摘要
锈蚀和疲劳荷载共同影响下的材料复合损伤机理十分复杂,会显著降低既有钢筋混凝土桥梁的使用寿命。为了能够准确地预测锈蚀钢筋混凝土梁的疲劳寿命,通过从材料到钢筋混凝土构件的跨尺度分析,提出了一种基于材料失效机理的锈蚀钢筋混凝土梁疲劳寿命评估方法。该方法以断裂力学和等效初始裂纹理论为基础,并且可以同时考虑钢筋的不同锈蚀形态。结合锈蚀钢筋的疲劳拉伸试验结果,提出了不同锈蚀水平下的应力集中因子表达式,结果表明随锈蚀率的增长,应力集中因子先增大后减小。然后将局部锈蚀导致的应力集中的影响融入到应力强度因子计算模型中;通过对试验数据进行拟合得到了钢筋疲劳裂纹速率增长分析模型,对该模型从等效初始裂纹尺寸到临界裂纹长度进行积分来实现钢筋混凝土梁的疲劳寿命预测。为了验证本评估方法的有效性,开展了电化学快速锈蚀钢筋混凝土梁的疲劳性能试验,试验梁失效形式均为受力主筋的疲劳断裂;采用扫描电子显微镜对疲劳失效后的锈蚀钢筋断口形貌进行了微观分析,对比了不同锈蚀程度下钢筋疲劳裂纹扩展形式的差异。将理论计算结果与本研究试验和已有文献中的试验值进行了比较,二者吻合较好,可为日后钢筋混凝土桥梁的腐蚀疲劳寿命评估提供科学依据。
The composite damage of materials under the coupled effect of corrosion and fatigue is very complex,significantly reducing the service life of reinforced concrete beams.To accurately predict the fatigue life of corroded RC beams,a material failure mechanism-based fatigue life assessment method for corroded RC beams is proposed by the cross-scale analysis of material and members.The method is based on the fracture mechanics and equivalent initial crack theory,and also considers different corrosion types of steel bars.Combing the fatigue tensile test result of corroded steel bars,an expression of stress concentration factor under different corrosion levels is presented.It shows that the stress concentration factor increases first then decreases as the corrosion rate decreases.Then the effect of stress concentration caused by pitting corrosion is incorporated into the stress intensity factor calculation model.A fatigue crack growth rate increment model of steel bars is fitted by experimental data.The fatigue life of RC beam is predicted by the integration from the equivalent initial crack size to the critical length.In order to verify the effectiveness of the prediction method,the fatigue test on the electrochemistry accelerated corroded RC beams are performed,and the failure modes of test beams are fatigue fracture of the longitudinal steel bars.Fatigue fracture morphology analysis of corroded reinforcement after fatigue failure is conducted by scanning electron microscope.The difference of fatigue crack propagation types under various corrosion levels is compared.Comparisons between the theoretical prediction and experimental result that available in our study and open literatures are performed,and a good agreement is observed,which may provide a reference for the corrosion fatigue life assessment of RC bridges.
作者
马亚飞
王磊
张建仁
MA Ya-fei;WANG Lei;ZHANG Jian-ren(School of Civil Engineering,Changsha University of Science & Technology,Changsha Hunan 410114,China)
出处
《公路交通科技》
CAS
CSCD
北大核心
2019年第4期80-87,共8页
Journal of Highway and Transportation Research and Development
基金
国家自然科学基金项目(51508036
51478050)
国家重点基础研究发展计划(九七三计划)项目(2015CB057705)
长沙市杰出创新青年培养计划项目(kq1802012)
湖南省教育厅科学研究项目(17B012)
关键词
桥梁工程
疲劳
等效初始裂纹原理
锈蚀
裂纹扩展
bridge engineering
fatigue
principle of equivalent initial crack
corrosion
crack growth
