FLEXURAL MICROCRACKING IN UNREINFORCED CONCRETE BEAMS

COMPRESSIVE AND TENSILE STRAIN MEASUREMENTS WERE MADE ON UNREINFORCED CONCRETE BEAMS AT DUKE UNIVERSITY IN 1967 TO OBTAIN THE STRESS-STRAIN RELATION. PHOTOELASTIC STUDIES WERE MADE TO RECORD VISUAL MICROCRACKING OF SUCH UNREINFORCED BEAMS. THREE DIFFERENT TYPES OF BEAMS WERE AVAILABLE; THEY WERE MADE FOR AUXILIARY TESTS ON COMPOSITE PRESTRESSED CONCRETE BEAMS. ALTOGETHER, 24 BEAMS OF A 4 X 4 IN. CROSS SECTION AND A 3-FT. SPAN, TESTED WITH THE LOADS AT THE ONE-THIRD POINTS, WERE AVAILABLE AND ALSO FOUR BEAMS WITH A 3.5 X 8 IN. AND 3.5 X 10 IN. CROSS SECTION, RESPECTIVELY, TESTED AT 7 FT. 6 IN. SPAN BY TWO CENTRAL POINT LOADS 2 FT APART. AT TESTING OF THE FIRST QUARTER OF THE BEAMS, THE STRAINS WERE MEASURED BY MECHANICAL STRAIN GAGES, POSITIONED AT THE SIDE FACES OF THE BEAMS, BUT THE STRAIN READINGS WERE INSUFFICIENTLY EXACT. CONSEQUENTLY, ON THE REMAINING THREE-QUARTERS OF THE SPECIMENS, ELECTRICAL RESISTANCE STRAIN GAGES WERE ATTACHED TO THE COMPRESSIVE AND TENSILE FACES, RESPECTIVELY. THE DIAGRAMS OBTAINED FROM THESE STRAIN MEASUREMENTS CAN BE USED TO STUDY THE SHAPE OF STRESS-STRAIN CURVES ON A STATISTICAL BASIS. IN ADDITION, THE RELATION BETWEEN FLEXURAL MICROCRACKING AND MODULUS OF RUPTURE WAS STUDIED USING PHOTOSTRESS TECHNIQUES. /AUTHOR/

  • Supplemental Notes:
    • TITLE NO 68-69
  • Authors:
    • Abels, P W
    • Hu, C H
  • Publication Date: 1971-10

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00209638
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 16 1972 12:00AM