Validation of Simulated Earthquake Ground Motions Based on Evolution of Intensity and Frequency Content

Abstract eng:
Simulated earthquake ground motions can be used in many engineering applications that require time-series as input excitations. However, they need to be validated before they can be utilized with confidence in any engineering applications. Applicability and validation of simulations are subjects of debate in the seismological and engineering communities. We propose a validation methodology at the waveform level that is directly based on characteristics that are expected to influence most structural and geotechnical response parameters. In particular, three time-dependent validation metrics are used to evaluate the evolving intensity, predominant frequency, and bandwidth of a waveform. These validation metrics capture nonstationarities in intensity and frequency content of waveforms, making them ideal to address nonlinear response of structural systems. A two-component error vector is proposed to quantify the average and shape differences between these validation metrics for a simulated and recorded ground-motion pair. Because these metrics are directly related to the waveform characteristics, they provide easily interpretable feedback to seismologists for modifying their ground-motion simulation models compared to metrics that are based on structural and geotechnical responses. To further simplify the use and interpretation of these metrics for engineers, it is shown how six scalar key parameters, including Arias intensity, duration, and predominant frequency, can be extracted from the validation metrics. The proposed validation methodology is a step forward in paving the road for utilization of simulated ground motions in engineering practice, and is demonstrated using examples of recorded and four sets of simulated ground motions from the 1994 Northridge, California earthquake.

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