In-situ estimation of axial force in tie rods of masonry structures by radar interferometry

Tie rods are often used in historical masonry constructions to improve structural stability. Tensile force in tie rods can be estimated from experimental measurements through dynamic methods. Generally, these methods are based on the measurement of the vibration of the tie rod through contact sensors. Here, we study the in-situ application of an innovative remote sensing technique, the ground-based radar interferometry, to the estimation of tensile force in tie rods through dynamic methods. Our purpose is to highlight the main potentials and limitations related to this application. We found that one of the most critical issues that may arise concerns the presence of static clutters. Indeed, static clutters may generate spurious frequencies that could lead to errors in the estimation of tensile force. Results show that this issue could be overcome by applying robust and effective clutter removal techniques.