fa ارزیابی رفتار لرزه‌ای سکوهای پایه ثابت با استفاده از روش زمان دوام سازه های فراساحلی Offshore Structure يادداشت فنی Technical Note Evaluation of seismic behavior of offshore platforms is one of the important design steps in seismic regions. Nevertheless, because of complication and time cost of these methods, engineers usually do not study them deeply. Endurance Time (ET) method is a good solution for this problem. In this method, with acceptance of a reasonable region of errors, the time of analysis can be reduced considerably. Besides with one ET analysis, the behavior of structure can be evaluated in different seismic levels. In this paper, the ET and other usual methods in standards are introduced and then the seismic behavior of three platforms is compared with ET and response spectrum method. In this comparison, the acceleration function which is generated base on Iranian cod (2800 standard), is used and the differences are considered in relation to spectral analysis of 2800 standard. The results show appropriate conformity between two methods. Fixed Offshore Platform, Endurance Time Method, Seismic Behavior, Spectral Analysis 97 103 http://marine-eng.ir/browse.php?a_code=A-10-123-1&slc_lang=fa&sid=1 Mohammad Saeed Seif seif@sharif.edu 1003194753284600845 1003194753284600845 No Sharif University of Tech Hamid Mehdigholi mehdi@sharif.edu 1003194753284600846 1003194753284600846 No Sharif University of Tech Homayoon E. Estekanchi stkanchi@sharif.edu 1003194753284600847 1003194753284600847 No Sharif University of Tech Mohammad Ali Dastan Diznab dastan@mech.sharif.edu 1003194753284600848 1003194753284600848 Yes Sharif University of Tech