The measurement of strain in structural elements is a necessary means of investigating the condition of a structure, both in research and in practice. The measurement methods for recording strain considered in this work represent both well-established techniques (strain gauges), as well as techniques that are part of rather current research streams (fiber optic sensors, digital image correlation). This work's contribution lies in providing an overarching comparison of these approaches, thereby informing practitioners and researchers as to parameters concerning their assembly, application, and their accuracy. To such ends, two test series were carried out, one on RC tension rods and another on a RC beam in a four-point bending test. From the latter scenario, for example, certain generalizations were to be deduced for varying load levels: low strains are measured well using the fiber optic technique. Conversely, digital image correlation was discovered to be an adequate choice when assessing higher strain levels and concomitant concrete cracking, as this non-contact technique avoids imprecisions caused by adhesives. Findings are to assist the future user by contrasting the three techniques in terms of assembly, handling, application and resilience of sensors, external influences as well as measurement resolution and accuracy. Such practice-oriented remarks should simplify a selection of the suitable measurement techniques catering to the respective, context-dependent testing scenario.

中文翻译：

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钢筋混凝土结构应变测量技术的比较评估——装配、应用和精度的讨论

在研究和实践中，测量结构元素的应变是研究结构状况的必要手段。在这项工作中考虑的记录应变的测量方法既代表了成熟的技术（应变计），也代表了当前研究流（光纤传感器、数字图像相关）的一部分。这项工作的贡献在于提供这些方法的总体比较，从而告知从业者和研究人员有关其组装、应用和准确性的参数。为此，进行了两个测试系列，一个在 RC 拉杆上，另一个在 RC 梁上进行四点弯曲测试。例如，从后一种场景中，可以针对不同的负载级别推导出某些概括：使用光纤技术可以很好地测量低应变。相反，在评估更高的应变水平和伴随的混凝土开裂时，发现数字图像相关是一个合适的选择，因为这种非接触式技术避免了由粘合剂引起的不精确。通过在传感器的组装、处理、应用和弹性、外部影响以及测量分辨率和精度方面对比这三种技术，结果将有助于未来的用户。这种以实践为导向的评论应该简化适合相应的、依赖于上下文的测试场景的合适测量技术的选择。当评估更高的应变水平和伴随的混凝土开裂时，发现数字图像相关是一个合适的选择，因为这种非接触式技术避免了由粘合剂引起的不精确。通过在传感器的组装、处理、应用和弹性、外部影响以及测量分辨率和精度方面对比这三种技术，结果将有助于未来的用户。这种以实践为导向的评论应该简化适合相应的、依赖于上下文的测试场景的合适测量技术的选择。当评估更高的应变水平和伴随的混凝土开裂时，发现数字图像相关是一个合适的选择，因为这种非接触式技术避免了由粘合剂引起的不精确。通过在传感器的组装、处理、应用和弹性、外部影响以及测量分辨率和精度方面对比这三种技术，结果将有助于未来的用户。这种以实践为导向的评论应该简化适合相应的、依赖于上下文的测试场景的合适测量技术的选择。外部影响以及测量分辨率和精度。这种以实践为导向的评论应该简化适合相应的、依赖于上下文的测试场景的合适测量技术的选择。外部影响以及测量分辨率和精度。这种以实践为导向的评论应该简化适合相应的、依赖于上下文的测试场景的合适测量技术的选择。