Fatigue Reliability Updating Evaluation of Existing Steel Bridges.

Through modern nondestructive inspection (NDI) techniques, fatigue cracks can be detected with varying accuracies in steel bridge structures, and consequently assessment and updating of fatigue reliability can be performed. A probabilistic fracture mechanics method based on the Bayes theorem using information from NDI has been demonstrated to update the relevant parameters of crack growth models effectively. Using the probabilistic characteristics of the NDI techniques, the probabilistic fatigue failure method, and the Bayes theorem, a procedure for assessing and updating the fatigue reliability of existing steel bridge components is presented. Data collected from two steel bridges, the Zhejiang Street Bridge and Ganjiang River Bridge, are used to illustrate the fatigue reliability assessment and updating method. In the case study, the suspender curves of the Zhejiang Street Bridge and Ganjiang River Bridge are determined after inspection and updating. It is found in this research that the fatigue reliability of the selected members in the existing steel bridges increases with no cracks detected, decreases with no size cracks detected, and changes remarkably with cracks detected. [ABSTRACT FROM AUTHOR]