Ricerc@Sapienza

It has been known since the 1950s that under certain conditions, in the near-fault, earthquake ground motions can consist of a limited number of strong acceleration pulses. These types of ground motions have come to be referred to as ¿pulse-type¿ ground motions. These pulses are mostly associated with the normal to the fault direction, and amplify the long period coherent component of the ground motions, explicitly apparent in the velocity and the displacement time histories and the related response spectra. The identification of the near-fault velocity pulses requires further research for the definition of their characteristic parameters, mainly their period and amplitude. In this project a new procedure for the identification of the predominant pulse that is related to directivity phenomena and determination of the parameters of the velocity pulse inherent in pulse-like ground motions, will be developed and discussed. The existence of the directivity pulse in the ground motion has an important effect on the response of the structures. The aim of this study is to provide a dataset of near-source pulse-like strong motion records, suitable for seismic response analysis and ground motion studies in proximity to the seismic source.
Additional research will be developed to establish bounds on the different parameters that define the characteristics of severe long pulses, i.e., the largest incremental velocity, response spectra, displacement and energy spectra, and associated intensity measures. Such parameters will be derived from both linear and nonlinear analyses.
Finally, due to the fact that near-fault effects are still scarcely represented in design codes, a detailed discussion pertaining to the implication of near-fault ground motions on the design and assessment of structures will be presented.