PSI - Issue 64

Donato Fiore et al. / Procedia Structural Integrity 64 (2024) 740–748 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction The Cannavino bridge is located between km 42 + 703 and km 43 + 085 of the SS 107 "Silana- Crotonese”. It is composed by a 10.50 m wide single roadway, 4 piers and 5 spans and has shown problems since its construction in 1972. A multidisciplinary monitoring in continuous was performed to control the anomalies corresponding the buffer beams of the deck, between the third and fourth pier of the deck. Due to the results of the monitoring, it was possible to plan and design the interventions to make the structure safe and for its extraordinary maintenance. A complete topographic survey was carried out using total station and a laser scanner to draw some particular section and profile of the viaduct before starting the monitoring operation. In this way we obtained a model of the viaduct and we realized that there are multiple differences between the ideal line of the structure and the real piers. Therefore, it was necessary to set up a monitoring system that could control changes in the structure in real time. The monitoring system was designed to have a great redundancy, real time and long period monitoring without fake alarms. The system was constituted by: • Weather center - 15 minutes This system was then implemented with an online alert platform that gave the alarm in real time in case there were parameters that were strongly discordant from those expected: the management software receives, verify and process all data in real time and transmits the information to the storage system. This platform was able to send alert messages, when definite thresholds were exceeded, interrupting automatically the traffic. To validate this system, a more long-term monitoring was carried out which involved the use of the laser scanner every 60 days and the total station every 15 days. The repetition of the laser scanner survey was planned to detect mainly shape variation without displacements like bugles or fractures or spalling. The topographic monitoring was carried out each two weeks. A system of optical targets, already present on the two side of the viaduct, was expanded with some new target. The optical targets were sight by three different station. The measurement was done at 3:00 am in order to dissipate thermic dilatation. 2. IBIS-FS technology IBIS-FS is a microwave radar sensor, developed by the IDS company in collaboration with the Department of Electronics and Telecommunication of the Florence University. It is able to simultaneously measure the displacement response of several points belonging to a structure with accuracy on the order of a hundredth of a millimeter. With such systems, the highly accurate determination of movements or change rates of local limited objects is possible and has been shown by Pieraccini et al. (2006), Riedel et al. (2011), and Rödelsperger (2011). IBIS-FS can be used to remotely measure structural static deflections as well as vibrations to identify resonant frequencies and mode shapes. In addition to its non-contact feature, the measuring system provides other advantages including quick set-up time, a wide frequency range of response and portability. The IBIS-FS system was performed on the Cannavino Bridge. The primary objective of the monitoring was to measure the deflection time histories and maximum deflections of the structure under normal automobile traffic loading. The IBIS-FS radar system consist of a sensor module, control PC and a power supply unit. The sensor module (Fig.1) is a coherent radar, including two horn antennas for reception and transmission of the electromagnetic waves. • Two interferometric system - 15 seconds • Four displacement transducers - 15 seconds