EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS Earthquake Engng Struct. Dyn. 2010; 39:1155–1180 Published online 11 March 2010 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/eqe.997 Simulation of synthetic ground motions for specified earthquake and site characteristics Sanaz Rezaeian ∗, †, ‡ and Armen Der Kiureghian § University of California, Berkeley, CA 94720, U.S.A. SUMMARY A method for generating a suite of synthetic ground motion time-histories for specified earthquake and site characteristics defining a design scenario is presented. The method employs a parameterized stochastic model that is based on a modulated, filtered white-noise process. The model parameters characterize the evolving intensity, predominant frequency, and bandwidth of the acceleration time-history, and can be identified by matching the statistics of the model to the statistics of a target-recorded accelerogram. Sample ‘observations’ of the parameters are obtained by fitting the model to a subset of the NGA database for far-field strong ground motion records on firm ground. Using this sample, predictive equations are developed for the model parameters in terms of the faulting mechanism, earthquake magnitude, source- to-site distance, and the site shear-wave velocity. For any specified set of these earthquake and site characteristics, sets of the model parameters are generated, which are in turn used in the stochastic model to generate the ensemble of synthetic ground motions. The resulting synthetic acceleration as well as corresponding velocity and displacement time-histories capture the main features of real earthquake ground motions, including the intensity, duration, spectral content, and peak values. Furthermore, the statistics of their resulting elastic response spectra closely agree with both the median and the variability of response spectra of recorded ground motions, as reflected in the existing prediction equations based on the NGA database. The proposed method can be used in seismic design and analysis in conjunction with or instead of recorded ground motions. Copyright 2010 John Wiley & Sons, Ltd. Received 10 September 2009; Revised 10 December 2009; Accepted 17 December 2009 KEY WORDS: earthquake ground motions; model validation; NGA database; simulation; stochastic models; strong-motion records; synthetic motions 1. INTRODUCTION Synthetic ground motions have been of interest in the field of earthquake engineering for many years. These motions are used in the evaluation of seismic demand on structures by response-history ∗ Correspondence to: Sanaz Rezaeian, University of California, Berkeley, CA 94720, U.S.A. † E-mail: sanazr@Berkeley.edu ‡ Doctoral Candidate. § Taisei Professor of Civil Engineering. Contract/grant sponsor: State of California Copyright 2010 John Wiley & Sons, Ltd.