毕业论文之建筑

1、附录一、英文原文BuildingAbstract:Therearealotofbuildinghistoryandhistoricalbuildings,andthedevelopmentofsuchasbuildingmaterialsandsoon.Tillnowwehaveabettertechnologyandscienceaboutbuilding.Keywords:modernbuildingsandstructuralmaterials,buildingtypesanddesign,componentsofabuilding.ModernBuildingsandStructuralMaterialsManygreatbuildingsbuiltinearlieragesarestillinexistenceandinuse.AmongthemarethePantheonandColosseuminRome,HagiaSophiainIstanbul;theGothicchurchesofFranceandEngland,andtheRenaissancecathedra。

2、ls,withtheirgreatdomes,liketheDuomoinFlorenceandSt.Peter’sinRome.Theyaremassivestructureswiththickstonewallsthatcounteractthethrustofthegreatweight.Thrustisthepressureexertedbyeachpartofastructureonitsotherparts.Thesegreatbuildingswerenottheproductsofknowledgeofmathematicsandphysics.Theywereconstructedinsteadofthebasisofexperienceandobservation,oftenastheresultoftrialanderror.Oneofthereasonstheyhavesurvivedisbecauseofthegreatstrengththatwasbuiltintothem-strengthgreaterthannecessaryinmostcases.Bu。

3、ttheengineersofearliertimesalsohadtheirfailure.InRome,forexample,mostofthepeoplelivedininsula,greattenementblocksthatwereoftentenstorieshigh.Manyofthemwerepoorlyconstructedandsometimescollapsedwithconsiderablelossoflife.Today,however,theengineerhastheadvantagenotonlyofempiricalinformation,butalsoofscientificdatathatpermithimtomakecarefulcalculationsinadvance.Whenamodernengineerplansastructure,hetakesintoaccountthetotalweightofallitscomponentmaterials.Thisisknownasthedeadload,whichistheweightofth。

4、estructureitself.Hemustalsoconsidertheliveload,theweightofallthepeople,cars,furniture,machines,andsoonthatthestructurewillsupportwhenitisinuse.Instructuressuchasbridgesthatwillhandlefastautomobiletraffic,hemustconsidertheimpact,theforceatwhichtheliveloadwillbeexertedonthestructure.Hemustalsodeterminethesafetyfactor,thatis,anadditionalcapabilitytomakethestructurestrongerthanthecombinationofthethreeotherfactors.Themodernengineermustalsounderstandthedifferentstresstowhichthematerialsinastructureare。

5、subject.Theseincludetheoppositeforcesofcompressionandtension,Incompressionthematerialispressedorpushedtogether;intensionthematerialispulledapartorstretched,likearubberband.Inadditiontotensionandcompression,anotherforceisatwork,namelyshear,whichwedefinedasthetendencyofamaterialtofracturealongthelinesofstress.Theshearmightoccurinaverticalplane,butitalsomightrunalongthehorizontalaxisofthebeam,theneutralplane,wherethereisneithertensionnorcompression.Altogether,threeforcescanactonastructure:vertical-。

6、thosethatactupordown;horizontal-thosethatactsideways;andthosethatactuponitwitharotatingorturningmotion.Forcesthatactatanangleareacombinationofhorizontalandverticalforces.Sincethestructuresdesignedbycivilengineersareintendedtobestationaryorstable,theseforcesmustbekeptinbalance.Theverticalforces,forexample,mustbeequaltoeachother.Ifabeamsupportsaloadabove,thebeamitselfmusthavesufficientstrengthtocounterbalancethatweight.Thehorizontalforcesmustalsoequaleachothersothatthereisnottoomuchthrusteithertot。

7、herightortotheleft.Andforcesthatmightpullthestructurearoundmustbecounteredwithforcesthatpullintheoppositedirection.Oneofthemostspectacularengineeringfailuresofmoderntimes,thecollapseoftheTacomaNarrowsBridgein1904,wastheresultofnotconsideringthelastofthesefactorscarefullyenough.Whenstronggustsofwind,uptosix-fivekilometersanhour,struckthebridgeandalsoalateralmotionthatcausedtheroadwaytofall.Fortunately,engineerslearnfrommistakes,soitisnowcommonpracticetotestscalemodelsofbridgesinwindrunnelsforaero。

8、dynamicresistance.Theprincipalconstructionmaterialsofearliertimeswerewoodandmasonrybrick,stone,ortile,andsimilarmaterials.TheGreeksandRomanssometimesusedironrodsorclampstostrengthentheirbuildings.ThecolumnsoftheParthenoninAthens,forexample,haveholesdrilledinthemforironbarsthathavenowrustedaway.TheRomansalsousedanaturecementcalledpozzolana,madefromvolcanicash,thatbecomeashardasstoneunderwater.Bothsteelandcement,thetwomostimportantconstructionmaterialsofmoderntimes,wereintroducedinthenineteenthcen。

9、tury.Steel,basicallyanalloyofironandasmallamountofcarbon,hadbeenmadeuptothattimebyalaboriousprocessthatrestrictedittosuchspecialusesasswordblades.AftertheinventionoftheBessemerprocessin1856,steelwasavailableinlargequantitiesatlowprices.Theenormousadvantageofsteelisitstensilestrength;thatis,itdoesnotloseitsstrengthwhenitisunderacalculateddegreeoftension,aforcewhich,aswehaveseen,tendstopullapartmanymaterials.Newalloyshavefurtherincreasedthestrengthofsteelandeliminatedsomeofitsproblems,suchasfatigu。

10、e,whichisatendencyforittoweakenasaresultofcontinualchangesinstress.Moderncement,calledPortlandcement,wasinventedin1824.Itisamixtureoflimestoneandclay,whichisheatedandthengroundintoapowder.Itismixedatorneartheconstructionsitewithsand,aggregate(smallstones,crushedrocks,orgravel),andwatertomakeconcrete.differentstrengthandweight.Concreteisveryversatile;itcanbepoured,orevensprayedintoallkindsofshapes.Andwhereassteelhasgreattensilestrength,concretehasgreatstrengthundercompression.Thus,thetwosubstances。