The methods of diagnosis of damage through measuring the changes in dynamic structural properties have been intensively studied for many years now. On the contrary to mechanical or aeronautical engineering, however, the practical application of the methods in the case of civil engineering structures meets a number of difficulties indicating the need for further research. This concerns in particular the need for the shaking table investigations since the results of such tests are very limited. Therefore, the aim of the present paper is to show the results of the shaking table study conduced on a model of two-storey steel frame building. The 1.56 m high model structure was constructed of columns with cross section of mm. Damage was defined as a reduction in stiffness and introduced by replacing the columns with elements having mm cross section. Seven different structural damage cases described by different number of columns with the reduced cross section were considered in the study. During the shaking table experiment the base of the structure was excited under the sweep-sine loading. The results of the study show a characteristic decrease in the natural frequencies with the progression of damage. This trend has been especially observed for the first natural frequency, for which the decrease in the frequency value has been found to be uniform. The results of further analysis show the scattered values of the structural damping ratios without showing any relation with the level of structural damage.