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Introduction The dynamic response of structural systems subjected to earthquake ground shaking is sig-nificantly affected by the frequency content of input ground motions. When the frequency content of a predominant earthquake ground motion closely matches the natural period of a structural sys-tem, the dynamic response is significantly enhanced and thus may cause severe damage (Chopra, 1995). Therefore, it is of great importance to evaluate the frequency content of ground motions. In recent … 相似文献
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通风竖井对隧道内的通风换气、车辆动力效应调整以及防灾救援起到至关重要的作用，是长大型隧道的重要组成部分。由于受到周围岩土的约束，海底隧道穿岛通风竖井结构的稳定性往往优于水中自立式竖井。但在地震动作用下，受周围岩土的约束及土体变形的影响，隧道通风竖井的地震响应将与普通井筒及井筒式基础存在明显差异。基于大型有限元分析软件ABAQUS建立海底隧道穿岛通风竖井结构的数值模型，考虑周围岩土及底部隧道对竖井的约束，利用时程分析法计算竖井在垂直于隧道轴向的水平地震作用下的动力响应，得出了竖井内力及位移沿深度的分布特点，通过考虑不同类型的岩土材料得到了竖井结构动力响应随场地剪切波速的变化规律。 相似文献
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近断层长周期地震动是一类较特殊的破坏性地震动.为了深入探讨近断层地震动的低频分量组成及其脉冲特性,基于小波理论中的多尺度分析方法提出了一种地震动分量分解方法,据此可将一条地震动分解成频率各不相同的多条分量.首先从频域、时域以及动态响应三个方面阐述了该分解方法的有效性和精确性.进而采用这种方法对近期12次大地震中的53条典型近断层地震动进行了分解,共获得266条地震动分量.分析了近断层地震动中的长周期分量随场地、断层距等影响因素的变化特征;再以卓越分量作为最大脉冲的简化模型,探讨了速度幅值和脉冲周期随震级、断层距的变化关系.结果表明：近断层长周期地震动主要由周期为0.2~2 s的分量组成;近断层土层场地地震动中的长周期分量比岩石场地多;在0~15 km的近断层区域,随断层距的增加,地震动中长周期分量的比重明显减小;卓越分量的速度幅值PGVp约为原始地震动速度幅值PGV的0.6倍,且两者之间具有明显的线性关系;PGVp随断层距的增大而减小,随震级的增大而增大;卓越分量周期Tp随震级的增大呈对数线性增大趋势. 相似文献
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To develop uniform and seismic environment-dependent design spectrum, common acceleration response spectral characteristics need to be identified. In this paper, a bi-normalized response spectrum (BNRS) is proposed, which is defined as a spectrum of peak response acceleration normalized with respect to peak acceleration of the excitation plotted vs. the natural period of the system normalized with respect to the spectrum predominant period, Tp. Based on a statistical analysis of records from the 1999 Chi-Chi earthquake, the conventionally normalized response spectrum(NRS) and the BNRS are examined to account for the effects of soil conditions, epicentral distance, hanging wall and damping. It is found that compared to the NRS, the BNRS is much less dependent on these factors. Finally, some simple relationships between the BNRS for a specified damping ratio and that for a damping ratio of 5%, and between the spectra predominant period and epicentral distance for different soil types are provided. 相似文献
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具有向前方向性效应特征的地震动与普通远场地震动存在明显差异. 作者曾尝试结合简单脉冲和近断层地震动参数衰减关系提出此类地震动的设计谱模型. 为进一步检验所提出设计谱的适用性，分析了53条典型近断层方向性效应地震动的伪速度谱、 规准伪速度谱和双规准伪速度谱，发现方向性效应地震动的双规准伪速度谱在土层和岩石场地上具有差别明显, 且离散性小的特点.考虑场地条件的影响, 基于双规准伪速度谱预测了近断层方向性效应地震动的设计谱， 并与此前的研究结果进行了对比. 结果表明, 场地条件对于近断层方向性效应地震动影响显著；位于近断层岩石场地的建筑结构, 尤其是中、短振动周期结构， 可能比土层场地更易于遭受破坏. 最后, 提出了用于近断层结构抗震分析的简单脉冲模型的建议. 相似文献
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竖向地震动加速度反应谱特性 总被引：3，自引：0，他引：3
以33次地震中的地表地震动记录为数据基础,考虑场地条件、震级和距离的影响,分别对竖向地震动的加速度规准化反应谱和双规准化反应谱进行了研究。结果表明,规准反应谱明显受到场地条件、震级和震中距的影响,不同场地、距离和震级的平均规准反应谱之间差别显著;相比较而言,不依赖于场地、距离和震级的平均双规准反应谱之间却表现出良好的规律性和一致性。双规准反应谱的统一特性可以为竖向地震动设计谱的预测提供参考依据。 相似文献
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Ground motions with forward-directivity effect in the near-fault region are obviously different from ordinary far-field ground motions. Design spectral models for this kind of motions have been proposed by correlating sim-ple pulses with parameters attenuation relationships in a previous study of the authors. To further test the applica-bility of the established design spectral model, we analyze ground motion pseudo-velocity response spectra (PVS), normalized pseudo-velocity spectra (NPVS) and bi-normalized pseudo-velocity spectra (BNPVS) of 53 typical near-fault forward-directivity ground motions. It is found that BNPVS not only has more salient features to reflect the difference between soil and rock sites, but also has less scattering to reveal the nature of forward-directivity motions. And then, BNPVS is used for prediction of design spectra accounting for the influence of site conditions, and the constructed design spectra are compared with those spectra established previously. It is concluded that site condition can heavily affect ground motions, buildings on rock can be even more dangerous than those on soil sites, in particular for ordinary buildings with short to middle vibration periods. Finally, pulse models are also suggested for structural analyses in the near-fault region. 相似文献
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为考查远场地震动的场地相关性并评价一些场地特性分析方法的适用性,采用不同方法对汶川地震山东省12个远场台站的强震记录进行了分析.选取台站分别位于按建筑抗震设计规范(CBC)场地划分中的Ⅰ—Ⅲ类场地上.地震动记录的分析方法包括傅里叶幅值谱法,地震反应谱法,水平与竖向谱比率法,参考点谱比率法,以及尾波分析等.结果表明,按傅里叶幅值谱法,地震反应谱法,水平与竖向谱比法计算得到的卓越周期均远大于台站场地的卓越周期,不同方法得到的结果之间也有较大差别,且主要反映长周期地震动的卓越频率;参考点谱比率法的结果未反映地震动的卓越周期,也与场地的卓越周期差别较大;对完整记录尾波分析所得的结果比较接近场地的卓越周期.希望本文能为考虑远场地震作用时设计谱的建立,以及场地特性估计时地震动分析方法的选取提供参考依据. 相似文献