Load‐carrying capacity of Vierendeel bridges in Mechelen

From 1930 to 1960, in Belgium, steel railway bridges were regularly designed using the vierendeel system. Three railway lines cross the Mechelen‐Leuven canal in the town of Mechelen, providing a unique example of this type of application. Two of these bridges, which were constructed in 1953 were renovated in 2021–2022, including the installation of a new rail fastening. It was discovered that the 1936‐built third and oldest bridge had multiple cracks, mostly in the vertical members of the Vierendeel structure. Furthermore, secondary components like longitudinal beams and cross beams are severely harmed by corrosion. As a result, uncertainty grew over this bridge's ability to support loads. The monuments organization promotes the preservation of these old structures. The material properties, as well as the load‐bearing capacity and the fatigue strength, were evaluated by a thorough experimental and numerical investigation. The results of the examinations suggest that the significant strength variation of the steel components may be the cause of the cracking. It is more likely that cracks developed during the bridge's construction and subsequent repairs than that fatigue is to blame. In conclusion, the arrangement of the three bridges is too special to be destroyed and replaced, and the third bridge may also be sufficiently repaired and rebuilt for long‐term further use.