Seismic response analysis on the stability of running vehicles

The seismometer network of the Japanese expressway system has been enhanced since the 1995 Kobe earthquake. Using earthquake information from the instruments, the expressways are closed if the peak ground acceleration (PGA) is larger than or equal to 80cm/s². The aim of this regulation is to avoid secondary disasters, e.g. cars running into the collapsed sections. However, recent studies on earthquake damage have revealed that expressway structures are not seriously damaged under such‐level of earthquake motion. Hence, we may think of relaxing the regulation of expressway closure. But before doing this, it is necessary to examine the effects of shaking to automobiles since the drivers may encounter difficulties in controlling their vehicles and traffic accidents may occur. In this study, a vehicle was modelled with a six‐degree‐of‐freedom system and its responses were investigated with respect to PGA, peak ground velocity (PGV) and Japan Meteorological Agency (JMA) seismic intensity using five ground motion records. It was observed that the response of the vehicle shows a larger amplitude for the record that has larger response spectrum in the long period range compared to other records. However, similar response amplitudes of the vehicle were observed for all the records with respect to the JMA seismic intensity. The response characteristics of the vehicle model may be very useful for decision‐making regarding the relaxation of the expressway closure under seismic motion. Copyright © 2002 John Wiley & Sons, Ltd.     

Effect of earthquake ground motions on fragility curves of highway bridge piers based on numerical simulation

Fragility curves express the probability of structural damage due to earthquakes as a function of ground motion indices, e.g., PGA, PGV. Based on the actual damage data of highway bridges from the 1995 Hyogoken‐Nanbu (Kobe) earthquake, a set of empirical fragility curves was constructed. However, the type of structure, structural performance (static and dynamic) and variation of input ground motion were not considered to construct the empirical fragility curves. In this study, an analytical approach was adopted to construct fragility curves for highway bridge piers of specific bridges. A typical bridge structure was considered and its piers were designed according to the seismic design codes in Japan. Using the strong motion records from Japan and the United States, non‐linear dynamic response analyses were performed, and the damage indices for the bridge piers were obtained. Using the damage indices and ground motion indices, fragility curves for the bridge piers were constructed assuming a lognormal distribution. The analytical fragility curves were compared with the empirical ones. The proposed approach may be used in constructing the fragility curves for highway bridge structures. Copyright © 2001 John Wiley & Sons, Ltd.     

粤西沿海震动图的生成和研究

震动图是描绘地震产生的地面运动和可能破坏情况的有效工具,主要包括峰值地面速度(PGV)等值线图、峰值地面加速度(PGA)等值线图和仪器烈度分布图等.基于华南数字地震台网记录到的2010年7月9日MS3.7级阳江地震的数据资料,利用SAC和GMT软件从记录到的地震波形数据提取地面运动参数,生成了PGV和PGA等值线图,并...     

长周期地震动强度指标与SDOF体系残余变形相关性分析

为分析两类长周期地震动作用下如何选取合理的强度指标作为结构抗震设计的输入,从2011年东日本9.0级地震、2003年十胜冲8.0级地震和2016年熊本7.3级地震数据库中选取90条可靠的远场长周期地震动。从1994年美国北岭6.7级地震和1999年台湾集集7.6级地震数据库中选取60条近场长周期地震动,以SDOF体系为研究对象,讨论了阻尼比、屈服刚度折减系数和强度折减系数对残余变形与18个地震动强度指标的相关系数的影响,对比分析了两类长周期地震作用下相关系数之间的异同。研究结果表明:在考虑近场长周期地震动作用时,建议应根据结构周期的大小来选择合适的强度指标作为地震动的输入。远场长周期地震动作用下,以PGA、PGV和PGD为代表的强度指标与残余变形的相关程度均较高,PGV稳定性略好于PGA和PGD,建议PGV作为地震动输入的控制指标。残余变形相关系数受阻尼比、屈服刚度折减系数以及强度折减系数影响不大。     

中强地震活动区地震动衰减关系的确定

地震动衰减关系是影响地震安全性评价特别是地震区划结果的重要因素.我国现行的地震动衰减关系主要是依据6级以上地震的地面运动资料得到的,并没有考虑中强地震的衰减特性.为此,文中利用现有的烈度资料和其他可供参考的研究成果来建立我国中强地震活动区的地震动衰减关系.收集了我国华中、华南、东北等地区的51次地震的烈度等震线资料,运用单随机变量加权最小二乘回归法得到中强地震活动区烈度衰减关系.然后以美国西部地区为参考地区,运用缺乏地震动参数的地震动估计方法-地震对映射法得到中强地震活动区峰值加速度和有效峰值加速度衰减关系.最后,通过与我国强地震区和中强地震区已有的烈度衰减关系和地震动衰减关系的对比,验证了得出的我国中强地震活动区烈度衰减关系和地震动衰减关系的合理性.     

南北地震带南段水平向地震动衰减特征

地震动衰减关系作为抗震救灾的重要依据,一直都是现代地震学研究的重点之一.本研究使用南北地震带南段区域2009—2016年共217个地震事件获得随震中距变化的水平向地震动峰值速度(PGV)和地震动峰值加速度(PGA)经验衰减关系,并计算场地响应.研究结果显示PGV衰减关系的拟合效果较PGA更好,两者的距离衰减系数会随事件矩震级增大呈线性减小;相较于大矩震级事件,中矩震级事件在近场可能产生较衰减关系理论值更大的PGV和PGA,同时衰减关系的拟合标准差会随事件矩震级的增大而减小.进行场地响应校正后的PGV和PGA更加符合经验衰减关系,PGA的场地响应影响较PGV更强但两者的趋势一致,并与该区域前人计算得到的地壳Qs值分布对应,表明地壳介质放大或压制地震波振幅和其传递地震波能量的能力是相关联的.本文结果一定程度上揭示了南北地震带南段的地震动强度衰减特征,为未来中国西南部的抗震减灾工作提供了重要的参考.     

几种仪器烈度算法在汶川地震与芦山地震中的可靠性比较

破坏性地震发生后, 特别是在通信中断的情况下, 利用仪器烈度快速估计地震动强度(烈度)的分布情况, 可为开展最有效的地震应急救援提供决策依据. 该文介绍了现有的几种仪器烈度算法, 并利用汶川地震与芦山地震中获得的强震加速度记录对各种算法的可靠性进行了比较. 结果表明, 在这两次地震中只利用地震动峰值参数确定仪器烈度的算法可靠性较低, 而考虑反应谱特性的算法可靠性更高. 在未得到更多强震数据的检验前, 建议采用袁一凡提出的仪器烈度算法, 或利用谱烈度值确定仪器烈度的算法, 或利用加速度反应谱值确定仪器烈度的算法.      

Effect of peak ground velocity on deformation demands for SDOF systems

The effect of peak ground velocity (PGV) on single‐degree‐of‐freedom (SDOF) deformation demands and for certain ground‐motion features is described by using a total of 60 soil site records with source‐to‐site distances less than 23 km and moment magnitudes between 5.5 and 7.6. The observations based on these records indicate that PGV correlates well with the earthquake magnitude and provides useful information about the ground‐motion frequency content and strong‐motion duration that can play a role on the seismic demand of structures. The statistical results computed from non‐linear response history analyses of different hysteretic models highlight that PGV correlates better with the deformation demands with respect to other ground motion intensity measures. The choice of PGV as ground motion intensity decreases the dispersion due to record‐to‐record variability of SDOF deformation demands, particularly in the short period range. The central tendencies of deformation demands are sensitive to PGV and they may vary considerably as a function of the hysteretic model and structural period. The results provided in this study suggest a consideration of PGV as a stable candidate for ground motion intensity measure in simplified seismic assessment methods that are used to estimate structural performance for earthquake hazard analysis. Copyright © 2005 John Wiley & Sons, Ltd.     

面向地震烈度仪的现地地震动预测模型的构建与验证

利用初期P波预警参数构建现地地震动预测模型,使其在达到设定阈值时快速发出报警信息,是现地地震预警系统面临的一个关键问题,直接关系到发布信息的准确性和及时性。针对地震烈度仪基于微机电系统传感器记录到的数据质量较差,通过两次积分获取的位移存在较大偏差,会引起更多的误报和漏报,本文采用不同阶数(1—4阶)的巴特沃斯滤波器,分别构建了基于P波3 s和全P波段数据的位移幅值PD、速度幅值PV和加速度幅值PA与地震动峰值速度PGV和峰值加速度PGA的现地地震动预测模型,然后利用收集到的川滇示范预警网地震事件记录进行验证。结果表明,对于地震烈度仪微机电系统传感器的记录,采用1阶巴特沃斯滤波器处理、基于全P波段波形拟合获取到的PV与PGV的相关性和PA与PGA的相关性为两种最优现地地震动预测模型。具体应用时,应同时利用两种或两种以上的统计关系进行现地地震动预测,并将实际地震动观测值作为额外的判定条件,以降低误报率和漏报率。     

2021年5月21日云南漾濞6.4级地震强震动记录特征分析

对2021年5月21日云南漾濞6.4级地震获取的28组84条强震动记录进行零线调整和滤波等常规处理,分析了此次地震记录的幅值、频谱以及持时特征。分析结果表明,此次地震峰值加速度范围为0.8~720.3 cm/s²,峰值速度范围为0.1~29.4 cm/s,计算最大仪器地震烈度为8.3度。将实际观测数据与YU2013分区地震动衰减关系对比,结果显示PGA总体上分布于衰减公式误差范围内,预测效果良好。在远场（>250 km）较多台站的PGV观测值大于预测值中位值的加一倍标准差。幅值较大2个台站的加速度反应谱峰值周期均在0.5s以内,其中漾濞台在高频部分三分向加速度反应谱值均超过8度罕遇地震的设计反应谱值。最后计算了5%~75%和5%~95%两种重要持时,结果整体上符合随震中距增大而增大的规律。将两种能量持时结果与BOOMER等（2009）^[12]以及TRIFUNAC等（1975）^[13]的持时预测方程对比,结果较为一致。     

鲁甸 MS6.5级地震强震动记录及震害分析

2014年8月3日发生的鲁甸地震是我国继2013年芦山地震之后的又一次破坏性浅源地震,造成了严重的人员伤亡和工程结构破坏.本文处理了我国数字强震动台网捕获的60余组主震三分量强震动记录,绘制了震中附近区域的峰值加速度等值线图,长轴沿西北-东南方向展布.通过与中国西部常用衰减关系的对比,发现各模型的预测值均不同程度高估了峰值加速度、峰值速度的观测值.最后以水平向峰值加速度较大的三个典型台站为例,详细调查了附近建筑的破坏情况,结合宏观烈度分布结果,分析了地震动特征与震害的相关性.     

2016年2月6日美浓6.4级地震P-alert台网强震动记录初步分析

P-alert台网实时数据对地震预警及烈度速报和工程地震研究都是重要的补充,处理分析这些数据对客观衡量P-alert台网数据质量和数据用途有重要意义。对2016年2月6日台湾美浓ML6.4地震P-alert台网获取的记录进行了处理和初步分析,统计分析显示100gal以上加速度记录有112条,200gal以上加速度记录有33条,400gal以上加速度记录有7条,东西向最大峰值加速度为466.4gal,南北向最大峰值加速度为498.4gal,竖直向最大峰值加速度为258.6gal,最大仪器地震烈度为9.5度。竖直向峰值加速度和峰值速度比水平向峰值加速度和峰值速度衰减快。峰值加速度比峰值速度衰减快,观测峰值加速度和峰值速度与台湾西南地区峰值加速度和峰值速度衰减公式比较一致。计算得到了近场台站的永久位移,显示P-alert台网绝大多数永久位移在1cm到5cm之间,最大永久位移达8cm。     

地震波参数对柱顶隔震体系的水平向减震性能影响研究

为了研究地震波参数对柱顶隔震体系的水平向减震性能的影响,选取台湾集集地震中8条地震波作为输入,进行了柱顶隔震体系模型的振动台试验。分析了柱顶隔震体系的水平向动力响应特点,研究了地震波的PGV/PGA、卓越周期、平均周期和断层距及幅值对其水平向减震性能的影响,并进行了数值模拟的对比分析。结果表明:柱顶隔震体系的水平向减震性能良好。相同地震强度下地震波参数的PGV/PGA、卓越周期、平均周期和断层距对柱顶隔震体系水平向减震性能的影响明显,其中:PGV/PGA的影响程度最大,可以作为主要的分析指标;随着地震动强度的增大柱顶隔震体系的水平向减震效果更加明显,地震动强度达到一定幅值后,减震率缓慢下降;与远场地震相比,近场地震不利于柱顶隔震体系的水平向减震性能的发挥,脉冲型近场地震作用下其减震效果更差。振动台试验结果与数值模拟结果基本一致,表明分析结果的可靠性。     

Rating damage potential of ground motion records

In this study, a total of 115,246 ground motions recorded during earthquakes of Moment magnitudes ranging from M_w 5.0 to M_w 9.0 are analyzed statistically. A total of 21 ground motion parameters characterising the recorded acceleration time histories are used in the analysis. Classification of these parameters through statistical correlation is reported and a parameter called "distance from zero-amplitude axis," or d_Z-A, is formulated in the principal component space. The ability for d_Z-A to rate the damage potentials of strong motion records is evaluated through correlation of d_Z-A with Japan Meteorological Agency(JMA) instrumental seismic intensities. This parameter can be used to rate damage potential of any strong motion record irrespective of the magnitude and location of the earthquake. It can also be used in selecting ground motion records of appropriate damage potential in seismic design and probabilistic analysis.     

Investigation on directional effects of Vrancea subcrustal earthquakes

This paper evaluates possible directional effects from strong ground motions recorded during the last four significant subcrustal earthquakes produced in the Vrancea seismic zone(Romania) in August 1986(M_w=7.1),May 1990(M_w=6.9 and 6.4) and October 2004(M_w=6.0).Several measures of the horizontal component of the ground motion given in the literature(Boore et al.,2006;Boore,2010) are computed and are related to the geometric mean of the as-recorded horizontal components.ANOVA method is applied in order to quantify the influence of the earthquake magnitude and of the soil class on some strong ground motion parameters(e.g.Arias intensity,PGV/PGA,or mean period T_M).The study of the directional effects is performed using the distribution of I_(JMA) and of the rotation angle corresponding to a measure of the horizontal component of the ground motion(RotD 100) and the results reveal a visible directional pattern for I_(JMA),while in the case of RotD100 the directional patterns are less visible.     

多种表征强震动记录特性的参数对比分析

为研究强震动记录的破坏特性,对多条国内外常用的强震动记录的特性参数进行了对比分析.结果表明,强震动记录特性参数之间的相关件很小;PGA(PGV)和EPA(EPV)大小关系受震级和震中距影响较大;VSI较ASI能够更准确的评价强震动记录的破坏特性;与其它参数相比,强震动记录破坏强度参数(PD)同时考虑了地震加速度、时间和...     

2020年10月22日四川北川MS4.7地震强震动特征分析

2020年10月22日11时03分37秒四川省绵阳市北川县发生MS4.7地震,四川强震动台网与预警烈度速报台网在震区建成较密集的台站,获取了532组三分量加速度记录,有助于开展区域地震动衰减和地震动特征研究.本文对强震记录进行常规处理后计算出强震动记录的相关参数,利用克里金插值方法得到地震动峰值加速度PGA和峰值速度PGV的空间分布图,长轴呈北西—南东方向.分析强震动记录PGA、PGV随距离的衰减规律,与常用衰减关系预测值进行对比,此次地震PGA的衰减特性与俞言祥和汪素云(2006)提出的中国西部地区水平向基岩加速度衰减关系有较好的一致性.北川MS4.7地震获得的密集强震动记录为建立区域衰减关系,以及开展基于经验格林函数方法(EGFM)再现大震强地震动场展布等研究提供了重要的数据支撑.     

A simplified method of constructing fragility curves for highway bridges

Fragility curves are found to be useful tools for predicting the extent of probable damage. They show the probability of highway structure damage as a function of strong motion parameters, and they allow the estimation of a level of damage probability for a known ground motion index. In this study, an analytical approach was adopted to develop the fragility curves for highway bridges based on numerical simulation. Four typical RC bridge piers and two RC bridge structures were considered, of which one was a non‐isolated system and the other was an isolated system, and they were designed according to the seismic design code in Japan. From a total of 250 strong motion records, selected from Japan, the United States, and Taiwan, non‐linear time history analyses were performed, and the damage indices for the bridge structures were obtained. Using the damage indices and ground motion parameters, fragility curves for the four bridge piers and the two bridge structures were constructed assuming a lognormal distribution. It was found that there was a significant effect on the fragility curves due to the variation of structural parameters. The relationship between the fragility curve parameters and the over‐strength ratio of the structures was also obtained by performing a linear regression analysis. It was observed that the fragility curve parameters showed a strong correlation with the over‐strength ratio of the structures. Based on the observed correlation between the fragility curve parameters and the over‐strength ratio of the structures, a simplified method was developed to construct the fragility curves for highway bridges using 30 non‐isolated bridge models. The simplified method may be a very useful tool to construct the fragility curves for non‐isolated highway bridges in Japan, which fall within the same group and have similar characteristics. Copyright © 2003 John Wiley & Sons, Ltd.     

A spatial correlation model of peak ground acceleration and response spectra based on data of the Istanbul Earthquake Rapid Response and Early Warning System

Ground motion intensity measures such as the peak ground acceleration (PGA) and the pseudo-spectral acceleration (PSA) at two sites due to the same seismic event are correlated. The spatial correlation needs to be considered when modeling ground-motion fields for seismic loss assessments, since it can have a significant influence on the statistical moments and probability distribution of aggregated seismic loss of a building portfolio.Empirical models of spatial correlation of ground motion intensity measures exist only for a few seismic regions in the world such as Japan, Taiwan and California, since for this purpose a dense observation network of earthquake ground motion is required. The Istanbul Earthquake Rapid Response and Early Warning System (IERREWS) provides one such dense array with station spacing of typically 2 km in the urban area of Istanbul. Based on the records of eight small to moderate (M_w3.5–M_w5.1) events, which occurred since 2003 in the Marmara region, we establish a model of intra-event spatial correlation for PGA and PSA up to the natural period of 1.0 s.The results indicate that the correlation coefficients of PGA and short-period PSA decay rapidly with increasing interstation distance, resulting in correlation lengths of approximately 3–4 km, while correlation lengths at longer natural periods (above 0.5 s) exceed 6 km. Finally, we implement the correlation model in a Monte Carlo simulation to evaluate economic loss in Istanbul's district Zeytinburnu due to a M_w7.2 scenario earthquake.     

面向地下结构的最优地震动峰值指标随埋深变化规律

选取了50条实际地震动,采用一维场地等效线性化方法分别对均匀半空间场地和成层半空间场地进行地震响应分析,同时选择效益性作为判别标准来探究最优地震动峰值指标(峰值加速度PGA,峰值速度PGV,峰值位移PGD)随埋深变化的规律.研究结果表明:对于选取的两类场地,最优地震动峰值指标均随埋深的改变而变化,埋深浅时PGA效益性最...