分布式光纤监测混凝土梁的应变传递系数与布设工艺

Strain Transfer Coefficient and Layout Technology of Concrete Beam Monitored by Distributed Optical Fiber

分布式光纤由于其长距离、分布式、实时在线监测,适用于土木工程结构的健康监测。本文基于光频域反射技术(OFDR)的分布光纤技术在型钢构件和混凝土梁外表面分别布置光纤传感器及传统电阻应变片,验证光纤监测数据的有效性,探究钢梁表面光纤封装厚度对应变传递系数的影响及一种适合混凝土表面的光纤布设方式。试验结果表明:分布式光纤传感器能够对结构应变、损伤开裂进行准确的监测,可以有效弥补应变片易损及测试精度不足。在相同布设条件下,0.9 mm分布光纤与2 mm分布光纤在光滑的钢梁表面应变测试偏差率与理论计算应变传递系数差值基本符合。推荐的一种分布光纤表面粘贴布设方式可以弥补传统布设工艺的缺点,在小应变时测试更准确。

Distributed optical fiber is suitable for the health monitoring of civil engineering structures because of its long distance,distributed and real-time online monitoring.In this paper,based on the distributed optical fiber technology of OFDR,optical fiber sensors and traditional resistance strain gauges are placed on the outer surface of steel members and concrete beams,respectively,to verify the effectiveness of optical fiber monitoring data,explore the influence of optical fiber packaging thickness on the surface of steel beams on the strain transfer coefficient,and a suitable optical fiber layout method on the surface of concrete.The test results show that the distributed fiber optic sensor can accurately monitor the structural strain and damage cracking,and can effectively make up for the weakness of strain gauge and the deficiency of test accuracy.Under the same arrangement condition,the deviation rate of strain test between 0.9 mm and 2 mm distributed fiber on smooth steel beam surface is basically consistent with the difference of strain transfer coefficient calculated theoretically.A distributed fiber surface sticking layout is recommended to make up for the shortcomings of the traditional layout technology,and the test result is more accurate when the strain is small.