STRESS HISTORY OF A CURVED BOX BRIDGE

Stress history data obtained through field testing of a curved composite box girder bridge were analyzed to evaluate the fatigue strength of the structure's details. Details examined were the termination of transverse stiffener, the discontinuous backup bar, and the longitudinal stiffener cutoff. Strains measured at these details indicate very small equivalent constant amplitude stress ranges. These stress ranges combined with estimates on the future loadings predict the fatigue strength of the structure to a greater than that required for a service life of 30 to 40 years. Relatively large bending stresses in the vertical direction were detected at the transverse stiffener-to-flange gap. Analysis shows that these stresses are produced when out-of-web plane forces are applied to the stiffener. Graphs are presented relating the maximum gap stresses to detail geometry and load. Connection of the stiffener to the flange at diaphragms is recommended. The fatigue strength of the discontinuous backup bar detail is estimated to be represented by the AASHTO Category E detail. A recommendation is made to fabricate all backup bars as continuous members. /FHWA/

  • Supplemental Notes:
    • Prepared in cooperation with the U.S. Department of Transportation, Federal Highway Administration. From the study: High Cycle Fatigue of Welded Bridge Details.
  • Corporate Authors:

    Lehigh University

    Fritz Engineering Laboratory
    Bethlehem, PA  USA  18015
  • Authors:
    • Inuka, G J
    • Yen, B T
    • Fisher, J W
  • Publication Date: 1978-6

Media Info

  • Pagination: 67 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00193735
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA-RD-79-S0831 Intrm Rpt., FCP 45F2-212
  • Contract Numbers: 72-3
  • Files: TRIS, USDOT
  • Created Date: Aug 15 1979 12:00AM