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1、EngineeringSeismology(2)GroundMotionInstrumentationandDataProcessing地震動的觀測(observationofGM)可以提供定量的數(shù)據(jù)可以測量地震破壞作用的全過程,能夠分別研究并測量導致建筑物破壞的各種因素不但為地震烈度和工程抗震措施提供定量數(shù)據(jù)和理論依據(jù),同時又檢驗從抗震研究實踐中總結(jié)出來的認識、理論和辦法是否符合實際,從而加深人們對于抗震客觀規(guī)律的認識,成為不斷推動地震工程研究發(fā)展的重要手段。Observationofstrongmoti
2、onismoredifficultthantheobservationsinotherfieldsofseismologyduetotheinfrequencyoflargeearthquakesandthedifficultyofanticipatingareasofstrongshakingforinstrumentation.Weakmotionsfromanearthquakewithmagnitudegreaterthan6.0canberecordedworldwide.Thusaseismol
3、ogistwhostudiesteleseismscanrecordontheorderof100earthquakesperyear,forinterpretationsofearthstructureortectonics.Similarly,localnetworksaregenerallysettothemostsensitivelevelpossibletodetectandlocatethesmallestearthquakes,whicharemuchmoreabundant.Aspecial
4、izedinstrument,thestrongmotionaccelerograph,wasdevelopedinthe1930’storecordstrongmotion.Anetworkofthesespecializedinstrumentsmustfurthermorehavethegoodfortunetobelocatedclosetotheearthquake,andmustbemaintained,oftenfordecades,inastateofreadinesstorecordthe
5、rarestrongshaking.Inthe1990’s,thesituationchangedsomewhatwithimprovementsindigitalrecordingtechnology.如果沒有強震觀測及其所取得的科學資料,就談不上現(xiàn)代地震工程學的發(fā)展。地震工程之所以能成為一間定量的科學是和強震觀測的成果分不開的。根據(jù)測量得到的地震加速度記錄,計算了大量的反應(yīng)譜曲線,獲得了“平均反應(yīng)譜”或“標準反應(yīng)譜”,使反應(yīng)譜分析得以真正應(yīng)用于工程設(shè)計。地震動特征的統(tǒng)計分析和結(jié)構(gòu)抗震理論的發(fā)展。例如,從
6、震源參數(shù)、傳播介質(zhì)的性質(zhì)演算地震動,隨機合成地震動時程,從彈性反應(yīng)譜到非彈性反應(yīng)譜,烈度定量標準及其觀測儀器的建立,以及場地條件對地震動的影響,地震時地基與結(jié)構(gòu)的相互作用等研究,都是在取得了強震觀測記錄的基礎(chǔ)上發(fā)展起來的。ThefoundingfatherofthestrongmotioninstrumentationprogramintheUnitedStatesisJohnR.Freeman.AftertheTokyo,Japanearthquakeof1923,andtheSantaBarbara,C
7、aliforniaandMontreal,Quebecearthquakesof1925,hestimulatedimportantearlyinteractionsbetweenU.S.andJapaneseinstitutionsonearthquakeengineeringandwrotethefirstsignificantbookintheEnglishlanguageonearthquakeengineering,EarthquakeDamageandEarthquakeInsurance(Fr
8、eeman,1932).Heparticularlyrecognizedtheurgentneedforaninstrumenttorecordthestrongshakingduringearthquakes,andtheresultofhislobbyingeffortswasthattheCoastandGeodeticSurveywasauthorizedtodevelopandinstallsuchin