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As part of the 2007 Tri-Center Field Mission to Japan, a reconnaissance team comprised of fourteen graduate students and three faculty members from three U.S. earthquake engineering research centers, namely, Multidisciplinary Center for Earthquake Engineering Research (MCEER), Mid-America Earthquake Center (MAE), and Pacifi c Earthquake Engineering Research Center (PEER), undertook a reconnaissance visit to the affected area shortly after the 2007 Niigata- Chuetsu Oki earthquake. This mission provided an opportunity to review the nature of the earthquake damage that occurred, as well as to assess the signifi cance of the damage from an educational perspective. This paper reports on the seismological characteristics of the earthquake, preliminary fi ndings of geotechnical and structural damage, and the causes of the observed failures or collapses. In addition, economic and socio-economic considerations and experiences to enhance earthquake resilience are presented. 相似文献
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Bridges are crucial to the transportation network in a region struck by an earthquake. Collapse of a bridge determines if a road is passable. Ability of a bridge to carry traffic load after an earthquake determines the weight and speed of vehicles that can cross it. Extent of system and component structural damage in bridges determines the cost and time required for repair. Today, post‐earthquake bridge evaluation is qualitative rather than quantitative. The research presented in this paper aims to provide a quantitative engineering basis for quick and reliable evaluation of the ability of a typical highway overpass bridge to function after an earthquake. The Pacific Earthquake Engineering Research (PEER) Center's probabilistic performance‐based evaluation approach provides the framework for post‐earthquake bridge evaluation. An analytical study was performed that linked engineering demand parameters to earthquake intensity measures. The PEER structural performance database and reliability analysis tools were then used to link demand parameters to damage measures. Finally, decision variables were developed to describe three limit states, repair cost, traffic function, and collapse, in terms of induced damage. This paper presents the analytical models used to evaluate post‐earthquake bridge function, decision variables and their correlation to the considered limit states, and fragility curves that represent the probability of exceeding a bridge function limit state given an earthquake intensity. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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SNR changes of VLF radio signals detected onboard the DEMETER satellite and their possible relationship to the Wenchuan earthquake 总被引:3,自引:0,他引:3
M. Parrot 《中国科学D辑(英文版)》2009,52(6):754-763
Here we used the VLF signal data received by the DEMETER satellite, transmitted from various ground VLF transmitters which
are located around China, to study the changes in the signal to noise ratio (SNR) before and after the Wenchuan earthquake,
which had a magnitude of 8.0. We also found that the SNRs of different frequency signals decreased significantly over the
epicenter region before the earthquake, and reverted to their original levels after the earthquake. This phenomenon may be
related to the earthquake.
Special Foundation of Basic Research from Institute of Geophysics, China Earthquake Administration (Grant No. DQJB08Z08),
National Key Technology R & D Program (Grant No. 2008BAC35B01) 相似文献
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The objective of this research is to determine the effect earthquakes have on the performance of transportation network systems. To do this, bridge fragility curves, expressed as a function of peak ground acceleration (PGA) and peak ground velocity (PGV), were developed. Network damage was evaluated under the 1994 Northridge earthquake and scenario earthquakes. A probabilistic model was developed to determine the effect of repair of bridge damage on the improvement of the network performance as days passed after the event. As an example, the system performance degradation measured in terms of an index, “Drivers Delay,“ is calculated for the Los Angeles area transportation system, and losses due to Drivers Delay with and without retrofit were estimated. 相似文献
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汶川8.0级地震后中国大陆强震活动状态研究 总被引:1,自引:0,他引:1
本文从不同空间、 时间尺度对2008年四川汶川8.0级地震的影响意义进行了初步讨论, 并以此分析了其后我国大陆的强震活动状态。研究结果表明, 1800年以来中国大陆西部及邻区的大三角地区8级地震活动呈现为100年左右丛集性时间过程, 具有地震平静、 地震丛集、 地震丛集发生前的过渡和丛集发生后的调整等时间特征; 2001年11月14日昆仑山口西8.1级地震和2008年5月12日四川汶川8.0级地震的发生表明, 目前该地区可能处于8级地震丛集发生前的过渡时段。20世纪以来, 中国大陆7级强震的时间活动过程明显受大三角地区8级地震时间进程的影响, 在8级地震活动的1900—1955年时段内, 7级地震幕式活动划分不显著, 而在8级地震平静的1956—2000年时段内, 7级地震幕式活动划分清晰; 以2008年汶川8.0级地震为标志, 受大三角地区8级左右巨大地震活跃控制, 中国大陆可能将进入一组新的幕式活动不清晰的、 类似于1900—1955年的强震活跃时段。 相似文献
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回顾总结了2019年地震活动,从全球到局部,呈现了全球、中国和四川的地震活动概况;分析了全球、中国和四川地震活动的特征;记叙了2019年四川区域内发生的突出地震事件;追踪了2008年汶川8.0级地震以来四川区域内发生的3次7级以上地震的余震活动。结果显示:2019年全球M≥7.0地震活动特征呈现低频次、低强度,主体地区为环太平洋地震带;我国周边未发生M≥7.0地震,表明影响我国地震活动的动力边界地震活动偏弱,我国大陆和邻区地震活动表现出频次低、强度弱的特点,我国大陆地震分布总体显示强度西强东弱,区域上显示M≥5级地震分布于青藏地块、西域地块和华南地块;台湾及其附近海域地震活动频次和强度也偏低;四川区域地震活动强度呈现东强西弱特征,四川区域突出地震事件全部集中在川东南区域; 2008年以来,四川区域的汶川8.0级、芦山7.0级和九寨沟7.0级地震的余震持续活动。 相似文献
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本文明确提出了地震工程专业软件的概念,说明了它的作用;在总结我国地震工程专业软件发展概况的基础上,剖析了其发展缓慢的主客观原因;提出了现阶段我国地震工程专业软件的发展策略,并对其研发工作给出了几条具体的建议。 相似文献
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汶川8.0级地震前地震趋势分析意见的回顾 总被引:4,自引:1,他引:3
该文在系统整理自2001年昆仑山口西8.1级地震到汶川8.0级地震前年度地震趋势预测中提出的地震活动异常和分析意见的基础上, 研究汶川地震未能做出中长期预测的原因。 结果表明: 2001年昆仑山口西8.1级地震发生后, 判定中国大陆处于强震连发阶段, 仍有发生8级大震危险, 但此后的2002—2007年中国大陆周边接连发生大震, 而内部连续6年的7级地震平静, 以及中国大陆5、 6级地震相继出现的显著平静, 是导致2006年以后对中国大陆地震活动水平预测明显偏低的原因。 南北地震带中段一直是作为近几年可能发生强震的危险地区, 但2007年云南宁洱6.4级地震后, 对西南地区强震危险的紧迫性估计不足。 而汶川地震所在的龙门山地震带历史上没有7级以上地震记录, 也是该地震带未作为近几年地震重点危险区的原因之一。 相似文献
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Yifan Yuan 《地震工程与工程振动(英文版)》2008,7(3):247-254
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2008年5月12日T14:28汶川发生8.0级大地震,2008年5月13日T5:00江苏省发生滨海ML3.8地震。滨海地震是否是由汶川地震触发的、可指示滨海附近中短期内将发生中强地震的"诱发前震"?基于此,本文进行了如下研究:①统计南北地震带及中国台湾7.3级以上、日本7.5级以上大地震;②统计①中大震发生后3天时间(72 h)内,华北中南部地区发生的M_L 3以上地震;③统计大震发生后1年内在M_L 3地震附近地区(距震中350 km以内)发生的5级以上地震;④对上述3组地震是否存在链式关系进行统计研究,即研究特定条件下的A—F—B链式地震现象在华北中南部的预报效果。研究结果表明:根据目前所拥有的统计资料,无法确定2008年5月13日滨海M_L 3.8地震是由汶川8级地震诱发的"前兆地震"。 相似文献
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汶川大地震汉源县城建筑物震害调查 总被引:2,自引:0,他引:2
汶川地震中,距离震中约200公里的汉源县出现了明显烈度异常现象,汉源县城建筑物震害表现尤为明显.为了解释这一现象,在汶川大地震第一阶段科学考察中,相关调查小组对汉源县城建筑物震害开展了相应的调查.调查结果表明,该处烈度异常现象确实存在,烈度异常与该处局部场地条件有一定的联系. 相似文献
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Highway bridges in highly seismic regions can sustain considerable residual displacements in their columns following large earthquakes. These residual displacements are an important measure of post‐earthquake functionality, and often determine whether or not a bridge remains usable following an earthquake. In this study, a self‐centering system is considered that makes use of unbonded, post‐tensioned steel tendons to provide a restoring force to bridge columns to mitigate the problem of residual displacements. To evaluate the proposed system, a code‐conforming, case‐study bridge structure is analyzed both with conventional reinforced concrete columns and with self‐centering, post‐tensioned columns using a formalized performance‐based earthquake engineering (PBEE) framework. The PBEE analysis allows for a quantitative comparison of the relative performance of the two systems in terms of engineering parameters such as peak drift ratio as well as more readily understood metrics such as expected repair costs and downtime. The self‐centering column system is found to undergo similar peak displacements to the conventional system, but sustains lower residual displacements under large earthquakes, resulting in similar expected repair costs but significantly lower expected downtimes. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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地震序列是对地震现象的回顾性描述,只有在地震序列结束后它才有可能被确切无疑地判定.鉴于龙门山断裂带或地震带的整体性、统一性和系统性,不可否认在其西南段发生的芦山地震是与汶川地震一样的同属于龙门山断裂带的事件.鉴于芦山地震的震源位置、震源机制、震级大小和破裂区覆盖的范围,目前可认为它是汶川地震迄今最大的余震.鉴于地震序列的判定是对地震现象的唯象的描述,有相当的任意性,对芦山地震究竟是"新的主震"还是"汶川余震"的"讨论"实质上是在根据经验判定地震的类型,即使目前看"主震说"提出的4条"论据"明显缺乏说服力,"余震说"比较有说服力,但最后都需要等到地震序列结束之后才有可能"定论".作者认为,相对于需要等到地震序列结束之后才能"定论"、甚而在地震序列结束之后未必能"定论"的芦山地震究竟是"新的主震"还是"汶川余震"问题,应当更为关注芦山地震的发生引出的一些重要的亟待研究的科学问题与防震减灾问题. 相似文献
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本文从2008年中国汶川、2011年日本东北部巨震出发,论述我国地震预测,尤其是对应用实践中涉及的技术问题和需要重视的管理问题。 相似文献