Cumulative demand of the earthquake ground motions in the near source

In this paper the effects of near-fault earthquakes are investigated through the study of parameters related to both input energy and plastic cycles demand. Based on the results of two different regression analyses performed with 128 near-fault and 122 far-field registrations, respectively, the Cosenza and Manfredi adimensional I-d index was found to be the best seismological parameter correlated to the number n and amplitude m of plastic cycles in the vicinity of the source as well as far from it. Analytical formulations for n,m and for the equivalent number of plastic cycles n(eq) are proposed for near-fault and far-field regions. The study of I-d and n (eq) shows the tendency of such parameters to increase as the distance increases. Copyright (C) 2003 John Wiley Sons, Ltd.