光纤光栅监测技术在桥涵加固中的应用

On application of inspecting technology of fiber Bragg grating in reinforced bridge strain testing

在土木工程领域,光纤智能健康监测方法是对建筑物或构筑物的健康状况进行检测的一种新方法。采用200mm×300mm×3000mm试件,对比试验研究桥梁监测中广泛应用的振弦传感器与布拉格光栅传感器。结果表明,布拉格光栅传感器具有更好的检测精度、线性响应和重复性。根据光纤光栅传感器的应变传感特性标定试验,在武黄高速公路的典型桥涵中布设光栅传感器,采集分析加固前后静载试验工况下底部钢筋以及桥涵加铺层钢筋的应变数据,评估高速公路桥梁加固效果,并对桥涵结构进行长期监测。监测结果表明,埋入的光纤光栅可方便地监测桥涵安全状况,其稳定性与耐久性满足钢筋混凝土桥梁结构长期健康的要求。同时,根据光纤光栅传感技术在桥梁监测中的应用实践,探讨了其在桥梁监测中应用所面临的一些关键问题及解决途径。

The present paper aims at introducing a standard specimen beam in a volume of about 200 mm× 300 mm× 3 000 ram, with which the author has chosen to do a comparative strain testing by using FBG sensors and vibrating wire sensors. As is known, such sensors have now been widely used in the bridge and tunnel strength monitoring practice in the civil engineering, thus making such fiber optic sensors a new approach to evaluating the structural strain value. Our experimental resuhs show that the FBG sensors have a higher measuring precision, higher linearity and better noise resistance. To make the results more reliable, we have tried a traditional electrical resistance strength gage to calibrate the FBG sensors and obtained the sensitivity of the strain degree as well as applied them to monitoring practice of the bridge reinforcement in Wuhan-Huangshi Highway in order to collect the strains of reinforcement bars in the overlay and the beams before and after the bridge reinforcement. The above work is also targeted to evaluate the efficiency of the reinforcement projects for evaluating the long-term structural health monitoring. The results we have gained in this way indicate that the safety conditions can be monitored with no difficulty by using the FBG sensors whose durability and stability proved to be able to satisfy the need of bridge health monitoring. Finally, we have also given here in the paper a detailed discussion to the key problems and implementation approaches in the structural strain monitoring process by means of embedded FBG sensors.