This project will create and validate an analytical model for the complex behavior of unanchored liquid-filled tanks during an earthquake. This type of analysis is complicated, because the bases of these tanks separate from and lift off their foundations during strong ground motion excitations. This base uplift changes the dynamic behavior of these structures considerably and leads to severe loading conditions that can lead to stress or buckling failures and subsequent loss of contents. To advance the design of such structures, the response of the tank and its contents due to both lateral and vertical base excitation must be modeled. Attention will be paid to the formulation of the nonlinear base uplift problem. Effects due to shell flexibility, liquid sloshing and ground flexibility will be investigated. Results of this research effort will improve the seismic performance of liquid storage tanks related to critical urban services such as petroleum storage, water supply, and other distribution systems.
