Study on the propagation characteristics of acoustic-emission signals from damage to key truss components of a highway bridge-erecting machine

This study applied acoustic emission (AE) technology to the structural health monitoring of large steel truss structures by investigating AE signal propagation in the truss of a highway bridge-erecting machine. AE signals, generated using a spring impact hammer to simulate damage events, were employed to analyse signal attenuation, reflection, and transmission in representative truss members. The results demonstrate that AE propagation in bolted truss structures cannot be accurately described by the conventional single-exponential attenuation model because of strong reflection–transmission coupling at bolted splice plates. Quantitative analysis based on the AE energy transfer coefficient shows that splice plates generally exhibit stronger reflection than transmission. Based on these findings, propagation models were established for different types of truss members. The proposed models improve the understanding of AE signal propagation mechanisms in large bolted steel truss structures and provide theoretical support and practical guidance for AE-based damage detection and structural health monitoring of bridge-erecting machines and other large steel structures.