The Autostress method has been evolving as an extension to the AASHTO Load-Factor method for rolled-beam and plate-girder steel highway bridges. The Autostress method uses the same three load levels as the Load-Factor method: Service load, Overload, and Maximum Load. However, to satisfy the structural performance requirements, the Autostress method injects two new concepts into bridge design: mechanism formation at Maximum Load and shakedown at Overload. When a structure forms a mechanism, there are sufficient plastic hinges to cause failure. When a structure shakes down, residual stresses and residual moments are automatically developed and assure elastic behavior under subsequent loading--hence the term Autostress. Although results of both methods for a simple span are the same, the Autostress method provides economies in continuous-span bridges; it utilizes the same safety factor against mechanism formation in both simple-span and continuous-span bridges. As part of an AISI-sponsored project, nine Load-Factor bridges were redesigned according to the Autostress method; the average cost saving was 10.7 percent. The objective of the AISI project is to suggest that the Autostress method be incorporated into the AASHTO specification after experimental verification. /Author/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 255-261
  • Monograph Title: Bridge Engineering. Volume 1
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00183772
  • Record Type: Publication
  • ISBN: 0309026962
  • Files: TRIS, TRB
  • Created Date: Dec 12 1978 12:00AM