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降低光纤布拉格光栅(fiber Bragg grating,FBG)应变传感器的应变灵敏度是解决其量程小无法监测大应变问题的关键技术。为监测预应力钢绞线(特别是桥梁永久性构件的拉索、预应力混凝土)在施工及使用全过程的应力应变变化,本文提出螺旋倾斜式光栅复合技术,在实现预应力筋大应变监测的同时解决了裸光纤光栅易损坏、难以封装的难题;建立了光栅实测应变与钢绞线应变间的理论关系,通过不同倾角试验,测定光栅应变灵敏度的变化。试验研究结果表明,该方法有效降低了光栅应变灵敏度,从1.18pm/με降为0.88pm/με,实现了增大光栅应变测量量程的目的。
Reducing the strain sensitivity of fiber Bragg grating (FBG) strain sensors is the key technology to solve the problem of large strain range, which can not be monitored. In order to monitor the stress and strain of the prestressed steel strand (especially the cable and prestressed concrete of the bridge permanent component) in the whole process of construction and use, this paper proposes a helical tilting grating composite technology, While solving the problem that the bare fiber grating is easy to damage and difficult to encapsulate. The theoretical relationship between the measured strain of the grating and the strand strain is established. The variation of grating strain sensitivity is measured through different inclination tests. Experimental results show that this method can effectively reduce the grating strain sensitivity from 1.18pm / με to 0.88pm / με, and achieve the purpose of increasing the grating strain measurement range.