钢筋混凝土土木工程毕业设计外文文献翻译.docx

钢筋混凝土土木工程毕业设计外文文献翻译.docx

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钢筋混凝土土木工程毕业设计外文文献翻译

外文文献翻译

ReinforcedConcrete

Concreteandreinforcedconcreteareusedasbuildingmaterialsineverycountry.Inmany,includingtheUnitedStatesandCanada,reinforcedconcreteisadominantstructuralmaterialinengineeredconstruction.Theuniversalnatureofreinforcedconcreteconstructionstemsfromthewideavailabilityofreinforcingbarsandtheconstituentsofconcrete,gravel,sand,andcement,therelativelysimpleskillsrequiredinconcreteconstruction,andtheeconomyofreinforcedconcretecomparedtootherformsofconstruction.Concreteandreinforcedconcreteareusedinbridges,buildingsofallsortsundergroundstructures,watertanks,televisiontowers,offshoreoilexplorationandproductionstructures,dams,andeveninships.

Reinforcedconcretestructuresmaybecast-in-placeconcrete,constructedintheirfinallocation,ortheymaybeprecastconcreteproducedinafactoryanderectedattheconstructionsite.Concretestructuresmaybesevereandfunctionalindesign,ortheshapeandlayoutandbewhimsicalandartistic.Fewotherbuildingmaterialsoffthearchitectandengineersuchversatilityandscope.

Concreteisstrongincompressionbutweakintension.Asaresult,cracksdevelopwheneverloads,orrestrainedshrinkageoftemperaturechanges,giverisetotensilestressesinexcessofthetensilestrengthoftheconcrete.Inaplainconcretebeam,themomentsabouttheneutralaxisduetoappliedloadsareresistedbyaninternaltension-compressioncoupleinvolvingtensionintheconcrete.Suchabeamfailsverysuddenlyandcompletelywhenthefirstcrackforms.Inareinforcedconcretebeam,steelbarsareembeddedintheconcreteinsuchawaythatthetensionforcesneededformomentequilibriumaftertheconcretecrackscanbedevelopedinthebars.

Theconstructionofareinforcedconcretememberinvolvesbuildingafromofmoldintheshapeofthememberbeingbuilt.Theformmustbestrongenoughtosupportboththeweightandhydrostaticpressureofthewetconcrete,andanyforcesappliedtoitbyworkers,concretebuggies,wind,andsoon.Thereinforcementisplacedinthisformandheldinplaceduringtheconcretingoperation.Aftertheconcretehashardened,theformsareremoved.Astheformsareremoved,propsofshoresareinstalledtosupporttheweightoftheconcreteuntilithasreachedsufficientstrengthtosupporttheloadsbyitself.

Thedesignermustproportionaconcretememberforadequatestrengthtoresisttheloadsandadequatestiffnesstopreventexcessivedeflections.Inbeammustbeproportionedsothatitcanbeconstructed.Forexample,thereinforcementmustbedetailedsothatitcanbeassembledinthefield,andsincetheconcreteisplacedintheformafterthereinforcementisinplace,theconcretemustbeabletoflowaround,between,andpastthereinforcementtofillallpartsoftheformcompletely.

Thechoiceofwhetherastructureshouldbebuiltofconcrete,steel,masonry,ortimberdependsontheavailabilityofmaterialsandonanumberofvaluedecisions.Thechoiceofstructuralsystemismadebythearchitectofengineerearlyinthedesign,basedonthefollowingconsiderations:

1.Economy.Frequently,theforemostconsiderationistheoverallconstofthestructure.Thisis,ofcourse,afunctionofthecostsofthematerialsandthelabornecessarytoerectthem.Frequently,however,theoverallcostisaffectedasmuchormorebytheoverallconstructiontimesincethecontractorandownermustborroworotherwiseallocatemoneytocarryouttheconstructionandwillnotreceiveareturnonthisinvestmentuntilthebuildingisreadyforoccupancy.Inatypicallargeapartmentofcommercialproject,thecostofconstructionfinancingwillbeasignificantfractionofthetotalcost.Asaresult,financialsavingsduetorapidconstructionmaymorethanoffsetincreasedmaterialcosts.Forthisreason,anymeasuresthedesignercantaketostandardizethedesignandformingwillgenerallypayoffinreducedoverallcosts.

Inmanycasesthelong-termeconomyofthestructuremaybemoreimportantthanthefirstcost.Asaresult,maintenanceanddurabilityareimportantconsideration.

2.Suitabilityofmaterialforarchitecturalandstructuralfunction.Areinforcedconcretesystemfrequentlyallowsthedesignertocombinethearchitecturalandstructuralfunctions.Concretehastheadvantagethatitisplacedinaplasticconditionandisgiventhedesiredshapeandtexturebymeansoftheformsandthefinishingtechniques.Thisallowssuchelementsadflatplatesorothertypesofslabstoserveasload-bearingelementswhileprovidingthefinishedfloorand/orceilingsurfaces.Similarly,reinforcedconcretewallscanprovidearchitecturallyattractivesurfacesinadditiontohavingtheabilitytoresistgravity,wind,orseismicloads.Finally,thechoiceofsizeofsh