Variation of Near Fault Ground Motion Intensity Measures Due to Filtering

Abstract

Ground motions recorded at near fault zones ensures rich low frequency contents, and high velocity pulse signals which may result in large shear force and displacement demands in structural elements. During the recording of these seismic events by accelerometers, low-frequency noise may sometimes accompany the signal. Thus, extracting this noise from recorded acceleration data is a crucial step of post-processing performed prior to use of acceleration time series in structural analyses for both design or assessment purpose. The objective of this study is to assess the effect of high-pass filtering on the intensity measures of ground motions. A set of near fault ground motions that comprises both pulse-like and non-pulse like characteristics were selected and they were subjected to filtering for various cutting frequency contents. As a function of filtering, variation in several intensity measures of filtered ground motions namely, PGD, PGV, PGA, PGV/PGA and significant duration were analyzed. It is revealed that changing the cutting frequency of high pass filtering considerably changes the intensity measures of ground motion records.