Application of a Non-Invasive Technique for the Preservation of a Fortified Masonry Tower

Abstract

The Cultural heritage spread all over the World needs to be preserved with systems that do not compromise its architectural and historical value. Nowadays, the most advanced technology available is the ambient vibration test. It allows to obtain the current frequencies, modal shapes, and damping of structures, without being invasive. The comparison between different monitoring campaigns and their use in combination with Finite Element models can give an insight into the state of structures’ health. This paper presents two ambient vibration tests performed on a fortified masonry tower in the Marche region of Italy, carried out after one year each other, with different temperature and humidity conditions. To extract the structure’s dynamic parameters both a time and a frequency domain approaches were used. The comparison between the parameters obtained during the two experimental campaigns showed similar frequencies and modal shapes underlining that no damage occurred and that the dynamic response of the tower does not suffer temperature and humidity variations. In addition, the steps carried out for a first attempt manual calibration of the tower’s Finite Element model are shown. The match between the numerical model and the experimental data is evaluated through the absolute frequencies’ errors and the Modal Assurance Criteria between the modal vectors. The calibrated numerical model can be used for future and accurate assessment of the tower’s structural capacity.