en Structure-Steel Structure-Steel Research Paper Research Paper <p>An evolutionary structural optimization (ESO) method is used for plastic design of frames. Based on safe theorems some criteria are derived and made an effort to satisfy them during the optimization process. In this regard, equilibrium is checked and yield condition is gradually satisfied during the optimization process. In this method, the amount of used material and the stiffness for each element are improved, simultaneously, to impose upper bound of moment in the element. Frame analysis and optimization algorithm are implemented as PLADOF (PLAstic Design of Frames) computer code. Four examples are presented to illustrate the performance of the algorithm</p> Optimization, Plastic design, Evolutionary methods, Safe theorem, Plastic moments 165 170 http://ijce.iust.ac.ir/browse.php?a_code=A-10-416-1&slc_lang=en&sid=1 Mostafa Khanzadi khanzadi@iust.ac.ir 1800319475328460010152 1800319475328460010152 Yes Iran University of Science and Technology Seyed Mehdi Tavakkoli 1800319475328460010153 1800319475328460010153 No Iran University of Science and Technology