Fracture critical bridge

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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]

Contents

Definition

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. [2]

Examples of bridge designs that would typically be considered fracture critical are:

History

The designation and inspection protocols for fracture critical bridges were developed following the failure of an eyebar at the Silver Bridge at Point Pleasant, West Virginia, which precipitated the bridge's collapse into the Ohio River in 1967, resulting in 46 deaths. 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. These are:

See also

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References

  1. McGinty, Jo Craven; Overberg, Paul (March 29, 2024). "These Eight U.S. Bridges Are Vulnerable to a Repeat of the Baltimore Crash". The Wall Street Journal. News Corp. Archived from the original on April 1, 2024. Retrieved May 10, 2024.
  2. Connor, Robert H.; Frank, Karl; McEleney, Bill; Yadlosky, John (January 2015). "Bridge Crossings: Are You Sure That's Fractuire Critical?" (PDF). Modern Steel Construction. American Institute for Steel Construction. Retrieved 29 March 2024.
  3. 1 2 Kaviani, Peyman; Villalobos, Carlos (October 2016). "Fracture Critical Bridge Inspection". Structure. National Council of Structural Engineers. Retrieved 29 March 2024.
  4. Connor, Robert; Gilmer, Heather; LLoyd, Jason; Medlock, Ronnie; Wasserman, Ed. "Implementation of Redundancy Terms under 2022 NBIS" (PDF). Ameican Institute of Steel Construction. Retrieved 1 April 2024.