The Rupture of an External Tendon in Île de Ré Bridge: Diagnosis, Safety Measures and Management

Abstract

Ré Island Bridge connects Île de Ré to the mainland on the west coast of France and crosses four navigable sea passes, with a maximum air clearance of 30 m above sea level. This bridge is 2926 m long and is famous for its rapidity of construction and the first use of high performance concrete for such a long bridge. The bridge deck consists of a prestressed concrete box girder divided into six independent viaducts. It was commissioned in 1988, and 30 years later, the rupture of an external prestressing tendon occurred inside the box girder. At first, the article introduces the emergency measures taken by the strategic bridge’s owner. Then it presents an analysis of the causes of the failure and the strategy developed by the owner to deal with the possible rupture of other tendons. Safety measures against the whiplash of tendons by the installation of straps around the tendons are described and the design of the strapping is discussed. The studies for the replacement of deficient tendons are then presented, with the difficulty of replacing tendons anchored in the half-joints between viaducts. Finally, managements decisions and lessons learned from that case are explained.