en Optimal design Optimal design پژوهشي Research <font size="2">The main objective of this study is to present new method on the basis of genetic algorithms for attenuation relationship determination of horizontal peak ground acceleration and spectral acceleration. The proposed method employs the optimization capabilities of genetic algorithm to determine the coefficients of attenuation relationships of peak ground and spectral accelerations. This method has been applied to 361 Iranian earthquake records with magnitudes between 4.5 and 7.4 obtained from two seismic zones, namely Zagros and Alborz-Central Iran. The obtained results indicated that the proposed method can be characterized as a powerful tool for prediction horizontal peak ground and spectral accelerations. </font> Attenuation relationship; genetic algorithm; peak ground acceleration; spectral acceleration 597 607 http://ijoce.iust.ac.ir/browse.php?a_code=A-10-1-40&slc_lang=en&sid=1 A. Bagheria 18003194753284600336 18003194753284600336 Yes G. Ghodrati Amirib 18003194753284600337 18003194753284600337 No M. Khorasanib 18003194753284600338 18003194753284600338 No J. Haghdoust 18003194753284600339 18003194753284600339 No