PSI - Issue 78

Marco Nale et al. / Procedia Structural Integrity 78 (2026) 1095–1102

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A comparison between the proposed procedure and the Italian guidelines is provided in Figure 3b using bar plots. The plot shows the activation control levels according to the proposed method, with continuous blue and red bars representing CL1 and CL2, respectively. The recommended activation thresholds from the Italian guideline (IMIT, 2017) are represented by magenta and green lines for CL1 and CL2, respectively. Table 2 also includes the PGA values recorded at each site, along with the corresponding activation thresholds provided by the proposed protocol.

Table 2. PGA values for hydraulic infrastructure, derived from attenuation curves for the first shock of the 2012 Emilia earthquake, along with the corresponding Control Levels (CL1 and CL2) defined by the proposed protocol.

Event 20 May

Proposed Protocol

ID Investigated site

R epi [km] PGA [g]

CL1

CL2

HI1 Valle Lepri HI2 Tieni HI3 Fiscaglia HI4 Valpagliaro HI5 Pontelagoscuro HI6 Opera Po HI7 Opera Reno

69.1 61.8 55.7 47.9 27.1 14.5 16.0

0.023 0.045 0.070 0.027 0.085 0.160 0.033 0.150 0.260 0.043 0.150 0.260 0.108 0.150 0.260 0.248 0.045 0.070 0.223 0.100 0.150

From the bar plot, it is evident that the Italian guideline tends to be more conservative for five out of the seven hydraulic structures compared to the proposed approach. However, for Opera Po and Valle Lepri, both approaches suggest similar control level thresholds, reflecting the high seismic fragility at these locations. This vulnerability is primarily linked to the risk of column failure in shear that houses control systems and mechanical equipment. The main variation between the proposed protocol and the Italian guideline lies in the activation of PGA thresholds. Unlike the conventional acceleration thresholds defined in the guidelines, the proposed approach establishes vulnerability-based activation levels. As a result, the procedure recommends CL2 inspections for Opera Reno and Opera Po after the May 20 event. The other structures fall outside the CL1 and CL2 activation zones in both events but still require CL0 inspections due to their strategic importance in the network. Further insights from the case study include structures designed under modern seismic codes (e.g., those in Valpagliaro, Pontelagoscuro, and Fiscaglia) show higher activation thresholds due to lower structural vulnerability. In contrast, older structures like Valle Lepri and Opera Po exhibit greater vulnerability, particularly due to deficiencies in the control command buildings and structural details (e.g., wide stirrup spacing). The value of including preliminary vulnerability assessment as part of the control procedure enables a more rational, vulnerability based approach. The proposed procedure is demonstrably less precautionary than the current Italian guideline, owing to its incorporation of structural vulnerability in control activation. This feature allows for a more efficient, flexible, and targeted post-earthquake response, helping prioritize inspections and allocate resources more effectively. Infrastructure owners and managing authorities can use the proposed method to make informed decisions about deploying inspectors and planning interventions based on actual risk. This represents a major advantage for the management of the extensive network of small to medium-sized hydraulic infrastructure throughout the territory. 4. Conclusion This study introduces a vulnerability-based inspection protocol for hydraulic infrastructure in lowland areas exposed to seismic hazard. The main contribution of this approach is a three-level control strategy linked to fragility curves of the components, including structural, non-structural, and control components. The protocol also incorporates a standardized damage classification system to support inspectors during post earthquake surveys and facilitate consistent damage identification. The protocol is validated using the scenario of the 2012 Emilia earthquake. Future developments include the calibration of damage classification through the Failure Mode, Effects, and Criticality Analysis (FMECA) methodology (NASA,1966) to improve the damage assessment system. Finally, the