2018 年 67 巻 2 号 p. 163-169
Tozai line is the metro rail system serving the urban areas in Tokyo. It was built in 1960s and a construction method, PCT girder bridges is one of the most majority designs still in use through this rail system. In order to identify risk factors and determine appropriate ways to control the hazards, risk assessment for PC Bridge has to be conducted during maintenance activities. In this study, during the stage of construction, two main sources in risk analysis which cause a great failure or decline are insufficient PC grout filling and breaking of the PC steel member, respectively. On the other hand, according to the results of general inspection used in risk analysis, it reveals that although no severe deterioration occurred and the risk of present load-bearing capacity is low, the third-party disasters still retain risks. Therefore, the study reports herein attempt to address risk assessment process to evaluate hazards for PC bridges. Furthermore, considering the risks during the construction stage and the maintenance period, the former issue is evaluated by PC grouted filling condition; whereas the latter is judged by engineers to determine the proper protective approaches to that risks. Finally, by adopting the numerical analysis associated with above issues, the relationship between any changes in appearance and load-bearing capacity for PC bridges are assessed.