PSI - Issue 84

Irene Matteini et al. / Procedia Structural Integrity 84 (2026) 677–685

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In particular, regarding high density in data acquisition, the Nyquist Criterion [7] establishes the fundamental guidelines for acquiring GPR data to ensure the desired resolution without information loss. From a practical standpoint, however, it is only in recent years that high-frequency devices—with extremely small antenna spacing, dual polarization, broad bandwidth, and sufficiently powerful software—have become available on the market. These advancements now make GPR a fundamental tool for investigating structural details and assessing condition. 2. Practical Application: The arch bridge The following section includes a case study of a reinforced concrete bridge deck located in the northern part of Italy. This bridge was selected based on accessibility, and easier data collection, and included as a prototype example to illustrate a methodology that will be applied to a larger number of bridge decks as part of the next phase of this research. This approach includes performing periodic MCGPR surveys and analysing the data in a 4D framework comparing spatial and temporal changes to detect evolving deterioration patterns, confirm early signs of structural distress, and inform timely maintenance decisions. The current investigation was solely focused on the bridge deck, with the intent of gathering useful insights for the definition of structural details, as well as generating a database generated by carrying out periodic surveys for the monitoring of the bridge deck related to deterioration. In the end, the aim of this research is to continue to establish a methodology using MCGPR as a predictive maintenance tool. The bridge was constructed circa in the 1960’s according to information provided by the Regional Department of Transportation. It consists of a one span deck, with a total length of 32 meters, featuring a top-through arch supported by abutments made of reinforced concrete and masonry. The deck includes several asphalt-layers on top added overtime (Figure 1a). The static system is composed of 4 arch reinforced concrete arches with transverse distribution elements and a cast in place concrete deck of approximately 35 cm in thickness. The road is classified as a type “C” and is therefore characterized by a single carriageway with two lanes, one for each direction of travel. The structure develops along a straight horizontal alignment and crosses a river in its mountainous section, in a particularly incised area where the watercourse is confined with no significant possibility of lateral expansion. 2.1. Description of the Bridge and Initial Inspection

Fig. 1. (a) View of the bridge from the riverbanks; (b) View of the bridge from the underside (Photo credit: Matteini).