the spectra of relative input energy per unit mass of structure for iranian earthquakes

Energy criterion is a simple and scalar quantity, so it has been employed by many researchers for the assessment of seismic behavior. production and presentation of input energy spectra are effective steps for the employment of energy criterion in the seismic design of structures. ninety-two pairs of horizontal components of iranian earthquakes were used for this research. these records were divided into near-field and far-field, and in each field, soils categorized to types 1–3. using nonlinear dynamic analysis, 92 inelastic spectra of relative input energy per unit mass were generated for a damping ratio of 5% and a ductility factor of 3. then, for each category of records, a combined spectrum was produced at design level corresponding to 10% risk in 50 years. the evaluation of combined spectra led to the conclusion that the average value of combined spectrum in near-field is greater than that in far-field. in addition, the average value of combined spectrum is greater for softer soils. the corresponding period to the peak of combined spectrum in near-field is longer than that in far-field. the effect of soil type in near-field is more than that in far-field. for each field and each type of soil, a relation and its parameters have been proposed for the inelastic spectrum of relative input energy per unit mass.