Published by Elsevier Science Ltd. All rights reserved 12 th European Conference on Earthquake Engineering Paper Reference 242 (quote when citing this paper) STRUCTURAL DAMAGE IN THE NEAR-FAULT G. Manfredi 1 , M. Polese 1 and E. Cosenza 1 1 University of Naples Federico II, Department of Structural Analysis and Design, Via Claudio 21, 80125 Naples, Italy ABSTRACT Strong ground motion in the near-fault area may have very different characteristics from far- field earthquakes. Structures are often forced to absorb a large amount of energy with one or few plastic excursions of high-ductility, whether away from the source cyclic damage is of greater importance. Near-source earthquake effects are here studied through the investigation of Cosenza & Manfredi I d index, which is a seismological parameter correlated to input energy as well as to equivalent plastic cycles demand n eq . Its variation with distance from the source confirms that the importance of cyclic damage grows with distance. Moreover the comparison of inelastic strength spectra for sites close and far from the fault shows that high ductility demand is the main responsible of damage in the near-source, while in the far field damage due to the cumulative effect of reversal cycles is preponderant. Keywords: Near-fault; Cyclic damage; Inelastic strength spectra; Low cycle fatigue spectra INTRODUCTION The 1971 San Fernando earthquake was probably the first one to drive the attention of scientists on the peculiarity of earthquakes in the near-fault area and on their potential to damage structures. Since then many other destructive earthquakes occurred near densely built areas (Imperial Valley 1979, Whittier 1987, Northridge 1994, Kobe 1995, Chi Chi 1999 etc.) and the study of damage on structures coupled with the analysis of recorded seismograms helped to understand some of the most important aspects of earthquakes in the near-fault. In the present work earthquake effects near the source are studied through the investigation of parameters able to represent seismic damage potential, thus related to input energy and plastic cycles demand. The variation of Cosenza & Manfredi I d index, which is the seismological parameter better correlated to plastic cycles demand in the near fault as well as in the far field, with distance from fault is studied. Moreover inelastic strength spectra for sites close and distant from the source are built, taking into account both the ductility and low cycle fatigue criteria; the differences that can be underlined from their comparison are significant of the variation of cyclic demand with distance from the fault. Finally, the variation of the ratio of R μ /R dam , i.e. spectral reduction factor for ductility criterion versus spectral reduction factor for low cycle fatigue criterion, with distance from fault is investigated. Structural behaviour in the near-fault area Bertero et al [1] studied for the first time the effects of near-fault impulse-type ground motions on structures. They observed that structural damage was imputable mainly to few