混凝土梁内坑蚀钢筋的疲劳断裂特性及其压磁表征研究  

Research on fatigue fracture characteristics of pitting-corroded reinforcement in concrete beam and its piezomagnetic characterization

作　　者：张军[1] 张凯 金伟良[2] 毛江鸿[3] 钟小平 叶霄翔 Zhang Jun;Zhang Kai;Jin Weiliang;Mao Jianghong;Zhong Xiaoping;Ye Xiaoxiang(NingboTech University,Ningbo 315100,China;Zhejiang University,Hangzhou 310058,China;Sichuan University,Chengdu 610065,China;Yangzhou University,Yangzhou 225009,China)

机构地区：[1]浙大宁波理工学院,浙江宁波315100 [2]浙江大学,浙江杭州310058 [3]四川大学,四川成都610065 [4]扬州大学,江苏扬州225009

出　　处：《土木工程学报》2023年第2期34-45,共12页China Civil Engineering Journal

基　　金：国家自然科学基金(51908496,51820105012,51878610,52178171,51638013);浙江省自然科学基金(LQ19E080011)。

摘　　要：文章开展带蚀坑纵筋的混凝土梁疲劳试验,实时测量和分析坑蚀钢筋的压磁信号。研究结果表明:纵向钢筋在跨中蚀坑处的脆性断裂引发梁的疲劳失效,蚀坑会严重降低混凝土梁的疲劳寿命;跨中挠度、混凝土压应变和压磁信号均符合疲劳三阶段的变化规律,压磁滞回曲线变幅能够反映梁中坑蚀钢筋的疲劳损伤进程。基于断裂力学方法预测了梁内坑蚀钢筋的疲劳裂纹扩展过程,并通过建立压磁信号和钢筋蚀坑处应力强度因子的定量关系获取混凝土内坑蚀钢筋疲劳裂纹扩展速率,发现断裂力学方法和文章压磁方法预测的裂纹扩展结果基本一致且压磁信号对混凝土梁内坑蚀钢筋疲劳裂纹扩展很敏感。研究结果有望为基于压磁方法评估锈蚀钢筋混凝土梁疲劳损伤提供依据。The fatigue experiments of reinforced concrete(RC)beams with pitting-corroded longitudinal reinforcement were conducted.Piezomagnetic signals and compressive strain of concrete were measured in real-time.The experimental results indicate that:the brittle fracture of longitudinal reinforcement in concrete beam at the corrosion pit may induce the failure of beam.The corrosion pit may cause a serious reduction in the fatigue life of concrete beam;the variations of piezomagnetic signals,concrete compressive strain and mid-span deflection conform to the three-stage law of fatigue.The amplitude of the piezomagnetic hysteresis curve could reflect the fatigue damage process of the pitting-corroded steel bar embedded in the concrete.The fatigue crack propagation process was predicted based on fracture mechanics method,and the quantitative correlations between the piezomagnetic signals and the stress intensity factor at the root of corrosion pit were further established.Thus,the fatigue crack growth rate of pitting-corroded steel bar in concrete can be obtained.The fatigue crack propagation predicted by piezomagnetic method in this work was basically consistent with that predicted by the fracture mechanics method.The sensitivity of piezomagnetic signals to fatigue crack propagation of corroded steel bar in concrete was analyzed,and the research results can provide a basis for evaluating the fatigue damage of corroded reinforced concrete beams based on the piezomagnetic method.

关 键 词：钢筋混凝土 蚀坑钢筋 疲劳裂纹扩展 压磁信号 应力强度因子 

分 类 号：TU375.1[建筑科学—结构工程]