锈蚀钢筋疲劳断裂性能研究

发布时间：2018-01-14 21:06

本文关键词：锈蚀钢筋疲劳断裂性能研究　出处：《中南大学》2014年硕士论文　论文类型：学位论文

【摘要】：在有害介质侵蚀环境下钢筋混凝土构件的疲劳性能,是研究工程结构耐久性问题的一个重要方面。在锈蚀与疲劳复合作用下,钢筋混凝土构件的破坏往往是锈蚀钢筋的疲劳断裂。本文基于裸露钢筋的腐蚀试验和钢筋锈蚀后静力拉伸与疲劳试验,探讨钢筋的点蚀演化规律及锈蚀后的力学性能变化规律,分析锈蚀对钢筋疲劳寿命的影响。主要研究工作如下： (1)对钢筋试件进行了自然锈蚀试验,试验结果表明：钢筋的蚀坑形貌由为窄而深的半椭球体渐渐发展为浅而宽的长椭球体,个别蚀坑可发展为浅宽的凹槽体。 (2)对锈蚀后构件进行了静力拉伸、疲劳拉伸试验及断口分析。对于锈蚀钢筋,其静力性能发生了退化且锈蚀对疲劳寿命有显著的降低作用；静力拉伸断口可分为正断和切断,疲劳拉伸断口可分为疲劳源区、疲劳裂纹扩展区和瞬时断裂区,疲劳裂纹萌生于试样近表面的材料蚀坑根部,并呈扇形向四周扩展。 (3)通过腐蚀后裂尖的应力场分析得到锈蚀钢筋疲劳裂纹扩展门槛值变化规律,结合混凝土中钢筋的点蚀演变规律,定量分析了混凝土中钢筋的疲劳裂纹扩展门槛值。 (4)依据Paris公式推导出锈蚀钢筋疲劳寿命模型,对锈蚀钢筋疲劳试验进行实例计算,计算结果表明：钢筋疲劳寿命对材料的断裂韧性并不敏感,其值主要取决于裂纹扩展前的初始长度与形状参数。基于锈蚀钢筋的疲劳试验,提出侵蚀环境下钢筋混凝土结构疲劳寿命的预测模式。图45幅,表17个,参考文献77篇
[Abstract]:The fatigue performance of reinforced concrete members under the corrosive environment of harmful medium is an important aspect of studying the durability of engineering structures . Under the action of rust and fatigue , the damage of reinforced concrete members is often the fatigue fracture of corroded steel bars . Based on the corrosion test of bare steel bar and the static tension and fatigue test after reinforcement corrosion , the law of pitting evolution and the change law of mechanical properties after corrosion are discussed . The influence of rust on fatigue life of steel bars is analyzed . The main research work is as follows : ( 1 ) The test of natural corrosion on the reinforced concrete specimens is carried out . The test results show that the shape of the corrosion pits of the steel bars is gradually developed into a shallow and broad - long ellipsoid with a narrow and deep semi - ellipsoidal body , and the individual etching pits can be developed into shallow groove bodies . ( 2 ) Static tension , fatigue tensile test and fracture analysis are carried out on the corrosion - resistant members . The static properties of the corroded steel bars are degraded and the corrosion has a significant reduction in fatigue life . The static tensile fracture can be divided into the fatigue source region , the fatigue crack propagation region and the transient fault zone , and the fatigue crack is formed on the root of the material etching pit near the sample near surface , and is expanded in a fan shape . ( 3 ) The change law of fatigue crack propagation threshold value of corroded steel bar is analyzed by the stress field analysis of the back crack tip , and the fatigue crack propagation threshold value of the steel bar in the concrete is quantitatively analyzed in combination with the law of the point erosion evolution of the steel bar in the concrete . ( 4 ) According to Paris formula , the fatigue life model of corroded steel bars is deduced , and the fatigue test of corroded steel bars is calculated . The results show that the fatigue life of steel bars is not sensitive to the fracture toughness of the material .

【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375

【参考文献】