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This study proposes an improved energy-based approach for quantitative classification of velocity-pulse-like ground motions. The pulse amplitude is determined, in its value and in time location, by the amplitude of the half-cycle pulse having the largest seismic energy. After conducting statistical analyses, a newly-determined threshold level for selecting pulse-like ground motions is derived; and then what followed is a comparison analysis of three pulse-detecting schemes, one using the wavelet analysis, the other two using the energy concept. It is believed that other than providing a useful way of classifying pulse-like ground motions for structural demand analysis, knowledge of this work could also benefit the development of the ground motion prediction equations accounting for pulse effects, and further to aid the probabilistic seismic hazard analysis in a near-fault environment. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for constructing seismic design spectra in near-fault regions. By analyzing the characteristics of near-fault pulse-type ground motions, an equivalent pulse model is proposed, which can well represent the characteristics of the near-fault forward-directivity and fling-step pulse-type ground motions. The normalized horizontal seismic design spectra for near-fault regions are presented using recorded near-fault pulse-type ground motions and equivalent pulse-type ground motions, which are derived based on the equivalent pulse model coupled with ground motion parameter attenuation relations. The normalized vertical seismic design spectra for near-fault regions are obtained by scaling the corresponding horizontal spectra with the vertical-to-horizontal acceleration spectral ratios of near-fault pulse-type ground motions. The proposed seismic design spectra appear to have relatively small dispersion in a statistical sense. The seismic design spectra for both horizontal and vertical directions can provide alternative spectral shapes for seismic design codes. [ABSTRACT FROM AUTHOR]

Abstract: Structures located in seismically active regions may be subjected to mainshock–aftershock sequence-type ground motions, which are characterized by the presence of strong aftershock ground motions after the mainshock and separated by short intervals of time. This manuscript investigates the damage of inelastic SDOF structure with four hysteretic models and three response demand parameters. The relative intensity of the aftershock ground motion to the mainshock ground motion is defined, denoted by PGA as/PGA ms. The aftershock ground motions are scaled to have different levels of PGA as/PGA ms. The results indicate that the effect of aftershock on ductility demand is slight for PGA as/PGA ms≤0.5 and can be ignored in engineering practice. The aftershock ground motion has more significant influence on the normalized hysteretic energy and damage index than on ductility demand. The effect of aftershock ground motion with larger PGA as/PGA ms on the response demand is generally more obvious for non-degrading system than for degrading system. [Copyright &y& Elsevier]