Identification of the Local Environmental Condition Acting on Bridges over Tidal Rivers and Prediction of Future Deterioration

The maintenance of the RC substructure of bridges over tidal rivers is crucial as it deteriorates quickly due to chloride ions from tidal and wave action. Implementing preventive maintenance is an efficient way to lessen maintenance expenses, particularly for structures in urban areas that will remain in service for a considerable period. Preventive maintenance works efficiently under the condition that accurate prediction of deterioration allows to decide the optimal timing of maintenance. Although the local environmental condition is one of the key factors in deterioration, it is challenging to identify the actual condition due to local disturbances. Additionally, due to construction errors, the precise value of cover thickness is unknown, even if the design value can be obtained from the blueprints. Due to the lack of knowledge surrounding this subject, there are limited studies that employ high-resolution analysis to predict degradation over extended periods of time while accounting for environmental factors and construction errors. Hence, this study utilizes the material-structure integrated analysis to conduct parametric study on the corrosion progress of steel bars within a bridge's abutments located along tidal rivers. The environmental conditions where the structure is located are estimated by comparing the investigation result and the analytical result of the actual structure. The parameters are relative humidity and surface chloride ion concentration. The estimated environmental conditions are applied to the abutment with various cover thicknesses to predict deterioration through numerical analysis, and the optimal timing of maintenance is discussed based on the prediction.