This study presents a reliable and effective idealization scheme for the free vibration analysis

of buried cylindrical storage tanks. The three dimensional problem is transformed into a two

dimensional one by using a semi analytical finite element procedure. Conical shell of

revolution element is used. to represent the cylindrical wall, top plate, and bottom plate of the

tank by an appropriate method. The Combined effect of structure-soil-fluid interaction is of

primary importance as concluded in this work. The soil medium is idealized by the elastic half

space model, that is, linear springs are assumed to represent the structure-soil interface, added

masses and viscous dampers of soil are also included. The liquid region is treated analytically;

also analytical integration is used to got the added stillness and mass matrices for hydrostatic

and hydrodynamic pressure effects, respectively. The free vibration characteristics of the

liquid storage tank are validated against experimen.tal and theoretical results available in

literatures.