FUNCTIONAL PERFORMANCE INDEX OF SQUAT SHEAR WALLS IN NUCLEAR POWER PLANTS AND THEIR APPLICATION IN SEISMIC PROBABILISTIC SAFETY ASSESSMENT

In nuclear power plants, equipment connected to shear walls through embedded parts exhibits significant coupling effects that directly influence seismic performance. Current seismic design and probabilistic safety assessment methods inadequately consider these interactions, leading to deviations in performance predictions. This study proposes an evaluation methodology that simultaneously addresses global wall behavior and local embedded part response based on quasi-static tests of 15 specimens with embedded parts. The research demonstrates that equipment anchoring reduces functional drift ratio limits by 17%, with experimental evidence confirming that embedded part degradation precedes main structural damage. Statistical analysis yields functional drift ratio limits with 95% assurance probability. These functional performance points serve as criteria for equipment functional failure, enabling the development of a structural fragility model for seismic probabilistic safety assessment. The findings provide critical technical support for refined seismic design and safety evaluation of nuclear power plants.