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EnglishforCivilEngineeringMajorsChapter2NewBuildingStructureSectionASteelStructureName：LiJiayuanNumber：201210103004Major：DisasterPreventionandReductionEngineeringandProtectiveEngineeringCollegeofCivilEngineering&Architecture,CTGU.October,20131SectionASteelStructure1.Steelstructurereferstoabuildinginwhichsteelplaystheleadingrole.Theearlydevelopmentofhigh-risebuildingsbeganwithstructuralsteelframing.Withthedevelopmentofscienceandtechnology,thetypesofsteelstructureisgrowing.Steelframebuildingandspacestructurearewithinit.Keywordofparagraph1：Steelstructure

2SectionASteelStructure2-1.Steelframebuildingconsistsofaskeletalframeworkwhichcarriesallloadstowhichthebuildingissubjected.Itismadeupofseparateelements-beams,columns,portals,trusses,plates,bracing,purlins,etc.3Fig.1Steelframestructure4SectionASteelStructure2-3.Theseelementsmustbejoinedtogethersoastobeinpositionandcarryloadswithoutbulkingoutoftheplane.Steelframestructuresareextensivelyusedinoffice,flat,industry,hospital,etc.Keywordofparagraph2：elements6SectionASteelStructure3-1.Oneofthevisiblechangesonsteelstructureistheremarkabletrendtowardsgreateruseofspacestructures;thistrendisgrowingasaresultofarchitecturalpreference.Thisispartlydue,nodoubt,toreactionfrombeam-columnsystemsofpreviousdecades,butalsoduetotherealizationoftheadvantagesofspacesstructures.7SectionASteelStructure3-2.Structuralengineersrealizedmanyyearsagothefactthatspacestructurerequireslessmaterialthantheconventionallinearsystemsandthat,ifproperlydesigned,prefabricatedspacestructurescanhighlyeconomicalincost.Keywordofparagraph3：spacestructure8Fig.2SpacestructureBeijingNationalStadium(Bird'sNest/OlympicStadium)9Fig.3Spacestructure(BeijingNationalAquaticsCenter）10SectionASteelStructure4.Therearevarioustypesofspacestructures,differingintheirbehaviorunderloadandrequiringdifferentmethodsofanalysis.Double-layergridsaretypicalexamplesofspacestructuresandalsooneofthemostpopularformsofspaceframes;theyarefrequentlyusednowadaysallovertheworldforcoveringlarge-spanindustrialbuildings,sportshalls,churches,andexhibitioncenters.Keywordofparagraph4：double-layer-grids11SectionASteelStructure5.Presentexperienceshowsthatinmanycountriesdouble-layergridsstructurescancompleteverysuccessfullyonacostbasiswithmoreconventionalsystems,providingatthesametimeadditionaladvantages,suchasgreaterrigidity,simplificationoferectionandthepossibilityofcoveringlargerspans.Keywordofparagraph5：advantages12SectionASteelStructure6.Designofconnectionisimportantinsteelstructuredesign.Jointsaredesignedtotransmitaxialload,shear,momentandtorsionastheframeanalysisanddesignofmembers.Ingeneral,apinnedjointtransmitsaxialloadandshear;arigidjointtransmitsallactions.Slidingjointstotransmitareactiononlyareoftenrequiredwhereprovisionforexpansionisneeded.Jointsaremadebyrivets,boltsandwelds.Keywordofparagraph6：joints13SectionASteelStructureFig4.Steeljoint14SectionASteelStructure7.Weldingresultsinimportantadvantages,forexample,thestructureiscleanerandbetterlooking,maintenancecostsarelower.Butthedefectswhichoccurinweldsleadtoareductioninstrengthofthejointandtheymayalsoinitiatefailureduetobrittlefractureoffatigue.Themaindefectsconsistof:slaginclusions,gaspockets,incompletepenetration,undercutting,residualstressanddistortion.Keywordofparagraph7：weldingFig5.Welding15SectionASteelStructure8-1.Thetwotypesofboltsingeneraluseinstructuralsteelworkareblackboltsandhigh-strengthfractiongripbolts.Theblackboltsareforgedfromroundbarswithmachinedthreadsonboltsandnuts,theyareusedinholeswith2mmclearance,theymaybeusedinshear,tension,torsionorincombinedshear,tensionandtorsion.16SectionASteelStructure8-2.Thehigh-strengthfractiongripboltsmustbetightenedtogivetherequiredshanktension,theboltsareusedinholeslessthan2mmclearanceandinshear,tension,bendingorincombinedshear,tensionandbending.Jointswithhigh-strengthfractiongripboltscangivehighercapacityandlittledeformationcomparedwithblackbolts.Keywordofparagraph8：boltsFig6.Bolt17SectionASteelStructure9.Steelsectionsincludehotrolledandformedsections,cold-rolledsectionsandbuild-upsections.Thehotrolledandformedsections,suchas,equalandunequalangles,channels,structuraltees,circular,squareandrectangularhollowsections.Thecold-rolledsections,suchaszed,lippedchannel.Build-upcolumnandboxcolumnarebuild-upsections.Forasymmetricalsections,theneutralaxismustbelocatedfirst.Forbuild-upsections,thepropertiesmustbecalculated.Keywordofparagraph9：Steelsections

18Structureoftheco