Monitoring fatigue cracks on eyebars of steel bridges using acoustic emission: A case study

摘要

A cost-effective inspection procedure was conducted using Acoustic Emission (AE) monitoring to detect fatigue crack initiation and/or growth and to assess the crack activity in eyebars of a steel bridge. An eyebar is a straight steel bar with an eye shape hole at each end for fixing to other components. Eyebars are used in settings in which only tension is applied. Multiple AE sensors were installed on critical eyebars of a bridge. These eyebars were selected based on the bridge maintenance history and field inspection reports. The AE characteristics and source localization were dynamically monitored and recorded on-site in real-time under the impact of normal traffic operation and controlled loading test. In the loading test, a loading truck ran at different speeds and stopped at critical floor beams. The parameters of AE signal such as counts, amplitude, duration, rise time, and energy were analyzed. Analysis of the Kaiser effect for AE activities was performed to confirm or deny the initiation or propagation of possible fatigue cracks. The results of AE monitoring showed that AE is a very reliable technology for confirm or denying the fatigue cracks initiation and assessing the condition of existing cracks and is a cost-effective component in Structure Health Monitoring (SHM).