Seismic dynamic response analysis of liquid storage tank under uneven foundation settlement based on fluid-structure interaction

Large storage tanks are commonly used to store liquefied petroleum gas, liquefied natural gas, etc. In actual service process, the storage tank is not only vulnerable to foundation settlement, but also prone to structural damage caused by accidental loads such as earthquakes. This paper proposed a seismic dynamic response analysis method for storage tanks under uneven foundation settlement. Through the wet modal analysis, the self-vibration characteristics of the storage tank were obtained. Using a two-way fluid-solid coupling method, the structural response of the tank under combined action of settlement and seismic load was studied. The results showed that when the tank with uneven foundation settlement was subjected to seismic load, the maximum mises stress, maximum circumferential stress, and maximum axial compressive stress increased by 56.7%, 28.5%, and 30.8% respectively compared to the tank without settlement, and the maximum stress occurred at the location of the circumference angle deflection of about +/- 25 degrees, where was exactly the position that the maximum stress occurred under the action of uneven settlement alone. Under the combined action of seismic load and uneven settlement, the storage tank was in its elastic stage with no large deformation most of the time. The maximum deformation recovered from 8.21mm to 3.83mm at the end of the seismic load. These results can provide some theoretical reference for seismic design of storage tank and earthquake damage investigation.