ABSTRACT
For describing near-fault excitation a comprehensive stochastic model is used (Taflanidis et al., 2008); according to it the high-frequency and longperiod components of the motion are independently modeled and then combined to form the acceleration time history. The fairly general, point source stochastic method is selected for modeling the higher-frequency component. This method is based on a parametric description of the ground motion’s radiation spectrum A( f;M,r), which is expressed as a function of the frequency, f, for specific values of the earthquake magnitude, M, and epicentral distance, r, The duration of the ground motion is addressed through an envelope function e(t;M,r), which again depends on M and r. The acceleration time-history for a specific event magnitude, M, and source distance, r, is obtained according to this model by modulating a whitenoise sequence by e(t;M,r) and subsequently by A(f;M,r). For describing the pulse characteristic of near-fault ground motions, the simple analytical model developed by Mavroeidis and Papageorgiou (2003) is selected, with pulse characteristics that can be related to M and r as well (Bray and Rodriguez-Marek 2004). The stochastic model for near-fault motions is finally established by combining the above two components.
