中文摘要：

采用超声波检测仪和基于超声波速自定义的损伤变量对杂散电流环境下钢筋混凝土梁弯曲疲劳损伤过程进行实时跟踪研究。结果表明：定义的损伤变量对杂散电流与疲劳荷载共同作用下钢筋混凝土梁损伤发展状态较敏感,能够有效跟踪损伤不同发展阶段。损伤变量跟踪显示：杂散电流环境下钢筋混凝土梁弯曲疲劳损伤过程,与一般大气环境下弯曲疲劳损伤过程类似,具有明显3阶段特性,即初始快速增加、稳定增加和临近破坏的急速增加;随杂散电流强度增大,钢筋混凝土疲劳损伤发展加快。疲劳断裂试件表明：杂散电流环境下混凝土梁弯曲疲劳损伤劣化进程加速,主要是由于杂散电流与氯离子一样会引发混凝土中钢筋发生电化学腐蚀,且与疲劳荷载构成损伤劣化耦合作用。

英文摘要：

Real-time investigation of the damaging development of reinforced concrete（RC） beams under coupling loads of stray current and flexural fatigue was carried out by using the ultrasonoscope and the self-defined damage variable based on the transverse ultrasonic wave velocity.The results show that the damage variable is sensitive to the damage progressing states of RC beams under the coupling loads and can be used to effectively trace the different stages of damage growth.Tracing of the damage variable shows as follows： The damaging process of the RC beams under the coupling loads,as that of the RC beams in the general atmospheric environment is characterized by three distinguished stages,viz,the initial stage of fast growth,the stage of steady growth and the final stage of rapid growth close to failure;the stronger the stray current,the faster the development of fatigue damages.The broken beam specimen indicates the flexural fatigue damage and deterioration of the beam specimen speed up with stray currents.This is mainly due to the electrochemical corrosion induced by stray current in the rebar of concrete as by chloride ions and its coupling effects with the flexural fatigue loads.