Experimental and numerical study of dynamic response of elevated water tank of AP1000 PCCWST considering FSI effect

AP1000 passive containment cooling system water storage tank (PCCWST) is set at the top of a shield building. Its function is to hold the water which will flow by gravity to help cool the containment vessel in the highly unlikely event of an emergency - one of the AP1000 plant's innovative passive safety systems. The huge amount of water may pose a threat to the integrity of the shield building during an earthquake. In this paper, both modal characteristics and transient response of a scaled elevated water tank model were studied by a shaking table experiment. The acceleration of the supporting structure and displacement of water sloshing were recorded under transient loading. Four numerical models were built, including two-mass equivalent model, single lumped-mass model, and finite element models using Fluid30 and Fluid80 elements. The advantages and disadvantages of different numerical methods were discussed. Moreover, finite element (FE) models of AP1000 shield building were established considering the fluid-structure interaction (FSI) effect. The sloshing phenomenon in PCCWST under resonant three-cycle sine (RTCS) wave and seismic loading was studied. The response of shield building under seismic loading was also studied. The results showed that the maximum von Mises stress occurred at the corner of the air inlet. The shaking table experiment can provide a benchmark for seismic response of an elevated water tank. The FE model of shield building may help improve the design of the AP1000 and CAP1400 in the future.