Uplift effect and soil-structure interaction on seismic responses of column supported steel tanks under multi-dimensional earthquakes

The objective of this research is to perform seismic analysis for column supported tanks, focusing on the performance assessment under multi-dimensional earthquakes and considering fluid-structure interaction (FSI), soilstructure interaction (SSI), and the uplift effect. A finite element model (FEM) capable of integrating the above complicated factors is generated to study the seismic response of two types of tanks, including anchored and resilient tanks. The FEM of tanks considering these effects is first verified by using experimental and numerical results, and then the FSI and SSI effects on the natural frequencies of tanks are investigated. Subsequently, their seismic responses, i.e., structural displacements, member stresses, base shear and overturning moments, are obtained, and the influences of multi-dimensional excitations, SSI and uplift effects on them are further studied. The results show that the inclusion of multi-dimensional seismic components causes significantly increase in structural responses in perpendicular direction, making column supported tanks more susceptible to damage. The SSI effect leads to larger displacement, but smaller stress level especially for softer soil type. Resilient tanks do not suffer plastic failure of their walls and columns, and outperform anchored tanks regardless of soil conditions even under severe multi-dimensional earthquakes. In addition, resilient tanks have quick resilience capability, which provides favorable references to seismic design of column supported tanks.