Comparative Study of Fatigue Provisions for the AASHTO Fatigue Guide Specifications and LRFR Manual for Evaluation

摘要

The recently developed Manual for condition evaluation and load and resistance factor rating (LRFR) of highway bridges in 2003 provides an alternative procedure for practicing engineers to evaluate the fatigue life of steel bridge structures. Although the evaluation manual maintains several aspects used in the AASHTO fatigue guide specification in 1990, it also utilizes formulas and values specified in the AASHTO LRFD bridge design specifications in 1998. A comparative study of the fatigue lives provided by the procedures in the Evaluation manual and the Guide specifications was performed using a life prediction of 14 steel bridges with different structural configurations and various fatigue details. It has been shown that longer predicted fatigue lives are typically obtained when using the Evaluation manual. The ratio of the finite evaluation fatigue lives for the two procedures was found to be in a range of 0.99-2.14.