2019 Volume 19 Issue 5 Pages 5_46-5_58
Effects of rotation of orientation on amplitude and duration characteristics have been evaluated by use of two orthogonal horizontal components of accelerograms of ground motions. Amplitude (PGA and total power) and three kinds of duration (significant duration, uniform duration and bracketed duration) are calculated for rotated waveform of acceleration by various angle ranging from 0 to 180 degree using accelerograms recorded during Off the Pacific Coast of Tohoku Earthquake, 2011. PGA and total power show partially and completely sinusoidal functional form, respectively, in terms of rotation angle. Significant duration is approximately sinusoidal with negative correlation with total power. Bracketed and uniform duration show rather irregular tendencies. Furthermore, histograms of the ration of the maximum and minimum values to the median for each index and corresponding rotation angle are calculated and the mutual relationships among the indices are examined.
