FATIGUE OF CONCRETE

LABORATORY AND FIELD TESTS ARE REVIEWED ON THE PHENOMENON OF FATIGUE OF CONCRETE. DIFFERENT RATIOS OF FATIGUE STRENGTH TO STATIC STRENGTH ARE FOUND DEPENDING UPON THE AGE AND CONDITION OF THE CONCRETE AND ITS MOISTURE CONTENT. TWENTY-EIGHT DAY TESTS SHOW NO DEFINITE ENDURANCE LIMIT BETWEEN 40 AND 60 PERCENT OF THAT STATIC LOAD REQUIRED TO BREAK THE BEAM UNDER A SINGLE APPLICATION CAN BE ASSIGNED TO CEMENT MORTAR OF THIS AGE. THE FOUR MONTH TEST SHOWS THAT THE ENDURANCE LIMIT IS APPROXIMATELY 50 TO 55 PERCENT OF THE STATIC LOAD. TESTS CONDUCTED OVER 6 MONTHS SHOW THE ENDURANCE LIMIT IS 54 TO 55 PERCENT OF THE STATIC LOAD. THE FOLLOWING INDICATIONS WERE FOUND IN THE TEST: (1) THE ENDURANCE LIMIT DOES NOT SEEM TO DIFFER MATERIALLY FOR BEAMS UNDER CONTINUOUS FATIGUE LOADING FROM THAT FOR BEAMS UNDER FATIGUE LOADING WITH SHORT REST PERIOD, (2) THE NUMBER OF REVERSALS OF STRESS NECESSARY TO CAUSE FAILURE DECREASES IN A PROPORTION TO THE RESPECTIVE INCREASE OF THE PERCENTAGE OF STATIC LOAD ABOVE THE ENDURANCE LIMIT, (3) STRESSES ABOVE THE ENDURANCE LIMIT CAUSE CONTINUAL PROGRESSIVE DEFORMATION, (4_ STRESSES BELOW THE ENDURANCE LIMIT MAY CAUSE PROGRESSIVE DEFORMATION FOR SHORT PERIODS WITH A TENDENCY TO BECOME CONSTANT OR TO DECREASE WITH CONTINUED LOADING, (5) THE ENDURANCE LIMIT MAY BE RAISED BY FATIGUING BELOW THE 55 PERCENT STATIC LOAD, (6) THE AMOUNT OF RECOVERY IN DEFORMATION SEEMS TO DEPEND SOMEWHAT UPON THE LENGTH OF REST PERIOD, AND (7) PLASTIC SET IN FATIGUE IS MORE PRONOUNCED IN MORTAR OF EARLY AGE.

Media Info

  • Monograph Title: Proceedings of the Fourth Annual Meeting of the Highway Research Board Held at Washington, D.C., December 4-5, 1924
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00213723
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Nov 9 1970 12:00AM