腐蚀钢绞线预应力混凝土梁的弯曲疲劳性能退化特征

发布时间：2019-04-25 16:43

【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。
[Abstract]:In order to produce different degree of corrosion, four specimens of steel strand prestressed concrete beams with different ratio of salt were made and placed for 90 days, which is more similar to the actual corrosion effect in the environment of chloride salt, and the corrosion of prestressed concrete beams with different ratio of salt is produced by using the accelerated corrosion method with internal salt admixture. Then the corrosion beam specimens are subjected to fatigue loading and then broken wire, in which one static loading test is carried out after every 1 脳 10 ~ 5 times fatigue action to investigate the characteristics of fatigue failure, fatigue life degradation and bending stiffness degradation. The results show that the steel strands exhibit typical pitting corrosion characteristics, and many fatigue cracks will appear under the fatigue action of the steel wire, in which one crack will eventually develop to instantaneous fracture and become the symbol of fatigue failure of the beam. The fatigue fracture surface of steel wire is characterized by typical macroscopic brittle fracture surface, such as corrosion pit zone, fatigue fracture zone and instantaneous fracture area, and the fatigue life of the beam degrades exponentially with the increase of salt doping rate, and the fatigue life of the steel wire decreases exponentially with the increase of salt content. Fatigue causes the load-deflection curve of corroded beam to be composed of two sections with different stiffness but approximately straight line, and the stronger the action of chloride and fatigue is, the more obvious the stiffness degradation of the beam is caused by the superposition of the two kinds of curves.
【作者单位】：中国矿业大学江苏省土木工程环境灾变与结构可靠性重点实验室;南通航运职业技术学院交通工程系;
【基金】：国家自然科学基金项目(51178454) 徐州市科技基金项目(XM13B125)
【分类号】：TU378.2

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