Monitoring the Akashi Kaikyo Bridge: First Experiences

From monitoring and maintenance work on the Akashi Kaikyo Bridge, a super long-span suspension bridge, new information has been obtained. This paper describes some of the new technologies used. To protect the main cables from corrosion, a dry-air injection system was newly developed and found capable of keeping the relative humidity low enough in the cable bundles. To suppress unexpected wind-induced oscillation observed in hanger ropes, an aerodynamic countermeasure was employed and its performance was confirmed in typhoon-strength winds. Girder displacement records were stored by monitoring with Global Positioning System (GPS) measuring instruments. The relationships between girder displacement and both wind speed and temperature were analysed to compare actual bridge behaviour with design values. Results indicate the possibility of more accurately diagnosing the soundness of bridges. These technologies are expected to contribute towards maintaining the soundness of the Akashi Kaikyo Bridge.