SYSTEM RELIABILITY MODELING IN BRIDGE MANAGEMENT

Most decisions required during the process of bridge management are made under conditions of uncertainty. Uncertainties associated with mechanical and environmental bridge loadings and with bridges' actual load-carrying capacities make it impossible to predict exactly the lifetime performance of these structures. Therefore, realistically, satisfactory bridge performance can be predicted only in terms of a probabilistic measure of assurance of performance (i.e., in terms of reliability). Also, uncertainties associated with future maintenance and user costs make it impossible to predict exactly the whole life costing of bridge maintenance programs. In light of these uncertainties, bridge management systems have to be reliability-based. A framework was developed for modeling system reliability in bridge management. The proposed framework is applicable to both individual bridges and bridge groups. Examples of bridge system reliability modeling under various maintenance scenarios and selection of the optimum solution in a reliability-based context were also developed.