Dynamical testing of axially loaded tie-rods

The determination of the axial load acting in structural tie-rods is of crucial importance in order to ensure safety and efficiency, especially in case of ancient masonry buildings. In this process of assessment a non-destructive, non- invasive technique, as the vibration-based monitoring, is strictly required. However, due to age and environment, ancient tie-rods integrity can be affected not only but high loads but also by cracks and localized damages that are dangerous, hidden enemies. This work introduces a novel technique for the detection of cracks, which is based on the measure of the dynamical behaviour of the rod, in conjunction with compliance estimation. The method is refined and validated by extensive laboratory tests