低周期循环荷载下内嵌式光纤光栅自感知钢绞线的性能

钢绞线是预应力结构和桥梁结构中不可或缺的重要组成部分,光纤光栅与钢绞线耦合成的自感知钢绞线为其受力状态的健康监测提供了新的有效途径。为研究光纤光栅在高应变低周期循环荷载作用下能否有效跟踪钢绞线的受力状态,将中心丝持荷值、循环周期数、应力幅作为变化参数,对内嵌式自感知钢绞线进行了低周期循环拉伸试验,分析不同情况下应变与波长的关系以及监测性能。试验结果表明,内嵌式自感知钢绞线在低周期循环荷载作用下依然能保持良好监测性能,可跟踪监测钢绞线屈服力直至接近极限力,可监测钢绞线全生命周期受力状态。

Performance of Self-sensing Steel Strand Under Low Cycle Load Measured by Embedded Fiber Bragg Grating

As an indispensable and important part of prestressing structure and bridge structure,steel strand plays an important role. The self-sensing steel strand coupled by fiber Bragg grating(FBG)and strand provides a new and effective way for health monitoring of its stress state. In order to study whether FBG can effectively track the stress state of steel strand under high strain and low cycle load,the low cycle tension test of embedded self-sensing steel strand was carried out by taking the load-holding value of the central wire,the number of cycles and the magnitude of stress as variable parameters. The relationship between strain and wavelength and monitoring performance under different conditions were studied and analyzed. The test results show that the embedded self-sensing strand can maintain good monitoring performance under low cycle load. It can track and monitor the yield force of the strand and approach its ultimate force,and monitor the stress state of steel strand in the whole life cycle.