Identification of near-fault multi-pulse ground motion

Abstract

The near-fault pulse-like ground motion is of practical importance since it tends to cause severer damage to structures than ordinary ground motion in engineering and helps characterize the seismic source and the kinematic characteristics of the geological fault in seismology. However, previous investigations mainly focus on single-pulse ground motion. As one of the particular seismic records in the near-fault earthquake, the multi-pulse ground motion is rarely considered caused by the absence of an effective identification method. Hence, a generalized continuous wavelet transform (GCWT) method is proposed by combining convolution analysis with evaluation parameters to facilitate wider studies on multi-pulse ground motion. In identification, the proposed method requires each pulse in the multi-pulse ground motion to satisfy the same criteria and excludes the effects of attenuation component. In methodology, the proposed method overcomes the limitations of the classical CWT method that requires a wavelet basis and provides a workable and flexible framework for pulse-like ground motion identification. Based on the method, single- and multi-pulse ground motions from two typical near-fault earthquakes on the PEER NGA-West2 database were identified. The effects of the pulse model and ground motion orientation on identification are discussed. Besides, the 5% damped spectral velocity of multi-pulse ground motions potentially contain multiple peaks in the high-period range. This phenomenon implies that the risk would be underestimated for the response spectrum-based seismic hazards and risk analysis if the multi-pulse features are not, or are insufficiently taken into account.