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潜在震源区地震活动性参数、地震动衰减关系对地震危险性分析结果至关重要。以中国第五代地震动区划图潜在震源区划分方案为基础,采用2类震级分档分别建立自编及五代图潜在震源区空间分布函数,收集4组青藏高原及周缘地区地震动衰减关系,采用不同组合对青藏工程走廊沿线的81个场点进行概率地震危险性分析计算,得到50年超越概率10%(地震重现期475年)的各场点基岩地震动峰值加速度(PGA),并转换为一般场地(Ⅱ类)PGA,对计算结果进行对比分析,并与第五代地震动区划图归档上下限值进行比较。结果显示:采用我国西部地区地震动衰减关系计算得到的PGA最大,采用云南地区地震动衰减关系得到的PGA最小,采用川藏地区及青藏高原东北缘地震动衰减关系时居中;在同一地震动衰减关系下,采用自编空间分布函数计算得到的PGA普遍略大于采用第五代图空间分布函数时;在震级上限为8.5的潜在震源区及附近地区,潜在震源区空间分布函数震级分档对计算结果有显著影响。综合分析表明,采用自编Ⅱ型震级分档空间分布函数方案与川藏地区地震动衰减关系组合方案的计算结果最为理想。最后,采用该组合方案对青藏工程走廊50年超越概率10%的基岩场地PGA及一般场地PGA进行了区划。 相似文献
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针对一种具有可更换构件的新型铁路高墩结构,基于增量动力分析(IDA)曲线,采用易损性分析方法对9度设计、罕遇与极罕遇害地震时的墩柱进行抗震性能评价。建立全桥有限元分析模型,以墩柱最不利截面材料的应变为损伤指标,以地面峰值加速度为地震动强度指标,以357条地震波作为地震动输入,IDA分析得到墩柱关键截面的IDA曲线簇及50%、84%和16%的分位曲线,结合定义的极限状态,探讨墩柱可能产生的塑性铰数量及位置,并通过绘制易损性曲线,对墩柱进行基于概率性的抗震性能评估。研究结果表明：可更换构件在桥墩中首先屈服,从PGA=0.5g时开始屈服、到PGA=1.1g时全部屈服,可更换构件实现分级耗能;墩柱在9度罕遇地震作用下处于基本完好的概率约为99.5%;可更换构件新型高墩结构在9度巨震下超越基本完好状态的概率为36.6%,超越可修复性损伤状态的概率不足1%,其大概率处于可修复性损伤状态。可更换构件高墩抗震性能优越,在近断层地区具有较好的应用前景。 相似文献
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2021年5月21日云南漾濞发生6.4级地震,中国数字化强震动观测网络在主震中捕获28组加速度数据。对84条三分向加速度记录进行常规处理,计算出对应的地震动参数,并绘制震中附近水平向PGA和PGV等值线图,结果显示其走向和形态与震后烈度调查结果相近。将实际观测的相对持时进行曲线回归,求得相关系数,并据此计算出T_d(5%～95%)持时对应的震源持续时间在10.22～13.06 s间,与震源破裂过程反演结果基本一致。再通过分析近场6个台站记录的加速度反应谱,并与抗震设计谱比较,总结此次地震的频谱特性,为该区域抗震设防提供参考依据。 相似文献
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核电厂在遭遇超设计基准地震时需要考虑安全停堆,以避免造成核泄漏事故。采用地震动的峰值加速度参数(PGA)作为判别停堆的参数具有一定的局限性,PGA参数不能反映地震动的频谱和持时特征,因而可能引起不必要的停堆。针对此问题,基于我国本土大量实际强震记录,遴选出7种典型的工程相关地震动参数,进而基于地震烈度指标,分析发现地震动的标准累计绝对速度参数能更好地表征地震对核电厂的整体潜在破坏能力,适合作为判别停堆的参数,然后提出两种确定预警参数阈值的方法,最终建议考虑我国强震数据特征的核电厂判别停堆的预警参数阈值,为我国核电厂的地震安全停堆参数的确定提供了参考。 相似文献
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冶勒沥青混凝土心墙堆石坝最大坝高为124.5m,坝址区地震烈度高,地质条件复杂。大坝上布设了9台强震仪组成的强震监测台阵,自2005年12月开始投入运行至2014年12月底共获得有效记录57次,其中包括汶川地震、攀枝花地震和芦山地震记录。对典型强震记录进行时域分析和频谱分析,初步总结了冶勒大坝的动力反应特性。研究结果表明,大坝坝顶部位的动力反应主要以放大为主,并且随着底部PGA的减小,坝体放大倍数明显增大;由于地震动本身震源特性、传播途径的差异,大坝在不同地震中动力反应的频谱特性明显不同,但多次记录均显示土石坝体有较为明显的滤波作用。 相似文献
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将土体视为固-液两相介质,基于饱和土体有效应力原理,建立饱和土体-地下综合管廊结构体系相互作用动力模型:在地应力平衡的静力状态下采用Duncan-Chang非线性弹性本构模型,在地震波作用的动力状态下采用Davidenkov非线性黏弹性本构模型;考虑饱和土体黏弹性动力人工边界条件,将地震动作用转化为作用在人工边界节点上的动力荷载。模型考察不同地震波时程、地震波加速度峰值、入射角度、孔隙率以及地应力场的影响,得出如下结论:(1)地震波的卓越周期与场地卓越周期相近时引起结构上的变形最大;随着地震波加速度峰值的增大结构变形增大;随着地震波入射角度的增加结构变形增大,地震波斜入射情况下产生的行波效应使得结构变形最大。(2)土体材料的孔隙水压力是影响地震中结构变形的主要因素之一。(3)将土体材料考虑为单相介质时结构上的变形要比考虑为固-液两相介质时大得多,直接将饱和土体场地中得到的地震波等效荷载施加到单相土介质-结构动力相互作用模型上,能够得到与完全基于有效应力法一致的结果。 相似文献
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利用首都圈强震台网比较密集的数字地震记录,研究2003年4月发生在唐山震区的2次4级地震。利用布设在四川、甘肃、陕西的强震台网和临时强震台网的资料,研究2008年7月和8月发生在四川汶川的2次6级地震。得到正断层和走向滑动断层、逆冲断层和走向滑动断层的地震近场PGA分布的差异。结果表明,这种差异是显著的。不仅大震的PGA近场分布复杂,中小地震也是如此。经频谱分析发现,这种影响出现差异的地震波频率较低,城市化的建筑向高层大型发展,其自振周期相应较长。近直立走向滑动地震的PGA高值区沿断层对称分布,而正断层和逆断层则集中在断层上盘,这对于破坏性地震应急救援中力量、物资的投入有借鉴意义。 相似文献
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2021年5月22日,青海省果洛州玛多县发生7.4级地震,中国强震动观测网络在主震中捕获16组强震动数据。对48条三分向加速度记录进行基线校正、滤波等常规处理,计算相应的地震动参数,发现位于断层破裂前向位置的63DAW台NS向记录的地震动速度波形具有长周期分量丰富的特征。分析6个典型台站的单自由度加速度反应谱,并与我国建筑抗震设计谱比较,分析此次地震的频谱特性。将实际观测到的PGA、PGV和S_a(T=0.1 s、T=1.0 s、T=2.0 s、T=5.0 s)与国内广泛使用的几种地震动预测模型对比,研究此次地震的影响场。通过分析S_a-S_d曲线,探讨此次地震靠近断层区域地面运动大位移与桥梁落梁震害间可能存在的关系。 相似文献
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研究黄土丘陵河谷场地在地震作用下强地面运动特征的变化情况,可以揭示强震对该类场地上震害的触发机理。结合黄土高原的地貌特征,建立具有代表性的动力数值分析模型,通过输入不同幅值、频谱特性和持续时间的地震波,对起伏地形和覆盖黄土层共同影响下的黄土河谷场地进行地震反应分析。结果表明:黄土层和地形耦合作用控制了地表的PGA变化,使其趋于复杂,在同一输入波不同振幅作用下,与基岩河谷各测点相比,黄土覆盖河谷场地的地震动频谱幅值均有所增加,并且频谱主峰均向高频移动。在不同地震波输入下,场地不同部位的固有频率受地形高程和土层影响;而地震动大小和频谱幅值不仅与场地的基本频谱和地形起伏有关,也与输入地震波的频谱成分相关。输入波PGA与地震频谱特征都不变时,同一场地输出的地震频谱形状具有相似的特征,随着地震持时增长,能量向场地基本频率附近集中,从而可能导致场地上相应频率建筑物震动幅值增加,造成累积破坏。 相似文献
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Rupture model of the 2013 M_W 6.6 Lushan (China) earthquake constrained by a new GPS data set and its effects on potential seismic hazard 
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下载免费PDF全文 Vertical records are critically important when determining the rupture model of an earthquake, especially a thrust earthquake. Due to the relatively low fitness level of near-field vertical displacements, the precision of previous rupture models is relatively low, and the seismic hazard evaluated thereafter should be further updated. In this study, we applied three-component displacement records from GPS stations in and around the source region of the 2013 MW6.6 Lushan earthquake to re-investigate the rupture model.To improve the resolution of the rupture model, records from both continuous and campaign GPS stations were gathered, and secular deformations of the GPS movements were removed from the records of the campaign stations to ensure their reliability. The rupture model was derived by the steepest descent method(SDM), which is based on a layered velocity structure. The peak slip value was about 0.75 m, with a seismic moment release of 9.89 × 10~(18) N·m, which was equivalent to an M_W6.6 event. The inferred fault geometry coincided well with the aftershock distribution of the Lushan earthquake. Unlike previous rupture models, a secondary slip asperity existed at a shallow depth and even touched the ground surface. Based on the distribution of the co-seismic ruptures of the Lushan and Wenchuan earthquakes, post-seismic relaxation of the Wenchuan earthquake, and tectonic loading process, we proposed that the seismic hazard is quite high and still needs special attention in the seismic gap between the two earthquakes. 相似文献
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《Geofísica Internacional》2013,52(2):173-196
An analysis of local and regional data produced by the shallow, thrust Ometepec-Pinotepa Nacional earthquake (Mw 7.5) of 20 March 2012 shows that it nucleated at 16.254°N 98.531°W, about 5 km offshore at a depth of about 20 km. During the first 4 seconds the slip was relatively small. It was followed by rupture of two patches with large slip, one updip of the hypocenter to the SE and the other downdip to the north. Total rupture area, estimated from inversion of near-source strong-motion recordings, is ~25 km × 60 km. The earthquake was followed by an exceptionally large number of aftershocks. The aftershock area overlaps with that of the 1982 doublet (Mw 7.0, 6.9). However, the seismic moment of the 2012 earthquake is ~3 times the sum of the moments of the doublet, indicating that the gross rupture characteristics of the two earthquake episodes differ. The small-slip area near the hypocenter and large-slip areas of the two patches are characterized by relatively small aftershock activity. A striking, intense, linear NE alignment of the aftershocks is clearly seen. The radiated energy to seismic moment ratios, (Es/M0), of five earthquakes in the region reveal that they are an order of magnitude smaller for near-trench earthquakes than those that occur further downdip (e.g., 2012 and the 1995 Copala earthquakes). The near-trench earthquakes are known to produce low Amax. The available information suggests that the plate interface in the region can be divided in three domains. (1) From the trench to a distance of about 35 km downdip. In this domain M~6 to 7 earthquakes with low values of (Es/M0) occur. These events generate large number of aftershocks. It is not known whether the remaining area on this part of the interface slips aseismically (stable sliding) or is partially locked. (2) From 35 to 100 km from the trench. This domain is seismically coupled where stick-slip sliding occurs, generating large earthquakes. Part of the area is probably conditionally stable. (3) From 100 to 200 km from the trench. In this domain slow slip events (SSE) and nonvolcanic tremors (NVT) have been reported.The earthquake caused severe damage in and near the towns of Ometepec and Pinotepa Nacional. The PGA exceeded 1 g at a soft site in the epicentral region. Observed PGAs on hard sites as a function of distance are in reasonable agreement with the expected ones from ground motion prediction equations derived using data from Mexican interplate earthquakes. The earthquake was strongly felt in Mexico City. PGA at CU, a hard site in the city, was 12 gal. Strong-motion recordings in the city since 1985 demonstrate that PGAs during the 2012 earthquake were not exceptional, and that similar motion occurs about once in three years. 相似文献
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A common type of ancient monuments around the Mediterranean is the ancient Greek temple. Unfortunately, very few remain intact; most of them surviving in the form of free‐standing multidrum columns. Composed of stones resting on top of each other without any connection, such columns are considered vulnerable to earthquakes. The paper presents an experimental study of such structures, aiming to explore their seismic vulnerability and derive insights on the key factors affecting their response. Reduced scale models of a single multidrum column and of a portal were tested at the shaking table of the National Technical University of Athens Laboratory of Soil Mechanics. The models, constructed of marble just as the originals, were excited by idealized Ricker pulses and real seismic records. Single columns exhibit a remarkable earthquake resistance. Subjected to the strongest motions ever recorded in Greece, where many such monuments are situated, the columns hardly suffered any permanent deformation. Collapse is probable only for extremely harsh directivity‐affected seismic motions. Portals proved even more robust, surviving extreme seismic excitations. Their superior performance is related to the beneficial role of the epistyle, which adds energy dissipation and restoring force to the system. Their performance is very sensitive to minor changes in geometry or input motion. The complexity increases exponentially with the number of drums, being directly associated with the number of drum‐to‐drum interfaces and the increased probability of interface imperfections. In contrast to PGA, the maximum spectral displacement SDmax and the length scale Lp have turned out to be effective intensity measures. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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The sensitivity of seismic energy dissipation to ground motion and system characteristics is assessed. It is found that peak ground acceleration, peak ground velocity to acceleration (V/A), dominant period of ground excitation and effective response duration are closely correlated with the energy dissipated by a SDOF system. Ductility ratio and damping ratio have no significant influence on the energy dissipation. An energy dissipation index is proposed for measuring the damage potential of earthquake ground motion records which includes the effects of basic excitation and response characteristics contributing to the seismic energy dissipation. The proposed index is compared with several intensity measures for the set of 94 ground motion records considered in the study. 相似文献
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The problem addressed in this paper is the estimation of the (de)amplification of ground motion at soil sites (compared to rock sites) as a function of the intensity of the ground motion. A non‐parametric empirical approach, called the Conditional Average Estimator (CAE) method, has been used, which is different from all existing approaches. Site factors (SFs) for sites characterized with Vs30 between 180 and 360 m/s were predicted for the peak ground acceleration (PGA) and the spectral accelerations by using a combined database of recorded ground motions. Based on the results of the study, site factors for PGA and selected spectral accelerations are proposed, separately for weaker and stronger ground motions. Comparisons are made with the SFs used in two standards (Eurocode 8 and ASCE 7‐10) and with SFs proposed in the literature, including four Next Generation Attenuation (NGA) ground‐motion prediction equations. The study reveals that (i) SFs depend strongly on the ground‐motion intensity. In the case of stronger ground motions, they decrease with increasing acceleration. (ii) The SFs predicted in this study agree reasonably well with the existing SFs in the case of weak ground motion. For higher intensities of ground motion, they are generally smaller than the existing ones. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Antonio Rovelli 《Physics of the Earth and Planetary Interiors》1983,33(2):94-110
Stochastic modelling is applied to the analysis of local earthquake recordings, which are usually extremely rich in random incident-wave trains that are chaotically superimposed because of scattering effects in the Earth's crust. The presence in the seismic signal of effects connected with the scale of inhomogeneity in the lithosphere cannot be deterministically described in detail. The application of a stochastic second-order autoregressive model to accelerometric records for the higher magnitude (ML ? 6) Friuli earthquakes and to short-period seismometric records for the aftershocks of the strong earthquake of 6 May 1976 has allowed inferences to be drawn about the spectral properties of seismic signals and the propagation mechanisms of seismic waves. These inferences are based on an extremely small number of parameters of a mathematical model suitable for simultaneously describing the random sequence of scattered wave trains in the time and frequency domains. Useful physical information has been obtained about the dynamic characteristic correlation times and the predominant frequency of the seismic signals; moreover, the strength, σ2e(t), of the innovation of the stochastic process fitting the real digital data set has been estimated. From the envelopes of σ2e(t), the quantity heuristically used in the stochastic approach to describe seismic excitation, the·mean free-path between successive scatterings (l), or the equivalent diffusivity coefficient (d) and turbidity (g), and their dependence on seismic wave frequency have been investigated. For Friuli, using seismometric data at an epicentral distance of ～ 20 km and earthquakes with a magnitude just under 2, mean free-path estimates obtained by means of autoregressive parameters vary from ～ 5 km for the strong interaction model to ～ 30 km for the single scattering model. Furthermore, by means of accelerometric records for the strongest earthquakes in Friuli during May and September 1976, the dependence for the maximum of the seismic excitation on the epicentral distance R was estimated as (σ2e)max ～ R?ν (with ν 1.94 ± 0.13), which is in good agreement with results obtained for the same region using standard methods by means of acceleration peaks versus R. Lastly, stochastic modelling provides a method of estimating change versus time for the predominant frequency and characteristic correlation time of narrow band digital recordings. These two parameters were computed by means of autoregressive parameters in different physical situations and were found to be functions of the earthquake source, the instrumentation frequency response, and the Earth's filtering effects. 相似文献
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Empirical evaluation of peak ground velocity and displacement as a function of elastic spectral ordinates for design 下载免费PDF全文
下载免费PDF全文 In the framework of the revision of Part 1 of Eurocode 8, this study aims at developing new empirical correlations to compute peak values of ground velocity (PGV) and displacement (PGD) as a function of elastic spectral ordinates for design. At variance with the expressions for PGV and PGD currently adopted in the Eurocode 8, based solely on the peak ground acceleration (PGA), in this paper reference is made to spectral ordinates of the short and intermediate period range, namely Ss, which is the constant acceleration spectral ordinate, and S1, which is the spectral ordinate at 1 s. On the one hand, a relationship between PGV and the product (Ss?S1) was found based on the regression analysis on a high‐quality strong‐motion dataset. On the other hand, the PGD was estimated by extrapolating to long periods the constant displacement branch of the elastic response spectrum, introducing a correlation between the corner period TD and S1. For this purpose, results of a long period probabilistic seismic hazard assessment study for Italy, encompassing low to high seismicity areas, were considered. Furthermore, verification of the proposed relationship against strong‐motion records was carried out, and differences justified in terms of the concept of uniform hazard spectrum. 相似文献
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Ho Choi Yasushi Sanada Hisatoshi Kashiwa Yasuhiro Watanabe Jafril Tanjung Huanjun Jiang 《地震工程与结构动力学》2016,45(6):999-1018
This study proposes a procedure for identifying spectral response curves for earthquake‐damaged areas in developing countries without seismic records. An earthquake‐damaged reinforced concrete building located in Padang, Indonesia was selected to illustrate the identification of the maximum seismic response during the 2009 West Sumatra earthquake. This paper summarizes the damage incurred by the building; the majority of the damage was observed in the third story in the span direction. The damage was quantitatively evaluated using the damage index R according to the Japanese guidelines for post‐earthquake damage evaluation. The damage index was also applied to the proposed spectral response identification method. The seismic performance of the building was evaluated by a nonlinear static analysis. The analytical results reproduced a drift concentration in the third story. The R‐index decreased with an increase in the story drift, which provided an estimation of the maximum response of the building during the earthquake. The estimation was verified via an earthquake response analysis of the building using ground acceleration data, which were simulated based on acceleration records of engineering bedrock that considered site amplification. The maximum response estimated by the R‐index was consistent with the maximum response obtained from the earthquake response analysis. Therefore, the proposed method enables the construction of spectral response curves by integrating the identification results for the maximum responses in a number of earthquake‐damaged buildings despite a lack of seismic records. Copyright © 2016 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd. 相似文献