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为研究混合结构PBL剪力键群各剪力键的剪力传递,在开孔板界面摩擦效应测试中引入了光纤传感测试技术。阐述了PPP-BOTDA(Pulse-Pre Pump Brillouin Optical Time Domain Analysis)技术的测量原理,根据多中间层的剪滞理论,建立了基体-光纤间的应变传递模型,推导了表贴式光纤的应变传递公式,基于4个四排PBL剪力键群试件的静载破坏试验,实现了对PBL剪力键开孔钢板及混凝土应变的空间分布式测量,并对分布式传感光纤的应变传递进行了敏感性分析。测试结果及分析表明:在仪器的空间分辨率一定时,传感光纤的粘贴宽度、光纤护套的厚度对应变传递影响显著,粘结层胶体的剪切模量对应变传递影响不甚明显;对比剪力键试验中应变片与分布式光纤的应变数据,试验采用的两种光纤均具有良好的应变测量精度,试验结果与理论敏感性分析较为一致;基于PPP-BOTDA的分布式光纤测试方法,克服了传统应变片测试中的不足,在既定的光纤铺设工艺下,适用于结构的大应变、高精度、分布式测量。
In order to study the shear transfer of each shear key of the PBL shear bond cluster in hybrid structure, an optical fiber sensing technique was introduced in the friction effect test of the perforated plate interface. The measurement principle of PPP-BOTDA (Pulse-Pre Pump Brillouin Optical Time Domain Analysis) is described. According to the shear lag theory of multi-intermediate layer, the strain transfer model between substrate and fiber is established and the strain transfer of surface-mount fiber is deduced Based on the static load failure test of four four-row PBL shear bond group specimens, the spatial distributed measurement of PBL shear plate open-hole steel plate and concrete strain was realized. The strain transfer of distributed sensing fiber was carried out Sensitivity analysis. The test results and analysis show that: when the spatial resolution of the instrument is constant, the influence of the adhesive width of the sensing optical fiber and the thickness of the optical fiber sheath on the strain transfer is significant, and the shear modulus of the adhesive layer colloid has little effect on the strain transfer; Compared with the strain data of strain gauge and distributed optical fiber in the shear bond test, the two kinds of optical fibers used in the experiment have good strain measurement accuracy. The experimental results are in good agreement with the theoretical sensitivity analysis. The distributed optical fiber testing method based on PPP-BOTDA , Overcoming the shortcomings of traditional strain gage testing. Under the established optical fiber laying technology, it is suitable for large strain, high precision and distributed measurement of structures.