RELAXATION LOSSES IN STRESS RELIEVED SPECIAL GRADE PRESTRESSING STRANDS

THE PRELIMINARY EVALUATION IS PRESENTED OF RELAXATION LOSSES BASED ON TEST DATA OVER A PERIOD OF 444 DAYS. FORTY SPECIMENS OF THE SEVEN-WIRE STRESS-RELIEVED STRANDS OF THE SPECIAL GRADE (270 K) WERE TESTED UNDER A CONSTANT LENGTH CONDITION. PRIMARY CONTROLLED VARIABLES ARE STRAND SIZE, MANUFACTURER AND INITIAL STRESS LEVEL. EXPRESSIONS FOR RELAXATION LOSS ARE DEVELOPED IN TERMS OF TIME AND INITIAL STRESS. TWO SETS OF EXPRESSIONS ARE SUGGESTED FOR THE ESTIMATION OF RELAXATION LOSS FOR AN INITIAL PERIOD UP TO APPROXIMATELY 500 DAYS. A SEPARATE, SIMPLIFIED EXPRESSION IS PROPOSED FOR LONG TERM PROJECTION OF THE TOTAL RELAXATION LOSS AT THE END OF FIFTY YEARS. ALSO INCLUDED IN THIS REPORT IS A REVIEW OF PREVIOUS RESEARCH ON THIS SUBJECT AND A SUMMARY OF THE RELEVANT PROVISIONS IN SEVERAL FOREIGN AS WELL AS UNITED STATES DESIGN CODES. /AUTHOR/

Subject/Index Terms

Filing Info

  • Accession Number: 00212087
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: 66-17
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Oct 19 1970 12:00AM