考虑黏结性退化的锈蚀PC梁抗弯承载力计算方法∗

钢绞线锈蚀降低了其与混凝土间的黏结性，导致钢绞线与其周围混凝土间的变形不协调，影响预应力混凝土梁的抗弯性能。采用快速锈蚀试验得到了不同锈蚀程度的16个有箍筋和无箍筋拉拔试件，通过拉拔试验得到了试件开始滑移及破坏时的拉拔力；回归了黏结折减系数与锈蚀率之间的关系式，并将其融入到预应力混凝土梁的抗弯承载力分析模型中，提出了考虑黏结性退化的锈蚀预应力混凝土梁抗弯承载力计算方法。试验结果表明：有箍筋试件的黏结强度大于无箍筋试件；随着钢绞线锈蚀水平的增大，箍筋对黏结强度退化的约束作用逐渐减小；黏结折减系数随锈蚀率的增加呈指数函数规律递减。将理论值与本文及已有文献中锈蚀预应力混凝土梁抗弯性能试验结果进行了比较，计算结果表明本方法预测精度较高，最大误差在6%以内，验证了本抗弯承载力计算方法的适用性，可为服役预应力混凝土桥梁抗弯承载力评估提供参考。

Calculation Method for Flexural Capacity of Corroded PC Beams Considering Bond Degradation

Strand corrosion degrades the bond behavior between the strand and concrete, resulting in deformation incompatibility between the strand and surrounding concrete and affecting the flexural performance of the prestressed concrete beams. Sixteen pull-out specimens with and without stirrups under different strand corrosion levels are obtained by accelerated corrosion test. The pull-out forces corresponding to the initial slip and failure are measured, respectively. The relationship between the bond degradation coefficient and strand corrosion loss is regressed. Following this, a modified calculation method for the flexural capacity of corroded prestressed concrete beams considering bond degradation is proposed by incorporating the bond degradation coefficient. The experimental results show that the bond strength of the pull-out specimens with stirrup is larger than that of without stirrup. The effect of the stirrup on the deterioration of bond strength decreases as corrosion loss increases. The bond degradation coefficient decreases exponentially with the increase of strand corrosion loss. The theoretical values are compared with the test results of corroded prestressed concrete in this paper and those available in the published literatures. The calculation results show that the method has a higher prediction accuracy, and the maximum error is less than 6%, which demonstrates the applicability of the presented method. The proposed method may provide a reference for the evaluation of the bending bearing capacity of existing prestressed concrete bridges.