The objective of a site response analysis is to estimate the ground shaking intensity during an earthquake. The Miyaneh city and its suburban areas are located in the northwest of Iran in AzarbayjanSharghi province. This area is prone to high seismic risk due to the presence of several active faults. In this paper, a case study on ground response analysis of a geotechnical site in Miyaneh region during the Ardabil earthquake (28 February, 1997, Mw6.1) is presented. For site characterization, deep site investigations have been undertaken and a seismic geotechnical procedure for the proposed bridge over the rivers at the mentioned site, which is performed for Iran railway network, subjected to earthquake provokes, has been notified. The effect of nonlinearity on site response analysis for the selected site with the assumption of elastic and rigid half space bedrock (by use of nonlinear standard hyperbolic model) was evaluated and the results obtained over a number of geotechnical areas were compared to each other. Test of the capability of designed computer codes by authors, namely; “Abbas converter”, which describes and evaluates the nonlinearity of the subsurface soil conditions encountered at the sites to analyze, evaluate the obtained test, site response and quantify the site effect on the surface over a number of geotechnical areas, were the targets of this study. The results clearly
showed that the effect of bedrock and local soil conditions on soil behavior under the earthquake excitation is one of the main effective factors on computed response spectra in ground response prediction. The key factor in this work was to develop and use “Abbas converter”. It has several advantages, which can make and render the study easier, than previous studies done, and take over the
encountered problem.