Optimization of reinforced concrete bridges maintenance by Markov chains

摘要

In France the management and the rehabilitation of bridge stocks are concepts that were really taken into account in public policies only after the seventies. Indeed despite an institutionalization of French bridges maintenance in 1716 with the establishment of the "Ponts et Chaussees" corps, the bridge maintenance was progressively neglected after the Second World War to the advantage of building policies. The aim was then to build rather than to rehabilate. But lacks of service levels due to the increase of traffic, the collapse of deteriorated bridges like these of the bridge of Elme in 1977, or these of the bridge of Tours in 1978 led to the awareness of the importance to assess bridge stocks. This is how was written the "Instruction Technique pour la Surveillance des Ouvrages d'Art" on the nineteenth of October in 1979 which was a rationalization of the maintenance actions and that is still used nowadays.The management of bridge stocks associated to scarce capital resources led in the last years to the development of bridge management systems. Those models are based on life cycle costs analysis and try to optimize maintenance costs. Several management policies are generally compared to maintain the level of the bridge stock above a certain limit acceptable for the bridges manager. The knowledge of how the bridges deteriorate is essential in those decision processes. Some models like Pontis or Bridgit in the United States use probabilistic methods to simulate bridges ageing. Those models are particularly interesting because unlike deterministic methods they include all the possible cases of failure and make it possible to consider all the hazards that can occur in the life of a facility.