In this study an equivalent mechanical model was developed to simulate the dynamic behavior of truncated conical-shaped steel tanks. The study is conducted numerically using a coupled boundary-finite element formulation that was developed in a previous study. Shake table tests of a small-scale conical tank model are reported in the current study. Results of these tests, in terms of natural frequencies, mode shapes, base shear force and overturning moment are used to verify the numerical model. The study proceeds numerically by performing a parametric study using the validated numerical model. A large number of conical tanks were analyzed under harmonic excitations and results of the analyses were used to develop an equivalent spring/mass system simulating the dynamic characteristics of conical tanks. Charts that provide the mechanical properties of various components of this mechanical system are also provided. These charts can be easily used for evaluating the seismic response of liquid-filled conical steel tanks by means of response spectrum analysis.