PSI - Issue 62

Gianluca Bottin et al. / Procedia Structural Integrity 62 (2024) 177–184 G. Bottin et al./ Structural Integrity Procedia 00 (2019) 000–000

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2.1. Geometrical survey The geometry of the entire artefact was detected through a detailed survey with laser-scanner technique. Fig. 2a shows, as an example, the longitudinal view of the bridge and the correspondent image obtained by the point cloud detected by laser scanner survey. In addition to the laser scanner survey, a drone survey was carried out. Surveying with a drone allows to acquire photos of parts of the structure that are not visible or reachable directly (for example parts above the watercourse, supports etc..). It is worth noting that the drone survey turns out to be very effective in terms of diagnostics and degradation mapping of inaccessible structural elements. Fig. 2b reports an example of photo obtained with the drone survey.

Fig. 2. Example of: (a) geometrical survey with laser scanner technique: longitudinal view; (b) correspondent image obtained by the point cloud; (c) photo obtained with the drone survey.

2.2. Degradation survey A preliminary degradation map was carried out in order to provide a global view of the degradation regions of the artefacts. Then, for each structural elements, the degradation level was defined specifying the intensity and extension according to the Guidelines approach (Italian Guidelines, 2020). The degradation analysis was summarized according to the format required by “defect forms”. Fig. 3 reports an example of the degradation maps for a bridge portion, with the associated orthophoto and an extract of the corresponding “defect form” for the lateral bridge girder of the end “span 1” and for the corresponding pier.

Fig. 3. Degradation map of a bridge portion with some photos and an extract of the corresponding “defect forms” Italian Guidelines (2020) for the lateral girder (top) and the pier (bottom).

The surface of lateral girders and piers are characterized by degradation phenomena due to the combined effects of ageing and exposure to atmospheric events. In addition, it is possible to observe a concrete scouring due to water leakage in the end portions of the lateral girders and of the external pillars of the pier. A limited corrosive attack can be also observed on the edges of the elements with limited portions of exposed rebars.