Characterizing Effects of Near-fault Earthquakes in Context of Response Spectra

This paper characterized the effects of near-fault earthquakes in the context of response spectra. ۸۴ real earthquake records, including ۴۲ near-fault and ۴۲ far-fault records, were selected based on six velocity spectrum intensities. The results revealed that near-fault ground motions do not always impose higher demand on structures than far-fault ground ones, whereas the effects of near-fault earthquakes depend on the fundamental periods (T) of structures; therefore, constant scaling of the response spectrum over the whole period domain seems inappropriate for all structures. For structures with T ≤ ۱.۱۷s, near-fault motions have much higher acceleration response spectra than far-fault ones. In contrast, for structures with T ≥ ۱.۱۷s, near-fault motions have lower acceleration response spectra than far-fault ones. A scaling factor of ۱.۲۹۴ is proposed to scale the acceleration response spectra of far-fault motions to account for the effects of near-fault earthquakes on structures with T ≤ ۱.۱۷s. When T ≥ ۱.۱۷s, scaling is not recommended. The outcomes of this study can be useful for structural engineers in the seismic design of structures in near-fault earthquake regions.

Keywords:

Near-fault earthquake , Far-fault earthquake , Response Spectrum , structure , Near-fault factor , Single Degree of Freedom