BRIDGE CORROSION COST MODEL IMPLEMENTATION AND COATING MAINTENANCE MODEL USING DYNAMIC PROGRAMMING

This paper is the second of two investigating cost minimization of coating maintenance for steel bridges. Computer implementation of a life-cycle cost analysis in a spreadsheet environment using equivalent annual costs to compare three maintenance options is addressed. The development of a coating maintenance model using a dynamic programming approach that can optimize combinations of maintenance procedures for minimum cost is also discussed. The flexibility of the life-cycle cost spreadsheet implementation allows the user to adjust key parameters to account for variability in costs and environmental conditions between regions. The program is easily adapted to different climatic conditions. The second coating maintenance model using the dynamic programming approach minimizes the sum of the costs resulting from a sequence of rehabilitation choices. It is more flexible than the equivalent annual cost approach in that it can determine the optimal sequence of rehabilitation activities over the service life of the bridge. Results from a preliminary analysis of in-service bridges with good coating condition assessments using the two different approaches suggest that spot repair is the most cost-effective rehabilitation method. Oevercoating is the second most effective strategy, leaving recoating as the most expensive strategy. The difficulty in obtaining adequate deterioration and cost functions for the coating systems significantly reduces the accuracy of the analytical procedures. A uniform data collection system should be initiated so that data are available for these models.