土木工程专业英语 陈瑛 6.4.analysis of rigid reinforced concrete frame structures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64ANALYSISOFRIGIDREINFORCEDCONCRETEFRAMESTRUCTURES2018/1/102RIGIDFRAMEBEHAVIOR框架结构性能NAFORCESANDDEFORMATIONSCAUSEDBYEXTERNALSHEARNBFORCESANDDEFORMATIONSCAUSEDBYEXTERNALMOMENT框架总体剪切变形框架总体弯曲变形RIGIDFRAMEBEHAVIOR框架结构性能RIGIDFRAMEBEHAVIORNTHESHEARCAUSESTHESTOREYHEIGHTCOLUMNSTOBENDINDOUBLECURVATUREWITHINFLECTIONPOINTS反弯点ATAPPROXIMATELYMIDSTOREYHEIGHTLEVELSNTHEMOMENTSAPPLIEDTOAJOINTFROMTHECOLUMNSABOVEANDBELOWARERESISTEDBYTHEATTACHEDGIRDERS,WHICHAREALSOBENTINDOUBLECURVATURE,WITHINFLECTIONPOINTSATAPPROXIMATELYMIDSPANRIGIDFRAMEBEHAVIORNTHESEDEFORMATIONSOFTHECOLUMNSANDGIRDERSALLOWRACKINGOFTHEFRAMEANDHORIZONTALDEFLECTIONINEACHSTOREYNTHEOVERALLDEFLECTIONSHAPE总体变形OFARIGIDFRAMESTRUCTUREDUETORACKINGHASASHEARCONFIGURATION剪切变形WITHCONCAVITY凹度UPWIND,AMAXIMUMINCLINATIONNEARTHEBASE,ANDAMINIMUMINCLINATIONATTHETOP框架总体剪切变形RIGIDFRAMEBEHAVIORNTHEOVERALLMOMENTOFTHEEXTERNALHORIZONTALLOADISRESISTEDINEACHSTOREYLEVELBYTHECOUPLE力偶RESULTINGFROMTHEAXIALTENSIONANDCOMPRESSIVEFORCESINTHECOLUMNSONOPPOSITESIDESOFTHESTRUCTURENTHEEXTENSIONANDSHORTENINGOFTHECOLUMNSCAUSEOVERALLBENDING总体弯曲ANDASSOCIATEDHORIZONTALDISPLACEMENTOFTHESTRUCTURE框架总体弯曲变形RIGIDFRAMEBEHAVIORNBECAUSEOFTHECUMULATIVEROTATIONUPTHEHEIGHT,THESTOREYDRIFT层间位移DUETOOVERALLBENDINGINCREASESWITHHEIGHT,WHILETHATDUETORACKINGTENDSTODECREASENCONSEQUENTLYTHECONTRIBUTIONTOTHESTOREYDRIFTFROMOVERALLBENDINGMAY,INTHEUPPERMOSTLEVEL,EXCEEDTHATFROMRACKING框架总体弯曲变形NTHECONTRIBUTIONOFOVERALLBENDINGTOTHETOTALDRIFT,HOWEVER,WILLUSUALLYNOTEXCEED10OFTHATRACKINGEXCEPTVERYTALL,SLENDER,RIGIDFRAMESNTHEREFORETHEOVERALLDEFLECTIONSHAPEOFAHIGHRISERIGIDFRAMEUSUALLYHASASHEARCONFIGURATIONRIGIDFRAMEBEHAVIORNTHERESPONSEOFARIGIDFRAMETOGRAVITYLOADINGNEGATIVEMOMENTSAREINDUCEDADJACENTTOTHECOLUMNS,ANDPOSITIVEMOMENTSOFUSUALLYLESSERMAGNITUDEOCCURINTHEMIDSPANREGIONSRIGIDFRAMEBEHAVIORNTHECONTINUITYALSOCAUSESTHEMAXIMUMGIRDERMOMENTSTOBESENSITIVETOTHEPATTERNOFLIVELOADINGTHISMUSTBECONSIDEREDWHENESTIMATINGTHEWORSTMOMENTCONDITIONSAPPROXIMATEDETERMINATIONOFMEMBERFORCESCAUSEDBYGRAVITYLOADINGFLOORFRAMESUBSTRUCTUREMETHOD分层力矩分配法NFORBUILDINGFRAMESWITHAREGULAROUTLINE,NOTINVOLVINGUNUSUALASYMMETRYOFLOADINGORSHAPE,THEINFLUENCEOFSIDEWAYCAUSEDBYVERTICALLOADSCANBENEGLECTED框架的侧移忽略不计NMOMENTSDUETOVERTICALLOADSAREDETERMINEDWITHSUFFICIENTACCURACYBYDIVIDINGTHEENTIREFRAMEINTOSIMPLESUBFRAMESAPPROXIMATEDETERMINATIONOFMEMBERFORCESCAUSEDBYGRAVITYLOADINGFLOORFRAMESUBSTRUCTUREMETHOD分层力矩分配法NEACHOFSUBFRAMESCONSISTSOFONECONTINUOUSBEAM,PLUSTHETOPANDBOTTOMCOLUMNSFRAMINGINTOTHATPARTICULARBEAMNTHEFARENDSOFTHECOLUMNSARECONSIDEREDFIXED柱端设为固定端APPROXIMATEDETERMINATIONOFMEMBERFORCESCAUSEDBYGRAVITYLOADINGFLOORFRAMESUBSTRUCTUREMETHOD分层力矩分配法NONLYTWOCYCLESARECARRIEDOUTINTHEANALYSISNMOMENTSTRANSFERREDFROMONEFLOORTOANOTHERFLOORARESMALLHENCE,THEMOMENTSFOREACHFLOORARESEPARATELYCALCULATED每层梁上的竖向荷载对本层梁及与本层梁相连的柱产生弯矩分层法计算步骤及要点1选择某榀框架作为计算单元2计算梁柱线刚度以及节点处分配系数1）对于现浇框架，要考虑梁有效截面惯性矩的调整；2）柱端设为固定端；3）底层柱固定在基础顶面，可以视为固定端，其它层柱要考虑到实际有柱端转动，故上层各柱线刚度乘以09修正系数；4）梁和底层柱的传递系数CARRYOVERFACTOR按远端FARENDSOFMEMBERS固定，取1/2；上层各柱的传递系数取1/3。3统计各层梁上竖向荷载GRAVITYLOADING设计值，并计算梁的固端弯矩FIXEDENDMOMENT。4按前面规定的分配系数DISTRIBUTIONFACTOR和传递系数CARRYOVERFACTOR，采用力矩分配法MOMENTDISTRIBUTIONMETHOD对每一层框架分别进行计算。5求得每层内力后，将同属于上下两层的柱弯矩值进行叠加，作为原框架该柱的最终弯矩，梁的弯矩仅属于本层，不需叠加。6得到框架最终弯矩图后，根据节点静力平衡可求得梁跨中弯矩，支座剪力以及柱剪力和轴力。例题NTHEGRAVITYLOADAXIALFORCEINACOLUMNISESTIMATEDFROMTHEACCUMULATEDTRIBUTARYDEADANDLIVEFLOORLOADINGABOVETHATLEVEL,WITHREDUCTIONSINLIVELOADING活荷载折减ASPERMITTEDBYDESIGNCODENTHERESISTANCETOMOMENTSATANYFLOORORROOFLEVEISESTIMATEDBYTAKINGTHEMAXIMUMDIFFERENCEOFTHEENDMOMENTSINTHECONNECTEDGIRDERSANDDISTRIBUTINGTHEMOMENTBETWEENCOLUMNSIMMEDIATELYABOVEANDBELOWTHEGIVENFLOORINPROPORTIONTOTHERELATIVECOLUMNSTIFFNESS6层5层24层1层APPROXIMATEDETERMINATIONOFMEMBERFORCESCAUSEDBYHORIZONTALLOADINGNALLOCATIONOFLOADINGBETWEENCOLUMNSASSUMPTIONFLOORSLABSARERIGIDINPLANEFORASYMMETRICSTRUCTURESUBJECTEDTOSYMMETRICLOADINGNTOTALEXTERNALSHEARATALEVELWILLBEDISTRIBUTEDBETWEENTHECOLUMNSINPROPORTIONTOTHEIRSHEARRIGIDITIES抗侧刚度D0ATTHATLEVELNTHESHEARRIGIDITYOFACOLUMNISLINEARRIGIDITYOFCOLUMNHEIGHTOFTHESTOREYAPPROXIMATEDETERMINATIONOFMEMBERFORCESCAUSEDBYHORIZONTALLOADINGNINFLECTIONPOINTMETHOD反弯点法THEINFLECTIONPOINTSOFALLMEMBERS,COLUMNSANDGIRDERS,ARELOCATEDMIDWAYBETWEENJOINTSEXCEPTTHATOFTHEGROUNDFLOOR对上层柱，假定各柱上下转角相等，则柱上下端弯矩相等，反弯点在柱中央THEINFLECTIONPOINTSOFTHEGROUNDFLOORCOLUMNSAREASSUMEDTOBEATADISTANCE2/3HFROMTHEBOTTOM对于底层柱，柱脚转角为零，而上端转角不为零，故反弯点向上端移动铰接无约束作用，弯矩为零，自由转动；固接约束作用强，弯矩很大，转角为零。INFLECTIONPOINTMETHOD反弯点法NTHEHORIZONTALSHEARATAMIDSTOREYLEVELOFSTOREYIISSHAREDBETWEENTHECOLUMNSINPROPORTIONTOTHESHEARRIGIDITYOFEACHCOLUMNDVALUEMETHODD值法NDVALUEMETHODISAMODIFICATIONOFINFLECTIONPOINTMETHODJOINTROTATIONSARETAKENINTOCONSIDERATIONLOCATIONOFINFLECTIONPOINTSVARIESACCORDINGTOSUPPORTCONDITIONSDVALUEMETHODD值法NASSUMINGTHATTHECHORDROTATIONANDLINEARRIGIDITYOFCOLUMNABARETHE