DESIGN OF PRESTRESSED CONCRETE BRIDGES BASED ON THE FATIGUE LIFE FOR THE EXPECTED LOAD SPECTRUM

DATA ARE REPORTED ON THE DAILY LOAD FREQUENCY AT 21 BRIDGES OVER THE OHIO RIVER. SPECIFIED AXLE LOADS IN THE UNITED STATES AND THE UNITED KINGDOM ARE COMPARED. BASED ON THE UNITED KINGDOM DATA, IT IS POSSIBLE TO EVALUATE THE NUMBER OF LOADING CYCLES FOR DIFFERENT LOAD INTENSITIES DURING THE EXPECTED LIFE TIME OF THE BRIDGE AND TO DESIGN THE BRIDGE TO WITHSTAND THE CUMULATIVE EFFECT OF THESE LOAD- INGS. INCREASED STRESSES ARE PERMITTED FOR STEEL AND REINFORCED CONCRETE, BUT THIS CANNOT BE APPLIED TO PRESTRESSED CONCRETE. THE REFERENCE PAPER DISCUSSES FIVE DIFFERENT DESIGN METHODS FOR PRESTRESSED CONCRETE BRIDGES. ONE METHOD RELATES TO A DESIGN THAT WHICH ONLY COMPRESSIVE STRESSES OCCUR AT THE MAXIMUM LOAD. THIS INSURES A SAFE BUT UNECONOMICAL SOLUTION. LIMITED TENSILE STRESSES ARE PERMITTED UNDER THE MAXIMUM LOAD AND THE METHOD EMPLOYED BY BRITISH RAILWAYS. ANOTHER METHOD RELATES TO THE FATIGUE RESISTANCE OF A DEFINITE STRESS RANGE ACCORDING TO THE GOODMAN DIAGRAM. ANOTHER METHOD RELATES TO A DESIGN AT WHICH COMPRESSIVE STRESSES OCCUR UNDER THE NORMAL LOADING, WHEREAS TEMPORARY CRACKS MAY OCCUR UNDER THE ABNORMAL LOADING. THE SUGGESTED METHOD IS BASED ON THE CUMULATIVE FATIGUE RESISTANCE TO THE ENTIRE LOAD SPECTRUM DURING THE BRIDGE LIFE, BEARING IN MIND RANDOM LOADINGS. TESTS AT DUKE UNIVERSITY SHOW THAT PRESTRESSED CONCRETE CAN WITHSTAND A RELATIVELY LARGE NUMBER OF LOAD CYCLES OVER A HIGH LOADING RANGE. IT IS SHOWN THAT THE CUMULATIVE LOADING EFFECT CAN BE OBTAINED FROM MINOR'S HYPOTHESIS. DUKE UNIVERSITY TESTS SHOW THAT IT IS IN GOOD AGREEMENT WITH PRESTRESSED CONCRETE WITH WELL BONDED TENDONS. SEVERAL OF THE DESIGN METHODS ARE ILLUSTRATED IN FIGURES.

• Supplemental Notes:
  • Vol 4, pp 219-221, 2 FIG, 8 REF
• Corporate Authors:

  International Association for Bridge and Structural Engineering

  ETH-Honggerberg, Wolfgang-Pauli-Strasse 15
  Zurich 8093,   Switzerland  CH-8093
• Authors:
  • Abeles, P W
• Publication Date: 1969

Subject/Index Terms

• TRT Terms: Axle load force; Bridge design; Bridges; Compressive strength; Concrete bridges; Fatigue (Mechanics); Loads; Prestressed concrete; Structural design; Tension
• Uncontrolled Terms: Fatigue life; Loading rate; Tensile stress
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00209164
• Record Type: Publication
• Files: TRIS
• Created Date: Mar 30 1970 12:00AM