Wavelet-Based Stochastic Model for Jointly Simulating Three-Component Ground Motions

Abstract

ABSTRACT A large number of ground motions are needed in performance-based earthquake engineering. To date, most existing stochastic models are limited to simulating a single horizontal component of earthquake motions. This study proposes a wavelet-based stochastic method for jointly simulating three-component accelerograms using earthquake magnitudes, source-to-site distances, and site conditions as input. Based on the Pacific Earthquake Engineering Research Center Next Generation Attenuation (NGA)-West2 database, prediction equations are developed for wavelet-packet parameters of two horizontal and one vertical components. Correlations among these components are obtained to jointly simulate three-component motions based on earthquake scenarios. The simulated ground motions are systematically compared with existing ground-motion attenuation equations. The model has the capability to simulate the different frequency content of horizontal and vertical motions. The simulated vertical-to-horizontal spectral ratios are found to be consistent with observed strong-motion data. The model is applicable to shallow crustal earthquakes in an active tectonic region with a moment magnitude between 5 and 8, source-to-site distance from 0 to 100 km, and shear-wave velocity in the top 30 m (VS30) in the range of 150–1000 m/s. It can find important applications in 3D time-history analyses in performance-based earthquake engineering.