Effects of time series analysis protocols on transfer functions calculated from earthquake accelerograms
Effects of time series analysis protocols on transfer functions calculated from earthquake accelerograms
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DOI：
10.1016/j.soildyn.2007.10.018
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发表时间：
2008-09
影响因子：
4
通讯作者：
A. Mikami;J. Stewart;M. Kamiyama
中科院分区：
文献类型：
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作者：
A. Mikami;J. Stewart;M. Kamiyama
传递函数表示一种地震动与另一种地震动在频域中的比率。传递函数是研究土-结构相互作用的一种方便的方法，它可以量化结构从自由场到基础水平的地震地面运动变化。除了普通的滤波和基线校正外，在传递函数的计算中还会进行大量的信号处理，包括加窗(以提取记录的S波部分)和平滑(以减少可能掩盖物理上有意义的趋势的散射)。在样本数据集上利用几种信号处理技术，我们发现传递函数纵坐标的细节特征(即，频率到频率的变化)可能受平滑程度和窗口长度(例如，整个记录与S窗口)的影响。但是，传递函数的整体形状和大小是相对一致的。比信号处理细节更重要的是结果被认为有效的频率带宽，因为频谱的很大一部分可能被几乎没有物理意义的随机过程所支配。我们认为，传递函数应该在具有最小噪声影响的频谱部分上解释，如高相干性所表明的那样。
Transfer functions represent the ratio in the frequency domain of one ground motion to another. Transfer functions are a convenient way by which the variation of earthquake ground motions from the free-field to the foundation level of a structure can be quantified for studies of kinematic soil–structure interaction. Aside from ordinary filtering and baseline correction, substantial signal processing occurs in the computation of transfer functions, including windowing (to extract the S-wave portion of the record) and smoothing (to reduce scatter that can obscure physically significant trends). Utilizing several signal processing techniques on a sample data set, we find that detailed features of the transfer function ordinates (i.e., frequency-to-frequency variations) can be affected by the degree of smoothing and by the window length (e.g., whole record versus S-window). However, the overall shape and magnitude of the transfer functions are relatively consistent. More important than signal processing details is the frequency bandwidth over which the results are considered valid, because significant portions of the spectrum can be dominated by stochastic processes with little physical meaning. We argue that transfer functions should be interpreted over those portions of the spectrum having minimal noise impact, as indicated by high coherence.