Long Life Bridges

Bridges, like many Civil Engineering structures, are designed quite conservatively – the probability of dying due to collapse of a new bridge is about 1 in 10 million. Part of the reason for this conservatism is that adding extra strength to a bridge when it is being built is not expensive. For older bridges however, the situation is quite different. There is a huge difference between the cost of strengthening an existing bridge and not doing so. It is frequently possible to prove that a bridge is perfectly safe despite having deteriorated since it was first built. Sometimes the deterioration is in a non-critical element of the bridge and often the bridge has significant reserve capacity due to conservatism in the initial design process. Long Life Bridges investigates the use of probabilistic techniques in analysing the performance of bridges. This approach reduces the conservatism present in current deterministic methods, particularly in the Dynamic Amplification Factor (DAF) employed in the code. This will allow bridges to be kept in service that would otherwise have been deemed unsafe preventing unnecessary repair or replacement works and resulting in significant savings for the bridge owner