Analysis of the fragility of NPP ventilation chimney structure considering the influence of NPP buildings to wind impact

This paper describes the experimental and numerical analysis of the wind impact on the ventilating chimneys considering the effect of surrounding buildings. The wind load was generated using a probabilistic evaluation of the measured data at the study site for a return period of 104 years. The article presents experimental and numerical models for defining the wind load on a ventilated concrete chimney. Wind tunnel experiments were carried out to physically measure the wind pressures/thrusts acting on the chimney, which allowed to verify the plausibility of the results from the numerical simulations. Computational fluid dynamics software (FLUENT in ANSYS) was used to simulate and analyze the wind flow around the chimney to help determine the wind load. The safety and reliability of the chimney construction was assessed using probabilistic methods. Uncertainties in input data, such as meteorological data, loads and material properties, as well as model uncertainties are considered. This analysis was performed in accordance with the requirements of the Joint Committee on Structural Safety (JCSS). The fragility curve of the chimney structure was determined. This curve represents the likelihood of chimney failure or damage at different wind load levels. It was created based on Latin Hypercube Sampling (LHS) simulations using software called FREET.