Abstract: In structural vibration analyses, vibration damping of viscoelastic structures is equivalently reduced to a visco-damping model by the wellknown energy equivaent principle. The approach of energy equivalent principle is at first introduced inthis paper, and a new method based on the equivalent eigenvalues of the system is also suggested to reduce viscoelastic damping to a visco-damping model. The detailed discussion and comparison of the two methods are conducted for the obtained equivalent systems. It is a...