Minimum expected cost-oriented optimal maintenance planning for deteriorating structures: application to concrete bridge decks

Civil engineering structures are designed to serve the public and often mus t perform safely for decades. No matter how well they are designed, all civ il engineering structures will deteriorate over time and lifetime maintenan ce expenses represent a substantial portion of the total lifetime cost of m ost structures. It is difficult to make a reliable prediction of this cost when the future is unknown and structural deterioration and behavior are as sumed from a mathematical model or previous experience. An optimal maintena nce program is the key to making appropriate decisions at the right time to minimize cost and maintain an appropriate level of safety. This study prop oses a probabilistic framework for optimizing the timing and the type of ma intenance over the expected useful life of a deteriorating structure. A dec ision tree analysis is used to develop an optimum lifetime maintenance plan which is updated as inspections occur and more data is available. An estim ate which predicts cost and behavior over many years must be refined and re optimized as new information becomes available. This methodology is illustr ated using a half-cell potential test to evaluate a deteriorating concrete bridge deck. The study includes the expected life of the structure, the exp ected damage level of the structure, costs of inspection and specific repai rs, interest rates, the capability of the test equipment to detect a flaw, and the management approach of the owner towards making repairs. (C) 2001 E lsevier Science Ltd. All rights reserved.