IMPORTANCE OF REDUNDANCY IN BRIDGE-FRACTURE CONTROL

Because of component redundancy, riveted structures have tended to be fail-safe. It has been far less important to be aware of the limits of fatique and brittle fracture in riveted structures than in welded structures, which are generally not component fail-safe. In the change from riveted to welded-plate girders, the safety factor protecting against brittle fracture in nonredundant load-path structures has weakened. The inherent crack stoppers at interfaces between components of riveted structures do not exist in structures that are welded or repaired by welding. Designers must therefore design fabricators must produce, and inspectors must examine relatively crack-free structures and ensure that they will not develop large cracks during their service lives. This safe-life approach is an absolute requirement for nonredundant load-path structures. Several examples of cracked structures that have not collapsed because of redundancy are given, and the effect of welded repairs is dicussed. The paper illustrates the redundancy of several simple trusses with a discussion of bridge fires. Strict application of these guidelines will force many designers to change to redundant load-path or component-redundant structures (e.g., bolted) in many instances, particularly in the short-span range, as alternatives to the additional material that may be required to avoid fracture. /Author/

Media Info

  • Media Type: Print
  • Features: Figures; Photos; References;
  • Pagination: pp 23-30
  • Monograph Title: Probabilistic design, redundancy, and other bridge papers
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00302393
  • Record Type: Publication
  • ISBN: 0309029589
  • Files: TRIS, TRB
  • Created Date: Jan 30 1980 12:00AM