The dynamic response of liquid-containing structures is governed by their modal properties, which are affected by the mass of liquid and other fluid-structure interaction mechanisms. Therefore, knowledge of the effects of different parameters on modal properties is helpful in conducting a precise dynamic response analysis. In this paper, the effects of liquid on the modal properties of two structures, i.e., a pipe structure and a cylindrical storage tank, are investigated experimentally. The experimental results are then used to construct accurate analytical/numerical models for these structures. The models are capable of regenerating the experimental dynamic characteristics of the structures with an acceptable accuracy, indicating a proper modeling of the effects of liquid and the corresponding interaction mechanisms.