Fracture critical bridge

A fracture critical bridge is a bridge or similar span that is vulnerable to collapse of one or more spans as a result of the failure in tension of a single element.

While a fracture critical design is not considered unsafe, it is subject to special inspection requirements that focus on the tension elements of its structure.

[1] For a bridge to be defined as fracture critical: While members subject to compressive stress may also fail catastrophically, they typically do not fail from crack initiation.

The disaster resulted in the establishment of the National Bridge Inventory, using the National Bridge Inspection Standards (NBIS) (CFR Title 23, Part 650).

[3] In May 2022 new NBIS guidance established additional terminology to describe new forms of redundancy.