PSI - Issue 62

Carla Assunta Trifarò et al. / Procedia Structural Integrity 62 (2024) 57–64 C.A. Trifarò et al./ Structural Integrity Procedia 00 (2019) 000 – 000

61 5

In particular, the total relative defect index is the sum of the mean relative defect assessed for each group of structural components k (e.g., piers, abutments, beams, etc.) composed of n elements. In this sense, it must be highlighted that, despite not fully compliant with the Italian Guidelines for existing bridges, the proposed defect measure may be considered as an indicator of the state of conservation of the structures. Thus, it should not be adopted for determining the defectiveness level according to the procedure therein proposed. 3.2. Interpretation of the results Based on the collected data, a first consideration was made based on the positions of the structures along the highway network. This was performed by relating the kilometric progressions with the determined average defect index of the structures D r,m . The bar chart of Fig. 3 shows such an elaboration. As can be qualitatively observed, the structures between the 120 th and 140 th kilometer present, on average, the highest level of such an index (higher than 10). This can be related to the fact that in this zone severe environmental conditions during the winter seasons are frequent, such as low temperature and snow. As a consequence, to allow the easy transit of vehicles, the frequent use of de-icing salts may have triggered and favored degradation phenomena of concrete structures.

Fig. 3. Relationship between D r and kilometric progression

The obtained D r were also statistically interpreted. In particular, the bars of the graph of Fig. 4 show the frequency of occurrence among the entire stock of structures of the different values of the D r index. As it can been seen, the data can be reliably interpreted by a lognormal distribution probability function ( D r,m =7.00 and C.o.V. =45%).

Fig. 4. Distribution of D r in the considered stock (black line represents a lognormal distribution probability function).