Distributed acoustic sensing-based real-time monitoring of far-field cracks in reinforced concrete bridge decks

Monitoring cracks is critical for the safety and efficiency of the construction and operation of civil infrastructure. Distributed fiber optic sensors offer advantages for crack monitoring, but their applications are largely limited to near-field cracks. This paper presents an approach for in situ, real-time monitoring of far-field cracks using distributed acoustic sensing. The approach is developed through multi-physics modeling of a representative concrete highway bridge. The influence of key configuration parameters, including gauge length, channel spacing, and sampling rate, is evaluated for crack detection and localization. Results show that cracks located up to 6 m from a fiber optic cable are detected and localized with an average error of 0.94 m across 60 tests with varying crack scenarios and configurations. A cost-benefit analysis compares the proposed approach with state-of-the-art methods based on acoustic emission and distributed fiber optic sensing, demonstrating its benefits for far-field crack monitoring.