Correct and efficient model of the dynamics of the laminated core structure is essential for the design of quiet power transformers. In this paper, the viscosity and friction between two adjacent laminas of a laminated beam were included in the derivation of the equivalent bending stiffness of the beam subject to transverse vibration. As a result, the equivalent stiffness and loss factor of the beam were obtained as functions of the lamina number and relative deformation ratio due to the friction factor between the layers. The equivalent material properties were then used to determine the frequency response functions of laminated beams using the finite element method. The comparison between the simulated and measured frequency response functions of laminated beams showed good agreement.