GIRDER WEB BOUNDARY STRESSES AND FATIGUE

THE OBJECTIVE OF THIS REPORT IS TO DEFINE THE PRIMARY CAUSE OF FATIGUE CRACKS OBSERVED IN THE WEBS OF WELDED PLATE GIRDER TEST SPECIMENS. THE IN-PLANE MEMBRANE STRESSES, WHICH CONFORMED REASONABLY WELL TO BEAM THEORY PREDICTIONS AT THE PANEL BOUNDARIES, ARE SHOWN TO HAVE LITTLE CONNECTION WITH THE OCCURRENCE OF FATIGUE CRACKS, EXCEPT IN THE TENSION REGION OF PANELS UNDER PURE BENDING. THE PLATE BENDING STRESS IS THEN EXAMINED AND A METHOD OF CALCULATING THESE STRESSES THROUGH USE OF MEASURED WEB DEFLECTIONS IS DEVELOPED. BY TAKING INTO ACCOUNT THE TORSIONAL RIGIDITIES OF THE FLANGES AND TRANSVERSE STIFFENERS, A PARTIAL DIFFERENTIAL EQUATION IS ESTABLISHED AS THE NECESSARY CONDITION TO ENSURE EQUILIBRIUM AND COMPATIBILITY BETWEEN THE WEB AND ITS BOUNDING ELEMENTS. THE SUBSEQUENT SOLUTION OF THE EQUATION IS PERFORMED THROUGH THE USE OF THE FINITE DIFFERENCE TECHNIQUE. THE ACCURACY OF THE RESULTING PLATE BENDING STRESSES IS THEN EXAMINED. IN COMPARISON WITH STRESSES COMPUTED FROM MEASURED STRAINS, THE METHOD IS PROVEN RELIABLE. IT IS SHOWN THAT FATIGUE CRACKS ALWAYS INITIATED AT THE POINTS OF MAXIMUM PLATE BENDING STRESS, THAT THE SEQUENCE OF CRACK FORMATION ON A SINGLE TEST GIRDER IS READILY EXPLAINED BY THESE STRESSES AND THAT A TYPICAL S- N DISTRIBUTION IS OBTAINED WHEN THE FATIGUE DATA OF SEVERAL GIRDERS ARE COMPARED. IT IS CONCLUDED THAT THE PLATE BENDING STRESS IS A PRIMARY CAUSE OF FATIGUE CRACKS IN THIN-WEB WELDED PLATE GIRDERS. /AUTHOR/

• Supplemental Notes:
  • Hpr-1/4/, STATE NO 036
• Corporate Authors:

  Pennsylvania Department of Highways

  400 North Street
  Harrisburg, PA  United States  17120-0095

  Lehigh University

  Bethlehem, PA  United States  18015
• Authors:
  • Mueller, J A
  • Yen, B T
• Publication Date: 1967-7

Subject/Index Terms

• TRT Terms: Bending; Bending stress; Cracking; Fatigue (Physiological condition); Finite differences; Partial differential equations; Plate girders; Specimens; Stresses; Webbing; Weldments
• Subject Areas: Bridges and other structures; Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00215864
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS
• Created Date: Dec 29 1994 12:00AM