Operation of a damaged prestressed-concrete girder bridge with repair in Japan

摘要

The Myoko Bridge is a prestressed-concrete (PC) box-girder bridge located in the heavy-snowfall area in Japan. It was opened in 1972, and failure of PC cables due to severe corrosion was found in 2009. It was decided to replace the bridge with a new one based on results of a detailed survey in 2011. It will take 10 years or longer until the new bridge is completed; therefore, the damaged bridge is still used after repair and reinforcement. This paper first reviews the results of a survey on the PC cable failure and the repair work in 2011, when outer tendon cables were installed, reported by the bridge owner. The specific maintenance plan and emergency response system, which were developed based on results of loading tests and continuous structural monitoring, are also presented. Furthermore, a study of structural health monitoring (SHM) on the Myoko Bridge conducted by the authors is also introduced. Results of the quality evaluation of long-term fibre-optic strain data and the applicability verification of time-series analysis to the structural condition assessment are introduced in a discussion about using long-term SHM data in decision-making for bridge operation.