Seismic performance of wood‐frame houses in south‐western British Columbia

The seismic performance of conventional wood‐frame structures in south‐western British Columbia is analytically investigated through incremental dynamic analysis by utilizing available UBC‐SAWS models, which were calibrated based on experimental test results. To define an adequate target response spectrum that is consistent with information from national seismic hazard maps, record selection/scaling based on the conditional mean spectrum (CMS) is implemented. Furthermore, to reflect complex seismic hazard contributions from different earthquake sources (i.e. crustal events, interface events, and inslab events), we construct CMS for three earthquake types, and use them to select and scale an adequate set of ground motion records for the seismic performance evaluation. We focus on the impacts of adopting different record selection criteria and of using different shear‐wall types (Houses 1–4; in terms of seismic resistance, House 1>House 2>House 3>House 4) on the nonlinear structural response. The results indicate that the record selection procedures have significant influence on the probabilistic relationship between spectral acceleration at the fundamental vibration period and maximum inter‐story drift ratio, highlighting the importance of taking into account response spectral shapes in selecting and scaling ground motion records. Subjected to ground motions corresponding to the return period of 2500 years, House 1 is expected to experience very limited extent of damage; Houses 2 and 3 may be disturbed by minor damage; whereas House 4 may suffer from major damage occasionally. Finally, we develop statistical models of the maximum inter‐story drift ratio conditioned on a seismic intensity level for wood‐frame houses, which is useful for seismic vulnerability assessment. Copyright © 2010 John Wiley & Sons, Ltd.     

海域俯冲带高频地震动模拟?以2021年2月13日日本福岛MS7.1地震为例

2021年2月13日,日本福岛近海发生M_S7.1地震,震中距海岸线约70 km,震源深度接近60 km,造成了较大范围的震害影响。考虑地震应急及地震动强度特征预测的应用前景等,利用经验格林函数法快速估计了本次地震的高频地震动（1.0～20.0 Hz）空间分布特征及加速度时程,并结合实际地形、场地覆盖层等信息对部分台站地震动模拟结果进行修正,最终获得较可靠的地震动预测结果。研究结果表明,在具备合适小震记录时（余震及前震）,可较准确地再现大震的高频地震动主要特征,模拟结果与真实记录拟合较好;地震动模拟过程中需考虑盆地等特殊地形及覆盖土层对地震动的放大作用影响,这也是未来利用经验格林函数法合成大震时需重点考虑的因素。     

Finite-element simulations of long-period ground motions: Japanese subduction-zone earthquakes and the 1906 San Francisco earthquake

Large earthquakes at shallow depths commonly excite long-period ground motions in distant sedimentary basins, thereby inflicting damage upon large-scale structures. For example, the 2003 Tokachi-oki earthquake, Japan, damaged oil tanks in the Yufutsu Basin, located 250 km from the epicenter. Similar long-range effects were also observed during the 2004 earthquake off Kii Peninsula, Japan. In this study, we present the results of simulations of these earthquakes undertaken using the finite element method (FEM) with a voxel mesh. In addition, to examine whether the 1906 San Francisco earthquake excited long-period ground motions in the Los Angeles-area basins, we performed long-period ground motion simulations of most of the California region. The FEM simulations confirmed the importance of path effects for the development of long-period ground motions.     

盆地对三分量地震动持时的影响初探

利用关东盆地及其周边KiK-net台网井上台站记录的2004—2017年15次中强地震（矩震级为5.1～6.9级）构建三分量记录显著持时Ds_5-95数据库。针对该数据库,基于残差分析方法和3种水平向地震动持时参数预测方程,计算并给出事件间残差和事件内残差及其随不同类别参数的变化。在此基础上,初步探讨了水平向地震动持时预测方程应用于预测竖向地震动持时的可行性及盆地对三分量地震动持时的影响。研究结果表明,对于震源距和场地V_S30相当的情况,盆地内台站持时普遍大于盆地外台站持时,盆地内、外台站竖向地震动持时均大于水平向地震动持时;3种预测方程均可实现对盆地外台站水平向地震动Ds_5-95的合理估计,但在一定程度上低估了盆地内台站的水平向地震动Ds_5-95;3种预测方程均无法直接应用于竖向地震动持时预测。     

Characteristics of amplitude and duration for near fault strong ground motion from the 1999 Chi-Chi, Taiwan Earthquake

A great number of free-field ground motion records are obtained during the 1999 Chi-Chi, Taiwan, earthquake. Records from 130 near fault free-field stations within 55 km to the causative fault surface are used as database, and characteristics of earthquake peak ground acceleration, velocity, displacement and duration are analyzed. According to this study, near fault ground motions are strongly affected by distance to fault, fault rupture directivity, site condition, as well as thrust of hanging wall. Compared with empirical strong ground motion attenuation relations used in China, US and Japan, the PGAs and PGVs recorded in this earthquake are not as large as what we have expected for a large earthquake as magnitude 7.6. However, the largest PGV and PGD worldwide were recorded in this event, which are 292 cm/s and 867 cm, respectively. Caused by nonlinear site effects of soil, peaks and corresponding ratios on E-class site were markedly different from those on other sites. Just as observed in historic earthquakes, fault rupture directivity effects caused significant differences between peaks of ground motion of two horizontal components, but took very slight effects on the duration of ground motion. The significant velocity pulses associated with large PGVs and PGDs, as well as large permanent displacements, which may result from the large thrust of the hanging wall, became the outstanding character of this event. Based on this study, we point out that 3D waveform modeling is needed to understand and predict near fault ground motion of large earthquakes.     

Estimation of strong ground motions from hypothetical earthquakes on the Cascadia subduction zone,Pacific Northwest

Strong ground motions are estimated for the Pacific Northwest assuming that large shallow earthquakes, similar to those experienced in southern Chile, southwestern Japan, and Colombia, may also occur on the Cascadia subduction zone. Fifty-six strong motion recordings for twenty-five subduction earthquakes ofM _s7.0 are used to estimate the response spectra that may result from earthquakesM _w<81/4. Large variations in observed ground motion levels are noted for a given site distance and earthquake magnitude. When compared with motions that have been observed in the western United States, large subduction zone earthquakes produce relatively large ground motions at surprisingly large distances. An earthquake similar to the 22 May 1960 Chilean earthquake (M _w 9.5) is the largest event that is considered to be plausible for the Cascadia subduction zone. This event has a moment which is two orders of magnitude larger than the largest earthquake for which we have strong motion records. The empirical Green's function technique is used to synthesize strong ground motions for such giant earthquakes. Observed teleseismicP-waveforms from giant earthquakes are also modeled using the empirical Green's function technique in order to constrain model parameters. The teleseismic modeling in the period range of 1.0 to 50 sec strongly suggests that fewer Green's functions should be randomly summed than is required to match the long-period moments of giant earthquakes. It appears that a large portion of the moment associated with giant earthquakes occurs at very long periods that are outside the frequency band of interest for strong ground motions. Nevertheless, the occurrence of a giant earthquake in the Pacific Northwest may produce quite strong shaking over a very large region.     

基于条件均值反应谱的特大地震强震记录的选取及调整方法

在PEER地震动数据库(PGMD)的基础上, 结合近几年国内外特大地震的地面运动记录, 建立了地面运动数据库, 同时根据日本M_W9.0特大地震获得的141组记录进行统计回归建立加速度反应谱衰减关系, 并采用条件均值反应谱法, 即设定地震与结构概率需求结合的方法选择地面运动. 选波实例表明, 当设定地震为特大地震时, 基于条件均值反应谱法选取地面运动记录时, 扩展数据库中大震记录并建立符合大震记录加速度反应谱的衰减关系是十分必要与迫切的. 该思路为进一步研究结构动态时程分析中地面运动记录选取问题及所选记录提供了依据.      

Empirical green's function corrected for source effect

One of the severe problems in the semi-empirical method for the prediction of strong ground motions is that there is no objective criterion for choosing empirical Green's functions. It is undesirable that synthesized strong ground motions are affected by the source process of an earthquake whose record is adopted as an empirical Green's function. Through the analysis of strong motion accelerograms of two aftershocks of the 1983 Japan Sea earthquakes, it is found that characteristics of the accelerograms are dependent on the moment rate function derived from teleseismic observations. A procedure is presented for removing the effect of the source process from observed strong motion accelerograms. The thus obtained empirical Green's function expresses approximately the impulse response of the medium between the earthquake source and the observation site.     

俯冲带地震动特征及其衰减规律探讨

随着我国南海不断开发建设,海洋工程的抗震问题日益受到重视.我国南海东部区域位于大陆板块与海洋板块共同作用的俯冲带地区,地震活动频繁,震级较大,潜在地震对南海开发建设有重要影响.为了研究俯冲带地震的地震动特征及其衰减规律,本文基于实际俯冲带地震数据,并结合数值模拟方法,分析和探讨了俯冲带板内、板缘地震与浅地壳地震的地震动特征和衰减规律的差异.研究结果表明:俯冲带地震动存在区域性差异,在地震动衰减特征方面,同一区域的俯冲带板缘地震要比浅地壳地震衰减慢,俯冲带板内地震要比浅地壳地震衰减得快;数值模拟分析不同深度海水对海底地震动的影响表明,海底地震动水平分量几乎不受海水介质的影响,但是竖向分量随海水深度的增加有减小的趋势.最终,基于数值模拟和经验关系的混合方法建立了南海俯冲带地震动衰减关系模型,其结果可为海域区划等相关研究和海域工程建设提供参考.     

中小震近场地震动估计中地震动衰减关系的适用性分析

核工程场地设计基准地震动确定中涉及弥散地震的地震动估计，这导致中小震近场地震动估计成为被关注的研究课题。本文基于一些中小震近场地震动记录资料，分析和探讨了国内外多种地震动衰减关系对中小震近场地震动估计的适用性问题，并结合我国几个核工程地震问题研究工作的实践对中小震近场地震动衰减关系确定的思路和原则提出了建议。     

地震动幅值沿深度变化研究

以美国加州强震观测计划(CSMIP)的6个土工台阵和日本Hosokura矿台阵为研究对象, 以323组三分量地表和地下地震动峰值数据为基础, 按照台阵场地的软硬和土层分布, 将其分为基岩、 土层和ldquo;土层/基岩rdquo;台阵. 对于同一类台阵记录的所有地震, 分别按照震级和地表地震动峰值的大小将其分类. 对于同一类台阵的各类地震, 分别对加速度、 速度和位移峰值沿深度的变化进行统计分析, 得到沿深度变化的峰值比, 并且用非线性最小平方法, 采用指数衰减模型, 对峰值比沿深度变化曲线进行拟合. 通过对各类场地的各类地震的分析, 得到了地震动峰值沿深度变化的初步规律.      

Variation of earthquake ground motionwith depth

Introduction The 21st century is the time for the exploitation and utilization of underground spaces. It is astrategic way to defeat the severe challenge that human are now confronting with, such as the lackof land, contamination of environment, traffic jam, waste of sources, and so on. The exploitationand utilization of underground space has become a global tendency, and a significant sign inevaluating the speed of modernization of cities. Facing the challenge, it is significantly necess…     

水库诱发地震的地震动特征

利用新丰江、美国奥洛维尔和蒙蒂赛洛水库地震极近场地面运动资料，研究了水库诱发地震的地震动峰值加速度衰减。结果表明，水库地震的峰值加速度高，衰减快。利用国内水库地震资料研究了水库地震烈度。水库地震烈度与同级天然地震烈度相比，一般是烈度高，衰减慢。水库地震的地震动反应谱频率高，地震动持续时间短     

A ground motion prediction equation for JMA instrumental seismic intensity for shallow crustal earthquakes in active tectonic regimes

The JMA (Japan Meteorological Agency) seismic intensity scale has been used in Japan as a measure of earthquake ground shaking effects since 1949. It has traditionally been assessed after an earthquake based on the judgment of JMA officials. In 1996 the scale was revised as an instrumental seismic intensity measure (I_JMA) that could be used to rapidly assess the expected damage after an earthquake without having to conduct a survey. Since its revision, Japanese researchers have developed several ground motion prediction equations (GMPEs) for I_JMA using Japanese ground motion data. In this paper, we develop a new empirical GMPE for I_JMA based on the strong motion database and functional forms used to develop similar GMPEs for peak response parameters as part of the PEER (Pacific Earthquake Engineering Research Center) Next Generation Attenuation (NGA) project. We consider this relationship to be valid for shallow crustal earthquakes in active tectonic regimes for moment magnitudes ( M ) ranging from 5.0 up to 7.5–8.5 (depending on fault mechanism) and rupture distances ranging from 0 to 200 km. A comparison of this GMPE with relationships developed by Japanese researchers for crustal and shallow subduction earthquakes shows relatively good agreement among all of the relationships at M 7.0 but relatively poor agreement at small magnitudes. Our GMPE predicts the highest intensities at small magnitudes, which together with research on other ground motion parameters, indicates that it provides conservative or upwardly biased estimates of I_JMA for M <5.5. Copyright © 2010 John Wiley & Sons, Ltd.     

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.     

福州盆地强地面运动特征的有限元数值模拟

区域性地震波强地面运动的量化数值模拟分析结果可以用来指导城市规划建设,并在防震减灾中发挥重要作用. 本文采用有限元数值模拟方法来模拟由地震激发的区域地震波强地面运动过程,并得到地表峰值速度和加速度的分布特征.考虑到福州是东南沿海的重要省会城市,其明显的盆地结构特征使它很容易遭受强地震灾害的影响. 因此本文以福州盆地为主要研究对象,假定盆地的主要断层某一位置在未来可能发生灾害性地震,则该地震会激发地震波的强地面运动,并由于地形、沉积层等主要影响,在盆地内部发生放大.通过对地震波传播过程的数值模拟和后处理分析,给出了该盆地的地表峰值位移、峰值速度和峰值加速度分布图谱.该图谱可为未来的福州城市规划和抗震减灾提供定量科学参考依据.     

The Influence of 3-D Structure on the Propagation of Seismic Waves Away from Earthquakes

-- The seismic records from significant earthquakes are profoundly affected by 3-D variations in crustal structure both in the source zone itself and in propagation to some distance. Even in structurally complex zones such as Japan and Mexico relatively coherent arrivals are found associated with different classes of propagation paths. The presence of strong lateral variations can disrupt the arrivals, and impose significant variations in propagation characteristics for different directions from the source as illustrated by observations for the 1995 Kobe and 2000 Tottori-ken Seibu earthquakes in western Japan. Such effects can be modelled in 3 dimensions using a hybrid scheme with a pseudospectral representation for horizontal coordinates and finite differences in depth. This arrangement improves parallel implementation by minimising communication costs. For a realistic 3-D model for the structure in western Japan the 3-D simulations to frequencies close to 1 Hz provide a good representation of the observations from subduction zones events such as the 1946 Nankai earthquake and the 2000 Tottori-ken Seibu earthquake. The model can therefore be used to investigate the pattern of ground motion expected for future events e.g., in current seismic gaps.     

九寨沟MS7.0地震强地震动模拟及漳扎镇地震动强度预测

破坏性地震强度预测可用于工程领域抗震设防以及地震危险性分析评估,是防震减灾中一项很重要的基础工作.为了再现九寨沟地震的地震动强度,评估缺失强震记录的九寨章扎台站的地震动强度,本文用经验格林函数法对九寨沟地震进行了数值模拟.选取了震源周边地震动峰值加速度超过10 Gal的10个强震台站进行模拟.因未得到九寨沟地震的余震,初次尝试将汶川地震和定西地震的余震作为格林函数模拟九寨沟地震.模拟结果整体上可以反映各台站地震动的强度特征,尤其是地震动高频成份拟合较好.模拟值的地震动峰值加速度、时程数据、反应谱等与观测值拟合较好.预测结果显示漳扎镇的地震动峰值加速度值约为180~200 Gal.预测结果也表明在缺少大震的余震记录时,经验格林函数法使用其他大震的余震同样可以再现目标地震的强度特征.本研究也为经验格林函数方法在缺乏小震记录地区的使用积累了经验.最后总结了格林函数的选取标准,为经验格林函数方法来预测未来强震动特征积累了经验.     

用改进的经验格林函数方法模拟唐山地震动

建筑物的抗震设防需要尽可能地掌握未来大地震强震动记录信息,但大地震强震动记录的匮乏阻碍了抗震设防实践的发展。经验格林函数方法作为模拟地震动的主要方法,可以提供可靠的大地震强震动记录,但也存在着许多问题,如缺乏对大地震断层滑动分布不均匀的描述、用经验确定小震数目、模拟方法受到大小地震相似条件的限制等。文中对上述经验格林函数方法存在的问题进行了研究,改进的经验格林函数方法,有效地解决了上述问题。并用其对唐山大地震进行了模拟,并把模拟的地震动时程和反应谱与实际记录相比较,发现用改进方法模拟的地震动加速度反应谱比用未改进方法模拟结果更接近实际的地震动记录加速度反应谱。由此说明改进的经验格林函数可更准确的模拟地震动。     

近场地震下竖向刚度不同的混合结构动力性能分析

近场地震的动力特性明显不同于远场地震,因此有必要对结构在近场地震作用下的动力性能展开研究。以上部钢结构-下部混凝土结构这类竖向刚度不同的加层混合结构为研究对象,对其在近场脉冲型地震、近场无脉冲型地震及远场地震作用下的动力响应进行研究。结果表明:在多遇、设防、罕遇地震作用下,近场脉冲型地震会使结构的层间位移角、层间剪力、加速度等动力响应均放大并出现超限的情况,而且都比罕遇地震作用下结构的响应增大更明显;在进行近场区加层混合框架结构的设计和建设时,近场脉冲效应会使结构存在不满足规范的情况,有必要对竖向刚度不同的加层混合结构在近场区的适用性进行深入研究。