Diagnosis of a large steel bridge close to collapse during a fire‌

The Mathilde Bridge is one of the six bridges over the Seine River in the city of Rouen and supports heavy traffic. It was built in 1976-79 and is composed of a single metal span 115 m long, consisting of an orthotropic steel deck resting on two girders. On October 29th, 2012, the Mathilde bridge was subjected to a heavy fire and was immediately closed to traffic. After recalling the events, the article describes the decisions that had to be taken in an emergency, then the extended diagnosis which was conducted in order to be able to take a rapid decision on repair or reconstruction.

The diagnosis consisted of a detailed inspection including the examination of cracks and the condition of the paint, extensive investigations carried out on samples of metal, an accurate measurement of the global deformations of the entire span, a recalculation of the stability of the burned areas, and an expertise of damaged support bearings.