共查询到20条相似文献,搜索用时 531 毫秒
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建立了北京盆地含起伏地形的地下介质三维速度结构模型, 以有限差分方法对盆地内的3次地震动进行了数值模拟. 计算了地表加速度反应谱, 论证了反应谱的有效周期范围, 从而获得了盆地结构对长周期段反应谱的平均放大系数, 并对不同周期时反应谱的平均放大系数进行了分区, 为今后城市的合理规划和长周期建筑物的建设提供了抗震设防参考. 最后对反应谱平均放大系数与等效沉积物厚度之间的关系进行了回归, 得出了反应谱放大系数随沉积物厚度增大而增强, 以及随周期增大而减弱等结论. 相似文献
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抗震设计规范中的场地设计反应谱是一般工程抗震设计的依据,各国的抗震设计规范对场地设计反应谱的规定不尽相同。主要表现在反应谱的形状和谱参数的差异。本文收集了若干国家的抗震设计规范;在总结各国抗震设计规范中关于场地设计反应谱规定的基础上,对中国、美国、日本、欧洲、土耳其和智利等有代表性的国家和地区的抗震设计规范进行分析和对比研究;总结了我国抗震设计规范场地设计反应谱的演化历史和发展过程;提出了进一步开展这一领域研究工作的若干建议,本文的工作对从事场地设计反应谱研究的科技人员有重要的参考价值。 相似文献
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在搜集了大量近断层具有速度脉冲的记录后,对有速度脉冲和无速度脉冲的记录的反应谱和特征周期进行了对比,将近断层记录的反应谱与我国规范标准反应谱进行了比较, 还将各次地震有速度脉冲记录的反应谱和特征周期与规范标准谱及规范给出的特征周期进行了比较. 通过比较可知,在长周期段(大约在1.5 s以后),有速度脉冲记录的反应谱值要比无速度脉冲记录的反应谱值大;计算特征周期时,对于近断层记录,T1和T2有后延的趋势, 采用不固定频段的方法计算更加合理; 无论是相对我国规范的Ⅰ类还是Ⅱ类场地, 有速度脉冲记录的特征周期比规范中给出的值都要大,均在规范值的2倍以上. 相似文献
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能力谱方法在桥梁抗震性能评估中的应用研究 总被引:1,自引:0,他引:1
位移延性是桥梁抗震性能的重要指标之一,以Pushover分析为基础的能力谱方法能够考察结构在地震下的弹塑性位移响应,是抗震性能评估的一种有效手段.文中阐述了能力谱法的基本原理,说明了基于弹塑性反应谱的能力谱方法在求解性能点时不需要进行迭代计算;基于弹性设计反应谱建立了相对应的弹塑性反应谱,结合某实桥,将能力谱方法和增量动力分析方法进行了对比,并根据不同的地震基本烈度和场地土类型进行了抗震性能评估.分析认为,能力谱方法计算简便,对结构1阶振型的地震响应占主导时,具有较好的精度,并能够基于设计反应谱来考察结构的弹塑性抗震性能,可用于桥梁抗震性能的评估. 相似文献
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W. D. Liam Finn E. Zhai T. Thavaraj X. -S. Hao C. E. Ventura 《Soil Dynamics and Earthquake Engineering》2003,23(4):323-329
The 1996 Duvall earthquake in Washington State triggered ground motion stations in the Fraser Delta, British Columbia, located on varying depths of Holocene and Pleistocene soils to a maximum depth of 800 m and one station on bedrock. Recorded ground motions were used to examine the applicability of 1-D and 2-D site response analyses for amplification studies in the Delta. 1-D response analysis gave a good indication of the period of peak response. Response spectra computed by 1-D analysis did not compare well with recorded spectra except at very deep sites. The use of 2-D analyses to include buried topography generally improved the predictions of site response spectra at the shallow sites. However, for the shallow earth sites, the recorded motions showed a strong spectral response at short periods in the range of 0.1–0.25 s. Neither 1-D nor 2-D analysis predicted this response. 相似文献
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DISCUSSION ON THE SPECTRA SHAPE OF SEISMIC MARGIN EARTHQUAKE OF NUCLEAR POWER PLANT IN CHINA 下载免费PDF全文
Fukushima nuclear accident caused widespread concern of earthquake initiated severe accident. Under this background, China nuclear utilities carried out research and application of seismic margin assessment(SMA)approach to evaluate the seismic margin of the existing nuclear power plants(NPP)by different spectra shape of seismic margin earthquake(SME). By reviewing the method used to determine SME of operational NPP in central and eastern United States(CEUS), this paper analyzed the seismic hazard characteristic of China NPP sites, contrasted the design basis ground motion between NPP in CEUS and China, and suggested giving priority to evaluating the seismic margin of operational NPP that adopted the improved second generation technology for the urgency and importance of assessment on the actual seismic capacity of NPP. Comparing RG1.60 spectrum to normalized site-specific SL-2 level acceleration spectra, we found that some normalized spectra overtook the RG1.60's in high frequency range, so it is not always adequate to scale RG1.60 spectrum to evaluate the seismic margin for sites of the improved second generation NPP. We selected a sample site whose site-specific SL-2 level ground motion is close to the standard design of improved second generation NPP(0.2g scaled RG1.60 spectrum)to determine the seismic margin earthquake by probabilistic seismic hazard analysis method of the sample site. Compared to the given PGA(0.3g)scaled scenario earthquake ground motions and the uniform hazard response spectrum(UHRS), whose PGA is 0.3g to PGA(0.3g)scaled standard spectra(median NUREG/CR0098 spectrum and RG1.60 spectrum), the results demonstrated that uniform hazard response spectrum and scaled scenario earthquake ground motions are both significantly higher than the PGA scaled median NUREG/CR0098 spectrum, and all the three spectra are enveloped by PGA scaled RG1.60 spectrum. Then, this paper suggests adopting the uniform hazard response spectrum or scenario earthquake ground motions to evaluate the seismic margin of improved second generation NPP beyond site SL-2 ground motion; and to evaluate the seismic margin of improved second generation NPP beyond standard design, we recommend to use PGA scaled RG1.60 spectrum. 相似文献
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不同地震作用水准的设计反应谱长期以来一直采用各水准谱形完全一致的假定。这与地震危险性分析的一般结论不符。《建筑抗震设计规范》(GB50011-2001)对此作出了修订。本文基于设计反应谱的三参数标定模型推导了罕遇和多遇地震作用设计反应谱的关系,指出两者谱值之比在高频、中频和低频段分别对应于峰值加速度、速度和位移之比。引入地震动衰减规律进行了罕遇和多遇地震作用设计谱关系的近似估计,提出了基于多遇地震作用设计谱确定罕遇地震作用设计谱的调整方案,验证了现行规范将反应谱特征周期适当延长以得到罕遇地震作用设计谱的做法的合理性。 相似文献
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地震反应谱是城市地震小区划的关键,也是房屋抗震设计和减灾的基础。反应谱最大值,即地震影响系数最大值是地震反应谱的最重要参数之一,由于地震影响系数最大值受到场地条件、基岩条件和特殊地质现象等诸多因素的共同影响,相互关系复杂且不能用经验公式简单表示,故地震影响系数最大值的精确计算是困扰科技工作者多年的难题。地震影响系数最大值分布的精细预测,关键在于如何选择基岩指标,以及如何确定基岩条件、场地条件和特殊地质现象等指标的分布与地震影响系数最大值分布之问的关系。根据唐山市具体情况,应用人工神经网络方法建立预测模型,探讨较为准确的地震影响系数最大值分布计算方法,为确定唐山市地震反应谱小区划奠定了基础。 相似文献
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A new neural‐network‐based methodology for generating artificial earthquake spectrum compatible accelerograms from response spectra was proposed in 1997, in which, the learning capabilities of neural networks were used to develop the knowledge of the inverse mapping from the response spectra to earthquake accelerograms. Recently, this methodology has been further extended and enhanced. This paper presents a new stochastic neural network that is capable of generating multiple earthquake accelerograms from a single‐response spectrum. A new stochastic feature to the neural network has been combined with a new scheme for data compression using the replicator neural networks developed in the original method. A benefit of this extended methodology is gaining efficiency in compressing the earthquake accelerograms and extracting their characteristics. The proposed method produces a stochastic ensemble of earthquake accelerograms from any response spectra or design spectra. An example is presented that used 100 recorded accelerograms to train the neural network and several design spectra and response spectra to test this improved methodology. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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A new method is proposed for generating artificial earthquake accelerograms from response spectra. This method uses the learning capabilities of neural networks to developed the knowledge of the inverse mapping from the response spectra to earthquake accelerogram. In the proposed method the neural networks learn the inverse mapping directly from the actual recorded earthquake accelerograms and their response spectra. A two-stage approach is used. In the first stage, a replicator neural network is used as a data compression tool. The replicator neural network compresses the vector of the discrete Fourier spectra of the accelerograms to vectors of much smaller dimension. In the second stage, a multi-layer feed-forward neural network learns to relate the response spectrum to the compressed Fourier spectrum. A simple example is presented, in which only 30 accelerograms are used to train the two-stage neural networks. This example demonstrates how the method works and shows its potential. © 1998 John Wiley & Sons, Ltd. 相似文献
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不同类别场地地震动参数的计算分析 总被引:45,自引:2,他引:45
基于188个工程场地计算剖面及场地地震反应分析的等线性化波动分析方法,通过对场地地震反应的计算及计算结果的分析,研究了4类场地条件对场地地震动影响的特点及规律,给出了每一类场地地震动参数变化的经验关系。 相似文献