土木工程英语论文.doc
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StructureofBulidings
Abuildingiscloselyboundupwithpeople,foritprovidespeoplewiththenecessaryspacetoworkandlivein.Asclassifiedbytheiruse,buildingsaremainlyoftwotypes:
industrialbuildingsandcivilbuildings.Industrialbuildingsareusedbyvariousfactoriesorindustrialproductionwhilecivilbuildingsarethosethatareusedbypeoplefordwelling,employment,educationandothersocialactivities.
Theconstructionofindustrialbuildingsisthesameasthatofcivilbuildings.However,industrialandcivilbuildingsdifferinthematerialused,andinthestructureformsorsystemstheyareused.
Consideringonlytheengineeringessentials,thestructureofabuildingcanbedifinedastheassemblageofthosepartswhichexistforthepurposeofmaintainingshapeandstability.Isprimypurposeistoresistanyloadsappliedtothebuildingandtotransmitthosetotheground.
Intermsofarchitecture,thestructueofabuildingisanddosemuchmorethanthat.Itisaninseparablepartofthebuildingformtovaryingdegreesisageneratorofthatform.Usedskillfully,thebuildingstructurecanestablishorreinforceordersandrhythmsamongthearchitecturevolumesandplanes.Itcanbevisuallydominantorrecessive.Itcandevelopharmoniesorconflicts.Itcanbebothconfiningandemincipating.And,unfortunatelyinsomecases,itcannotbeingored.Itisphysical.
Thestructuremustalsobeengineeredtomaintainthearchitectureform.Theprinciplesandtoolsofphysicsteandmathematicsprovidethebasisfordifferentiatingbetweenrationalandinrationalformsintermsofconstruction.Artistscansometimesgenerateshapesthatobviateanyconsiderationofscience,butarchitectscannot.
Thereareatleastthreeitemsthatmustbepresentinthestructureofabuilding:
stabily,strengthandstiffness,economy.
Takingthefirstofthethreerequiements,itisobviousthatstabilityisneededtomaintainshape.Anunstablebuildingstructureimpliesunbalancedforcesoralackofequilibriumandaconsequentaccelerationofthestructureoritspieces.
Therequirementofstrengthmeansthatthematerialsselectedtoresistthestressesgeneratedbytheloadsandshapesofthestructure(s)mustbeadequate.Indeed,a“factorofsafety”isusuallyprovidedsothatundertheanticipatedloads,agivenmaterialisnotstressedtoalevelevenclosetoitsrupturepoint.Thematerialpropertycalledstiffnessisconsideredwiththerequirementofstrength.Stiffnessisdifferentformstrengthinthatitdirectlyinvolveshowmuchastructurestrainsordeflectsunderload.Amaterialthatisverystrongbutlackinginstiffnesswilldeformtoomuchtobeofvalueinresistingtheforcesapplied.
Economyofabuildingstructurereferstomorethanjustthecostofthematerialused.Constructioneconomyisacomplicatedsubjectinvovlingrawmaterials,fabrication,erection,andmaintenance.Designandconstructionlaborcostsandthecostsofenergyconsumptionmoney(interest)areconsumptionmustbeconsiedered.Speedofconstructionandthecostofmoney(interest)arealsofactors.Inmostdesignsituations,morethanonestructuralmaterialrequiresconsideration.Completivealternativesalmostalwaysexist,andthechoiceisseldomobvious.
Apartformthesethreeprimaryrequirements,severalotherfactorsareworthyofemphasis.First,thestructureorsuctructuralsystemmustrelatetothebuilding’sfunction.Itshouldnotbeinconflictintermsofform.Forexample,alinearfunctiondemandsalinearstructure,andthereforeitwouldbeimpropertoroofabowlingalleywithadome.Similarly,atheatermusthavelarge,unobstructedspansbutafinerestaurantprobablyshouldnot.Statedsimply,thestructuremustbeappropriatetothefunctionitistoshelter.
Second,thestructuremustbefire-resistant.Itisobviousthatthestructuralsystemmustbeabletomaintainitsintegrityatleastuntiltheoccupuantsaresafelyout.Buildingcodesspecifythenumberofhoursforwhichcertainpartsofabuildingmustresisttheheatwithoutcollapse.Thestructuralmaterialsusedforthoseelementsmustbeinherentlyfire-resistantorbeadequentlyprotectedbyfireproofingmaterials.Thedegreeoffireresistancetobeprovidedwilldependuponanumberofitems,includingtheuseandoccupancyloadofthespace,itsdimensions,andthelocationofthebuilding.
Third,thestructureshouldintegratewellwiththebuilding’scirculationsystems.Itshouldnotbeinconflictwiththepipingsystemsforwaterandwaste,theductingsystemsforair,or(mostimportant)themovementofpeople.Itisobviousthatthevariousbuildingsystemsmustbecoordinatedasthedesignprogresses.Onecandesigninasequentialstep-by-stepmannerwithinanyonesystem,butthedesignofallofthemshouldmoveinaparallelmannertowardcompletion.Spatially,a