体内预应力钢绞线光纤光栅监测技术及其应用

Research and Application of FBG Monitoring Technology in Internal Prestressed Steel Strand

设计了一种在预应力钢绞线中心丝上设置倾斜凹槽封装光纤光栅的自感知钢绞线,以解决体内预应力钢绞线其它传感器无安装空间,易碎断导致封装成活率低以及监测量程不够等技术难题.理论分析了不同凹槽倾角封装的光纤光栅传感器的监测应变与钢绞线应变,根据复合材料剪滞模型理论建立了二者之间的应变关系.以倾角为变化参数,研制了系列光纤光栅自感知钢绞线,并对其进行张拉试验,测定光纤光栅传感器量程的变化情况.试验结果表明:该方法能有效扩大光纤光栅传感器的监测量程,当倾斜角度为30°时,所能监测的应变范围与0°相比,提高了44%.采用该技术,利用光纤光栅传感器对某高速公路预应力箱梁的施工张拉及服役进行实时监测,传感器成活率为100%,同时将光纤光栅的理论及标定应变关系与现场张拉及二次张拉的数据进行对比,误差均在5%以内.该技术实现了对体内预应力钢绞线施工张拉和服役全生命周期的监测.

A self-sensing steel strand is designed,which is set a spiral and slant groove on the steel strand center wire and embedded with fiber Bragg grating (FBG) sensor.Hence,the problems of lack of installation space,fragile broken which leads to low survival rate and insufficient monitoring range can be solved.The monitoring strain of FBG sensor with groove and the strain of steel strand are analyzed theoretically.According to the theory of shear lag model of composite material,the relationship between both strains is established.A series of self-sensing steel strand are developed with different helix angle,and the tensile experiments are carried out to determine the variation of the measurement range of FBG sensor.The experimental results show that this method can effectively improve the monitoring range of FBG sensor,When the tilt angle is 30°,the strain range that can be monitored is increased by 44% compared with 0°.Owing to this technique,the prestressing tensioning construction and service of a prestressed box beam of a highway are monitored in real time by using FBG sensor,the survival rate of the sensor is 100%.The strain relationship determined by theoretical and calibration test is compared with the data of the construction tensioning and the secondary tensioning on site,and the errors are less than 5%.This technology achieve the purpose of the whole lifecycle monitoring of the internal prestressed steel strand during construction and service.