evaluation site effects on groundmotion by elasto-plastic model and numerical approach

seismic response of a site depends on geological and specifically on geotechnical properties of the soil. in this paper, nonlinear dynamic analyses of 4 different sites, selected based on soil types in the iranian earthquake code (2800), have been carried out. the flac software, one of the powerful packages in modeling the soil media, has been used. the analyses have been performed in time-domain with elastoplastic model and results are presented as normalized acceleration spectra. comparing the obtained spectra using nonlinear approach with those obtained from iranian code, the reliability and accuracy of the equivalent linear method are investigated and discussed. also the effects of some main geotechnical parameters of the site such as soil cohesion and angle of internal friction on the amplification factor of the site are evaluated.