PSI - Issue 57

J. Berthellemy / Structural Integrity Procedia 00 (2023) 000 – 000

Jacques BERTHELLEMY et al. / Procedia Structural Integrity 57 (2024) 872–903

901

7.2 Recent evolution in the United States After a bridge collapse in Pennsylvania at the end of 2022, shown in figure 49, uncoated weathering steel is not considered any more as a maintenance-free materialin the United States as well. The National Transportation Safety Board (NTSB) issued recommendations [41] to prioritize inspections and assessment of bridges with uncoated weathering steel components after this collapse and after findings from other bridges as in figure 50.

Fig. 50: Example of deterioration occuring on uncoated bridges

Fig. 49: Collapse of a bridge in Pennsylvania

7.3 Recent evolution in France The French “Note d'information” [42] issued in November 2023 is all along the same lines, and introduce new recommendations regarding the risk of fatigue cracks without going into the details of the calculation of the modified stresses because the applica tion of the results set out in the present chapter 3 follows from Clause 7.1(5) of the 2011 French National Annex to EC3 1-9. 8. Conclusion Of course, the use of weathering steels is economical during the construction phase and avoids transport and application of chemicals, but because of fatigue, it must be done with precautions in case of double I -girders bridges carrying heavy motorway traffics. All these examples presented in this paper show that the calculation for right fatigue design of the stress concentration factors, i.e. the modified stresses, is important for the correct calculation of bridges with regard to fatigue. Again, the condition of the surface is critical in terms of sensitivity to fatigue cracking. Misunderstanding this important point regarding fatigue has led some people to encourage the use of a discontinuity of the bridge stiffeners shown in Figure 11-a, and the use of cope holes, as well as the use of weathering steel without precaution. However, there is no need to add new statements in the Eurocodes regarding fatigue to obtain a common use of the presented results, then Clause 7.1(5) of the 2011 French National Annex to EC3 1-9 and the future Eurocode 3 Part 1-9 codify the use of the Hot Spot and Effective Notch methods to calculate the modified stresses. As far as the use of FEM is actually mandatory to solve this problem, it should be introduced in the French AFGC « Finite elements Guide » [43].