A new conjoint method aiming at analyzing the nonlinear non-stationary near-fault multi-pulse ground motion based on continuous wavelet transformation and extreme-point symmetric mode decomposition is proposed in this paper.The relating fundamental analysis principle and the advantage of the method are also introduced.The conjoint analysis code are implemented in Matlab and the case study are carried out on the basis of the real strong ground motions recorded at seismic stations.The empirical mode functions and the transient frequencies are obtained.And the results are analyzed and compared with those from both the empirical mode decomposition and the continuous wavelet decomposition method.The results indicate that:(1)The proposed method is characterized by the adaptive choose of the optimal sifting time and no need to setup the frequency boundary manually
which is superior to both empirical mode decomposition method and continuous wavelet transformation method;(2)The variance ratio distribution curve could be used to get the optimal sifting time adaptively
and the corresponding global optimal mean curve could also be obtained;(3)The transient frequencies of the empirical mode functions could be obtained by the direct integration method and the results from the direct integration and the Hilbert transformation agree with each other
but the former is more efficient in algorithm;(4)The peak ground velocity of the example seismic motion at the direction of maximum pulse energy increases by 50% compared with that of the original two horizontal peak ground velocities;(5)The peak value of the pulse component at the direction of maximum pulse energy extracted by the proposed method decreases 0.56%compared with the original signal at the same direction.
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