The purpose of the study is the development of a tool for the prediction of the structural damage by means of the numerical damage simulation in the design stage. For the evaluation of the structural integrity in the numerical damage analysis, a global damage indicator was defined based on the modal parameters obtained from the tangential equation of motion: a set of natural frequencies and mode shapes. As they are given in a set, it may be difficult to treat them as a damage indicator. In this study a new damage indicator based on the natural frequencies was defined using the contribution factors of the mode shapes under consideration of the external modal energy. A numerical example of a frame structure showed the efficiency of the damage indicator defined in the study.