STUDY ON FATIGUE OF HYBRID PLATE GIRDERS UNDER CONSTANT MOMENT

AS PART OF A PROGRAM TO STUDY THE STATIC AND FATIGUE STRENGTH OF STRUCTURAL MEMBERS, AN ANALYSIS HAS BEEN MADE OF THE FATIGUE BEHAVIOR OF WELDED HYBRID PLATE GIRDERS UNDER CONSTANT HIGH STRESS AND ITS RESULTS HAVE BEEN RELATED TO AVAILABLE TEST DATA IN LOWER STRESS RANGES. THE MATERIALS TESTED WERE CONSTRUCTIONAL ALLOY STEEL ASTM A514, WHOSE USE IN SEVERELY STRESSED FLANGES INCREASES LOAD CAPACITY, AND CARBON STEEL ASTM A36 WEB, WHICH HAS HIGH SHEAR RESISTANCE. FOUR GIRDERS WITH A 36-INCH WEB WERE USED, TWO WITH A SLENDERNESS RATIO OF 197 AND TWO OTHERS WITH ONE OF 267. ALL GIRDERS WERE SUBJECTED TO A STRESS RANGE OF 30 KSI WITH A MAXIMUM LOAD OF 50 KSI. A LIMITED STATISTICAL ANALYSIS IS MADE TO DETERMINE THE INFLUENCE OF SEVERAL VARIABLES ON THE FATIGUE LIFE OF HYBRID PLATE GIRDERS. IT WAS FOUND THAT BY LIMITING CERTAIN VARIABLES IT IS POSSIBLE TO REDUCE SECONDARY BENDING STRESSES IN THE WEB SO AS TO AVOID FATIGUE CRACKS IN THE COMPRESSION SIDE OF THE GIRDERS. HOWEVER, BECAUSE OF FABRICIATION AND STRESS CONCENTRATIONS, CRACKS WILL APPERAR IN THE TENSION SIDE. REGRESSION ANALYSIS SHOWED THAT FATIGUE CRACKS IN THE HIGH STRESS RANGE OCCUR AFTER A GREATER NUMBER OF CYCLES THAN SUGGESTED IN PREVIOUS REPORTS. WHILE MOST OF THE FACTORS ARE INTERRELATED, ANALYSIS OF A SINGLE MAIN VARIABLE IS SUFFICIENT TO DERIVE AN APPROXIMATE RELATIONSHIP FOR THE NUMBER OF CYCLES REQUIRED TO PRODUCE A CRACK. SEVERAL DESIGN CRITERIA BASED ON THE TEST RESULTS AND ON EMPIRICAL ANALYSES ARE SUGGESTED. /AUTHOR/

• Supplemental Notes:
  • Res Rept. 96-3, 61 PP, 29 FIG, 6 TAB, 11 REF, 1 APP
• Corporate Authors:

  University of Texas, Austin

  Center for Highway Research, 200 West 21st Street
  Austin, TX  United States  78712
• Authors:
  • Yinh, J
  • Toprac, A A
• Publication Date: 1969-1

Subject/Index Terms

• TRT Terms: Alloy steel; Engineering moments; Fatigue (Mechanics); Girders; Plate girders; Static loads; Steel; Structural steel
• Uncontrolled Terms: A36 steel; Fatigue life; Hybrids
• Old TRIS Terms: Astm a514 steel; Moments
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00209351
• Record Type: Publication
• Files: TRIS
• Created Date: Aug 1 1971 12:00AM