Debonded Strands in Prestressed Concrete Bridge Girders

  • Some prestressing strands are draped to reduce the strand eccentricity at the ends of the beams. This process is time-consuming, costly and challenging for fabricators.
  • Debonding sleeves protect prestressing strands from bonding with concrete, reducing stress and cracking at beam ends.

Status:  Complete
Report Date:  07/29/2019

Summary:

Debonding and draping the steel strands in prestressed concrete beams are two methods of reducing beam end stresses while still getting the benefit of prestressing. Local beam manufacturers consider draping a technical and safety challenge that increases concrete cost and fabrication time. MnDOT, on the other hand, has not deployed debonding because of concerns that water and salt will enter the beam ends along the debonded strands and cause corrosion. Research on the state of the practice found that many transportation agencies facing climates similar to Minnesota's use debonding successfully with little impact from corrosion. The study recommends MnDOT begin the practice starting with a limit where up to 40 percent of the strands may be debonded.

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