Long-term follow-up study on retrofitting works for vibration fatigue in high-speed railway bridges

<title>Abstract</title> The Tokaido Shinkansen, Japan's first high-speed train system, opened in 1964. After about ten years of operation, a very specific type of fatigue, called vibration fatigue, occurred due to local resonance phenomena at the lower end of vertical stiffeners of web and the connections between intermediate diaphragm and longitudinal rib. Extensive retrofitting works were carried out between 1987 and 1989 targeting this vibration fatigue. Measures were taken to install ribbed plates with the aim of stopping vibration. TIG dressing was employed as retrofitting works for the large number of cracks with surface lengths of less than 20 mm. In subsequent maintenance, the retrofit sites were intensively inspected. After approximately 35 years of use, reoccurrence ratio of fatigue cracks in the locations where measures were taken was about 0.2%, very low, which is good performance as retrofitting works.