多龄期桥梁斜拉索疲劳损伤演化声发射监测技术研究

Acoustic emission technique for momitoring stay cable fatigue damage evolution of multi-aged bridge

斜拉索在斜拉桥体系中有着举足轻重的作用,但易遭受腐蚀和疲劳累积损伤。目前对多龄期斜拉索腐蚀疲劳损伤演化规律的研究还较少。拟采用声发射技术监测国内某大桥腐蚀斜拉索疲劳损伤演化过程。首先,通过拉伸试验,得到了斜拉索中腐蚀钢丝和未腐蚀钢丝的应力-应变关系曲线,其实验结果表明腐蚀对斜拉索力学性能有较大的影响;其次对大桥拆下来的多龄期斜拉索进行疲劳测试,运用声发射技术监测了它的动态损伤过程,获得了斜拉索整个损伤过程的声发射特征参数,根据声发射累积能量参数分析结果,得到了多龄期斜拉索疲劳损伤演化规律;最后,对斜拉索疲劳损伤演化的各个阶段声发射波形进行小波分析,提取出各自的特征波形,并运用FFT分析其频率分布范围,进一步分析了损伤的形成原因,实现了对多龄期斜拉索损伤声发射源类型的确定。

Acoustic emission（AE） technique was used to monitor the fatigue damage evolution process of stay cables in bridge systems.The relation between stress and strain was gained through tensile test for corroded and non-corroded steel wires,and the results show that the mechanical performance of corroded cable experiences great change.The changing process of AE characteristic parameters during the whole fatigue damage period was obtained.It is found energy cumulative parameters of AE can be used to accurately describe the fatigue damage evolution of multi-aged stay cable.Based on wavelet singularity theory,in each stage of AE,the burst signal was obtained and its time-frequency distribution was achieved through wavelet and FFT analysis.According to the analysis results,failure modes in each phase and types of acoustic emission source can be then easily determined.The characteristics of waveform,types of damages,and frequency distribution of multi-aged stay cable in different damage phases were collected.