عنوان مقاله [English]
The effect of near-field earthquake records on the strain input energy of structures is investigated in this paper. Near-field
records differ from other types of record by special characteristics. Long-period pulses, which are added to background records, are examples of those special features that are studied in this paper. Although both pulses and background records are statistical objects, the pulses usually behave more deterministically than underlying records. Considering this point, it is reasonable to compute the response of a structure to such earthquakes in two steps (i.e. deterministic and probabilistic phases) and, then, superimpose the results. Handling responses to near-field records in this way leads to more accurate response evaluations, because of extracting the deterministic part of the results from the statistical procedure. For this purpose, the response of different structures to near-field records is evaluated and the results are proposed in the form of energy spectra. The findings show that, in near-fault zones, an increase in ground motion magnitude results in higher spectral peak strain energy and, also, a higher period of occurrence,respectively. It is found that, close to the fault, the response is primarily governed by the pulse characteristic rather than by the background record. This trend inverts gradually as the distance to the fault increases. In intermediate regions, the
energy spectra experience two major peaks, which correspond to the site dominant period and the pulse period, correspondingly.