氯盐环境下锈蚀预应力混凝土梁抗弯性能试验

为探讨氯盐环境下锈蚀预应力混凝土梁的抗弯性能，制作了5根先张预应力混凝土梁，采用电化学法分别对其进行了0 d、7 d、14 d、28 d及42 d的快速腐蚀，随后进行了四点弯曲试验。研究了不同锈蚀程度对预应力混凝土梁自振频率、钢绞线滑移、结构变形、弯曲开裂、破坏模式及极限承载力等性能的影响。结果表明:氯盐环境下锈蚀对预应力混凝土梁高阶频率影响较小，导致一阶频率逐渐增大，28 d后锈蚀裂缝较大且局部混凝土脱落，一阶频率迅速减小；轻微腐蚀对预应力混凝土梁的抗弯性能影响较小，腐蚀程度增大，抗弯性能明显降低，腐蚀42 d后，极限挠度减小了18.7%，抗弯承载力减小了17.3%，延性降低了19%；锈蚀钢绞线与混凝土间滑移速率增大，极限滑移值由5 μm增加至11.4 μm；钢筋锈蚀对弯曲裂缝高度发展的影响不大，但促进了裂缝宽度的扩展，结构屈服后，底部裂缝开裂速率由0.0062 mm/kN增加至0.0252 mm/kN。在试验研究基础上，采用有限元软件ANSYS对各锈蚀梁的受载全过程进行了有限元模拟计算，极限荷载和钢绞线滑移量的模拟值与实测值误差分别小于5%和10%，吻合较好。 

Flexural behavior test of corroded prestressed concrete beams under chloride environment

In order to study the flexural capacity of corroded prestressed concrete beams under chloride environment, five pretensioned prestressed concrete beams were manufactured, and subjected to accelerated corrosion for 0 d, 7 d, 14 d, 28 d and 42 d by electrochemical method, then four points bending tests were carried out on all beams. The influence of different corrosion level on the natural frequency of prestressed concrete beams, the slip of steel strands, the structural deformation, crack propagation, failure mode and ultimate bearing capacity were researched. The results indicate that corrosion in chloride environment affects slightly the high-order frequency of prestressed concrete beams, and increases the first natural frequency of prestressed concrete beams. After 28 d, the corrosion cracks are large and part of the concrete falls off, the first natural frequency decreases rapidly. Slight corrosion has little effects on flexural behavior of prestressed concrete beams, and the flexural behavior decreases significantly with the increase of corrosion level. After 42 d corrosion, the ultimate deflection decreases by 18.7%, the flexural capacity decreases by 17.3%, and the ductility decreases by 19%. The slip rate between the corroded steel strand and concrete increases, and the ultimate slip value increases from 5 μm to 11.4 μm. Corrosion affects slightly the development of crack height, and promotes the expansion of crack width. After yielding, the cracking rate of bottom cracks increase from 0.0062 mm/kN to 0.0252 mm/kN. Based on the test, the loading process of corroded beam was simulated through finite element software ANSYS, the errors of ultimate load and ultimate slip value between the simulated value and the experimental value are less than 5% and 10%, respectively, the simulated values are in good agreement with the experimental data.