Experimental validation of strand breakage localisation in prestressed box girders of high-speed railways using acoustic emission and waveguide rod-guided waves

High-speed railways are key infrastructure in China, and box girders are the main structure. Prestressed strands, crucial for girder integrity, can be monitored via acoustic emission (AE), a non-destructive method. However, AE signals weaken quickly in box girders due to material unevenness. To enable cost-effective AE-based safety monitoring, this study combined waveguide rods with AE technology to detect damage in prestressed strands. Installing waveguide rods at girder ends to link strands enabled transverse AE signal propagation. Damage was located using time differences between the two sensors. Results showed that the tied connections localised edge damage but with errors, while welded connections located most strands. Adding acoustic black holes (ABHs) boosted accuracy, with a 0.9977 Pearson correlation between measured and theoretical values. ABHs reduced signal loss, offering a practical SHM solution for large structures like high-speed railway girders.