretespecimenssuchasprismsorcylindersunderuniaxialcompressionandthestressdistributioninthecompressionzoneofacross-sectionattheultimatelimitstate

asproposedbycurrentcodesofpracticesuchasCP110[1]

exhibitsashapesimilartothatshowninfigure1.Thefigureindicatesthatthelongitudinalstressincreaseswiththe

distancefromtheneutralaxisuptoamaximumvalueandthenremainsconstant.Suchashapeofstressdistributionhasbeenarrivedatonthebasisofbothsafetyconsiderationsandthewidelyheldviewthatthestress-strainrelationshipofconcreteincompressionconsistsofbothanascendingandagraduallydescendingportion（seefig.2）.Theportionbeyondultimatedefinesthepost-ultimatestresscapacityofthematerialwhich

Typicalstress-strainrelationshipforconcreteincompression.asindicatedinfigure1

isgenerallyconsideredtomakeamajorcontributiontothemaximumload-carryingcapacityofthebeam.

　　However

arecentanalyticalinvestigationofthebehaviourofconcreteunderconcentrationsofloadhasindicatedthatthepost-ultimatestrengthdeformationalresponseofconcreteundercompressivestatesofstresshasnoapparenteffectontheoverallbehaviourofthestructuralformsinvestigated（[2]

[3]）.Ifsuchbehaviouristypicalforanystructure

thenthelargecompressive

strains（inexcessof0.0035）measuredonthetopsurfaceofareinforcedconcretebeamatitsultimatelimitstate（seefig.1）

cannotbeattributedtopost-ultimateuniaxialstress-straincharacteristics.Furthermore

sincethecompressivestrainattheultimatestrengthlevelofanyconcreteunderuniaxialcompressionisoftheorderof0.002（seefig.2）

itwouldappearthatarealisticpredictionofthebeamresponseunderloadcannotbebasedsolelyontheascendingportionoftheuniaxialstress-strainrelationshipofconcrete.

　　Inviewoftheabove

theworkdescribedinthefollowingappraisesthewidelyheldviewthatauniaxialstress-strainrelationshipconsistingofanascendingandagraduallydescendingportionisessentialfortherealisticdescriptionofthebehaviourofareinforcedconcretebeaminflexure.Resultsobtainedfrombeamssubjectedtoflexureundertwo-pointloadingindicatethatthelargestrainsexhibitedbyconcreteinthecompressionzoneofthebeamsareduetoatriaxialstateofstressratherthantheuniaxialpost-ultimatestress-straincharacteristicsofconcrete.Itisshownthattheassumptionthatthematerialitselfsuffersacompleteandimmediatelossofload-carryingcapacitywhenultimatestrengthisexceedediscompatiblewiththeobserved"ductile"structuralbehaviourasindicatedbyload-deflexionormoment-rotationrel