PSI - Issue 64

Mariniello Giulio et al. / Procedia Structural Integrity 64 (2024) 2101–2108 G. Mariniello, D. Coluccino, A. Bilotta, D. Asprone / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 2 – Section of the bridge deck.

The structure has been subjected to a real-time monitoring system, allowing for the measurement of deflection, which plays a fundamental role in assessing the load-bearing capacity and structural integrity of complex and large scale structures. Indeed, real-time monitoring of bridge deflection is a challenging task that requires complex solutions, especially for structures built on roads and rivers. To address this issue, the authors propose no-contact sensors for distance evaluation. Specifically, the study aims to demonstrate the feasibility of using laser sensors to monitor the structural deflection of bridges. High-performance laser sensors are used to precisely detect structural and behavioral changes in bridges. These sensors provide accurate measurements of the distance between the sensor and the bridge's surface, which allows even small changes in the structure's geometry to be detected. Additionally, they enable continuous and real-time monitoring of the bridge's structural conditions, making it easier to detect anomalies and take timely action if needed. Moreover, the precision and reliability of the sensors allow for an accurate assessment of the structure's health over time. To estimate the deck deflection, the structure was equipped with seven laser sensors as shown in Figure 3. The system consists of three vertical sensors (L2, L3, and L6) and four diagonal sensors (L1, L4, L5, and L7).

Fig. 3 Layout of monitoring system: L2, L3, and L4 sensors measure the vertical displacement of the girder, targeting a concrete box positioned beneath the bridge. Diagonal sensors are mounted on the columns, oriented towards the midpoint of the longitudinal girder.

The optoNCDT ILR2250-100 laser sensor, manufactured by Sigma Epsilon, features a box-shaped design with dimensions of 70x70x100 mm. According to the manufacturer's datasheet, this sensor can measure distances ranging from 0 to 150 meters with a precision of 0.1 millimeters using the Multiple Frequency Phase Shift Method. It records measurements at a sampling frequency of 10 Hz. Vertical displacement is monitored by sensors mounted on the