土木工程毕业设计外文翻译最终中英文.docx

土木工程毕业设计外文翻译最终中英文.docx

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土木工程毕业设计外文翻译最终中英文土木工程毕业设计外文翻译最终中英文7Rigid-FrameStructuresArigid-framehigh-risestructuretypicallycomprisesparallelororthogonallyarrangedbentsconsistingofcolumnsandgirderswithmomentresistantjoints.Resistancetohorizontalloadingisprovidedbythebendingresistanceofthecolumns,girders,andjoints.Thecontinuityoftheframealsocontributestoresistinggravityloading,byreducingthemomentsinthegirders.Theadvantagesofarigidframearethesimplicityandconvenienceofitsrectangularform.Itsunobstructedarrangement,clearofbracingmembersandstructuralwalls,allowsfreedominternallyforthelayoutandexternallyforthefenestration.Rigidframesareconsideredeconomicalforbuildingsofuptoabout25stories,abovewhichtheirdriftresistanceiscostlytocontrol.If,however,arigidframeiscombinedwithshearwallsorcores,theresultingstructureisverymuchstiffersothatitsheightpotentialmayextendupto50storiesormore.Aflatplatestructureisverysimilartoarigidframe,butwithslabsreplacingthegirdersAswitharigidframe,horizontalandverticalloadingsareresistedinaflatplatestructurebytheflexuralcontinuitybetweentheverticalandhorizontalcomponents.Ashighlyredundantstructures,rigidframesaredesignedinitiallyonthebasisofapproximateanalyses,afterwhichmorerigorousanalysesandcheckscanbemade.Theproceduremaytypicallyincludethefollowingstages:

1.Estimationofgravityloadforcesingirdersandcolumnsbyapproximatemethod.2.Preliminaryestimateofmembersizesbasedongravityloadforceswitharbitraryincreaseinsizestoallowforhorizontalloading.3.Approximateallocationofhorizontalloadingtobentsandpreliminaryanalysisofmemberforcesinbents.4.Checkondriftandadjustmentofmembersizesifnecessary.5.Checkonstrengthofmembersforworstcombinationofgravityandhorizontalloading,andadjustmentofmembersizesifnecessary.6.Computeranalysisoftotalstructureformoreaccuratecheckonmemberstrengthsanddrift,withfurtheradjustmentofsizeswhererequired.Thisstagemayincludethesecond-orderP-Deltaeffectsofgravityloadingonthememberforcesanddrift.7.Detaileddesignofmembersandconnections.Thischapterconsidersmethodsofanalysisforthedeflectionsandforcesforbothgravityandhorizontalloading.Themethodsareincludedinroughlytheorderofthedesignprocedure,withapproximatemethodsinitiallyandcomputertechniqueslater.StabilityanalysesofrigidframesarediscussedinChapter16.7.1RIGIDFRAMEBEHAVIORThehorizontalstiffnessofarigidframeisgovernedmainlybythebendingresistanceofthegirders,thecolumns,andtheirconnections,and,inatallframe,bytheaxialrigidityofthecolumns.Theaccumulatedhorizontalshearaboveanystoryofarigidframeisresistedbyshearinthecolumnsofthatstory（Fig.7.1）.Theshearcausesthestory-heightcolumnstobendindoublecurvaturewithpointsofcontraflexureatapproximatelymid-story-heightlevels.Themomentsappliedtoajointfromthecolumnsaboveandbelowareresistedbytheattachedgirders,whichalsobendindoublecurvature,withpointsofcontraflexureatapproximatelymid-span.Thesedeformationsofthecolumnsandgirdersallowrackingoftheframeandhorizontaldeflectionineachstory.Theoveralldeflectedshapeofarigidframestructureduetorackinghasashearconfigurationwithconcavityupwind,amaximuminclinationnearthebase,andaminimuminclinationatthetop,asshowninFig.7.1.Theoverallmomentoftheexternalhorizontalloadisresistedineachstorylevelbythecoupleresultingfromtheaxialtensileandcompressiveforcesinthecolumnsonoppositesidesofthestructure（Fig.7.2）.Theextensionandshorteningofthecolumnscauseoverallbendingandassociatedhorizontaldisplacementsofthestructure.Becauseofthecumulativerotationuptheheight,thestorydriftduetooverallbendingincreaseswithheight,whilethatduetorackingtendstodecrease.Consequentlythecontributiontostorydriftfromoverallbendingmay,in.theuppermoststories,exceedthatfromracking.Thecontributionofoverallbendingtothetotaldrift,however,willusuallynotexceed10%ofthatofracking,exceptinverytall,slender,rigidframes.Thereforetheoveralldeflectedshapeofahigh-riserigidframeusuallyhasashearconfiguration.Theresponseofarigidframetogravityloadingdiffersfromasimplyconnectedframeinthecontinuousbehaviorofthegirders.Negativemomentsareinducedadjacenttothecolumns,andpositivemomentsofusuallylessermagnitudeoccurinthemid-spanregions.Thecontinuityalsocausesthemaximumgirdermomentstobesensitivetothepatternofliveloading.Thismustbeconsideredwhenestimatingtheworstmomentconditions.Forexample,thegravityloadmaximumhoggingmomentadjacenttoanedgecolumnoccurswhenliveloadactsonlyontheedgespana