腐蚀预应力混凝土梁抗剪性能试验

为研究预应力筋腐蚀对预应力混凝土梁抗剪性能的影响，设计制作了4片预应力混凝土梁，采用外加恒电流法对单侧弯剪区局部预应力筋进行了快速腐蚀，并对不同锈蚀程度混凝土梁进行了抗剪试验，分析了预应力筋腐蚀对梁开裂、变形、钢筋受力、破坏形态以及抗剪承载力的影响，并在试验基础上对锈蚀PC梁抗剪承载力计算方法进行了探讨。结果表明:相同剪跨比下预应力筋腐蚀对混凝土梁的破坏形态影响很小，但对构件裂缝发展影响较大，引起开裂荷载显著降低；开裂前，预应力筋腐蚀对其刚度影响较小；开裂后，腐蚀引起刚度退化较为明显；预应力筋腐蚀导致相同荷载下箍筋、纵筋应变增大，构件抗剪承载力退化；预应力筋腐蚀率为3.2%，7.9%，13.2%的混凝土梁抗剪承载力分别下降5.8%，9.1%，15.5%；考虑腐蚀预应力筋截面减小，采用《混凝土结构设计规范》(GB 50010—2010)公式对PC梁抗剪承载力计算具有较高的计算精度。

Experiment on Shear Behavior of PC Beams After Prestressed Tendons Corrosion

In order to study the influence of prestressed tendon corrosion on shear behavior of prestressed concrete (PC) beams, four PC beams were designed and manufactured. The prestressed tendon in the area of one-sided bending and shearing local zone was rapidly corroded by galvanostatic method, and the shear test was performed on the concrete beams with different corrosion rates of steel strands. The influence of corrosion of prestressed tendons on the cracking, deformation of steel beams, stress of reinforced bars, failure modes and shear bearing capacity were analyzed, and the calculation method of shear bearing capacity of corroded PC beams was discussed on the basis of test. The study results shows that the corrosion of prestressed tendons under the same shear-span ratio has little effect on the failure modes of concrete beams, but it has a greater impact on the development of component cracks, causing a significant reduction in cracking loads. Before cracking, the corrosion of prestressed tendon has little effect on its stiffness; after cracking, the stiffness degradation caused by corrosion is more obvious. Corrosion of prestressed tendon leads to the increased strains of stirrups and longitudinal reinforcement under the same load, it also leads to the degradation of shear capacity of components. The shear strength of concrete beam with corrosion rates of 3.2%, 7.9%, and 13.2%, respectively, decreases by 5.8%, 9.1%, and 15.5% compared to that of un-corroded beams. Considering reduction of cross section of corroded prestressed tendons, the calculation formula for shear strength of PC beams in Code for Design of Concrete Structures (GB 50010—2010) has high accuracy.