Selection of optimal alternative for bridge monitoring: Weighted objective decision analysis

Advanced monitoring techniques can help identifying problems in a structure so that appropriate maintenance and management decisions can be taken to deal with deteriorating infrastructure. But due to the scarcity of financial resources it is not always possible to use the best technology available, at the same time the safety and reliability of the structure can not be compromised. To satisfy these goals, the decision makers and owners need to select a solution which is optimal. In this paper a comparison is made among three monitoring methods (alternatives), (1) Visual Inspection, (2) Periodic Structural Health Monitoring (SHM) and (3) Continuous SHM. Using the information provided by each monitoring method, a Reliability Index (P) is calculated. This index is related to the structure's probability of failure. The reliability index provides important guidance on the condition of a structure, which can be used by the decision makers to decide on appropriate maintenance and rehabilitation strategies. The goal of this paper is to achieve the following two objectives: (a) minimization of the cost of monitoring, and (b) extracting the best value of the information provided by the monitoring system. To achieve the best balance of meeting these two objectives, Weighted Objective Decision Analysis approach has been used. The proposed methodology has been applied to an existing steel free deck continuous bridge in Canada. The periodic SHM is found to be the optimal alternative as it has the maximum relative utility.