Wavelet-based simulation of scenario-specific nonstationary accelerograms and their GMPE compatibility
Wavelet-based simulation of scenario-specific nonstationary accelerograms and their GMPE compatibility
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DOI：
10.1016/j.soildyn.2017.05.007
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发表时间：
2017-08
影响因子：
4
通讯作者：
V. Nithin;Sandip Das;H. Kaushik
中科院分区：
文献类型：
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作者：
V. Nithin;Sandip Das;H. Kaushik
在地震危险性分析中，地震动预测方程（GMPE）起着关键的作用，因为它提供了所选地震情景下危险性参数的统计分布。然而，GMPEs一般不提供非线性响应统计，后者应该理想地通过对特定于运动的一套运动的时程分析来获得。在本研究中，提出了一种新的基于小波变换的方法来模拟具有真实时频特性变化的特定于地球的加速度记录的集合。首先，提出了一种方法来随机表征记录过程的非平稳性记录的地震动小波系数的能量到达曲线。然后开发了一种新的经验缩放模型来估计具有模型不确定性的瞬时能量到达。此外，重建方法制定模拟的具体合奏的加速度记录从估计的具体的能量到达曲线。结果发现，模拟合奏表现出现实的变化的时频特性，因此，它自然成为可比的GMPEs（在中位数估计反应谱和强震持续时间）开发使用相同的数据库。最后，提出了一种算法来调整估计的能量到达，使得模拟运动的集合可以与目标GMPE兼容，无论是在中值估计还是标准偏差方面。结果发现，GMPE兼容的合奏，获得5%的阻尼PSV谱，显示出良好的协议相对于PSV缩放模型开发的阻尼比范围很广。
In seismic hazard analysis ground motion prediction equation (GMPE) plays a pivotal role because it provides the statistical distribution of hazard parameter for a chosen seismic scenario. However, GMPEs in general do not provide nonlinear response statistics, and the latter should be ideally obtained by time-history analyses of a scenario-specific suite of motions. In the present study a new wavelet-based method is proposed to simulate scenario-specific ensemble of accelerograms with realistic variability of time-frequency characteristics. Firstly, a methodology is proposed to stochastically characterize the nonstationarity of a recording process from the energy arrival curve of the wavelet coefficients of the recorded ground motion. Then a new empirical scaling model is developed to estimate the instantaneous energy arrival, with model uncertainty. Further, a reconstruction method is formulated to simulate the scenario-specific ensemble of accelerograms from the estimated scenario-specific energy arrival curves. It is found that the simulated ensemble exhibits realistic variation of time-frequency characteristics and hence, it naturally becomes comparable with GMPEs (in terms of median estimates for response spectrum and strong motion duration) developed using the same database. Finally, an algorithm is proposed to tune the estimated energy arrival such that the ensemble of simulated motions can be made compatible with the target GMPEs, both in terms of median estimates and standard deviations. It is found that the GMPE-compatible ensemble, obtained for 5% damping PSV spectra, shows good agreement with respect to PSV scaling models developed for a wide range of damping ratio.