土木工程专业英语 陈瑛 3.1.load conditions and load paths新

在线教务辅导网HTTP/WWWSHANGFUWANGCOM更多课程配套课件资源请访问在线教务辅导网31LOADCONDITIONSANDLOADPATHS2018/1/102VERTICALLOADSNGRAVITYLOADSACTINTHESAMEDIRECTIONASGRAVITYIE,DOWNWARDORVERTICALLYVERTICALLOADSNGRAVITYLOADSINCLUDENDEADLOADSNLIVELOADSNSNOWLOADSNWINDUPLIFTFORCESVERTICALLOADSNGRAVITYLOADSSTATICINNATUREUNIFORMLYDISTRIBUTEDLOAD/CONCENTRATEDLOADNTHUS,DETERMININGAGRAVITYLOADONABEAMORCOLUMNISARELATIVELYSIMPLEEXERCISETHATUSESTHECONCEPTOFTRIBUTARYAREAS从属面积TOASSIGNLOADSTOSTRUCTURALELEMENTSTRIBUTARYAREASLSQMLOADONBEAMWSKG/MFLOORLOADWKG/SQMLSSSSSPANINSHORTDIRECTIONLSPANINLONGDIRECTIONNTHETRIBUTARYAREAISTHEAREAOFTHEBUILDINGCONSTRUCTIONTHATISSUPPORTEDBYASTRUCTURALELEMENT,INCLUDINGTHEDEADLOADIE,WEIGHTOFTHECONSTRUCTIONANDANYAPPLIEDLOADSIE,LIVELOADTRIBUTARYAREASLSQMLOADONBEAMWSKG/MFLOORLOADWKG/SQMLSSSSSPANINSHORTDIRECTIONLSPANINLONGDIRECTIONNFOREXAMPLE,THETRIBUTARYGRAVITYLOADONAFLOORJOISTWOULDINCLUDETHEUNIFORMFLOORLOADDEADANDLIVEAPPLIEDTOTHEAREAOFFLOORSUPPORTEDBYTHEINDIVIDUALJOISTTRIBUTARYAREASLSQMLOADONBEAMWSKG/MFLOORLOADWKG/SQMLSSSSSPANINSHORTDIRECTIONLSPANINLONGDIRECTIONCASTINPLACEWITHSPANRATIOMS/L05ONEWAYSLABTRIBUTARYAREAONEWAYSLABLONGSPANABFLOORLOADQKN/M2TRIBUTARYAREASL/2S2/4M2LOADONBEAMKN/MSHORTSPANBCFLOORLOADQKN/M2TRIBUTARYAREAS2/4M2LOADONBEAMQS/4QS/3KN/M双向板TWOWAYSLAB45O45O45O45OADCBSLSPANRATIOMS/LBCBCNWINDUPLIFTFORCESAREGENERATEDBYNEGATIVESUCTIONPRESSURESACTINGINANOUTWARDDIRECTIONFROMTHESURFACEOFTHEROOFINRESPONSETOTHEAERODYNAMICS7ZEREUDAI5NAMIKS空气动力特性OFWINDFLOWINGOVERANDAROUNDTHEBUILDINGNWINDPRESSURESACTPERPENDICULARTOTHEBUILDINGSURFACENOTINTHEDIRECTIONOFGRAVITYANDTHATPRESSURESVARYACCORDINGTOTHESIZEOFTHETRIBUTARYAREAANDITSLOCATIONONTHEBUILDING,PARTICULARLYPROXIMITYTOCHANGESINGEOMETRYEG,EAVES,CORNERS,ANDRIDGES影响风荷载大小的因素N风速N建筑物的高度、形状N周围环境风载体型系数S风荷载与建筑体型的关系风压分布系数迎风面的风压力在建筑物的中间偏上为最大，两边及底下最小；侧风面一般近侧大，远侧小，分布也极不均匀；背风面一般两边略大，中间小。风荷载体型系数是指风作用在建筑物表面所引起的压力吸力与原始风速算得的理论风压的比值。LATERALLOADSNTHEPRIMARYLOADSTHATPRODUCELATERALFORCESONBUILDINGSAREATTRIBUTABLETO可归因于FORCESASSOCIATEDWITHWINDSEISMICGROUNDMOTIONSOILNLATERALFORCESFROMWINDAREGENERATEDBYPOSITIVEWINDPRESSURESONTHEWINDWARDFACEOFTHEBUILDINGANDBYNEGATIVEPRESSURESONTHELEEWARDFACEOFTHEBUILDING,CREATINGACOMBINEDPUSHANDPULLEFFECT,ANDRESULTINGUPLIFTING,RACKINGORSLIDINGOFBUILDINGRACKINGLOADALOADAPPLIEDINTHEPLANEOFANASSEMBLYINSUCHMANNERASTOLENGTHENONEDIAGONALANDSHORTENTHEOTHERNSEISMICLATERALFORCESAREGENERATEDBYASTRUCTURESDYNAMICINERTIAL惯性的RESPONSETOCYCLICGROUNDMOVEMENTNTHEMAGNITUDEOFTHESEISMICSHEARLOADDEPENDSONMAGNITUDEOFTHEGROUNDMOTIONBUILDINGSMASSDYNAMICSTRUCTURALRESPONSECHARACTERISTICSIE,DAMPENING,DUCTILITY,NATURALPERIODOFVIBRATION,ETCNFORLOWRISESTRUCTURES,ASIMPLIFIEDSEISMICLOADANALYSISEMPLOYSEQUIVALENTSTATICFORCESBASEDONFUNDAMENTALNEWTONIANMECHANICSFMAWITHSOMEWHATSUBJECTIVEIE,EXPERIENCEBASEDADJUSTMENTSTOACCOUNTFORINELASTIC,DUCTILERESPONSECHARACTERISTICSOFVARIOUSBUILDINGSYSTEMSLATERALLOADSLOADPATHOFAMAONRYSTRUCTURETHEVERTICALLOADPATHNDEADLOADALWAYSPRESENTNLIVELOADSTRANSIENTATONLYAFRACTIONOFTHEIRDESIGNLOADNCURRENTDESIGNLOADSTANDARDSGENERALLYALLOWFORMULTIPLETRANSIENTLOADREDUCTIONS楼面活荷载折减）LOADPATHOFAMAONRYSTRUCTUR