第四章隔震結(jié)構(gòu)的分析令第一節(jié)正交阻尼結(jié)構(gòu)11.1EquationsofMotionss2MassRatiosNominalFrequenciesAssume1.2DefinitionsofSeveralFactorsNominalDampingRatiosbands

31.3ModalAnalysisCharacteristicEquationfortheFrequenciesFreeVibrationEquationsofUndampedSystem4SolutionsofCharacteristicEquationModeShapesApproximationtofirstorderin5ModeCoordinatesqpremultiplyingbyTModalEquationswhereModalLoadFactor(振型參與因子)Li

isgivenby6UncoupledModalEquationsandmodaldampingratioi

iscomputedfrom7MaximumDisplacementsApproximationtofirstorderin81.4BaseShearCoefficientofSuperstructure9第二節(jié)非正交阻尼結(jié)構(gòu)2.1Significanceofoff-diagonaldampingterms10112.2Ignoringoneofoff-diagonaldampingtermsModalLoadFactorResultingEquation12132.3InterstoryDrift14(i)thatcontributedbytheuncoupledfirstmode(ii)thatfromtheuncoupledsecondmodeThreeItems15(iii)thatfromthecoupledtermRelationwithResponseSpectrum1617I3SVI4SV18ConstantVelocitySpectra注意意：：H()修正與與我國(guó)規(guī)規(guī)范的的差異異例如，，H()可取19Ignore2andinthe3rdterm20Kawashima-AizawaFunctionR=0.33whenb=0.1R=1.80whenbExample212.3FloorAcceleration22算例已知：隔震結(jié)結(jié)構(gòu)重量為W，周期為2.5s，阻尼比5％，=1/25，=1/2。按規(guī)范算得得的隔震層位位移為76cm，為減小位移移在隔震層設(shè)設(shè)置粘滯阻尼尼器，其阻尼尼比為50％。求增設(shè)粘滯阻尼尼器后的隔震層位移、、基底剪力和屋面加速度度。解：(1)隔震層位移為為23最大位移時(shí)的的底部剪力為為阻尼力最大剪力偽速度譜值按p22頁(yè)公式計(jì)算樓樓面加速度，，結(jié)果如下：：基底剪力屋面加速度2425參考文獻(xiàn)1.NaeimFandKellyJM,““Designofseismicisolatedstructures”