Evaluation of Bond Mechanics in Prestressed Concrete Applications
Successful designs of prestressed structural elements include
considerations for transfer and development lengths of prestressing
strand. The effectiveness of bond strength at the strand-concrete
interface controls the transfer and development lengths.
Three major mechanisms contribute to bond strength: adhesion at the
strand-concrete interface, frictional forces enhanced by radial forces in
the strand at prestress release (the Hoyer effect), and mechanical
resistance (interlock) due to axial bearing forces on the helical strand.
Current tests for bond strength use untensioned strand and thus only
incorporate adhesion and interlock mechanisms in the specimen. In this
research program, several tests will determine the relative contribution
of each of these three major mechanisms.
The research program includes testing on self consolidating
concrete (SCC) and high early strength concrete (HESC) specimens to
compare the effectiveness of bond strength development in each material.
Other influences, like the affect of confining reinforcement on strand
length development, will also be explored through additional specimen
Clay Naito, Principal Investigator
Tyler Tate, Graduate Student Researcher
Pennsylvania Infrastructure Technology Alliance
Schuylkill Products, Inc.
1. Tate, T., and Naito, C., "Evaluation of Bond Mechanics in Prestressed
Concrete Applications," ATLSS Report No.05-09, ATLSS Center, Lehigh University,
July 2005, 134 pages.
Page Last Updated Friday, 24-Jun-2005 18:23:32 EDT