PSI - Issue 64

Yago Cruz et al. / Procedia Structural Integrity 64 (2024) 732–739 Yago Cruz / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 2. Location and photographs of the staircase.

3.1. Experimental campaign Regarding the visual inspection, it should be noted that there are no cracks due to mechanical actions. At different points of the staircase there are uncovered reinforcing bars caused by carbonation. No important structural deformations can be seen, but there is a lifting of the floor on one of the steps. Another aspect to take into account is the presence of lichens on a large part of the concrete surface. This defect does not affect the load-bearing capacity of the structure, but it does affect the aesthetics of the staircase. The experimental measurements begin with a 3D laser scan of the structure. In this case, the FARO Focus 3D scanner is used, which is based on the phase difference methodology to obtain the data. The main characteristics of this data acquisition system is that it allows obtaining geometries in a range of 0.6m to 120m with an error of ± 2 mm and the acquisition of 976,000 points per second. For the complete definition of the structure, four scans are carried out. Three of them from the bottom and one at the landing between the two levels of the stairs (Fig. 3). The resulting point clouds are described in terms of file size and point density in Table 1.

Fig. 3. Scanning positions.

Once the different point clouds have been processed and aligned, a complete cloud of the structure is obtained (Fig. 3) with a file size of 1.3 GB and a density of 24,078,282 points. This cloud is used together with the visual inspection to recreate the 3D geometry of the structure in the BIM model and for the location of imperfections.