Temporal reliability evolution of a prestressed girder with post-tensioned tendons subjected to corrosion

This paper presents a methodology for the assessment of time-dependent reliability of post-tensioned (PT) girders. As possible lack of consistent maintenance efforts and the constraints of economic and temporal resources become increasingly apparent, there is a need to comprehend their remaining service life, intricately tied to the gradual evolution of their reliability over time. In this study, the primary focus is directed towards a combination of extreme load failure mechanisms and tendon corrosion. The proposed methodology is applied to a scenario involving a simply supported prestressed girder with PT tendons. The analysis takes into account the progressive reduction in bending capacity over time due to the adverse effects of tendon corrosion. Diverging from conventional approaches found in existing literature, the time-to-corrosion model embeds not only the chloride concentration in voids present in the grout injection but also considers the thermodynamic conditions necessary for the development of corrosion. A sensitivity analysis of the input variables is performed to identify the most influential parameters over time. The study shows that considering both chloride concentration and thermodynamic conditions can lead to a more realistic residual structural life. It is concluded that the consideration of the thermodynamic conditions is essential to avoid overly conservative safety assessments, which could lead to a poorly optimized management and sustainability of bridges.