STUDY OF CREEP IN CONCRETE, PHASES 3,4,5

TESTS TO DETERMINE PRESTRESSING LOSSES WERE MADE ON SMALL RECTANGULAR CONCRETE BEAMS LOADED IN COMPRESSION BY AXIAL PRESTRESSING STEEL STRESSED TO ABOUT ONE-HALF OF THE RECOMMENDED WORKING STRESS. RELATIONSHIPS WERE DISCLOSED WHICH INDICATE THE FEASIBILITY AND PRACTICABILITY OF PREDICTING LOSSES IN FULL-SIZED BEAMS BY TESTING SMALL PRESTRESSED CONCRETE BEAMS OF SUFFICIENT SIZE VARIATION TO PROVIDE SURFACE-AREA-TO-VOLUME /SA/V/ VALUES FOR EXTRAPOLATION CURVES. CONCRETE CYLINDRICAL SPECIMENS WERE SUBJECTED TO LONG-TIME COMPRESSIVE LOADING AT 1 DAY OF AGE INCLUDING 16 HOURS OF STEAM CURING. CREEP AND SHRINKAGE OF STEAM-CURED CONCRETE RANGES FROM 25 TO 46 PER CENT LESS THAN THAT OF THE SAME CONCRETE NORMALLY CURED, THE AMOUNT DEPENDING UPON SPECIMEN SIZE, APPLIED STRESS, AND STORAGE HUMIDITY. TESTS WERE MADE WHICH INDICATE THAT FOR A GIVEN CONCRETE SPECIMEN, TIME-DEPENDENT STRAINS ARE EQUAL WHETHER THEY ARE MEASURED END-TO-END OR IN THE CENTRAL PORTION OF THE SPECIMEN. THE EFFECTS OF AGE UPON SHRINKAGE WERE DETERMINED. SHRINKAGE MEASUREMENTS WERE MADE ON THE INSIDE OF THE CYLINDRICAL CONCRETE SPECIMENS WITH EMBEDDED CARLSON STRAIN METERS, AND ON THE OUTSIDE WITH A MECHANICAL STRAIN GAGE. RESULTS INDICATE THAT SHRINKAGE IS EQUAL WHETHER MEASURED INTERNALLY OR ON THE OUTSIDE OF THE SPECIMENS. THE EFFECTS UPON SHRINKAGE OF THE SIZE AND SHAPE OF SPECIMEN WERE DETERMINED, USING CYLINDERS, PRIMS, TEE- SECTIONS, AND I-SECTIONS. BY THE USE OF PHOTOELASTIC COATINGS, IT WAS DISCLOSED THAT LARGER AGGREGATE PARTICLES MAY CONTRIBUTE TO SOME NON-UNIFORMITY IN STRAIN DISTRIBUTION, BUT THEY DO NOT SEEM TO BE THE CENTER OF MAJOR STRAIN CONCENTRATIONS. TIME-DEPENDENT STRAIN DISTRIBUTION IN CONCRETE IS NON-UNIFORM. /AUTHOR/

  • Supplemental Notes:
    • No R333-111,84 PP,
  • Corporate Authors:

    Naval Civil Eng Lab, Port Hueneme /US

    ,    
  • Authors:
    • Keeton, J R
  • Publication Date: 1965-5

Subject/Index Terms

Filing Info

  • Accession Number: 00212381
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 20 1994 12:00AM