Determining an optimal maintenance period for infrastructure systems

:  This article proposes a maintenance policy that sets a limit to the cumulative failure rate over the life cycle of an infrastructure system. Under this policy, there are three maintenance scenarios in an arbitrary period of the life cycle: a maintenance action will be implemented in scenario 1 in which the failure rate limit has not been reached and the system does not fail; a preventive replacement will be implemented to renew the system in scenario 2 where the failure rate limit has been reached and the system does not fail; and a corrective replacement will be implemented at the time of failure to renew the system in scenario 3 where the system fails no matter whether the failure rate limit has been reached or not. The maintenance effect is measured by the type 1 effective age model. An optimization model is developed to determine the optimal length of the maintenance period on the basis of the proposed maintenance policy, with an objective to minimize the system's life cycle cost per unit time that includes maintenance cost, failure loss, and the cost of system unavailability. This optimization model and the search algorithm that is consequently formulated are applied to the maintenance of bridge decks. Weibull distribution is used to model the deterioration process of the bridge deck.