CREEP IN PRESTRESSED LIGHTWEIGHT CONCRETE

A PROCEDURE, USING THE RATE-OF-CREEP METHOD, IS DEVELOPED FOR PREDICTING CREEP STRAINS, CAMBER, AND PRESTRESS LOSS IN PRETENSIONED, PRESTRESSED CONCRETE HIGHWAY BRIDGE BEAMS. THE PROCEDURE USES SHRINKAGE DATA AND CREEP PER PSI DATA, BOTH EXPRESSED AS FUNCTIONS OF TIME, DEVELOPED FROM SMALL CONCRETE SPECIMENS. NON-LOADED PRETENSIONED PRESTRESSED LIGHTWEIGHT CONCRETE BEAMS 5 X 8 IN. IN SECTION, 8 FT. LONG, WERE USED TO TEST THE PROCEDURE. CREEP AND PRESTRESS LOSSES TAKEN FROM THE BEAMS WERE COMPARED WITH VALUE PREDICTED BY USING THE PROCEDURE DEVELOPED IN THE PAPER. THE METHOD WAS EXTENDED TO ACCOMODATE PRECAST PRESTRESSED BEAMS WITH CAST- IN-PLACE REINFORCED CONCRETE SLABS, AND LABORATORY BEAMS WERE TESTED TO VERIFY THE PROCEDURES. A FULL SIZE HIGHWAY BEAM AND SLAB WERE INSTRUMENTED IN FIELD INSTALLATION TO CHECK OUT TECHNIQUES PROPOSED FOR USE IN A FULL SIZE HIGHWAY BRIDGE INSTALLATION. A FULL SIZE HIGHWAY BRIDGE USING PRECAST PRESTRESSED BEAMS AND CAST-IN-PLACE SLABS WAS INSTRUMENTED FOR PURPOSES OF TESTING THE PREDICTION METHOD. DATA FROM BEAMS HAS BEEN COLLECTED FOR APPROXIMATELY ONE YEAR. THE SLAB WAS BEING READIED FOR PLACING AT THE TIME OF WRITING. CREEP, SHRINKAGE, CAMBER, AND PRESTRESS LOSSES WERE TAKEN BY MEASUREMENTS OF STRAIN AND ELEVATIONS FROM THE BRIDGE BEAMS. PREDICTED CREEP, CAMBER, AND PRESTRESS LOSS BASED ON DATA FROM SMALL SPECIMENS ARE COMPARED WITH DATA DEVELOPED FROM MEASUREMENTS WITH THE 10IN. MECHANICAL STRAIN GAGE AND AN ENGINEERS LEVEL. REASONABLE AGREEMENT IS REACHED BETWEEN PREDICTIONS AND MEASUREMENTS. PRESTRESS LOSSES IN LIGHTWEIGHT FULL SIZE BRIDGE BEAMS ARE APPROXIMATELY 23% AND FOR NORMAL WEIGHT, APPROXIMATELY 14% AT 300 DAY AGE. /AUTHOR/

• Supplemental Notes:
  • Rr 69-2, pp 1-153, 70 FIG, 12 TAB, 25 REF, 3 APP
• Corporate Authors:

  Texas Transportation Institute

  Texas A&M University System, 1600 E Lamar Boulevard
  Arlington, TX  United States  76011

  Texas State Department of Highways & Public Transp

  11th and Brazos Streets
  Austin, TX  United States  78701
• Authors:
  • Furr, H L
  • Sinno, R
• Publication Date: 1967-10

Subject/Index Terms

• TRT Terms: Beams; Bridge construction; Bridge foundations; Bridges; Cast in place structures; Concrete; Concrete tests; Construction; Creep; Curvature; Highway bridges; Lightweight concrete; Precast concrete; Prestressed concrete; Reinforced concrete; Shrinkage; Test procedures; Time
• Uncontrolled Terms: Concrete beams
• Old TRIS Terms: Concrete creep
• Subject Areas: Bridges and other structures; Construction; Highways;

Filing Info

• Accession Number: 00208466
• Record Type: Publication
• Files: TRIS, STATEDOT
• Created Date: Jun 18 1994 12:00AM