Reliability analysis of a post-tensioned railway bridge exposed to corrosion effects

Abstract

As bridges provide crossing at critical points such as waterways, valleys and other type of physical obstacles, they are invaluable assets within a rail network. However, these infrastructures are exposed to several hazards of different natures that compromise their structural safety and ultimately lead to critical events. Accord-ing to literature, there are commonly five levels of assessment of safety with increasing complexity per level. Level 1, consisting on an assessment based on partial coefficients, is the simplest one, whereas level 5 is the most complex involving a combination of non-linear analysis and probabilistic assessment. Within that scope, this paper analyses the structural safety of a pre-stressed reinforced concrete railway bridge located in Portugal, by using a combination of linear elastic and probabilistic analysis procedures. The proposed framework is adaptable and suitable for common safety analysis. The obtained reliability index is compared to threshold values given by different standards which validates that the bridge ensures the safety at ultimate limit state. The reliability levels along time are also determined assuming a reduction in the cross-section area of the steel reinforcement, resulting from corro-sion initiation based on onsite inspection evidences. From the analysis of this scenario over time, it may be concluded that the bridge under study exhibits sufficient load carrying capacity during its planned service life even under the proposed damage.