Seismic damage assessment of elevated RC water tank considering fluid-soil-structure interaction and foundation uplifting

The seismic damage of an elevated reinforced concrete water tank is evaluated in the present work, considering water effect and soil structure interaction with foundation uplifting. The effect of the soil-structure interaction is accounted for by using springs with gap elements to allow the foundation uplifting. The stored water inertia is reproduced by an impulsive and convective masses. The supporting framed structure is modelled by hinged beam elements, and the fibre element model based on the axial load - biaxial moment interaction (PMM) hinge section is selected to define the basic force-deformation relationship for each material in the hinge. Model validation and modal analyses of the intact tank are first presented. Then, several incremental dynamic analyses are conducted to evaluate the seismic capacity and degraded modal characteristics of the tank after damage. Finally, a global seismic damage index is proposed and evaluated to assess the soil structure and the foundation uplifting effects.