Safety Monitoring of Bearing Replacement for a Concrete High-Speed Railway Bridge Based on Acoustic Emission

As an important part of a bridge, bearings easily suffer damage when exposed to various loading and environmental changes during their lifetime. Bearing replacement should be performed in a timely manner if damage occurs to high-speed railway (HSR) bridges. The unique structural form and strict operation requirements mean that bearing replacements of HSR bridges are much more difficult than those of highway bridges. However, compared with bearing replacements of highway bridges, far fewer scientific and engineering studies have been conducted to guide the bearing replacement of HSR bridges. In this paper, based on a three-span continuous concrete box girder HSR bridge, an innovative bearing replacement method using reverse disassembly and assembly techniques is proposed and was implemented at a location under operating HSRs. In addition, safety monitoring measures were undertaken to guarantee the safety of the bridge during bearing replacement. In contrast to the usual monitoring practice focusing on the displacement and the external strain of the structure, this monitoring work adopted the acoustic emission (AE) detection technique to explore the internal structural damage formed in the process of construction. The results suggest that the proposed bearing replacement method, which requires the girder to be jacked up by no more than 9 mm, is a promising practice for this complicated construction, and the start time and evolution of damage in the concrete of a bridge during construction can be captured accurately by AE detection with a parameter-based analysis method. All practices presented in this case study can guide future bearing replacements in similar projects.