Multi-Methodological Geophysical Approach for Rapid and Non-invasive Structural Characterization of Infrastructures

In the context of health monitoring of structures/infrastructure, we propose a combination of different rapid and non-invasive experimental methods that allows the determination of the main structural parameters of an infrastructure. It is based on simultaneous acquisition of 20 minutes of seismic ambient noise with seismic arrays placed at different points of the infrastructure without diverting or blocking the traffic flow or interrupting the operation of a road infrastructure. The signals are analyzed using different analysis techniques such as standard spectral analysis (Fourier Amplitude Spectra, FAS), Frequency Domain Decomposition (FDD), Ambient Noise Deconvolution Interferometry (ANDI), and Non Parametric Damping analysis (NonPaDAn). These combined techniques were applied to two different types of viaducts: the Gravina bridge, located on the SS.655-Bradanica, and the Monticello viaduct on the SS.407-Basentana (Albano di Lucania), both located in the Basilicata region (Italy). The Gravina bridge is a newly constructed arch bridge whose structural parameters, evaluated using this approach, represent the zero-time reference point for further investigations on the temporal evolution of the structural parameters. The Monticello bridge is a multi-span viaduct built in the 1970s whose estimated structural parameters were compared to the various degrees of degradation observed on the girders. The application of different methods has facilitated and improved the interpretation of the results obtained, proving very promising for the estimation of the main vibrational modes, the associated mode shapes, the equivalent damping and the wave propagation velocities.