Abstract The combined application of distributed fibre optical strain measurements on reinforcing bars and digital image correlation (DIC) measurements on the concrete surface has a great potential to increase knowledge in many fields of structural concrete. This paper explores the advantages of these measurement techniques for concrete tests and the key aspects to be considered in order to obtain reliable measurements suitable for quantitative analysis. The uncertainty of DIC analysis is highly dependent on the test conditions and user carefulness, and should be assessed for each test. A procedure to quantify the DIC uncertainty in large scale structural tests is presented, showing that it is highly dependent on the quality of the calibration. Comparative tests on distributed fibre optical strain measurements with different fibre coatings show that polyimide-coated fibres capture properly high strain gradients and, therefore, should be used when instrumenting reinforcing bars in RC specimens. Moreover, the measuring noise was found to be dependent on the absolute strain level. Combined plots of crack kinematics and reinforcement strains, stresses and forces are shown for the results of a series of two concrete panel tests subjected to diagonal tension. Crack locations predicted by both measurements match perfectly in these experiments.

中文翻译：

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分布式光纤和数字图像相关测量在结构混凝土试验中的联合应用

摘要 钢筋分布式光纤应变测量和混凝土表面数字图像相关 (DIC) 测量的组合应用具有增加结构混凝土许多领域知识的巨大潜力。本文探讨了这些测量技术在具体测试中的优势以及为获得适用于定量分析的可靠测量而需要考虑的关键方面。DIC 分析的不确定度高度依赖于测试条件和用户的谨慎程度，应针对每次测试进行评估。介绍了在大规模结构测试中量化 DIC 不确定性的程序，表明它高度依赖于校准的质量。对具有不同光纤涂层的分布式光纤光学应变测量的比较测试表明，聚酰亚胺涂层光纤可以适当地捕获高应变梯度，因此，应在对 RC 试样中的钢筋进行检测时使用。此外，发现测量噪声取决于绝对应变水平。裂纹运动学和钢筋应变、应力和力的组合图显示了一系列受到对角线拉伸的两个混凝土面板测试的结果。在这些实验中，两种测量预测的裂纹位置完全匹配。裂纹运动学和钢筋应变、应力和力的组合图显示了一系列受到对角线拉伸的两个混凝土面板测试的结果。在这些实验中，两种测量预测的裂纹位置完全匹配。裂纹运动学和钢筋应变、应力和力的组合图显示了一系列受到对角线拉伸的两个混凝土面板测试的结果。在这些实验中，两种测量预测的裂纹位置完全匹配。