建筑英语论文--建筑材料地应用--英汉对照

1、WORD格式PAGE1 / NUMPAGES4Theapplicationofconstructionalmaterial建筑材料的应用Theavailabilityofsuitablestructuralmaterialsisoneoftheprincipallimitationsontheaccomplishmentofanexperiencedstructuralengineer.Earlybuildersdependedalmostexclusivelyonwood,stone,brick,andconcrete.Althoughironhadbeenusedbyhumansatlea

2、stsincethebuildingoftheEgyptianpyramids,useofitasastructuralmaterialwaslimitedbecauseofthedifficultiesofsmeltingitinlargequantities.Withtheindustrialrevolution,however,cameboththeneedforironasastructuralmaterialandthecapabilityofsmeltingitinquantity.JohnSmeaton,anEnglishcivilengineer,wasthefirsttous

3、ecastironextensivelyasastructuralmaterialinthemid-eighteenthcentury.After1841,malleableironwasdevelopedasamorereliablematerialandwaswidelyused.Whereasmalleableironwassuperiortocastiron,therewerestilltoomanystructuralfailuresandtherewasaneedforamorereliablematerial.Steelwastheanswertothisdemand.Thein

4、ventionoftheBessemerconverterin1856andthesubsequentdevelopmentoftheSiemens-Martinopen-hearthprocessformakingsteelmadeitpossibletoproducestructuralsteelatcompetitivepricesandtriggeredthetremendousdevelopmentsandaccomplishmentsintheuseofstructuralsteeloverthenexthundredyears.Themostseriousdisadvantage

5、ofsteelisthatitoxidizeseasilyandmustbeprotectedbypaintorsomeothersuitablecoating.Whensteelisusedinanenclosurewhereafirecouldoccur,thesteelmembersmustbeencasedinasuitablefire-resistantenclosuresuchasmasonry,concrete.Normally,steelmemberswillnotfailinabrittlemannerunlessanunfortunatecombinationofmetal

6、lurgicalcomposition,lowtemperature,andbi-ortriaxialstressexists.Structuralaluminumisstillnotwidelyusedincivilengineeringstructures,thoughitsuseissteadilyincreasing.Byaproperselectionofthealuminumalloyanditsheattreatment,awidevarietyofstrengthcharacteristicsmaybeobtained.Someofthealloysexhibitstress-

7、straincharacteristicssimilarthoseofstructuralsteel,exceptthatthemodulusofelasticityfortheinitiallinearlyelasticportionisabout10,000,000psi(700,000kgf/cm*cm)oraboutone-thirdthatofsteel.Lightnessandresistancetooxidationare,ofcourse,twoofthemajoradvantagesofaluminum.Becauseitspropertiesareverysensitive

8、toitsheattreatment,caremustbeusedwhenrivetingorweldingaluminum.Severaltechniqueshavebeendevelopedforprefabricatingaluminumsubassembliesthatcanbereadilyerectedandboltedtogetherinthefieldtoformanumberofbeautifulandwell-designedshellstructures.Thisgeneralprocedureofprefabricationandheldassemblybyboltin

9、gseemstobethemostpromisingwayofutilizingstructuralaluminum.Reinforcedandprestessesconcretesharewithstructuralmaterial.Naturalcementconcreteshavebeenusedforcenturies.Modernconcreteconstructiondatesfromthemiddleofthenineteenthcentury,thoughartificialPortlandcementwaspatentedbyAspidin,anEnglishman,abou

10、t1825.Althoughseveralbuildersandengineersexperimentedwiththeuseofsteel-reinforcedconcreteinthelasthalfofthenineteenthcentury,itsdominantuseasabuildingmaterialdatesfromtheearlydecadesofthetwentiethcentury.Thelastfiftyyearshaveseentherapidandvigorousdevelopmentofprestressedconcretedesignandconstructio

11、n,foundedlargelyonearlyworkbyFreyssinetinFranceandMagnelinBelgium.Plain(unreinforced)concretenotonlyisaheterogeneousmaterialbutalsohasoneveryseriousdefectasastructuralmaterial,namely,itsverylimitedtensilestrength,whichisonlyoftheorderofone-tenthitscompressivestrength.Notonlyistensilefailureinconcret

12、eofabrittletype,butlikewisecompressionfailureoccursinarelativelybrittlefashionwithoutbeingprecededbytheforewarningoflargedeformations.(Ofcourse,inreinforced-concreteconstruction,ductilebehaviorcanbeobtainedbyproper1selectionandarrangementofthereinforcement.)Unlesspropercareisusedintheselectionofaggr

13、egatesandinthemixingandplacingofconcrete,frostactioncancauseseriousdamagetoconcretemasonry.Concretecreepsunderlong-termloadingtoadegreethatmustbeconsideredcarefullyinselectingthedesignstressconditions.Duringthecuringprocessanditsearlylife,concreteshrinksasignificantamount,whichtoadegreecanbecontroll

14、edbyproperlyproportioningthemixandutilizingsuitableconstructiontechniques.Withallthesepotentiallyseriousdisadvantages,engineershavelearnedtodesignandbuildbeautiful,durable,andeconomicalreinforced-concretestructuresforpracticallyallkindsofstructuralrequirements.Thishasbeenaccomplishedbycarefulselecti

15、onofthedesigndimensionsandthearrangementofthesteelreinforcement,developmentofpropercements,selectionofproperaggregatesandmixproportions,carefulcontrolofmixing,placing,andcuringtechniquesandimaginativedevelopmentofconstructionmethods,equipmentandprocedures.Theversatilityofconcrete,thewideavailability

16、ofitscomponentmaterials,theuniqueeaseofshapingitsformtomeetstrengthandfunctionalrequirements,togetherwiththeexcitingpotentialoffurtherimprovementsanddevelopmentofnotonlythenewerprestressedandprecastconcreteconstructionbutalsotheconventionalreinforcedconcreteconstruction,combinetomakeconcreteastrongc

17、ompetitorofothermaterialsinaverylargefractionofstructures.Inmoderntimes,withtheincreaseduseofsteelandreinforced-concreteconstruction,woodhasbeenrelegatedlargelytoaccessoryuseduringconstruction,touseintemporaryandsecondarystructures,andtouseforsecondarymembersofpermanentconstruction.Moderntechnologyi

18、nthelastsixtyyearshasrevitalizedwoodasastructuralmaterial,however,bydevelopingvastlyimprovedtimberconnectors,varioustreatmentstoincreasethedurabilityofwood,andlaminatedwoodmadeofthinlayersbondedtogetherwithsyntheticgluesusingrevolutionarygluingtechniques.Plywoodwithessentiallynondirectionalstrengthp

19、ropertiesisthemostwidelyusedlaminatedwood,buttechniqueshavealsobeendevelopedforbuildinglargelaminatedwoodmembersthatforcertainstructuresarecompetitivewithconcreteandsteel.Materialswithfuturepossibilitiesaretheengineeringplasticsandtheexoticmetalsandtheiralloys,suchasberyllium,tungsten,tantalum,titan

20、ium,molybdenum,chromium,vanadium,andniobium.Therearemanydifferentplasticsavailable,andthemechanicalpropertiesexhibitedbythisgroupofmaterialsvaryoverawiderangethatencompassestherangeofpropertiesavailableamongthemorecommonlyusedstructuralmaterials.Thusinmanyspecificdesignapplicationsitispossibletosele

21、ctasuitableplasticmaterialforanalternativedesign.Experiencewiththeuseofplasticsoutdoorsislimited.Generallyspeaking,however,plasticsmustbeprotectedfromtheweather.Thisaspectofdesignisthereforeamajorconsiderationintheuseofplasticsforprimarystructuralelements.Oneofthemostpromisingpotentialusedofplastics

22、isforpanelandshell-typestructures.Laminatedorsandwichpanelshavebeenusedinsuchstructureswithencouragingresultsthatindicateanincreaseduseinthistypeofconstructioninthefuture.Anothermaterialsdevelopmentwithinterestingpossibilitiesisthatofcompositesconsistingofamatrixreinforcedbyfibersorfiberlikeparticle

23、s.Althoughglass-fiber-reinforcedcompositeswithaglassorplasticmatrixhavebeenusedforyears,theyappeartohavemuchbroaderpossibilitiesforalargevarietyofsecondarystructuralcomponents.Fiber-reinforcedconcreteisanothercompositebeingactivelystudiedanddeveloped.Severalexperimentalapplicationsarebeingobservedun

24、derserviceconditions.Experimentshavebeenconductedwithbothsteelandglassfibers,butmostoftheserviceexperiencehasbeenwithsteelfibers.2建筑材料的应用适当有效的建筑材料是限制富有经验的结构工程师成就的主要原因之一。早期的建筑者几乎都只使用木材，石头，砖块和混凝土。尽管铸铁在修建埃及的金字塔中已被人们使用,但是把它作为建筑材料却由于大量熔炼它比较困难而被限制。藉由产业革命，然而，受到把铸铁作为建筑材料和在大量融炼它的能力的两者对其双重需要的影响。JohnSmeaton，一个

25、英国土木工程师,在十八的世纪中时，是第一广泛地使用铸铁作为建筑材料的。在1841之后，可锻金属被发展成更可靠的材料并且广泛地被应用。尽管可锻金属优于铸铁,但仍有很多结构破坏从而需要有更可靠的材料。钢便是这一需要的答案。1856年的贝色麦转转炉炼钢法和后来发展的马丁平炉炼钢法的发明使以竞争的价格形成了生产建筑用钢并且兴起了建筑用钢在下个百年的快速发展。钢的最严重缺点是它容易被氧化而需要被油漆或一些其他的适当涂料保护。当钢被用于可能发生火灾环境时,钢应该包围在一些耐火的材料中,例如石料或混凝土。通常，钢的组合结构不易被压碎除非是在冶金成分不好，低温的不利组合,或空间压力存在的情况下。建筑用铝仍然不

26、广泛被在土木工程结构中用,虽然它的使用正在稳定地增加。藉着铝合金作为一个适当的选择和对其进行热处理,可获得各式各样的强度特性。一些合金所展现的抗压强度特性相似于钢,除线形弹性模量大约是7,000,000牛/平方厘米，相当于刚的三分之一。质量轻和耐氧化是铝的两个主要优点。因为它的特性对热处理是非常敏感的,当铆接或焊接铝的时候，一定要小心仔细。一些技术已为制造预制铝组合配件及形成若干的美丽的设计良好的外型结构的铝制结构而发展起来。组合房屋配件制造的一般程序藉由螺栓连接，这似乎是利用建筑用铝的最有前途的方法。加强和预应力混凝土是主要的建筑材料。天然的水泥混凝土已经被使用长达数世纪之久。现代的混凝土建

27、筑兴起于十九世纪中叶,尽管人造水泥被Aspidin，一个英国人于1825年申请了专利.虽然一些建筑者和工程师在十九世纪后期用钢筋混凝土作实验,但作为一种建筑材料它占统治地位是在二十世纪初期。后五十年钢筋混凝土结构设计和建筑得到迅速发展,早期在法国的Freyssinet和比利时的Magnel被大量使用。素混凝土作为建筑材料有一个非常严重的缺点：就是它的抗拉强度非常有限,只是它的抗压强度的十分之一。素混凝土不仅受拉破坏是脆性破坏，而且受压破坏也是在没有多大变形预兆的情况下发生的准脆性破坏。(当然,在钢筋混凝土建筑中,可以得到适当的延性)。只有进行适当的养护和合理的选择并且掺加适当的混合天加剂,否则霜冻破坏能严重的损害混凝土。在长期荷载作用下混凝土在选择设计受压情况方面要仔细考虑。在硬化的时候和它的早期养护下,混凝土收缩占主要地位,因此需要添加