PSI - Issue 57

Jacques BERTHELLEMY et al. / Procedia Structural Integrity 57 (2024) 872–903 J. Berthellemy / Structural Integrity Procedia 00 (2023) 000 – 000

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Fig 48: Options to avoid fatigue problems when using double I-girder bridge with weathering steel for motorways

7. Consequence of the fatigue consideration for W-steel bridge maintenance : 7.1 A v ery demanding maintenance

High Frequency Mechanical Impact Treatment (HFMI) cannot be efficiently used to improve the resistance of weathering steel as specified by Annex F of Eurocode 3 part 9.1. See the scope and field of application of HFMI treatments at F2(5). It should be noted that only the chancroid notchs observed during the ideal patina formation on the surface of the weathering steel have been introduced in the study presented in chapter 3. In other words, the categories of detail obtained and summarized for instance in the Figure 45 assume that there is no water retention or bird droppings at the hot spot. As a consequence, the maintenance of weathering steel bridges with large exposed surfaces such as in the case of twin-girder bridges is actually very demanding in comparison with the case of coated bridges. Any debris or water stagnation must be cleaned up as quickly as possible. Water and debris "traps" within the steelwork create conditions to promote and accelerate corrosion and steel section loss, but create also pits where fatigue cracks may initiate with the effect of the traffic. If it is not possible to ensure a regular cleaning of these areas, there a need for retrofitting to eliminate the "traps". A maintenance program must be planned to repair and paint the ends of the steel members at the joints if any bridge joints are leaking. There must be a planned maintenance to repair the drainage system if the deck drainage system discharge onto the steelwork.