Bond model of 15·2 mm strand with consideration of concrete creep and shrinkage

Abstract

The bond between prestressing strands and concrete in the transfer zone of pretensioned concrete members is a complicated mechanism. Concrete creep and shrinkage are dominant time-dependent factors that affect the strand bond. In this study, a semi-analytical bond stress–slip model was developed, based on test results of the standard test for strand bond for 15·2 mm strands. Effects of concrete creep and shrinkage are incorporated in the model. Measured transfer lengths collected from the literature are compared with predicted values, to validate the accuracy of the bond stress–slip model. Analytical results indicate that the strand bond decreases over time, and is almost constant after 360 d of age. An equation is proposed to predict the transfer length of the prestressing strand at 28 d, with an incorporation of concrete creep and shrinkage effects.