Arbitrarily Oriented Phase Randomization of Design Ground Motions by Continuous Wavelets

Haoyu Xie,Riki Honda

doi:10.3390/infrastructures6100144

Abstract

For dynamic analysis in seismic design, selection of input ground motions is of huge importance. In the presented scheme, complex Continuous Wavelet Transform (CWT) is utilized to simulate stochastic ground motions from historical records of earthquakes with phase disturbance arbitrarily localized in time-frequency domain. The complex arguments of wavelet coefficients are determined as phase spectrum and an innovative formulation is constructed to improve computational efficiency of inverse wavelet transform with a pair of random complex arguments introduced and make more candidate wavelets available in the article. The proposed methodology is evaluated by numerical simulations on a two-degree-of-freedom system including spectral analysis and dynamic analysis with Shannon wavelet basis and Gabor wavelet basis. The result shows that the presented scheme enables time-frequency range of disturbance in time-frequency domain arbitrarily oriented and complex Shannon wavelet basis is verified as the optimal candidate mother wavelet for the procedure in case of frequency information maintenance with phase perturbation.

Highlights

IntroductionAs a slight fluctuation of input ground motion in time-history analysis results in huge difference of nonlinear structural response [1], uncertainty of design input ground motions should be considered, which raises a significant challenge [2,3]
Input ground motions for seismic design are accessible from history records of previous earthquakes and artificial ground motion simulation technique by empirical relationships on fault models [4,5]
The objective of the present paper is to introduce a novel scheme to have timefrequency characteristics of an original signal fluctuated with arbitrary orientation of wavelet phase by using complex continuous wavelet transform and to compare candidates of mother wavelets for optimization of the scheme

Summary

Introduction

As a slight fluctuation of input ground motion in time-history analysis results in huge difference of nonlinear structural response [1], uncertainty of design input ground motions should be considered, which raises a significant challenge [2,3]. Input ground motions for seismic design are accessible from history records of previous earthquakes and artificial ground motion simulation technique by empirical relationships on fault models [4,5]. Numerical and empirical simulations generate design ground motions based on considered fault parameters, specific parameters required for prediction cannot be determined accurately [6]. Due to the complexity of physical models for earthquake phenomenon, there is not a perfect empirical relationship to reproduce the exact ground motion

Objectives

Methods

Conclusion