There are many old steel bridges on Chinese transportation lines, which keep their normal
traffic service function. The old bridges are often required to carry an increasing volume of traffic and
heavier vehicles than the original design, so bridge management departments pay more attention to
the actual remaining fatigue life of such structures. Based on probabilistic fracture mechanics theory,
the member and the system fatigue failure evaluation models for old steel bridges are all proposed,
and the fatigue reliability analysis program is developed using Monte-Carlo. As a case study, the
evaluation models are used to predicate the fatigue reliability of Zhejiang Street Bridge. According to
evaluation results, the probabilistic remaining fatigue life, safe inspection intervals and maintenance
strategy are determined.