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 8-a: Important thickness transition case Fig 8-b: Usual case Figure 8: Example of motorway bridge features built in the 90’s with cope hole wrongly calculated without SCF for class category 71 MPa instead of 36 MPa The feature is presented in the “Guide for sustainable steel bridges” [24] conception chapter without any warning comment, p age 68

Figure 9: Mesh of a cope hole for the “hot spot” method and location af the two hot spots Along the rounded cutting line, the von Mises function avoids us to have to look for the governing principal stress. The formulae given by J. Berthellemy in [19] already include the so-called "size effect", which is also present in the Eurocodes. This "size effect" should therefore not be applied twice. However, in the extreme case of the bridge in Figure 6, the "cope hole effect" is very important: It cannot be neglected because it is about two, which means that the detail category is 36 MPa instead of the assumed 71 MPa category for the overpass of the A1 motorway. 2.5 Recalculation example of poor fatigue design inside a box girder bridge Continuous bottom flange stiffeners were recommended before 1987. But, the actual bridge presented in Fig. 10 was designed with non continuous bottom stiffeners. The bridges were even experimentally “calculated” regarding fatigue, but bureaucrats decided not to consider details 1 and 2 because the class of the longitudinal stiffener (detail 1) did not directly appear in the tables of the ECCS recommendations. The modified stress was not calculated for detail 2 either. It was decided in 1993, aftermy visit of the bridge to inspect every yearthe two wrong details. M. Virlogeux also decided Setra would design a pilot box girder bridge project with the right details for such box girder bridges in Nevers [20,21] in order to promote box girders [23]. In straight line on the plan, the Nevers box girder was cheaper than a twin I-girder deck. However, the bureaucrats never introduced the Nevers bridge in the French guidance books in 2010 [24].