Abstract
A simplified method for synthesizing spatially correlated earthquake ground motions is developed based on Hilbert transform and a reference earthquake record. In this method, one reference earthquake record is treated as the original ground motion, based on a series of generated ground motions. This procedure uses the instantaneous amplitude and the instantaneous phase of the record obtained using Hilbert transform to achieve the nonstationarity of ground motion. To establish the coherency between generated ground motions, an incoherence model is employed to describe the relation between the instantaneous phase at the present station and the instantaneous phases at previous stations. This type of phase is defined as the instantaneous coherence phase. In addition, time lag is included in the instantaneous coherence phase to prescribe the wave passage effect. The proposed Hilbert-transform-based method is efficient and avoids cumbersome parameter estimations as well as other drawbacks involved in some traditional synthesizing methods. Applications of this method demonstrate that the generated ground motions are statistically analogous with the reference record.
Highlights
In the past decades, the methods of generating spatially variable ground motions were studied thoroughly
Time lag is included in the instantaneous coherence phase to prescribe the wave passage effect
An approach was developed to simulate spatially correlated earthquake ground motions based on Hilbert transform and earthquake records where instantaneous coherence phase is defined
Summary
The methods of generating spatially variable ground motions were studied thoroughly. Intensity nonstationarity is usually achieved by multiplying the generated stationary process using an envelope function This method may not be applicable for simulations based on a recorded accelerogram, because the applied envelop function may not completely present the intensity nonstationarity of the original ground motion. A simplified conditional simulation method of synthesizing spatially correlated earthquake ground motions is proposed based on Hilbert transform and earthquake record. The proposed Hilbert-transformbased method can efficiently achieve intensity nonstationarity and frequency nonstationarity, and this approach avoids cumbersome parameter estimations, as well as other drawbacks involved in some traditional synthesizing methods. The application of this method demonstrates its validity and practical value
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