A STUDY OF THE BEHAVIOR OF I - SECTION PRESTRESSED CONCRETE GIRDERS SUBJECT TO TORSION

THE REPORT PRESENTS RESULTS OF PURE TORSION TESTS ON THREE SERIES OF I-BEAMS AND ONE SERIES OF RECTANGULAR BEAMS. VARIABLES IN THE STUDY WERE THE LEVEL OF PRESTRESS AND THE AMOUNT OF WEB REINFORCEMENT. PRESENTLY AVAILABLE THEORIES ON THE BEHAVIOR OF PRESTRESSED CONCRETE MEMBERS SUBJECTED TO TORSION ARE REVIEWED. SOME OF THE RESULTS OF THE STUDY ARE AS FOLLOWS: (1) THE TORSIONAL STIFFNESS AT TORQUES LESS THAN ABOUT 80 PERCENT OF THE CRACKING TORQUE IS CLOSE TO THE CALCULATED VALUE, ASSUMING ELASTIC BEHAVIOR OF THE CONCRETE, (2) THE CRACKING TORQUE IS CONSERVATIVELY ESTIMATED BY A CALCULATION ASSUMING ELASTIC BEHAVIOR OF THE CONCRETE, AND CRACKING WHEN THE MAXIMUM PRINCIPAL TENSILE STRESS BECOMES EQUAL TO THE SPLIT-CYLINDER TENSILE STRENGTH, (3) CRACK WIDTHS ARE APPROXIMATELY PROPORTIONAL TO WEB REINFORCEMENT STRAIN, (4) PRESTRESS APPARENTLY INCREASES THE ULTIMATE TORQUE BY INCREASING THE CONTRIBUTION OF THE CONCRETE TO ULTIMATE TORQUE, AND (5) THE MINIMUM AMOUNT OF WEB REINFORCEMENT NECESSARY TO ENSURE THAT THE ULTIMATE STRENGTH OF THE CRACKED SECTION SHALL BE AT LEAST EQUAL TO THE CRACKING TORQUE IS THE SAME FOR PRESTRESSED CONCRETE AS FOR REINFORCED CONCRETE. /BPR/

• Supplemental Notes:
  • Hpr-1(6) PaRT II, ITEM 9
• Corporate Authors:

  University of Washington, Seattle

  Seattle, WA  United States  98195

  Washington State Department of Highways

  Olympia, WA  United States 

  Bureau of Public Roads /US

  400 7th Street, SW
  Washington, DC  United States  20590
• Authors:
  • Wyss, A N
  • Garland, J B
  • Mattock, A H
• Publication Date: 1968-10

Subject/Index Terms

• TRT Terms: Concrete; Cracking; Girders; I beams; Material reinforcement; Prestressed concrete; Prestressing; Rectangles; Stiffness; Tensile strength; Tension; Theory; Torsion tests; Webbing
• Uncontrolled Terms: Concrete cracking; Tensile stress
• Subject Areas: Bridges and other structures; Highways; Materials;

Filing Info

• Accession Number: 00207898
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS, STATEDOT
• Created Date: Mar 5 1994 12:00AM