Theoretical and Experimental Assessment of Indirect Dynamic Measurements for Periodic Inspections of Road Bridges

Condition assessment of road bridges represents a relevant engineering challenge. The traditional approach is based on visual inspections aimed at detecting and tracking degradation phenomena and rating them in order to quantitatively assess the need for maintenance. Visual inspections show a number of drawbacks due to the lack of mechanical and physical global or local measures related to current conditions of key structural components. Recent advances in sensors and Information and Communication Technologies outline novel and beneficial applicative perspectives of data driven procedures in the field of inspection and management of road infrastructures. In particular, the extensive deployment of sensors aimed at measuring physical and mechanical parameters on vehicles call attention to the potential of indirect dynamic measurements as a supporting tool for bridge inspectors. The paper deals with a theoretical and experimental assessment of the potential use of instrumented vehicles for structural inspections. A numerical model of the vehicle-structure interaction designed in order to generate artificial acceleration records on simple bridge structures due to random traffic loads also provides the response of instrumented vehicles located at given locations. Thus, it has been used to investigate the opportunities offered by Operational Modal Analysis in extracting bridge modal parameters from indirect measurements. Results obtained from real measurements on a real vehicle commonly used for professional and technical purposes are illustrated afterwards aiming at providing a preliminary experimental insight on one of the key aspects of the process represented the basic dynamics of the vehicle as a prospective indirect measurement device.