VERTICAL GROUND MOTION PREDICTION EQUATION FOR VERTICAL TO HORIZONTAL (V/H) RATIOS OF GROUND MOTION IN TAIWAN
We develop a new empirical ground-motion prediction equation (GMPE) to estimate the vertical ground motion component for engineer application in Taiwan. The development of the model used a data set complied mainly crustal earthquakes occurring within the Taiwan island, and partly worldwide earthquakes with large magnitudes filling the gap where the Taiwan earthquakes are not available. The model undertakes the advantage of the vertical Chiou and Youngs (2013) functional form with considering the earthquake magnitude (Mw), source to site distance (Rrup), style of faulting (Sof), and the shear – wave velocity of soil deposits in the upper 30 m of the site (Vs30) for the peak ground acceleration (PGA) and spectral accelerations (PSA) at periods of 0.01 to 3s. The independent – rotation – angles, RotD50, pseudo spectral acceleration values are used to compute the median prediction, total standard deviation and site – corrected standard deviation. The proposed model is applicable to design structure in Taiwan island for distances in the range of 0-300 km and magnitudes within 4.0 - 8.0. The applicable range for Vs30 is of 150 – 1500 m/s. The estimate vertical-to-horizontal spectral ratio from a pairs of vertical and horizontal GMPE has strong dependence on the period of response spectra, Vs30 and source to site distance, but weak dependence of magnitude. The dependence of V/H ratios on magnitude stronger in the short period. The model shows the dominant period at which the peak of V/H ratio attains its maximum is in the period range of 0.05 to 0.075s, and the amplitude of the peak is dependent of M, Sof and Ztor. For short periods, the V/H ratio decreases with increasing of Vs30, but increases with Vs30 at long periods. The V/H ratio model is also compared with other available models for validation.
VAN-BANG PHUNG, Chin-Hsiung Loh, Bor-Shouh Huang, Shu-Hsien Chao, Brian S.J Chiou
Earthquake Engineering, Earthquake Engineering, Ground Motion Prediction Equation, Vertical Design Spectrum, Vertical to Horizontal Spectral Ratio