MONITORING OF EFFECTIVENESS OF DEHUMIDIFICATION SYSTEM FOR CORROSION CONTROL INSIDE UPPER STEEL BOX GIRDER IN YEONGJONG GRAND BRIDGE USING THIN-FILM ELECTRICAL RESISTANCE SENSORS

摘要

The typical method of preventing corrosion inside the steel upper box girder in a suspension bridge involves the use of paints. However, in an effort to reduce environmental impact and cost, the suspension portion of the Yeongjong Bridge utilizes dehumidification systems to control humidity and prevent corrosion inside its box girder. Maintaining a uniform humidity distribution at the proper level inside the box girder is critical to the successful prevention of corrosion. In this study, the humidity and the resultant corrosivity inside the box girder of the Yeongjong Bridge was monitored. The corrosion rate of the steel inside the box girder was obtained using thin-film electrical resistance (TFER) corrosion sensors. Time-of-wetness (TOW) measurements and the deposition rates of atmospheric pollutants (e.g. Cl and SO_x) were also obtained. Classification of the atmospheric corrosivity inside the box girder was evaluated per ISO 9223. No corrosion was found in the upper box girder, indicating that the dehumidification system used in the Yeongjong Bridge is an effective corrosion control method.