FATIGUE OF BEAMS WITH WELDED COVER PLATES

THE INCREASED USE OF WELDED MEMBERS AS BRIDGE ELEMENTS, TOGETHER WITH TRENDS TOWARD HEAVIER TRUCK GROSS WEIGHTS AND TRAFFIC VOLUMES, NECESSITATES THE STUDY OF THE BEHAVIOR OF WELDED COVER-PLATED GIRDERS SUBJECTED TO CONDITIONS OF VARYING LOAD AMPLITUDES. A SURVEY OF THE LITERATURE INDICATED THE EFFECT OF THE VARIOUS FACTORS WHICH INFLUENCE FATIGUE BEHAVIOR UNDER BOTH CONSTANT AMPLITUDE AND VARIABLE AMPLITUDE. A HYPOTHESIS, BASED ON THE ASSUMPTION THAT THE PLASTIC STRAIN AMPLITUDE DURING ANY GIVEN CYCLE OF STRESS IS AN INDEX OF THE INDUCED FATIGUE DAMAGE, IS PRESENTED. THE HYPOTHESIS IS SHOWN TO YIELD AN EXPONENTIAL CYCLE TO FAILURE-STRESS RANGE RELATIONSHIP AND A STRESS DEPENDENT DAMAGE-CYCLE RATIO EQUATION. A SERIES OF CONSTANT AMPLITUDE TESTS WERE CONDUCTED WHICH WERE DESIGNED TO YIELD THE MATERIAL CONSTANTS NECESSARY FOR THE APPLICATION OF THE HYPOTHESIS TO VARIABLE AMPLITUDE CASES. BOTH MULTI-LEVEL AND REPEATED BLOCK TESTS WERE ALSO CONDUCTED. THE PURPOSE OF THESE TESTS WAS TO STUDY THE PROCESS OF DAMAGE ACCUMULATION DUE TO VARIABLE LOADING AND ALSO CHECK THE ENDURANCE PREDICTIONS BASED ON THE HYPOTHESIS. THE TESTS WERE ALSO DESIGNED TO INDICATE THE DEPENDENCE OF DAMAGE ACCUMULATION ON THE ORDER OF LOADING AND THE INFLUENCE OF THE NUMBER OF CONSECUTIVE CYCLES OF A GIVEN STRESS RANGE LEVEL UPON THE ENDURANCE OF MEMBERS SUBJECTED TO REPEATED BLOCK LOADING. THE PREDICTIONS OF THE HYPOTHESIS WERE WITHIN 3-14% OF THE TEST RESULTS. PRELIMINARY DESIGN EQUATIONS ARE PRESENTED AND THEIR APPLICATION TO AN EXISTING BRIDGE ELEMENT IS ILLUSTRATED. THE USE OF THE HYPOTHESIS FOR FINAL DESIGN IS ALSO OUTLINED. CONCLUSIONS BASED ON THE RESULTS OF THIS STUDY AND THOSE OF PREVIOUS INVESTIGATIONS ARE PRESENTED AND USED AS A BASIS FOR PROPOSED CHANGES IN CODE PROVISIONS DEALING WITH FATIGUE. /AUTHOR/

• Supplemental Notes:
  • Aw 71-92-46, HPR-1 (6)
• Corporate Authors:

  University of Maryland, College Park

  Department of Civil and Environmental Engineering
  College Park, MD  United States  20742

  Maryland State Roads Commission

  ,    

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Murad, F A
  • Heinz, C P
• Publication Date: 0

Subject/Index Terms

• TRT Terms: Amplitude (Physics); Bridge design; Bridge members; Bridges; Fatigue (Physiological condition); Girders; Highway bridges; Loads; Loss and damage; Structural design; Structural plates; Traffic volume; Trucks; Weight; Welding
• Uncontrolled Terms: Loading; Plates
• Old TRIS Terms: Cover
• Subject Areas: Bridges and other structures; Geotechnology; Highways; Materials; Motor Carriers;

Filing Info

• Accession Number: 00215944
• Record Type: Publication
• Source Agency: Federal Highway Administration
• Files: TRIS, USDOT
• Created Date: Mar 7 1971 12:00AM