The implementation of advanced finite element analyses for the qualification of the seismic performance of an unanchored tank in a critical facility is demonstrated. The tank, which contains a hazardous fluid, is mounted on a flexible floor in a containment structure and could not be anchored. The exerted seismic overturning moment on the tank tends to lift the shell off its support which may possibly cause overturning of the tank, or buckling of the shell on one side and a separation of the base plate from the shell on the other. A nonlinear finite element program capable of handling the complexities associated with the transient response of unanchored tanks was used to examine the tank safety. Both horizontal and vertical base motions of the supporting floor, resulting from an earthquake excitation at the base of the supporting structure, are considered. The overall analysis, which included safety assessment under equivalent static loading and under time-dependent loading, has confirmed the safety of the tank.
展开▼
