Fatigue of reinforced concrete is often not considered for civil engineering structures since the self-weights of reinforced concrete structures are very high (in case of normal strength concrete) while live loads are relatively small, which leads to very small stress variations during service duration of the structure. However, particularly for bridge structures with increased use of high strength concrete and increase in traffic loads, this scenario is reversed and fatigue verification becomes much more important for the safety. This paper presents a probabilistic approach for reliability assessment of existing bridges along with reliability-based calibration of fatigue-design-factors based on the S-N approach, calibration of S-N approach with fracture-mechanics approach and reliability updating using inspections along with a case study for the Crêt de l’Anneau viaduct in Switzerland. It has been observed that, a designer needs to design the structure for fatigue life of 3.5–4.5 times the planned service life, in order to achieve the target annual reliability index of 3.7 at the end of the service life. Further, the presented framework can easily be extended to any other viaducts to estimate the fatigue reliability and maintain the safety level throughout the entire service duration.

土木工程结构通常不考虑钢筋混凝土的疲劳，因为钢筋混凝土结构的自重非常高（在普通强度混凝土的情况下），而活荷载相对较小，这导致在施工期间的应力变化很小。结构。但是，特别是对于增加使用高强度混凝土和增加交通负荷的桥梁结构而言，这种情况被逆转了，疲劳验证对于安全性而言变得更加重要。本文介绍了一种概率方法，用于对现有桥梁的可靠性进行评估，以及基于SN方法的基于疲劳的设计因素基于可靠性的标定，使用断裂力学方法对SN方法进行校准，并使用检查来更新可靠性，并以瑞士Crêtde l'Anneau高架桥为例进行研究。已经观察到，设计人员需要设计疲劳寿命为计划使用寿命3.5-4.5倍的结构，以便在使用寿命结束时达到3.7的目标年度可靠性指标。此外，所提出的框架可以容易地扩展到任何其他高架桥，以估计疲劳可靠性并在整个服务期间内维持安全水平。