FRICTION LOSS IN POST TENSIONED PRESTRESSED STEEL UNITS

A FIELD INVESTIGATION OF FRICTION LOSSES IN POST TENSIONED PRESTRESSING CABLES WAS CONDUCTED. THE CABLES WERE IMBEDDED IN A THREE-SPAN CONTINUOUS BOX GIRDER STRUCTURE, 360 FEET LONG, AND HORIZONTALLY CURVED. THREE DIFFERENT POST TENSIONING SYSTEMS WERE USED EMPLOYING BOTH BRIGHT AND GALVANIZED TENDONS AND DUCTS. WATER SOLUBLE OIL WAS USED AS A LUBRICANT ON FOUR OF THE TEN RESEARCH TENDONS IN ORDER TO DETERMINE THE OILS EFFECTIVENESS IN REDUCING FRICTION. JACKING FORCES WERE MEASURED WITH LOAD CELLS AS WELL AS STRAIN GAGES FASTENED TO THE TENDONS. MAJOR CONCLUSIONS FROM THE STUDY WERE' /1/ THE FRICTION COEFFICIENTS LISTED IN THE 1961 AASHO BRIDGE SPECIFICATIONS ARE APPLICABLE TO THIS TYPE OF STRUCTURE. /2/ THE OVERALL EXPERIENCE WITH STRAIN GAGES MOUNTED ON THE TENDONS WAS NOT VERY SATISFACTORY. INSTEAD, THE USE OF LOAD CELLS AT BOTH ENDS OF A TENDON IS RECOMMENDED FOR THE ACCURATE MEASUREMENT OF THE TOTAL FRICTION LOSS. /3/ FOR SOME OF THE TENDON-CASING COMBINATIONS, LUBRICATION APPEARED TO REDUCE THE FRICTION LOSS. HOWEVER, IT WAS NOT POSSIBLE TO COMPLETELY FLUSH OUT ALL THE OIL FROM THE CASINGS PRIOR TO GROUTING, AND POOR BONDING RESULTED BECAUSE OF THIS. /BPR/

• Supplemental Notes:
  • Hpr-1/2/, DO-4-03
• Corporate Authors:

  California Division of Highways

  Bridge Department
  Sacramento, CA  United States  05914
• Authors:
  • Bezouska, T J
• Publication Date: 1966-9

Subject/Index Terms

• TRT Terms: Box girders; Bridge superstructures; Cables; Field studies; Friction; Load cells; Losses; Oils; Posttensioning; Prestressing; Steel; Strain gages; Tendons
• Uncontrolled Terms: Bridge spans
• Subject Areas: Bridges and other structures; Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00207811
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS
• Created Date: Dec 1 1994 12:00AM