近场方向性效应等效脉冲地震动模型的频域分析
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摘要
等效脉冲模型在反应近场地震动对结构的影响上较反应谱方法有明显的优越性,然而由于缺乏对等效脉冲模型本身的深入研究,采用不同等效脉冲模型的研究结果之间往往不具有可比性,模型本身的缺陷也可能导致研究结果出现偏差。本文通过解析方法对常用的三种等效脉冲模型进行分析,明确三种模型之间的定量关系,指出了矩形脉冲模型的缺陷。结果表明,等效脉冲模型速度、加速度傅里叶变换各阶分量振幅的比例关系不随脉冲周期改变。当脉冲周期相等时,不同等效脉冲模型速度、加速度同阶分量之间存在固定的比例关系。正弦脉冲模型与三角脉冲模型速度、加速度各阶分量振幅数值较为接近。矩形等效脉冲能量集中于奇数阶分量,该特性与实际地震动不符。当结构固有频率较低且接近等效脉冲偶数阶分量频率或较高阶分量频率时,矩形等效脉冲激起的结构响应与正弦等效脉冲和三角等效脉冲相比可能有较大差异。当短周期结构固有频率接近等效脉冲较高奇数阶分量周期时,矩形等效脉冲激起的结构响应与正弦等效脉冲和三角等效脉冲可能有较大差异。
There is a growing recognition that a time history representation is better able to capture the effects of near-fault ground motions on structures.However,for the lack of quantitative knowledge on the relationship of equivalent pules,the results of studies on the response of structures to near-fault ground motions with different equivalent pules can not be united.Different equivalent pules produce variations in the response of a structure.3 simple equivalent pulses that widely used to characterize the forward-directivity effects are considered.The quantitative knowledge on the relationship of equivalent pules is presented.It is shown that the amplitude ratio of frequency components keep constant in a equivalent pules model.The amplitude ratio of the same frequency components in different equivalent models with the same pulse period keep constant.The difference of frequency components between sine-wave equivalent pulse and triangular equivalent pulse is not obvious.However,frequency components of rectangular pulse significantly different from sine-wave and triangular equivalent pulse.The energy of rectangular equivalent pulse concentrates in odd term frequencies of equivalent pules.The concentration can result in significant difference between the seismic responses of structures subjected to rectangular equivalent pulse and the seismic responses induced by other equivalent pulses.
There is a growing recognition that a time history representation is better able to capture the effects of near-fault ground motions on structures.However,for the lack of quantitative knowledge on the relationship of equivalent pules,the results of studies on the response of structures to near-fault ground motions with different equivalent pules can not be united.Different equivalent pules produce variations in the response of a structure.3 simple equivalent pulses that widely used to characterize the forward-directivity effects are considered.The quantitative knowledge on the relationship of equivalent pules is presented.It is shown that the amplitude ratio of frequency components keep constant in a equivalent pules model.The amplitude ratio of the same frequency components in different equivalent models with the same pulse period keep constant.The difference of frequency components between sine-wave equivalent pulse and triangular equivalent pulse is not obvious.However,frequency components of rectangular pulse significantly different from sine-wave and triangular equivalent pulse.The energy of rectangular equivalent pulse concentrates in odd term frequencies of equivalent pules.The concentration can result in significant difference between the seismic responses of structures subjected to rectangular equivalent pulse and the seismic responses induced by other equivalent pulses.
引文
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[4]Alavi B,Krawinkler H.Design considerations for near-fault ground motions[C]//Proceedings of the US-JapanWorkshop on the Effects of Near-Fault EarthquakeShaking.San Francisco,2000:55-63
[5]Alavi B.Effects of near-fault ground motions on framestructures[D].Stanford:Stanford University,2000
[6]Sasani M,Bertero V V.Importance of severe pulse-typeground motions in performance-based engineering:historical and critical review[C]//Proceedings of the 12thWorld Conference on Earthquake Engineering.NewZealand,2000
[7]Krawinkler H,Alavi B.Development of improved designprocedures for near-fault ground motions[C]//Seminar onUtilization of Strong Motion Data.Oakland,CA,1998
[8]徐龙军.统一抗震设计谱理论及其应用[D].哈尔滨:哈尔滨工业大学,2006
[2]Somerville P G.Development of an improved ground motionrepresentation for near-fault ground motions[C]//Seminaron Utilization of Strong Motion Data.Oakland,CA,1998:1-20
[3]Rodriguez-Marek A.Near-fault seismic site response[D].Berkeley:University of California,2000
[4]Alavi B,Krawinkler H.Design considerations for near-fault ground motions[C]//Proceedings of the US-JapanWorkshop on the Effects of Near-Fault EarthquakeShaking.San Francisco,2000:55-63
[5]Alavi B.Effects of near-fault ground motions on framestructures[D].Stanford:Stanford University,2000
[6]Sasani M,Bertero V V.Importance of severe pulse-typeground motions in performance-based engineering:historical and critical review[C]//Proceedings of the 12thWorld Conference on Earthquake Engineering.NewZealand,2000
[7]Krawinkler H,Alavi B.Development of improved designprocedures for near-fault ground motions[C]//Seminar onUtilization of Strong Motion Data.Oakland,CA,1998
[8]徐龙军.统一抗震设计谱理论及其应用[D].哈尔滨:哈尔滨工业大学,2006
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