CRACKING AND FAILURE OF CONCRETE TEST SPECIMENS UNDER FLEXURAL VIBRATORY LOADING

THE METHOD AND APPARATUS DESCRIBED ENABLE VIBRATORY STRESSES OF MAGNITUDES COMPARABLE WITH THOSE USED IN CONVENTIONAL QUASI-STATIC TESTS TO BE APPLIED TO A CONCRETE BEAM. THE BEAM IS MOUNTED ON RIGID SUPPORTS AND VIBRATED IN FLEXURE BY A MOVING-COIL VIBRATION GENERATOR. THE FREQUENCY OF RESONANCE AND THE STRAIN AT THE CENTER OF THE TOP FACE OF THE BEAM ARE MEASURED AND, IN NORMAL OPERATION, CHANGES OF FREQUENCY WITH TIME AT CONSTANT STRAIN ARE OBSERVED. DECREASES IN THE DYNAMIC YOUNG'S MODULUS OF THE CONCRETE ARE ASSOCIATED WITH MICROCRACKING AND INDICATED BY DECREASES OF FREQUENCY. CRACKING HAS BEEN OBSERVED BY A PHOTO-ELASTIC TECHNIQUE WHILE STILL INVISIBLE TO THE NAKED EYE. STRAINS BETWEEN 0.000060 AND 0.000120 HAVE ULTIMATELY LED TO FATIGUE OF THE CONCRETES TESTED. STRESS-STRAIN RELATIONSHIPS, DERIVED FROM CURVES RELATING RESONANT FREQUENCY WITH STRAIN, WERE FOUND TO BE APPROXIMATELY LINEAR FOR UNFATIGUED AND MARKEDLY NON-LINEAR FOR FATIGUED SPECIMENS. /RRL/A/

  • Supplemental Notes:
    • pp 238-243, 5 FIG, 1 TAB, 6 REF
  • Corporate Authors:

    Cement & Concrete Assoc, London /UK

    /Proc Intl Conference
    ,   USA 
  • Authors:
    • Jones, R
    • Gatfield, E N
  • Publication Date: 1968

Subject/Index Terms

Filing Info

  • Accession Number: 00213027
  • Record Type: Publication
  • Source Agency: Road Research Laboratory /UK
  • Files: TRIS
  • Created Date: Oct 19 1970 12:00AM