Title: Transfer Length of Strands in Prestressed Concrete Piles

Author(s): Baolin Wan, Kent A. Harries, and Michael F. Petrou

Publication: Structural Journal

Volume: 99

Issue: 5

Appears on pages(s): 577-585

Keywords: development length; pile; prestressed concrete; slip; strand; transfer length

DOI: 10.14359/12297

Date: 9/1/2002

Abstract:
A top bar effect has been identified in prestressed concrete piles. The effect that this top bar effect has on the development of the prestressing strand is investigated. Strand transfer length is found to be proportional to the observed end slip. While the average transfer length of all strands in a section may satisfy the assumptions inherent in the ACI transfer length equation, due to the top bar effect, top-cast strand transfer lengths are considerably in excess of the ACI-calculated value. The flexural behavior of the pile, accounting for varying transfer lengths through its section, is investigated. Finally, recommendations for in-plant testing and acceptance criteria for prestressed strand bond quality are proposed.