Quantitative Identification of Pulse-Like Ground Motions Based on Hilbert–Huang Transform

Zhen Liu

doi:10.1155/2021/9915362

Abstract

Aiming to address the problem of pulse-like ground motions being difficult to identify, this paper refines the Baker’s wavelet-based pulse-like ground motions identification method, followed by a new pulse-like ground motion identification method based on Hilbert–Huang Transform (HHT) being proposed. In this method, HHT is used to decompose ground motions instead of wavelet. HHT can overcome the dependence of wavelet analysis on the selection of mother wave, and thus more complex velocity pulses can be identified. In order to compare the effects of two pulse-like ground motion identification methods, HHT-based method and wavelet-based method, respectively, are used to identify ground motions in Pacific Earthquake Engineering Research Center (PEER). After identifying the 3066 groups of ground motions selected from PEER, it is found that the HHT-based method can identify 229 pulse-like ground motions, and the wavelet-based method can identify 150 pulse-like ground motions. More complex shapes of near-fault velocity pulses can be extracted by the HHT-based method. By analyzing the seismic response, fault distance, and cumulative squared velocity (CSV) of these pulse-like ground motions, it is found that the pulse-like ground motions identified by the HHT-based method have strong near-fault characteristics. If a high recognition quality can be guaranteed, the proposed HHT-based method can identify many kinds of near-fault velocity pulses and thus provide more pulse-like ground motions for seismic researches.

Highlights

Pulse-like ground motions are considered to be one of the most dangerous types of ground motions
A very important feature of the pulselike ground motion is that its response spectrum gets larger values at the frequency of the velocity pulse [31] than other frequency area. e velocity and acceleration responses of a pulse-like ground motion are calculated at its own velocity pulse frequency and the damping ratio is 0.05
In order to compare with the nonpulse-like ground motion, the velocity and acceleration responses of the nonpulse-like ground motion are calculated

Summary

Introduction

Pulse-like ground motions are considered to be one of the most dangerous types of ground motions. In the 229 pulse-like ground motions, 105 were extracted by the wavelet-based method and 124 are newly identified. E velocity pulse can be extracted in the low-frequency signal after increasing the threshold value, by the HHT-based method. E main function of the HHT-based method is to identify pulse-like ground motions with inconspicuous pulses. Technology used, the maximum pulse direction obtained by the two methods may be different, which leads to the difference of the original record of the extracted pulse The improvement of wavelet-based method is expected to extract more accurate velocity pulses, so as to reduce the misidentification of pulse-like ground motions

Evaluation of Pulse-Like Ground Motions

Method

Conclusion