PSI - Issue 84

Alessandro Vari et al. / Procedia Structural Integrity 84 (2026) 975–982

981

4.4. Holistic Integration: The "Native" SHM System Massive sensor deployment on existing bridges often generates unmanageable Big Data sets, complicating real-time diagnostics. Although Artificial Intelligence (AI) based techniques offer promising perspectives for damage identification via image analysis, they require vast training sets and significant technological maturation times. However, Managing Bodies, however, require immediate, deterministic, and unambiguous early warning systems. The CAM-Bridge ® system introduces an innovative frontier by utilizing the reinforcement system itself as a sensor. While traditional grouted cables inhibit the reliable use of strain gauges or accelerometers due to interference from sheaths and grouts, the CAM-Bridge ® system offers ideal characteristics for applied sensor technology: • Surface and Material: Sheath-free Duplex steel strips provide flat surfaces ideal for high-precision wireless strain gauge installation. • Global Sensitivity: The sliding deviators ensure that the strip integrates the deformative state of the entire beam rather than merely reading local strain, effectively "sensing" service stress variations in both static and dynamic fields. Validated through collaboration with the University of Rome "Tor Vergata," the integrated SHM system continuously monitors the reinforcement stress state. Due to the direct correlation between strip tension and bridge deformation, the system generates simplified outputs based on traffic-light (e.g., Green, Yellow, Red status) protocols triggered by pre-calibrated alert thresholds. (a) (b) Fig. 8. (a) Stress periodical recording for identify long term phenomena; (b) High frequency dynamic recording activated by stress thresholds for capture structure's dynamic response to transient events. The structural health monitoring system embedded within the CAM-Bridge ® technology is engineered to optimize the trade-off between energy efficiency (sizing of power sources and batteries) and data granularity. Unlike general purpose monitoring solutions that rely on heterogeneous sensor arrays (accelerometers, LVDTs, etc.) to reconstruct structural behavior, the CAM-Bridge ® approach leverages the reinforcement strip itself as the primary "native" transducer. Taking advantage of the uncoated Duplex stainless steel surface, strain gauges are applied directly to the tensioned element. Due to the free-sliding nature of the kinematic coupling, these sensors do not merely record local stress concentrations but provide a global index of the structural response. To ensure long-term reliability and minimize data redundancy, the acquisition algorithm is programmed according to a bifurcated protocol : • Periodic Static Logging (Trend Analysis): The system collects stress data at pre-assigned intervals (e.g., every 10 minutes to several hours). This mode generates a time-history curve essential for tracking long-term phenomena, such as rheological losses (steel relaxation, concrete creep) or the onset of permanent structural deformations. • Event-Triggered Dynamic Recording: The system switches to a high-frequency acquisition mode (50 Hz) upon exceeding specific stress thresholds. This allows the capture of the structure's dynamic response to transient events (e.g., heavy traffic loads, seismic actions). In this configuration, the strain gauge output effectively acts as a proxy for accelerometric data, providing insights into the vibration frequencies and