The dynamic characteristics of the structures, especially of the old masonry ones represent valuable starting parameter for every structural analysis and seismic assessment. The theory and experience show that we can experimentally determine the dynamic characteristics by using the ambient vibrations method while maintaining its operation without disruption.
In the framework of applicative projects of the Institute of earthquake engineering and engineering seismology during the month of October and November 2021 two national heritage objects were point of interest. The church of Saint Nicetas located on the slopes of Skopska Crna Gora and the church of Saint Atanasij in Prilep. With further post processing of the measured ambiental vibrations the eigen frequencies as well as eigen modal shapes are be determined. They can be further used as benchmark when seismic assessment will be performed by finite element models.