基于光纤Bragg光栅的预应力损失监测技术研究

Study on the Monitoring Technology of Pre-stress Loss Based on Optic Fiber Bragg-grating

预应力体系结构主要依靠钢绞线张拉来实施预加应力,钢绞线上建立的预应力值会因孔道摩擦、锚具滑移、混凝土收缩、徐变和钢绞线自身松弛等因素产生损失,其中短期损失使得大型预应力结构各部位预应力水平分布不均,长期损失会逐渐降低重要结构的安全裕度,这都会使结构受力性能难以判断。直接对预应力钢绞线进行全时程全长的预应力损失监控是解决这些问题的有效手段。传统的传感器和测试方法难以满足在这项测试中包含的诸如传感器量程、信号传输线路布设保护以及测试信号抗干扰能力等方面的要求。文中提出采用光纤Bragg光栅的测试技术,利用FRP包裹、钢绞线边丝缠绕保护和其固有的光信号传输中性测量的特点解决了上述问题,尤其适用于有粘结预应力钢绞线监测。

The load of pre-stress structure come from stretching of steel strand, but the stress built on the steel strand would be lost. The lost causes many problems on the structure, such as pre-stress uneven and margin of safety reduced. Monitoring stress lever on the steel strand can provide information of the structure, and then expert can estimate the behavior under load of structure. It is hardly to monitor the whole-span and whole length of steel strand by traditional senses and method because of measure range, protection and interference of electromagnetic environment. A new method based on Optic Fiber Bragg Grating （OFBG） , which mentioned in the article, provides a successful experience on the monitoring of pre-stress loss in whole-span and wholelength.