State of the art versus state of the practice in bridge evaluation

A comparison of the load rating method of bridge evaluation currently used in practice and the reliability-based evaluation method considered to be the method of choice in the future is presented. Evaluation methods may include techniques such as nondestructive evaluation, load testing, corrosion detection, and load rating. The most commonly used method of bridge evaluation in current state of practice is the load rating method mandated by the standards and manuals in this field. Performance assessment based on structural reliability has also been widely reported in the literature and in bridge code calibration as the state of the art bridge evaluation technique. The load rating and the reliability-based performance assessment techniques serve the same purpose (i.e., bridge evaluation) but have different theoretical bases and completely different formulations. Both rating and reliability can be used to measure either safety or serviceability of a bridge component or the bridge itself. In this paper, comparison of these two evaluation criteria is performed using the rating factor and the reliability index, based on the results of a comprehensive study focusing on reliability analysis of existing highway bridges