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Time-dependent interaction between load rating and reliability of deteriorating bridges

2004-10-01
Akgül, Ferhat
Frangopol, DM
Prioritization and allocation of federal funds for nationwide bridge replacements and rehabilitations are based on ratings listed in the National Bridge Inventory database. Distribution of funds is based on the sufficiency rating, represented by a formula considering structural safety, functional obsolescence, and essentiality for public use. Possessing the highest weight in sufficiency rating formula, load rating is a crucial measure for bridge management. While load rating represents the current practice in bridge evaluation, reliability methods, taking into account live load increase and material deterioration models, are more commonly used for lifetime bridge assessment. In this paper, time-dependent relationship between the reliability-based analysis results, representing the future trend in bridge evaluation, and the load ratings is investigated for different types of bridges located within an existing bridge network. The comparisons between live load rating factors and reliability indices are made over the lifetime of each bridge in the network. The rating-reliability profile and rating-reliability interaction envelope concepts are introduced. Furthermore, the rating-reliability profiles are collectively examined in order to evaluate the time-dependent performance of the overall bridge network.