Non-Stationary Frequency Content Characterization of Seismic Accelerograms Via the Slope “Alpha” of the Wavelet-Based Mean Instantaneous Period
Abstract eng: Typical recorded acceleration traces of seismic ground motions (GMs) exhibit a time-varying frequency composition, however, all GM properties currently considered in earthquake engineering to quantify the structural damage potential of GMs do not explicitly characterize the time-evolving trends of GM frequency content. Indeed, the intensity measures (IMs) and record selection criteria adopted in the context of performance-based earthquake engineering (PBEE) do not account for the non-stationary frequency content of GMs in a straightforward manner. In this regard, this paper considers a novel scalar quantity termed alpha, “a”, defined by the average slope (angle) of the wavelet-based mean instantaneous period (MIP) to characterize the temporal evolution of the mean frequency content of recorded GMs. Specifically, the MIP is the time-varying first-order average along the frequency or, equivalently, along the period axis of the wavelet-based GM spectrogram (squared magnitude of the GM wavelet transform) treated as a GM energy distribution on the time-frequency/period plane. Consequently, a captures the rate by which the mean frequency content of GMs changes in time. Linear regression analyses are undertaken involving a dataset of 684 GMs from 30 seismic events of Magnitude 6.5
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Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
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Record created 2017-01-18, last modified 2017-01-18
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