Abubakar Ali Mohamed, Tomann Christoph, Aldakheel Fadi, Mahlbacher Markus, Noii Nima, Oneschkow Nadja, Drake Karl-Heinz, Lohaus Ludger, Wriggers Peter, Haist Michael
Institute of Building Materials Science, Leibniz University Hannover, Appelstraße 9a, 30167 Hannover, Germany.
LPI Ingenieurgesellschaft, Völgerstraße 9, 30519 Hannover, Germany.
Materials (Basel). 2022 Jan 28;15(3):1025. doi: 10.3390/ma15031025.
The influence of a wet environment on the fatigue behaviour of high-strength concrete has become more important in recent years with the expansion of offshore wind energy systems. According to the few investigations documented in the literature, the fatigue resistance of specimens submerged in water is significantly lower compared to that of specimens in dry conditions. However, it is still not clear how the wet environment and the moisture content in concrete influence its fatigue behaviour and which damage mechanisms are involved in the deterioration process. Here the results of a joint project are reported, in which the impact of moisture content in concrete on fatigue deterioration are investigated experimentally and numerically. Aside from the number of cycles to failure, the development of stiffness and acoustic emission (AE) hits are analysed as damage inductors and discussed along with results of microstructural investigations to provide insights into the degradation mechanisms. Subsequently, an efficient numeric modelling approach to water-induced fatigue damage is presented. The results of the fatigue tests show an accelerated degradation behaviour with increasing moisture content of the concrete. Further, it was found that the AE hits of specimens submerged in water occur exclusively close to the minimum stress level in contrast to specimens subjected to dry conditions, which means that additional damage mechanisms are acting with increasing moisture content in the concrete.
近年来，随着海上风能系统的扩展，潮湿环境对高强度混凝土疲劳性能的影响变得愈发重要。根据文献中记载的少量研究，与处于干燥条件下的试件相比，浸泡在水中的试件的疲劳抗力显著更低。然而，目前仍不清楚潮湿环境以及混凝土中的含水量如何影响其疲劳性能，以及在劣化过程中涉及哪些损伤机制。在此报告一个联合项目的结果，其中通过实验和数值方法研究了混凝土中含水量对疲劳劣化的影响。除了失效循环次数外，还将刚度发展和声发射（AE）计数作为损伤指标进行分析，并结合微观结构研究结果进行讨论，以深入了解劣化机制。随后，提出了一种针对水致疲劳损伤的高效数值建模方法。疲劳试验结果表明，随着混凝土含水量的增加，其劣化行为加速。此外，发现与处于干燥条件下的试件相比，浸泡在水中的试件的声发射计数仅在接近最小应力水平时出现，这意味着随着混凝土含水量的增加，有额外的损伤机制在起作用。
