基于GFRP-OFBG筋的桥梁缆索索力测量技术研究

Study on Cable Force Measurement Based on Smart GFRP-OFBG Bars

基于内嵌光纤Bragg光栅传感器的光纤光栅-玻璃纤维增强塑料复合筋(GFRP-OFBG筋),研究了GFRP-OFBG筋自身的应变和温度传感特性,研究结果表明,GFRP-OFBG智能筋具有优异的线性传感性能,筋中光栅测量的应变极限达12 000με以上,波长变化达14 nm;对于用GFRP-OFBG筋替换普通钢绞线的中丝而得到的GFRP-OFBG智能钢绞线,进行了应变传感、温度敏感和钢绞线松弛试验,试验结果表明,GFRP-OFBG智能钢绞线具有优异的线性传感性能和较低的应力松弛率,并可实现钢绞线受载全过程监测,绞线中光栅测量应变极限为11 568.2με,光栅波长变化为15.966 nm;对直接增加GFRP-OFBG筋制成的光纤光栅平行钢丝智能索和直接增加GFRP-OFBG智能钢绞线得到的光纤光栅平行钢绞线智能索,进行荷载传感试验,试验结果表明,智能索的感知线性度和重复性都比较好,并可监测70%以上公称破断索力。智能索工程应用案例表明,GFRP-OFBG筋智能拉索在实际工程中很容易得到车辆荷载下的响应曲线。

Combining the strength properties of Glass Fiber Reinforced Polymer （GFRP） with the sensing properties of Optical Fiber Brag Grating （ OFBG）, a new kind of smart GFRP-OFBG composite bars have been developed. The stress and temperature sensing properties of GFRP-OFBG bars are studied. The result shows that GFRP-OFBG bars are perfect sensors and the maximum tensile strain is up to 12 000 We. The maximum range of wavelength shift for OFBG is up to 14 nm. The smart strand is made by GFRP-OFBG bar replacing the middle wire of normal strand. The sensing property test and stress relaxation test are carried out. The experimental resuits show that smart GFRP-OFBG strand has a good linear sensor performance and a low relaxation rate. OFBG sensor built in GFRP bar can monitor the whole load process. The maximum monitoring strain of OFBG is up to 11 568.2 με and the maximum range of wavelength shift for OFBG is up to 15. 966 nm. The smart parallel wire cables and strand cables can be obtained by adding smart GFRP-OFBG bars or smart strands. The load sensing property is investigated. The experimental results show that the ultimate sensor range of GFRP-OFBG bars is up to 70% ultimate lengths of stay cable. Engineering application of smart cables shows that the load effect of stay cable can be obtained easily by GFRP-OFBG bar sensor.