Probabilistic failure assessment of steel eyebars by considering multi-phase nonlinear corrosion model

Abstract

Corrosion measurements were performed on the 175-years-old historical Széchenyi Chain Bridge within the last four decades; most lately under its reconstruction process in 2022. Measurement results are evaluated, and the findings encompass the structural corrosion loss of the chain elements (eyebars). A multi-phase nonlinear corrosion model, with time-dependent Weibull distribution parameters, is developed for bridges over rivers in urban environment. The model is capable of considering the time prior to corrosion initiation corresponding to the start of corrosion protection coating failure. Prediction of structural integrity and performance of chain elements is crucial to ensure reliable operation of such a historical structure. Therefore, multiple scenarios of possible corrosion progression are analysed with and without maintenance to estimate the evolution of corrosion damage over time. Probabilistic finite element calculations are carried out to predict the probability of failure of the chain elements subjected to pure tension. Partial safety factor of Eurocode, determined through Monte Carlo simulations with a response surface, ranges from 1.16 to 1.41 for corroded elements, assuming no renewal of the corrosion protection. Renewal of the coating significantly reduces probability, resulting in a partial safety factor of 1.17. Stochastic analysis indicates adequate load-bearing capacity of the chain elements for at least 20 years without significant renewal of the corrosion protection system.