Seismic Fragility Analysis Of AP1000 Nuclear Island Shield Building Considering FSI

The unlimited desire for energy makes the vigorous development of nuclear energy. Nuclear energy has received wide attention for clear and efficient. However, the disaster that bringed by nuclear accident can not be ignored in recent years. By investigating thoroughly the inducing factors of the nuclear accident, the earthquake disaster is one of the major factors. Though the earthquake occurred by accident, our country suffered a number of major earthquakes in recent years and then the catastrophe caused by the earthquake disaster is still a shock for our hearts. There are a large amount of researchers over the sesmic response and the seismic performance of the normal nuclear island at domestic and abroad currently, but few of them are focus on the AP1000 nuclear island. The AP1000 nuclear island is a third-generation passive nuclear island, and the huge gravity water tank which is located at the top of the AP1000 nuclear island shield building is the important component of the passive cooling system that to ensure cooling down the tempreture of yhe steel containment vessel when an accident occuried. The research which considering the fluid-structure interaction between the gravity and the shield building abuout the seismic response and seismic performance of the shield building is so lack. Based on the above limitations,in this paper, an approach for analyzing the seismic fragility of the AP1000 nuclear island shield building considering the fluid-structure inteeraction is proposed. The whole study is centered on the vibration characteristic, seismic response and seismic fragility analysis of the AP1000 nuclear island shield building, the main research contents are as follows:1. In this study, a refinement finite element model for the AP1000 nuclear island shield building with suitable element types, reasonable element size, material characters and compatible boundary consitions was estabilished by using the finite element software ANSYS. In this study, five working conditions(the water ratio of the gravity water tank is 0%, 30%, 60%, 80%, 100%) were analysed that to study the influence of the water ratio on the shield building vibration characteristic considering fluid-structure interaction.2. Based on the refinement finite element model, the Kobe true ground motion with the peak ground acceleration of 0.3g which is consistant with RG1.60 seismic design spectrum was used for time history analysis. Via comparing the seismic response such as the displacement response, the first principle stress response and the floor response spectrum of major floor to analysis the influence of the fluid-structure interaction between the water and the shield building on the seismic response of the AP1000 nuclear island shield building.3. In this study, selecting twenty ground motions with a certain perniciousness, choosing the peak ground acceleration as the intensity index of ground motion, selecting the maximum first principle stress of the hole building as the limit damage index of the shield building were used in the incremental dymanic analysis. To analysis the influence of fluid-structure interaction on the shield building seismic fragility, two working conditions were considered in this paper, one working condition is no water in the gravity water tank and the other working condition is the usually working condition of the AP1000 nuclear island that the water ratio of the gravity water tank is 80%.