Diagnosis, Assessment and Repair of the Mathilde Bridge Close to Collapse during a Fire

Abstract

The Mathilde Bridge is one of the six bridges over the Seine River in the city of Rouen and supports a heavy traffic. It was built in 1977–1979 and is composed of a single steel span 115 m long, consisting of an orthotropic deck resting on two girders. On 29 October 2012, there was a major fire accident involving the Mathilde Bridge and it was immediately closed to traffic. After recalling the events, the article describes the emergency decisions that had to be taken, and then the extended diagnosis and the choice of the assessment method. Rapid decisions had to be taken regarding the waterway traffic under the bridge and the choice between repair or reconstruction.The diagnosis consisted of a detailed inspection including the search for cracks and the condition of the paint, extensive non-destructive specific investigations carried out on the bridge and laboratory investigations on a few samples of steel. The assessment consisted of an accurate measurement of the global deformations of the entire span, a recalculation of the stability of the burned areas, and an expert analysis of the damaged support bearings. The article is written in the spirit of a forensic engineering approach.