基于内嵌光纤栅技术的钢筋混凝土梁自振频率监测试验研究

推进单一传感器多功能化发展是结构工程监测技术领域中新的研究热点之一。本文通过对以内嵌光纤光栅(Fiber Bragg Grating,FBG)应变传感器的钢筋为受力筋的钢筋混凝土小梁进行ABAQUS模态分析、人工激励试验和抗弯试验,探究内嵌于钢筋的FBG应变传感器监测钢筋混凝土梁未加载和损伤状态下的自振频率方案的可行性。结果表明：通过人工激励试验获得的未加载试验梁的自振频率约为37.43Hz,与ABAQUS有限元模态分析结果38.366Hz和理论计算得出的试验梁横向振动一阶自振频率理论计算结果36.167Hz基本一致,误差不超过2.5%；在抗弯试验中,试验梁出现破损后FBG应变传感器仍能够稳定监测到结构的自振频率,在试验全过程中,FBG应变传感器能实时监测钢筋的应变变化情况,实现了用内嵌于钢筋的FBG应变传感器同时进行结构自振频率监测和应变监测的目的。

Experimental Research on Natural Frequency Monitoring of Reinforced Concrete Beam Based on FBG Technology

Promoting the multifunctional development of a single sensor is one of the new research hotspots in the field of structural engineering monitoring technology. In this paper, ABAQUS modal analysis, artificial excitation test and bending test are carried out on reinforced concrete beams with steel bars embedded with fiber bragg grating (FBG) strain sensors to explore the feasibility of the FBG strain sensor embedded in the steel bar to monitor the natural frequency of the reinforced concrete beam in the unloaded and damaged state.The results show that the natural frequency of the unloaded test beam obtained by the artificial excitation test is about 37.43 Hz, which is compared with the ABAQUS finite element modal analysis result of 38.366 Hz and the theoretical calculation result of the first-order natural frequency of the test beam lateral vibration. 36.167Hz is basically the same, and the error does not exceed 2.5%; In the flexural test, the FBG strain sensor can still stably monitor the natural frequency of the