Correlating peak ground A/V ratio with ground motion frequency content

Abstract

Peak ground A/V ratio has been used an empirical parameter to estimate ground motion frequency content and categorize ground motion suites for performing nonlinear time history analyses of structures. Ground motions are usually classified into three subjective categories: low A/V, intermediate A/V, and high A/V to reflect low-, moderate-, and high-frequency contents, respectively. However, the relationship between A/V and frequency is very complex as the A/V ratio depends on faulting processes, distance from source to recording station, and local geological conditions. Frequency content of earthquake waves is represented by single-frequency parameters, such as mean period, Tm, and predominant period, Tp. In this paper, the relationship between A/V and frequency parameters is explored. Linear regression analyses are performed on data obtained from three major earthquakes. Regression analyses indicate that the predominant frequency content of the ground motion exhibits little or no correlation with A/V ratio. The A/V ratio may be used as an empirical parameter to obtain an estimate of only the mean frequency content of the ground motion.