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1.
利用5个反映地震动频谱特征的周期(反应谱卓越周期Tp, 平滑化反应谱卓越周期To, 傅氏幅值谱平均周期Tm, 等效速度脉冲周期Tv和拟速度反应谱卓越周期Tpv), 对集集地震的近断层三分量地震动进行研究. 结果表明, 上盘地震动的频谱周期小于下盘地震动; Tp小于To和Tm, 且Tp反映的三分量之间的关系与To和Tm不同; 在地表断裂带的北端,Tv和Tpv所反映的近断层地震动长周期分量的频谱特征, 与走滑断层中方向性效应作用的规律相类似. 得出的定性或定量结论可以为近场抗震设计谱的建立与地震危险性区划研究提供参考. 相似文献
2.
基于999条具有完整信息的欧洲及其毗邻地区的近场强震动记录,对反映地震动频谱特性的不同特征周期参数(反应谱卓越周期T。、平滑化反应谱卓越周期T_o、傅氏幅值谱平均周期T_m)进行了研究,分析了场地条件、地震震级等因素对近场水平向及竖向地震动频谱特征周期的影响,并探讨了我国现行规范中设计反应谱特征周期T_g取值的合理性问题。统计结果表明:在近场区域场地和震中距仍是影响地震动频谱特征周期的重要因素,因为近场地震动的复杂性,震级对地震动频谱特征周期的影响不是很明显;近场区域竖向与水平向地震动的频谱特征周期有明显差别,且场地越软竖向与水平向地震动频谱特征周期的比值越小;我国现行抗震规范中设计反应谱的特征周期取值偏低,可能是偏于不安全的。 相似文献
3.
汶川地震反应谱特征周期统计分析 总被引：1，自引：0，他引：1
反应谱特征周期反映了地震动频谱特性,也是抗震设计中重要的特征参数.为了研究汶川特大地震反应谱特征周期的特性,本文以汶川地震中173个有详细地勘场地上的强震动记录为基础,统计分析了不同场地类别和断层距的反应谱特征周期,并与我国现行抗震设计规范中特征周期的规定值进行比较.本文研究结果显示随着场地变软,特征周期平均值有增大趋势;与汶川特大地震中反应谱特征周期的统计结果相比,我国抗震设计规范规定的远场反应谱特征周期值偏小. 相似文献
4.
用丰富的高质量数字强震记录对台湾集集大地震及余震的长周期地震动特性进行了研究. 本文主要研究了长周期地震动的强度随震级、距离及场地条件的变化情况;同时对近断层的长周期地震动特性进行了分析. 结果表明,集集大地震及余震的长周期地震动反应谱的形状主要受场地条件和震级控制（D+E类场地的反应谱要比B+C类的宽,震级大的反应谱要比震级小的宽）,而受距离影响并不显著;近断层长周期地震动明显受断层活动特性影响:上盘的长周期地震动比下盘的强,北部的比南部的强. 相似文献
5.
分析地震动的频谱周期参数和频率非平稳特征,是地震危险性分析和结构抗震设计的重要内容.本文对近断层地震动记录按照不同的运动特征分组,进行了Hilbert-Huang变换分析.结合相关的定义得到了表征地震动频谱特性的7个周期参数,包括:Fourier幅值谱平均周期Tm、Hilbert边际谱平均周期Tmh、特征周期Tc、卓越周期等,并计算了地震动的Hilbert谱瞬时频率时程变异系数.计算结果表明,从整体上把握地震动频谱特性的三个周期参数Tm 、Tmh 和Tc适合于表征近断层地震动的频谱成份.近断层地震动的频率非平稳特征显著,Hilbert谱瞬时频率变异系数良好地反映了地震动的频率非平稳性质和程度.而且,考察了近断层地震动运动特征对地震动频谱周期参数和频率非平稳性的影响. 相似文献
6.
为考查远场地震动的场地相关性并评价一些场地特性分析方法的适用性,采用不同方法对汶川地震山东省12个远场台站的强震记录进行了分析.选取台站分别位于按建筑抗震设计规范(CBC)场地划分中的Ⅰ—Ⅲ类场地上.地震动记录的分析方法包括傅里叶幅值谱法,地震反应谱法,水平与竖向谱比率法,参考点谱比率法,以及尾波分析等.结果表明,按傅里叶幅值谱法,地震反应谱法,水平与竖向谱比法计算得到的卓越周期均远大于台站场地的卓越周期,不同方法得到的结果之间也有较大差别,且主要反映长周期地震动的卓越频率;参考点谱比率法的结果未反映地震动的卓越周期,也与场地的卓越周期差别较大;对完整记录尾波分析所得的结果比较接近场地的卓越周期.希望本文能为考虑远场地震作用时设计谱的建立,以及场地特性估计时地震动分析方法的选取提供参考依据. 相似文献
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基于美国NGA数据库,在断层投影距小于25 km范围内挑选了1387条地震加速度记录,分别按照断层距和场地条件进行分组,对近断层速度脉冲型地震动的频谱特性、特征周期,及其与断层距、震级的相关性予以分析。结果显示:① 出现速度脉冲型地震动的比例与断层投影距之间存在明显的线性相关关系,但其与震级的变化不相关;② 地震动速度脉冲周期与震级之间存在强相关;③ 对于近断层速度脉冲型地震动,采用动态变化的加速度和速度反应谱峰值周期进行特征周期的计算,更加符合真实情况;④ 地震动速度脉冲有放大地震动特征周期的作用,水平向放大的比例与竖向相当,且放大作用与场地条件相关,在较硬场地上放大较多。本文基于上述近断层地震动的统计分析结果,对现行抗震设计规范中定义的特征周期提出了适合于工程应用的调整系数,并建立了速度脉冲周期与震级之间的关系模型,分析结果显示二者的拟合效果较好。 相似文献
8.
文中将921台湾集集地震主震的404组强震记录按照不同震中距和场地类别分组,对加速度水平分量和垂直分量的持时、峰值加速度(PGA)、包络线、反应谱比值进行了统计分析。结果表明,场地条件对不同分量加速度时间历程的若干特征有显著的影响,而且比较复杂。此外,断层方向对地震动水平特性也有一定的影响。具体研究结果为:1)地震动水平分量的持时随着场地依次变软而增大;2)断层方向对PGA衰减特征有一定影响;3)不同震中距离和场地条件下集散的时间里程的包线基本上都是单峰点的时间函数;地震动加速度水平分量包络线与竖向分量包络线有明显的不同;4)在震中距相同的条件下,场地愈软弱,周期愈短,谱比值EW/SN愈接近1。场地愈软,在短周期(<0.1s)段,V/H谱比值是变大的趋势,而在长周期(>特征周期)段则是变小的趋势;而且相对来说V/EW谱比值随场地变软而减小的趋势相对要强一些 相似文献
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近断层长周期地震动是一类较特殊的破坏性地震动.为了深入探讨近断层地震动的低频分量组成及其脉冲特性,基于小波理论中的多尺度分析方法提出了一种地震动分量分解方法,据此可将一条地震动分解成频率各不相同的多条分量.首先从频域、时域以及动态响应三个方面阐述了该分解方法的有效性和精确性.进而采用这种方法对近期12次大地震中的53条典型近断层地震动进行了分解,共获得266条地震动分量.分析了近断层地震动中的长周期分量随场地、断层距等影响因素的变化特征;再以卓越分量作为最大脉冲的简化模型,探讨了速度幅值和脉冲周期随震级、断层距的变化关系.结果表明：近断层长周期地震动主要由周期为0.2~2 s的分量组成;近断层土层场地地震动中的长周期分量比岩石场地多;在0~15 km的近断层区域,随断层距的增加,地震动中长周期分量的比重明显减小;卓越分量的速度幅值PGVp约为原始地震动速度幅值PGV的0.6倍,且两者之间具有明显的线性关系;PGVp随断层距的增大而减小,随震级的增大而增大;卓越分量周期Tp随震级的增大呈对数线性增大趋势. 相似文献
10.
选取了1999年9月21日台湾集集7.6级地震主震中68组断层距在20km以内的近断层台站记录和46组断层距在40~70km的东部台站记录,按台站的上下盘位置、场地条件和断层距分组,对其竖向和水平加速度反应谱比值V/H进行了统计分析。研究表明:1)断层的滑动方向和断层破裂的传播方向对断层距在3km以内的台站上的地面运动谱比值V/H有一定影响,且主要体现在中短周期范围内,例如平行断层方向的谱比值要比垂直断层方向的谱比值大。在下盘断层距3~20km的范围内,场地条件对V/H基本没有影响。2)在集集地震中长周期(>3s)部分的谱比值通常>32,且有一个较高的峰值,表明其竖向运动加速度中的长周期分量大于其它地震。3)对于下盘的台站,地面运动在短周期(<0.2s)段的谱比值不随断层距的增加而减少。与中远(>40km)距离的台站相比较,近断层台站的V/H在工程界关心的周期范围内普遍较大。4)场地条件对谱比值V/H的影响在近断层处不显著。在远离断层的东部台站上,硬土场地谱比值V/H在长周期段大于软土场地 相似文献
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Introduction The dynamic response of structural systems subjected to earthquake ground shaking is sig-nificantly affected by the frequency content of input ground motions. When the frequency content of a predominant earthquake ground motion closely matches the natural period of a structural sys-tem, the dynamic response is significantly enhanced and thus may cause severe damage (Chopra, 1995). Therefore, it is of great importance to evaluate the frequency content of ground motions. In recent … 相似文献
12.
Xiaowu Pu Lanming Wang Ping Wang Xiufeng Tian Shiyang Xu Shaofeng Chai Haitao Guo 《地震研究进展（英文）》2022,2(3):100114
A series of housing collapses and other serious damage was caused by the 2008 Wenchuan MS 8.0 earthquake in the seismic intensity Ⅵ areas of the Loess Plateau, which is hundreds of kilometers away from the epicenter, and which showed a remarkable seismic intensity anomaly. The seismic disasters are closely related to the seismic response characteristics of the site, therefore, the systematic study of the far-field seismic response law of the Wenchuan earthquake in the Loess Plateau is of great significance to prevent the far-field disaster of great earthquake. In this paper, the seismic acceleration records of several bedrock stations and loess stations from the seismogenic fault of the Wenchuan earthquake to the Loess Plateau were collected, and the attenuation law of ground motion along the propagation path and the characteristics of seismic response on the loess site are studied, and the mechanism of amplification effect of ground motion is analyzed based on the dynamic feature parameters of the loess site obtained through the HVSR method. Taking a typical loess site of thick deposit as the prototype, a series of shaking table tests of dynamic response of loess site models with different thicknesses were carried out. Amplification effect, spectral characteristics of acceleration in model sites were analyzed under the action of a far-field seismic wave of the Wenchuan earthquake. The results show that seismic attenuation on the propagation path along the NE strike of the seismogenic fault to the Loess Plateau is slower than that in other directions, and the predominant period range of ground motion on bedrock site of the Loess Plateau presents broadband characteristics. Because the natural periods of loess sites with thick deposits are within the predominant period range of bedrock input wave, loess sites appear significant amplification effect of ground motion, the horizontal acceleration of ground motion exceeds 0.1 ?g, the seismic intensity reaches 7°. The thicker the loess deposit is, the more significant the change of spectral characteristics of ground motion on loess sites, and the narrower the predominant period range of ground motion becomes, and the closer it is to the natural period of loess sites. Therefore, for some old houses on thick loess sites, the poor seismic performance and strong seismic response eventually led to their collapses and damages because their natural periods are very close to the predominant period of ground motion of the Wenchuan earthquake on thick loess sites; For these damaged high-rise buildings, the resonance effect might be the main reason for their damages because their natural periods are included in the predominant period range of ground motion of the Wenchuan earthquake on thick loess sites.These research results would provide a basis for seismic disasters prediction and evaluation and seismic design of construction engineering in the Loess Plateau. 相似文献
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以芦山地震震中距100km内20个台站的60条原始强震记录为依据,采用零交法计算台站处三方向卓越周期,采用线性加速法计算台站处阻尼比为0.05的三方向反应谱,考察反应谱峰值周期、卓越周期和放大系数在各台站位置处的分布以及在断裂上、下盘的均值。通过研究发现:芦山地震动卓越周期、反应谱峰值周期和放大系数在各台站不同方向上的分量不同;各台站处反应谱的计算表明地震动具有上盘效应以及上盘衰减迅速的特征;地震动卓越周期在芦山地震震中100km的上、下盘上差别不大,其中上盘EW和UD向卓越周期均值略小于下盘,而上盘NS向均值略大于下盘,断裂两盘UD向卓越周期总体小于水平向,断裂两盘三方向卓越周期变化范围为0.013~0.275s;计算得到的放大系数表明80%台站NS向放大系数大于EW向,因此NS向放大系数较大可能是芦山地震诱发崩滑地质灾害的主要因素。 相似文献
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Pulse-like ground motion observed during the 6 February 2023 MW7.8 Pazarcık Earthquake (Kahramanmaraş, SE Türkiye) 
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下载免费PDF全文 Fan Wu Junju Xie Zhao An Chenghao Lyu Tuncay Taymaz Tahir Serkan Irmak Xiaojun Li Zengping Wen Baofeng Zhou 《地震科学（英文版）》2023,36(4):328-339
In this study, we analyzed 100 three-component strong ground motion records observed within 200 km of the causative fault of the 6 February 2023 MW7.8 Pazarcık (Kahramanmaraş) Earthquake in SE Türkiye. The wavelet method was utilized to identify and analyze the characteristics of pulse-like ground motions in the near-fault region, while considering the uncertainty of the pulse orientation during the analysis. Our investigation focused on the effects of the focal mechanism and rupture process on the spatial distribution, pulse orientation, and maximum pulse direction of the observed pulse-like ground motion. We also analyzed the amplitude and period of the observed ground pulses and the effect of long-period amplification on the ground motion response spectra. Our results indicated the following: (1) A total of 21 typical ground velocity pulses were observed during this earthquake, exhibiting complex characteristics due to the influence of the strike-slip mechanism and rupture directivity. Most ground pulses (17 out of 21) were recorded within 20 km of the fault, in a wide range of orientations, including normal and parallel to the fault direction. The waveforms exhibited unidirectional features, indicating the effects of left-lateral fault slip. Distinct pulses observed more than 20 km from the fault were mainly oriented normal to the fault. The waveforms were bidirectional with double- or multi-round trips as a result of rupture directivity. (2) The amplitudes of the observed pulses ranged from 30.5 to 220.0 cm/s, with the largest peak velocity of 220.0 cm/s observed at Station 3138. The pulse periods ranged from 2.3 to 14.5 s, with the longest pulse period of 14.5 s observed at Station 3116. The amplitude and period of the pulses observed during this earthquake were comparable to those of similar-magnitude global earthquakes. The amplitude of the pulses decreased significantly with increasing fault distance, whereas the pulse period was not significantly affected by the fault distance. (3) Compared with non-pulse records, the velocity pulse records had a pronounced amplification effect on the acceleration response spectra near the pulse period, with factors ranging from 2.1 to 5.8. The larger velocity pulses also significantly amplified the velocity response spectra, particularly over the long periods. This significant amplification effect of the pulses on the response spectra leads to empirical models underestimating the long-period earthquake ground motion. 相似文献
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This paper aimed to examine the site dependence and evaluate the methods for site analysis of far-source ground motions. This was achieved through the examination of frequency content estimated by different methods based on strong ground motions recorded at twelve far-source stations in Shandong province during the Wenchuan earthquake. The stations were located in sites with soil profiles ranging from code classes Ⅰ to Ⅲ. Approaches used included the Fourier amplitude spectrum (FAS), the earthquake response spectrum (ERS), the spectral ratio between the horizontal and the vertical components (H/V), the spectral ratio between the spectra at the site and at a reference site (SRRS), and coda wave analysis (CWA). Results showed that major periods of these ground motions obtained by FAS, ERS and H/V ratio methods were all evidently larger than site dominant periods; the periods were also different from each other and mainly reflected the frequency content of long period components. Prominent periods obtained by the SRRS approach neither illuminated the long period aspect nor efficiently determined site features of the motions. The CWA resulted in a period close to site period for stations with good quality recordings. The results obtained in this study will be useful for the evaluation of far-source effect in constructing seismic design spectra and in selecting methods for ground motion site analysis. 相似文献
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Analyzing the effect of moving resonance on seismic response of structures using wavelet transforms 下载免费PDF全文
下载免费PDF全文 There is a complex interaction between the seismic response (i.e., peak displacements) of a nonlinear structure and the characteristics of a ground motion. One ground motion characteristic that contributes to record‐to‐record variability is spectral nonstationarity, or the variation of signal's frequency content with time. When the predominant natural periods of a nonlinear structure elongate in such a way as to match with the predominant frequency content in the ground motion, a phenomenon called moving resonance occurs. The effect of moving resonance on the response of nonlinear structures is investigated. Continuous complex wavelet transforms are used to examine the spectral nonstationarity of ground motion acceleration histories and associated structural displacement histories to identify the occurrences of moving resonance. A three‐dimensional displacement response spectrum is used to determine which combinations of initial period and strength create the largest displacements and thus are candidate configurations for experiencing moving resonance. A method is then proposed for quantifying the effect of moving resonance on structural response. The method utilizes discrete wavelet transforms to decompose a ground motion into component signals with limited frequency band and examines the structural response due to each individual component. A discussion is provided as to how these tools can be used to identify ground motion characteristics that may be conducive to moving resonance. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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ANALYSIS ON THE CHARACTERISTICS OF DURATION AND PERIOD OF GROUND MOTION OF THE LUSHAN EARTHQUAKE BASED ON THE STATION RECORDS 下载免费PDF全文
下载免费PDF全文 Based on 60 records from the 20 stations within 100km to the epicenter of Lushan earthquake, the predominant period, period of peak response spectrum, duration of ground motion, and source duration are investigated. By the study, we conclude that within 100km to the epicenter, the scope of predominant period is 0.013~0. 275s in EW, NS and UD direction; the scope of period of peak response spectrum for 5% damping ratio is 0.03~0.65s; the scope of 90% ground motion durations is 5. 1~35. 9s; the scope of averaging source duration is 6.41 (EW), 6.05 (NS) and 5.47s (UD). Furthermore, based on the ground motion duration calculated by 20 stations dada, the predictive curve and equation of ground motion duration is regressed and compared with the recent equation of ground motion duration by Bommer (2009). We find that the ground motion durations of most stations are larger than predictively mean value by Bommer (2009), which means that the source effect of Lushan earthquake is relatively larger. Lastly, by the contour figure of ground motion duration and source duration, we conclude that the directivity character of duration is relatively apparent in NE direction. The relatively larger source duration and ground motion duration in NE direction indicate more energy release in the main shock of Lushan earthquake, which perhaps causes the relatively less aftershocks in this direction. The duration has no hanging wall effect, which perhaps results from the blind-reverse fault structure of Lushan earthquake. 相似文献
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This paper focuses on the effects of long‐period pulse of near‐fault ground motions on the structural damage potential. Two sets of near‐fault ground motion records from Chi‐Chi, Taiwan earthquake and Northridge earthquake with and without distinct pulse are selected as the input, and the correlation analysis between 30 non‐structure‐specific intensity measure parameters and maximum inelastic displacements and energy responses (input energy and hysteretic energy) of bilinear single degree of freedom systems are conducted. Based on the frequency characteristic of near‐fault ground motions with remarkable long‐period components, two intensity indices are proposed, namely, the improved effective peak acceleration (IEPA) and improved effective peak velocity (IEPV). In addition a new characteristic period of these ground motions is defined based on IEPA and IEPV. Numerical results illustrate that the intensity measure parameters related to ground acceleration present the best correlation with the seismic responses for rigid systems; the velocity‐related and displacement‐related parameters are better for medium‐frequency systems and flexible systems, respectively. The correlation curves of near‐fault ground motions with velocity pulse differ from those of ground motions without pulse. Moreover, the improved parameters IEPA and IEPV of near‐fault impulsive ground motions enhance the performance of intensity measure of corresponding conventional parameters, i.e. EPA and EPV. The new characteristic period based on IEPA and IEPV can better reflect the frequency content of near‐fault ground motions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献