RELIABILITY ANALYSIS OF NUCLEAR POWER PLANT MAIN HOUSE UNDER THE EFFECT OF TRONADO LOAD BASED ON SSFEM

Based on the tornado observation records at a nuclear power plant site, a tornado intensity distribution of extreme value type III was derived. Modelling a computational model for a conventional island main house and taking into account the uncertainty of tornado load and structural resistance parameters, the stochastic response and reliability analysis of a spectral stochastic finite element method (SSFEM) was carried out in three load cases. The results show that: tornado loading produces a strong torsional effect on a structure and the exceeding probability of a top node random displacement to the specification limit is relatively high when the main house locates at the center of tornado; meanwhile, tornado loading produces a pushing effect on a structure and exceeding probability is fairly low when the main house sits at the radius of tornado maximum wind speed. Locating at a tornado center is the most unfavorable load position to the main house in three load cases.