Broadmeadow Railway Viaduct

 

In August 2009 two spans of the Malahide Railway Viaduct in Dublin collapsed following scour induced failure of one of the supporting piers resulting in complete closure of the Dublin-Belfast railway line for six months. Following structural repair, Irish Rail commissioned ROD-IS to carry out a probabilistic assessment of the superstructure to determine the;

 

  • Current safety of the structure with respect to that required by the Eurocode and

  • Evolution of this safety with respect to time.

 

The Probabilistic assessment undertaken allowed the derivation of an indicative maintenance strategy based on upon maintaining the minimum required safety whilst maximising performance with respect to economic cost.

The probabilistic assessment considered the critical limit state as identified in a deterministic assessment of the structure, which in this particular case was midspan bending at the ultimate limit state under the action of a particular loading fleet. The level of safety was reported in the terms of the reliability index (β-index) of the structure computed at the limit state considered and compared to the minimum value required by the Eurocode.

The probabilistic modelling undertaken considered the load and resistance of the structure, using both stochastic and deterministic variables, deterioration modelling (tendon corrosion as the main factor) and damage mechanisms, loading uncertainties, material uncertainties and prestress uncertainties.