Effects of near-fault and far-fault earthquakes on the site response

Investigation of previous earthquakes shows that the distance to the fault from which the earthquake is sourced is a paramount factor contributing to the site response and magnitude of the induced damages. In this research, equivalent linear and nonlinear methods were used to assess the effect of the earthquake field on the site response. Assessments included investigations of time histories of acceleration, velocity, displacement, as well as their peak values and response spectra. Records of the Bam earthquake acquired at two different stations were used for this purpose. Results showed that the peak values of the response spectrum induced by a near-field earthquake record occurred at higher frequencies than those seen in a far-field quake, with the nonlinear effects being more pronounced in the near-field earthquake record than in the far-field one. Additionally, the difference of the obtained responses from the nonlinear and equivalent linear methods was greater for the near-field earthquake record than for the far-field earthquake record. Finally, it is worth noting that the damage potential of an earthquake event cannot be adequately assessed unless the frequency content of the earthquake, soil effects, and structure stiffness are considered simultaneously.