PSI - Issue 84

Matteo Vozzi et al. / Procedia Structural Integrity 84 (2026) 425–432

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exception of bridge P4. In this case, the consequences influenced the results more than the vulnerability and deterioration of the structures. Moving to the prioritization of interventions based on APT BMS method, the results are reported in Figure 2. For a clearer interpretation of the ranking order in terms of the Priority Index α asset,int, results are represented on a logarithmic scale. In this case, the priority of intervention increases as the value of the index decreases. As it can be observed, the bridges requiring the greatest priority of intervention are those characterized by a poorer state of conservation (as indicated by the parameter Damage Index D in Table 1) and, therefore, by a smaller index value. It should be noted that for the estimation of the Defect Matrix and the resulting probability of failure no unique criterion exists in the literature, and each managing authority adopts arbitrary decisions for their definition [20].

Figure 1: Priority ranking according to the cost of postponing interventions by one year.

Figure 2: Priority ranking according to the cost-effectiveness of the interventions

Figure 3 shows a scatter plot in which the cost of postponing interventions by one year is represented on the horizontal axis, while the Priority Index α is represented on the vertical axis. Both metrics are reported in logarithmic scales. Bridges with lower priority of intervention are those characterized by a high cost-effectiveness of the interventions and by a limited postponement cost (see lower-left portion of the diagram). Bridges with higher priority cost are those characterized by a low Priority In dex α and by a high intervention deferral cost (see upper -right portion of the diagram). In Figure 3 it is noted that bridges that are distributed in clusters. This is due to the common characteristics of some bridges that lead to comparable evaluations of reliability and consequence. The lower-middle cluster, for example, appears as a priority according to the SINA method and not a priority according to the APT. This is due to the different ways consequences are considered in the two methods. Bridges P5, P6, P7 and P8 are part of a major highway in Italy and are associated with higher consequences by the first method with respect to the other bridges in the sample. The cluster in the top-left, appears as primary according to the APT method and not primary according to SINA method. This is due again to the different way consequences are considered in the two methods. Bridge P13 results being a priority according to both approaches. This is due to both the low reliability of the bridge and the high consequences associated with its collapse. P13 is indeed a bridge that presents relevant defects and has a significant dimension (this leads to high consequences due to the high fatality rate of humans in case of collapse).