Today, a strong expansion in the construction of timber bridges is being promoted by the use of glulam. However, durability issues related to wetting/drying cycles limit their development. Timber bridge supervisors have therefore expressed their needs concerning continuous moisture content (MC) monitoring in timber structures. Checks on the MC of timber bridges are commonly based on the resistive method. A recent study carried out in the laboratory has shown the great potential of surface-type electrodes for local MC measurement in the laminated timber of glulam. Nevertheless, many parameters influence MC measurements and no information exists concerning surface electrodes. The novelty of this paper is to make the MC measurements with surface-type electrodes more reliable and accurate. In this study, the influence of electrode size and boundary conditions was therefore investigated. The influence of embedded sensors on the bending strength and elastic modulus of glulam beams was also evaluated in order to validate the electrodes instrumentation. Then, the influence of temperature and MC on the electrical resistance was studied, allowing a calibration curve to be established. The results show that small electrodes reduce the measurement uncertainties and therefore permit a more reliable estimation of MC. The boundary conditions also influence the measurements and should be considered. The embedded electrodes have no significant influence on the bending strength and elastic modulus of glulam beams. Finally, based on the literature review, a model for estimating wood MC was established, considering temperature variation.

中文翻译：

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带有嵌入式电阻传感器的胶合木结构中的水分监测：影响参数的研究

今天，胶合木的使用促进了木桥建设的强劲发展。然而，与润湿/干燥循环相关的耐久性问题限制了它们的发展。因此，木桥监管人员表达了他们对木结构中连续含水量 (MC) 监测的需求。木桥 MC 的检查通常基于电阻法。最近在实验室进行的一项研究表明，表面型电极在测量胶合木层压木材中的局部 MC 方面具有巨大潜力。然而，许多参数会影响 MC 测量，并且不存在有关表面电极的信息。本文的新颖之处在于使表面型电极的 MC 测量更加可靠和准确。在这项研究中，因此研究了电极尺寸和边界条件的影响。还评估了嵌入式传感器对胶合木梁的弯曲强度和弹性模量的影响，以验证电极仪器。然后，研究了温度和 MC 对电阻的影响，从而建立了校准曲线。结果表明，小电极减少了测量的不确定性，因此可以更可靠地估计 MC。边界条件也会影响测量，应予以考虑。嵌入电极对胶合梁的弯曲强度和弹性模量没有显着影响。最后，在文献综述的基础上，建立了考虑温度变化的木材 MC 估计模型。