Trial Rating of Bridges Using Load and Resistance Factor Procedures

A draft version of the Manual for Condition Evaluation and Load and Resistance Factor Rating of Highway Bridges has been compiled through National Cooperative Highway Research Program 12-46. The manual extends the Load and Resistance Factor approach to the evaluation of highway bridges in the United States. The objectives of bridge rating are different from the objectives of new bridge design and these differences result in different limit states and reliability requirements. The draft manual proposes a system for bridge load rating and permit evaluation based on a uniform reliability index (where possible) that uses site specific information to narrow the uncertainty in some of the evaluation variables. The results of this system are compared to the current load factor ratings based on trial evaluations.