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. 84 real earthquake records, including 42 near-fault and 42 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 ≤ 1.17s, near-fault motions have much higher acceleration response spectra than far-fault ones. In contrast, for structures with T ≥ 1.17s, near-fault motions have lower acceleration response spectra than far-fault ones. A scaling factor of 1.294 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 ≤ 1.17s. When T ≥ 1.17s, 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.