PSI - Issue 78

Carlo Pettorruso et al. / Procedia Structural Integrity 78 (2026) 1190–1196

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confidence level, the minimum required number of tendon samples to test was determined: 6 for Population 1, 5 for Population 2, and 6 for Population 3. Finally, based on deterioration indicators, specific tendons and their most critical zones were selected for investigation. This completed Phase 0, setting the stage for the selection of the most suitable void detection method in Phase 1, as detailed in Section 2. 4.2. Results The proposed method is applied to select the most suitable testing technique for detecting the possible presence of voids in ducts, corrosion and residual tension. The available testing methods for void detection include Impact Echo (IE), Ultrasonic Echo (USE), Ultrasonic Tomography (UST), and X-Ray Radiography (XRR).

Table 2 Attributes

IE USE UST XRR

Accuracy

Deviation 0.2 0.5

1 1 1 1 1

1

Power

1 1

1 1

0.2 0.5

Personnel Calibration

Ease of use

0.5 0.5

1

Data processing

0.5 1 Ease of Use Score 0.75 0.875 1 0.675 1

Roadway occupancy Inspection duration

0.5 0.5 0.5 0.5

1

1

1

0.5

Traffic Impact

Inspection score

0.75 0.75 0.75 0.5

Traffic class 0.5 0.5 0.5 0.5 Traffic Impact score 0.625 0.625 0.625 0.5

Cost

Cost Score 1

1

0.5 0.5

Table 2 provides a summary of all attributes for each performance category of the selected testing methods. As proposed by Pettorruso (2025), the ranking regarding Accuracy, Ease of Use, and Cost is generally intrinsic to the testing method, whereas Impact must be assessed in the context of the specific structure. In fact, roadway occupancy depends on what bridge crossing, and the duration of the test is influenced by the number of measurements required and the speed at which equipment can be moved from one testing point to another. Based on the three scenarios outlined in Table 1, the most suitable testing method for each case can be identified by applying the corresponding weights to the performance categories. Table 3 presents the weighted scores for each category across the scenarios, highlighting the top two methods in each case. In the Accuracy-Driven Scenario, UST emerges as the most appropriate method, closely followed by XRR. In the Cost-Driven Scenario, these are replaced by USE and IE, respectively. For the Impact-Driven Scenario, the most suitable techniques are the ultra-sonic methods, with UST ranked first and USE second. Notably, the Impact-Driven Scenario generally yields lower overall scores. This is primarily due to the presence of a river beneath the structure, which naturally results in greater impact. In the case study presented, UST consistently emerged as one of the most effective methods, particularly in Accuracy and Impact-Driven Scenarios. Conversely, in cost-sensitive contexts, simpler and more accessible methods such as USE and IE prove to be more viable, offering a reasonable balance between performance and affordability. The results also highlight that traffic impact plays a pivotal role in reducing the total score of otherwise effective methods. This was evident in the Impact-Driven Scenario, where lower overall scores were observed due to contextual constraints, which inherently increases the inspection’s traffic disruption. This finding emphasizes the importance of integrating environmental and logistical factors into the selection framework.