Prediction of corrosion-induced retraction slip of prestressing strand in pre-tensioned concrete beams

An experimental study is conducted on ten pre-tensioned concrete (PC) beams with different local corrosion degrees and positions to investigate the effect of corrosion on the transfer length and retraction slip of prestressing strand. A novel model, incorporating the combined effects of Hoyer effect and strand corrosion, is proposed to predict the corrosion-induced retraction slip of prestressing strand in PC beams. The accuracy of the proposed model is validated by experimental results. Results indicate that the transfer length and retraction slip of prestressing strand increase with the increase of corrosion loss, and this effect weakens when the local corrosion position changes from the end of the beam to the mid-span of the beam. The transfer length and retraction slip of prestressing strand increase by 30.6% and 5.18 times, respectively, once the corrosion loss reaches 33.5%. The retraction slip of corroded prestressing strand is positively correlated with the diameter of strand, but negatively correlated with the compressive strength of concrete. The diameter of strand, compared with the compressive strength of concrete, has a more significant effect on the corrosion-induced retraction slip.