COMPARISON BETWEEN RESULTS OF BOTH LINEAR AND NONLINEAR METHODS FOR SEISMIC VULNERABILITY EVALUATION OF THE MAIN CONTROL BUILDINGS IN A THERMAL POWER PLANT BASED ON FEMA-356

Seismic evaluation of power plants is an extremely vital task in Iran. Iran being a seismically active region and experience of major earthquakes in recent years has created an environment that requires special attention to all major and important structure is throughout the country. In this study, the main control buildings of a 1000 mega watt thermal power plant was investigated for its vulnerability against seismic forces. Evaluation was carried out in two phases using screening techniques as well as analytical and numerical methods. Screening methods was based on recommendation provided by FEMA-310 while analytical investigations were performed by utilizing recommendations stated by FEMA-356 for both linear and nonlinear analysis. 3D modeling was considered and both linear response spectrum and nonlinear static pushover analysis were used in analyzing the structure. Structure was subjected to 475 and 2475 year return period earthquakes. In earthquake with 475 year return period, the effect of uplift was also considered for further detailed investigation. Results for different performance levels were then calculated and the vulnerability indexes were identified. This paper will present the procedures used, obtained results and also recommendations for dealing with this sort of important structures both in terms of modeling and dealing with the obtained analytical results in retrofit design phase.