Probabilistic model for predicting the corrosion-fatigue durability of reinforced concrete railway bridges

This study proposes a probabilistic model for assessing the service life of a reinforced concrete railway bridge based on the criterion of corrosion-fatigue durability, taking into account the dynamics of the moving load. Currently, there is no similar methodology approved in the standards of the Russian Federation, as well as in the Eurocodes, while corrosion-fatigue destruction of reinforcement is typical in conditions of chloride-aggressive environments and repetitive loads. In this model, total service life of reinforced concrete superstructure is sum of three periods: corrosion initiation period, crack nucleation period, and crack propagation period. In each period, stochastic variables are specified by probability density functions. As an example of calculating the service life, one of the bridges developed during the design of the Moscow — St. Petersburg High-Speed Railway was chosen. Monte Carlo method was used as the way to modelling the stochastic nature of problem. Failure criteria was the critical crack growth, and crack growth process was modelled using Paris law. The form of the obtained probability density functions for each stage is lognormal; the greatest contribution to the total service life was made by the period of corrosion initiation. In the future, the use of the method will allow the engineer to design structures with a given durability, increase the service life of reinforced concrete bridge spans and more accurately plan funds for repairs of reinforced concrete bridges.