In both seismic design and probabilistic seismic-hazard analyses, site effects are typically characterized as the ratio of the response spectral ordinate on the ground surface to that on the bedrock based on the scaling law borrowed from the Fourier spectral ordinate. Recent studies have shown that different from the Fourier spectral ratio (FSR), the response spectral ratio (RSR) does not purely reflect the site effects but also depends on the earthquake scenario even for linear analysis. However, previous studies are limited to theoretical analysis. This study statistically compares the two spectral ratios by analyzing many actual seismic ground motions recorded at nearby soil and rock sites. It is observed that the average RSR and FSR have similar overall shapes, and their maximum values occur at approximately the same period; however, the values around the peak are clearly different with FSRs consistently exceeding the RSRs. The RSR–FSR relationship depends on the earthquake scenario and the oscillator damping; their difference at periods longer than the site’s fundamental period decreases as the magnitude and epicentral distance increase, and the RSRs generally approach the FSRs as the oscillator damping decreases.

中文翻译：

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基于强运动记录统计分析的响应与傅里叶谱比关系研究

在抗震设计和概率地震危险分析中，场地效应通常被表征为基于从傅立叶谱纵坐标借用的比例律，地表上的响应谱纵坐标与基岩上的响应谱纵坐标之比。最近的研究表明，与傅里叶谱比（FSR）不同，响应谱比（RSR）不仅反映了场地效应，而且还取决于地震情景，即使是线性分析也是如此。然而，以往的研究仅限于理论分析。这项研究通过分析在附近土壤和岩石地点记录的许多实际地震地面运动，对这两种光谱比率进行了统计比较。观察到平均 RSR 和 FSR 具有相似的整体形状，并且它们的最大值出现在大致相同的时期；然而，峰值周围的值明显不同，FSR 始终超过 RSR。RSR-FSR 关系取决于地震情景和振子阻尼；随着震级和震中距离的增加，它们在比场地基本周期长的周期上的差异减小，并且随着振荡器阻尼的减小，RSR通常接近FSR。