Time-Dependent Reliability Assessment and Updating of Post-tensioned Concrete Box Girder Bridges Considering Traffic Environment and Corrosion

Abstract

In the reliability assessment of a bridge in operation with regards to its ultimate limit state, it should be noted that the strengths of members and effects of traffic load vary continuously over its lifespan due to the structural deterioration and changes of the traffic environment, respectively. Therefore, it is essential to collect relevant data, and incorporate the extracted information into a time-dependent reliability analysis. However, previous studies have not considered both traffic load effects and material deterioration models in time-dependent reliability assessment for prestressed concrete (PSC) box girder bridges. To overcome this limitation and assess the reliability efficiently, this paper presents a comprehensive framework for time-dependent reliability assessment of post-tensioned concrete box girder bridges that can consider the traffic environment change and the corrosion in steel strands. The proposed framework employs probabilistic models and methods to estimate the flexural strengths and traffic load effects of a PSC box girder over time based on (1) corrosion-related data collected in the current practice of structure safety inspection, and (2) the traffic environment data obtained through weigh-in-motion (WIM) devices and traffic investigation. The time-dependent reliability is then computed using structural reliability methods based on the estimated strengths and load effects. As a numerical example, the time-dependent reliability of the PSC box girder of an actual cable-stayed bridge, Hwayang-Jobal Bridge in South Korea, is evaluated using the proposed framework. It is demonstrated that the framework can effectively assess the time-dependent reliability of a bridge in operation based on the uncertainties in the traffic environment and corrosion, and update it through data obtained by monitoring and inspection.