PSI - Issue 84

Luca Ranedda et al. / Procedia Structural Integrity 84 (2026) 1191–1197

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Figure 5 – Linear scans on the cantilever With the second investigation technique, area scans of the C-scan type were performed. Area scans are obtained by interpolating horizontal and vertical linear scans carried out with a step of 30 cm. By knowing the areal dimensions of the scan and by measuring the X distance (longitudinal horizontal distance from the pier axis or from the outer edge of the beam) and the Y distance (vertical distance from the top surface of the deck slab) of one vertex of the scan, it is possible to determine the exact position of the cable layout within the structure. The area scan also makes it possible to reconstruct the arrangement of the passive reinforcement (Figure 6).

Figure 6 – Area scans on the cantilever

Technique 1, the linear scanning method, was carried out using the Proceq GPR Live GP8000 on the cantilever of Pier 4 and at the midspan of the buffer beam on the Fano side. Technique 2, the area scanning method, was performed using the Proceq GPR Live GP8100 on the cantilever of Pier 3 and at the midspan of the buffer beam on the Rome side. 3.3. Results The two techniques used made it possible to obtain the same results, confirming—within variations on the order of a few centimetres—the position of the cables as reported in the final as-built drawings. For a comparison between the two survey methods used, Table 1 below presents the main characteristics of the two scanning techniques. Table 1 – Summary of the characteristics of the scanning techniques Characteristic Technique 1 – Linear Scans Technique 2 – Area Scans Productivity Survey performed in approximately 2 hours, plus about 1 hour for confirmation endoscopies. Survey performed in approximately 3 hours.

(Survey of the cable layout on ½ span of the buffer beam)