This study explores an instrumentation strategy using distributed fiber optic sensors to measure strain and temperature through the concrete volume in large-scale structures. Single-mode optical fibers were deployed in three 12.8 m long steel and concrete composite floor specimens tested under mechanical or combined mechanical and fire loading. The concrete slab in each specimen was instrumented with five strain and temperature fiber optic sensors along the centerline of the slab to determine the variation of the measurands through the depth of the concrete. Two additional fiber optic temperature sensors were arranged in a zigzag pattern at mid-depth in the concrete to map the horizontal spatial temperature distribution across each slab. Pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA) was used to determine strains and temperatures at thousands of locations at time intervals of a few minutes. Comparisons with co-located strain gauges and theoretical calculations indicate good agreement in overall spatial distribution along the length of the beam tested at ambient temperature, while the fiber optic sensors additionally capture strain fluctuations associated with local geometric variations in the specimen. Strain measurements with the distributed fiber optic sensors at elevated temperatures were unsuccessful. Comparisons with co-located thermocouples show that while the increased spatial resolution provides new insights about temperature phenomena, challenges for local temperature measurements were encountered during this first attempt at application to large-scale specimens.

本研究探索了一种使用分布式光纤传感器通过大型结构中的混凝土体积测量应变和温度的仪器策略。单模光纤部署在三个 12.8 m 长的钢和混凝土复合地板试样中，在机械载荷或机械载荷和火载荷组合下进行测试。每个试样中的混凝土板沿板的中心线配备五个应变和温度光纤传感器，以确定混凝土深度范围内被测量的变化。两个额外的光纤温度传感器在混凝土的中间深度以锯齿形图案排列，以绘制每个板的水平空间温度分布图。脉冲前置泵布里渊光时域分析 (PPP-BOTDA) 用于以几分钟的时间间隔确定数千个位置的应变和温度。与位于同一位置的应变仪和理论计算的比较表明，在环境温度下沿梁长度的整体空间分布具有良好的一致性，而光纤传感器还捕获与试样局部几何变化相关的应变波动。在高温下使用分布式光纤传感器进行应变测量未成功。与同位热电偶的比较表明，虽然空间分辨率的提高提供了关于温度现象的新见解，