光频域反射与超弱光纤布拉格光栅技术的结构监测性能

Structural Monitoring Performance of Optical Frequency Domain Reflectometry and Ultra-Weak Fiber Bragg Grating Technologies

为研究光频域反射(OFDR)和超弱光纤布拉格光栅(UWFBG)技术在桥梁钢结构中的监测性能,开展了H型钢梁弯曲测量实验。沿钢梁通长布设了四根光纤,在重、轻载工况下进行了钢梁四点加载受弯变形的分布式应变测量实验。结果表明,OFDR和UWFBG技术在钢梁分布式应变测量中均表现出较好的监测性能,相比应变片的测试结果,重载工况下OFDR和UWFBG的平均测量误差分别在3με和2με内,轻载工况下OFDR和UWFBG的平均测量误差分别在2με和1με内。0.9 mm紧套光纤和裸纤的测试结果相同。这表明紧套不会降低光纤的应变传递率。此外,通过实验设计可提高UWFBG技术测量结果的空间分辨率,提高程度取决于布设光纤自身的栅点密度和相邻光纤之间的相对栅点间隔。

To examine the monitoring performance of optical frequency domain reflectometry(OFDR)and ultraweak fiber Bragg grating(UWFBG)technologies in the bridge steel structure,this study focuses on the bending measurement experiments of Hshaped steel beam.Four optical fibers are arranged along the full length of the steel beam and distributed strain measurement investigations are performed under heavy and light load conditions for the fourpoint loaded bending deformation of the steel beam.The findings reveal that both OFDR and UWFBG technologies indicate remarkable monitoring performance in the distributed strain measurement of the steel beam.Compared with the findings of the strain gage,the average measurement errors of the OFDR technology and UWFBG technology under heavy load conditions are within 3μεand 2μεand under light load conditions are within 2μεand 1με,respectively.The test findings for the 0.9 mm tightbuffered fiber and the bare fiber are similar,demonstrating that the tightbuffered fiber does not minimize the fiber’s strain transmissibility.In addition,the spatial resolution of UWFBG measurement findings can be enhanced through experimental design,and the degree of improvement depends on the grating density of the laid fibers and relative grating spacing between adjacent fibers.