BRIDGES: SYNTHESIS OF LOAD HISTORIES AND ANALYSIS OF FATIGUE PART III

THE PURPOSE WAS TO RECONSTITUTE OR SYNTHESIZE THE LOAD HISTORY OF CERTAIN BRIDGES AND TO DEVELOP A LOGICAL METHOD OF ESTIMATING THEIR REMAINING SERVICE LIFE. FIRST FATIGUE TESTING IS BRIEFLY EXAMINED AS REVIEW MATERIAL FOR UNDERSTANDING THE BASIC CONSIDERATION - FATIGUE EQUATION, VEHICLE LOADING DISTRIBUTIONS, TRANSFORMATION OF LOAD DISTRIBUTIONS INTO STRESS DISTRIBUTIONS, AND TRANSFORMATION OF STRESS DISTRIBUTIONS INTO FATIGUE HISTORY. COMPUTATION OF TOTAL FATIGUE INVOLVES (1) DETERMINING THE PROBABILITY OF THE NUMBER OF REPETITIONS OF EACH VEHICLE LOADING CONFIGURATION; (2) TRANSFORMING THE VEHICLE LOADING DISTRIBUTION GENERATED IN (1) INTO A CORRESPONDING DISTRIBUTION OF STRESSES IN STRUCTURAL MEMBERS; (3) DETERMINING THE APPROPRIATE FATIGUE CURVE FOR THE MEMBER BASED ON AVAILABLE DESIGN CRITERIA; (4) DETERMINING THE EQUIVALENT BRIDGE LOADING CONTRIBUTION RESULTING FROM THE APPLICATION OF ONE. STRESS IN EACH STRESS INTERVAL; (5) MULTIPLYING THE NUMBER OF STRESS APPLICATIONS IN EACH STRESS INTERVAL BY THE CORRESPONDING EQUIVALENT BRIDGE LOADING FACTOR (EBLF); AND (6) ADDING EBLF'S OVER ALL STRESS GROUPS AND COMPARING THE TOTAL TO THE MAXIMUM SAFE VALUE, (5) AND (6) ARE COMBINED INTO AN EQUATION. IT MUST BE NOTED THAT THE EXTENSION OF FATIGUE LIFE BY REINFORCING THE MEMBER WAS EXCLUDED FROM THIS STUDY.

Subject/Index Terms

Filing Info

  • Accession Number: 00209684
  • Record Type: Publication
  • Files: TRIS, STATEDOT
  • Created Date: Dec 13 1972 12:00AM