THE INELASTIC DEFORMATION OF CONCRETE

A KNOWLEDGE OF THE COMPLETE STRESS--STRAIN CURVE OF CONCRETE IS ESSENTIAL FOR ULTIMATE STRENGTH DESIGN. CONVENTIONAL STRESS-CONTROLLED TESTS GIVE LITTLE INFORMATION ON DEFORMATION BEYOND THE MAXIMUM LOAD. TESTS ARE REPORTED ON CONCRETE CYLINDERS AND PRISMS AT CONSTANT RATE OF STRAINING USING A SERVOMECHANISM CONNECTED TO THE HYDRAULIC SYSTEM AND AUTOMATICALLY RECORDING THE LOAD DEFORMATION. THE EFFECT OF SPECIMEN SIZE, AGGREGATE TYPE, AGE, STRENGTH, AND CYCLIC LOADING ON THE DEFORMATIONAL BEHAVIOR OF CONCRETE IS STUDIED. THE STRAIN AT MAXIMUM LOAD TENDS TO INCREASE WITH CONCRETE STRENGTH AND WITH AGE. THE ULTIMATE STRAIN AT COLLAPSE IS MANY TIMES THAT AT MAXIMUM LOAD AND IS INDEPENDENT OF STRENGTH AND HEIGHT-WIDTH RATIO OF SPECIMEN. AT EQUAL DEFORMATIONS BEYOND THE MAXIMUM LOAD, LOW-STRENGTH CONCRETE AND SPECIMENS OF SMALLER HEIGHT--WIDTH RATIO POSSESS GREATER LOAD RESISTANCE. AGE AND STRENGTH ALSO INFLUENCE THE SHAPE OF THE STRESS-STRAIN CURVE. THE ELASTIC MODULUS BASED ON TOTAL STRAIN IS ABOUT 55 TO 80 PERCENT OF THAT OBTAINED FROM STRAINS IN THE CENTRAL PART. THE PRESENCE OF THE FALLING BRANCH SUGGESTS DIFFERENT CRACKING AND FAILURE MECHANISMS IN THE ASCENDING AND DESCENDING PARTS, AND THE SIGNIFICANCE OF INTERNAL FRICTION AT DECREASING LOADS. THE ABILITY TO SUSTAIN DECREASING LOADS AT INCREASING DEFORMATION RELIEVES STRESS CONCENTRATIONS AND ENSURES PLASTIC FLOW WITHOUT VIOLENT FAILURE. /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrr/1970/324/324-007.pdf
• Supplemental Notes:
  • Paper sponsored by Committee on Mechanical Properties of Concrete. 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:
  • Swamy, Narayan
• Publication Date: 1970

Media Info

• Media Type: Print
• Features: Figures; Photos; References; Tables;
• Pagination: pp 89-99
• Monograph Title: Symposium on concrete deformation
• Serial:
  • Highway Research Record
  • Issue Number: 324
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Age; Aggregates; Concrete; Deformation; Deformation curve; Failure; Hydraulic equipment; Loads; Servomechanisms; Stiffness; Strain (Mechanics); Strength of materials; Testing; Testing equipment; Ultimate strength
• Uncontrolled Terms: Aggregate size; Inelastic deformation; Strain rate; Ultimate strain
• Old TRIS Terms: Hydraulic systems; Strains
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00213847
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Apr 25 1971 12:00AM