The corrosion morphology and the mechanical behavior of corroded prestressing strands are investigated in the present study. Nineteen corroded strands are obtained through controlling stress level, corrosion time and chloride ion concentration under artificial climate conditions. A total of 119 corrosion pits are counted to investigate the geometric morphology of corrosion pits. A depth-width ratio parameter is first defined to describe the distribution law of corrosion pits, which obeys the lognormal distribution. A tension test is conducted to investigate the mechanical behavior of corroded strands. The fracture morphology and micro-cracks of corroded steel wires are observed by the scanning electron microscopy. A constitutive model is proposed to predict the stress-strain curve of corroded prestressing strands and verified by the experimental results. Results show that the maximum corrosion loss of strand increases by 4.91% when the stress level changes from 45% to 75% of strand yield strength. The high stress level can promote the propagation of corrosion micro-cracks on strand surface. The propagation of corrosion micro-cracks has a significant effect on ultimate strength of strand, while has a little effect on elastic modulus. The proposed model can give an accurate prediction for the stress-strain of corroded prestressing strand.

本研究对腐蚀的预应力钢绞线的腐蚀形态和力学性能进行了研究。通过在人工气候条件下控制应力水平，腐蚀时间和氯离子浓度，可获得19条腐蚀的股。共计119个腐蚀坑，以研究腐蚀坑的几何形态。首先定义一个深宽比参数来描述腐蚀点的分布规律，该规律遵循对数正态分布。进行张力测试以研究腐蚀的股线的机械性能。通过扫描电子显微镜观察腐蚀的钢丝的断裂形态和微裂纹。提出了本构模型来预测腐蚀后的预应力钢绞线的应力-应变曲线，并通过实验结果进行了验证。结果表明，当应力水平从钢绞线屈服强度的45％变为75％时，钢绞线的最大腐蚀损失增加了4.91％。高应力水平可以促进腐蚀微裂纹在钢绞线表面上的扩展。腐蚀微裂纹的扩展对钢绞线的极限强度有显着影响，而对弹性模量的影响很小。所提出的模型可以对腐蚀的预应力钢绞线的应力应变给出准确的预测。高应力水平可以促进腐蚀微裂纹在钢绞线表面上的扩展。腐蚀微裂纹的扩展对钢绞线的极限强度有显着影响，而对弹性模量的影响很小。所提出的模型可以对腐蚀的预应力钢绞线的应力应变给出准确的预测。高应力水平可以促进腐蚀微裂纹在钢绞线表面上的扩展。腐蚀微裂纹的扩展对钢绞线的极限强度有显着影响，而对弹性模量的影响很小。所提出的模型可以为腐蚀后的预应力钢绞线的应力应变提供准确的预测。