THE EFFECT OF HOLES ON TENSILE DEFORMATIONS IN PLAIN CONCRETE

RECENT RESEARCH HAS SHOWN THAT CONCRETE CAN EXHIBIT CONSIDERABLE INELASTIC DEFORMATION IN TENSION. THIS IS PARTICULARLY EVIDENT IN FLEXURAL AND UNIAXIAL TENSILE TESTS IN STIFF MACHINES AND IN TESTS WHERE STRAIN GRADIENTS ARE PRESENT. THIS PAPER DESCRIBES EXPERIMENTAL WORK ON THE EFFECT OF CENTRALLY LOCATED HOLES ON TENSILE DEFORMATION IN THIN CONCRETE PLATES. TESTS WERE CONDUCTED IN A SPECIAL UNIAXIAL-TENSION MACHINE, AND STRAIN MEASUREMENTS ALONG THE HORIZONTAL AXES OF THE PLATES SHOWED THAT EXTENSIVE INELASTIC DEFORMATION OCCURRED IN THE VICINITY OF THE HOLE EDGES. STRAINS SOMEWHAT FURTHER AWAY REMAINED "ELASTIC" FOR MOST OF THE LOADING RANGE, BEING QUITE SMALL IN SPECIMENS WITH DIAMOND HOLES. THE PRESENCE OF HOLES HAD APPARENTLY LITTLE EFFECT ON TENSILE STRENGTH. SPECIMEN BEHAVIOR IS EXPLAINED IN TERMS OF THE ENERGY-RELEASE CONCEPT OF FRACTURE MECHANICS, IT BEING CONCLUDED THAT INELASTIC DEFORMATION IS THE RESULT OF PROGRESSIVE AND EXTENSIVE MICROCRACKING. SUCH MICROCRACKING, IN WHICH CRACK LENGTHS REMAIN RELATIVELY SHORT, APPARENTLY OCCURS WHEN THE CRITICAL STRAIN-ENERGY RELEASE RATE IS RETARDED, AND IT SEEMS CERTAIN THAT THE STRAIN GRADIENTS CREATED BY THE PRESENCE OF HOLES HAVE THIS RETARDING EFFECT. THESE GRADIENTS CLEARLY LOCALIZE CRACKING IN THE VICINITY OF THE HOLE EDGES AND INHIBIT IT CONSIDERABLY ELSEWHERE. WITH REGARD TO TENSILE STRENGTH, IT MAY BE CONCLUDED THAT, AS INELASTIC DEFORMATION NEAR HOLE EDGES REACHES A CERTAIN STAGE, STRESS REDISTRIBUTION AND EVENTUAL UNIFORMITY TAKE PLACE. /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrr/1970/324/324-004.pdf
• Supplemental Notes:
  • Paper sponsored by Committee on Mechanical Properties of Concrete and presented at the 49th Annual Meeting. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Authors:
  • Imbert, I D
• Publication Date: 1970

Media Info

• Media Type: Print
• Features: Figures; References;
• Pagination: pp 54-65
• Monograph Title: Symposium on concrete deformation
• Serial:
  • Highway Research Record
  • Issue Number: 324
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Concrete; Deformation; Holes; Inelastic stress; Loads; Microcracking; Structural plates; Tensile strength; Tension; Tension tests
• Uncontrolled Terms: Inelastic action; Inelastic deformation; Microcracks; Plates; Tensile stress; Uniaxial tension
• Old TRIS Terms: Axial tension; Microfracturing
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00213844
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: May 10 1971 12:00AM