END CRACKING IN PRESTRESSED MEMBERS DURING DETENSIONING

This report is concerned with an investigation to determine analytically as well as experimentally the theory that end cracking observed during prestress transfer in pretensioned operations is caused by tensile stress induced by the restraining effect of relatively short length of unbonded cables. Production line prestressed members were monitored for strain increase during detensioning and the castings were measured for elastic shortening. Results were compared with an analytic model capable of furnishing cable strains during any detensioning scheme in a multiple casting operation. Full scale experimental members were designed such that during transfer tensile stress in concrete due to cable restraint would be maximized. Cracks were indeed caused as predicted by analytic calculations. Finally as an example problem, full scale production line girders were monitored for cable strain during detensioning and compared with analytically calculated values.

• Supplemental Notes:
  • Sponsored in part by North Carolina Dept. of Transportation and Highway Safety, Raleigh and Federal Highway Administration, Raleigh, N.C. North Carolina Div.
• Corporate Authors:

  North Carolina State University, Raleigh

  Highway Research Program, P.O. Box 5993
  Raleigh, NC  United States  27607

  North Carolina Department of Transportation

  P.O. Box 25201, 1 South Wilmington Street
  Raleigh, NC  United States  27611

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Mirza, J F
  • Tawfik, M E
• Publication Date: 1976-7

Media Info

• Pagination: 86 p.

Subject/Index Terms

• TRT Terms: Analysis; Beams; Cables; Casting; Cracking; Flame cutting; Fracture mechanics; Girders; Mathematical models; Mechanical strain; Numerical analysis; Prestressed concrete; Prestressing; Pretensioning; Reinforced concrete; Reinforcing steel; Sheathing; Stresses; Tension; Tensioning
• Uncontrolled Terms: Crack propagation; Models; Reinforced concrete beams; Stress concentration; Tensile stress
• Old TRIS Terms: Analytical method; Strains
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00154783
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: FHWA/ERSD-110-75-6 Final Rpt., ERSD-110-75-6
• Files: NTIS, TRIS, USDOT, STATEDOT
• Created Date: Jun 17 1977 12:00AM