Prediction of Transfer Lengths Inclusive of Conventional and High-Strength Strands

Abstract

Twelve concrete prisms pretensioned with 2,400-MPa strands were fabricated to investigate the effects of initial prestress (fpi), concrete compressive strength at prestress release (fci′), and the spacing of the lateral confining reinforcement (S) on the transfer length. Test results showed that the transfer length increased with an increase in fpi and with decreases in fci′ and confinement level. A theoretical model incorporating rigid-linear local bond-slip relationships was developed and validated by its reasonable predictions of the distributions of the measured concrete strains in the transfer region. Based on the theoretical model, predictive formulas of transfer length were derived for both conventional and high-strength strands. © 2020 American Society of Civil Engineers.