UBC Theses and Dissertations
Life cycle consideration for steel bridges with consideration of usage, durability and maintenance Yuan, Jun
Because of rapid deterioration of existing steel bridge superstructures and transportation development in the recent decades, bridge rehabilitation has become an urgent technical and economical task in many countries. This report summarizes the factors that, lead to steel bridge deterioration and reviews typical damages of steel bridges. Bridge inspection and evaluation procedures for determining the technical condition o f bridges are also discussed. Numerous steel bridge rehabilitation strategies to extend the service life of steel bridges are presented in detail in this report. Paint systems are most widely used for corrosion protection, and there are three maintenance strategies with this coating method, i.e., touch-up painting, overcoating and recoating. Repair work usually concerns repair of cracks and deformed structural members. Strategies for strengthening superstructures of steel bridges include enlargement of cross sections, installation of additional members, external post-tensioning, replacement of structural members, additional carbon fiber reinforced plastic (CFRP) strips, continuity development, and other strengthening methods. To help engineers make rational decisions among these rehabilitation strategies, fundamental decision making principles about decision making under risk, uncertainty and incomplete knowledge are introduced, together with some useful mathematical tools such as decision tree, expected monetary value, and Monte Carlo simulation. A decision making model of an engineering example is developed to illustrate the practical application of decision making tools and the procedure for bridge engineers when face with the task of decision making for bridge rehabilitation. Life cycle cost analysis should be performed during this decision making process. The decision making model for steel bridge corrosion protection maintenance strategies is set up with life cycle cost analysis method. Touch-up painting is proven to be the most economical strategy for corrosion protection maintenance. This life cycle cost analysis model can also be applied to other situations about decision making of rehabilitation strategies for steel bridges.
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