中文摘要：

采用与实际氯盐环境腐蚀效果更为接近的内掺盐加速腐蚀方式,制作4根不同掺盐率的钢绞线预应力混凝土梁试件并放置90d以产生不同程度的腐蚀,然后对腐蚀梁试件进行疲劳加载直至出现断丝破坏,其中在每1×10~5次疲劳作用后进行1次静力加载试验,以考察疲劳破坏、疲劳寿命退化以及弯曲刚度退化等特征。结果表明：钢绞线表现出典型的坑蚀特征;坑蚀钢丝在疲劳作用下会出现多个疲劳裂纹,其中1个裂纹最终发展至瞬断而成为梁疲劳破坏的标志;钢丝疲劳断口呈现出典型的宏观脆性断口特征,断口表面清晰可见蚀坑区、疲劳断裂区及瞬断区;梁的疲劳寿命随掺盐率增加呈指数函数关系退化;疲劳作用导致腐蚀梁的荷载-挠度曲线由前、后2个刚度不同但都近似呈直线的区段组成;氯盐作用和疲劳作用愈强,二者叠加引起梁的刚度退化也愈显著。

英文摘要：

The accelerated corrosion method of mixing salt into concrete which had a similar corrosion result with the situation of actual chloride environment was used.Four prestressed concrete beams with steel strands and different salt contents were fabricated and placed for 90 dto achieve different corrosion degrees.Then the corroded specimens were loaded in fatigue until to failure with one steel wire fracturing,and a static loading test was executed after every 1×10~5 times fatigue loading.Based on the experiment,the characteristics of fatigue failure,fatigue life degradation and flexural rigidity degradation were studied.The results show that the steel strands are corroded in typical pitting appearance.Multiple fatigue cracks appear on the pitting corroded wires under the action of fatigue,and one of them develops to fracture ultimately and marks the failure state.The fatigue fractures of wires show typical macro-brittle characteristic.The pitting corrosion region,fatigue fracture region and final fracture region are presented clearly in the fatigue fractures.The fatigue life degenerates in the exponential function law with the increase of salt content.For the influence of fatigue action,the load-deflection curve of corroded beam is changed to be composed with two approximate straight lines with different slopes.The stronger the chloride action and fatigue action are,the more prominent the rigidity of the beam degenerates.