台灣位於環太平洋西側，地處歐亞板塊與菲律賓海板塊交界處，地震頻繁且斷層眾多，是以透過統計、靜力與動力分析制定合適之耐震規範非常重要。一般而言，水平向反應譜因比較重要而由地震危害度分析制定，垂直向反應譜可由水平向反應譜乘上垂直向相對水平向的譜加速度比值（簡稱V/H Ratio）推導。V/H Ratio受許多變因影響，本文透過最新的台灣地動資料庫計算V/H Ratio，分析其機率模式和重要變因，並建立V/H Ratio的中值與對數標準差隨週期變化的經驗公式，提供耐震分析與耐震規範制定之參考。

Taiwan is located on the west side of the Pacific Ocean and at the junction of the Eurasian plate and the Philippine Sea plate. Earthquakes occur frequently and there are a lot of faults in Taiwan. Therefore, it is very important to establish appropriate seismic codes by statistical, static and dynamic analysis. Generally speaking, a horizontal response spectrum is determined through probabilistic seismic hazard analysis because it is more important, and the vertical response spectrum can be derived by multiplying the horizontal one by the ratio of vertical to horizontal spectral acceleration (V/H Ratio). V/H Ratio is affected by many variables. This article calculates V/H Ratio through the latest Taiwan Earthquake Database, analyzes its probability pattern and important variables, and establishes empirical formulas of the median and the logarithmic standard deviation of V/H Ratio as functions of period. Such results provide a reference for the seismic analysis and the establishment of seismic codes.

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