What Are Fracture Critical Bridges — and How Should Agencies Manage Them?
A fracture critical bridge is a steel bridge that contains one or more fracture critical members (FCMs) — steel tension components whose failure would be expected to result in a partial or total collapse of the bridge. Because fracture critical members lack redundancy, a single fracture event can have catastrophic consequences. Managing fracture critical bridges requires heightened inspection protocols, meticulous documentation, and a data management infrastructure capable of tracking the condition and history of these high-consequence structures over time. What makes a bridge member 'fracture critical'? A bridge member is classified as fracture critical when it is a steel tension member — meaning it is subject to tensile stress — and the structure lacks sufficient redundancy for the load to be redistributed to other members in the event of that member's failure. In a non-redundant structure, the failure of a single fracture critical member creates a load path that no o...