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Numerisches Modell zur Beschreibung von Alkalientransport und AKR-induzierter Schädigung in Beton

描述混凝土中碱传输和 AKR 引起的损伤的数值模型

基本信息

批准号：
202256999
负责人：
Professor Dr. Günther Meschke
金额：
--
依托单位：
Lehrstuhl für Statik und Dynamik
依托单位国家：
德国
项目类别：
Research Units
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/202256999?language=en
关键词：
Numerisches Modell zur Beschreibung von

项目摘要

The goal of TP3 is the development of a computational model to predict ASR induced damage in concrete structures, specifically in concrete pavements for various environmental conditions, conditi-ons of degradation and types of concrete mixture. The numerical and analytical sub-models are developed and validated through close synergetic interaction with experimental sub-projects within the research group. The first phase of the project was concerned with modeling of the coupled transport of moisture and alkalis in intact and pre-damaged concrete. A multi-scale strategy based on continuum micromechanics for transport of pore-fluid and alkali in intact and pre-damaged concrete has been developed and implemented within the framework of a multiphase finite element method. The model has the capability to take into account the interactions of diffuse microcracks and the cement matrix. In contrast to existing models, the developed model confirms experimental observations for a threshold value for ion diffusivity. In the second phase, in addition to extending the transport model to take into account the influence of cyclic mechanical loads on alkali and fluid transport, the main focus will be on characterizing ASR induced damage. A modeling strategy similar to the first phase will be adopted, characterized by the adequate consideration of the spatial and temporal scales of the various transport and damage mechanisms. Through a micromechanical characterization of local damage in and around the reactive aggregate, at the macroscopic scale, the model should be capable of taking into account the influence of localized ASR induced damage processes through appropriate homogenization schemes as well as the inverse influence of external loads on micro-crack evolution. The combination of the transport and the ASR damage model and integration into a multifield finite element program will enable prognoses of the expected future degradation in concrete structures for various scenarios such as environmental conditions or the specific concrete mixture. In addition to model development and software design for durability predictions due to ASR, the project aims to gain a deeper understanding of the interactions between the effects (external cyclic loads, environmental factors) and the transport and damage processes in ASR affected concrete structures.

TP3的目标是开发一种计算模型来预测ASR在混凝土结构中的损伤，特别是在不同环境条件、降解条件和混凝土混合料类型下的混凝土路面损伤。通过与研究组内实验子项目的密切协同作用，开发和验证了数值和分析子模型。该项目的第一阶段涉及对完整和预先损坏的混凝土中水分和碱的耦合传输进行建模。在多相有限元方法的框架内，发展并实现了基于连续体细观力学的多尺度策略来研究完整和损伤混凝土中的孔隙流体和碱的运移。该模型能够考虑扩散微裂纹与水泥基材之间的相互作用。与现有模型相比，发展的模型证实了离子扩散系数阈值的实验观测结果。在第二阶段，除了扩展传输模型以考虑循环机械载荷对碱和流体传输的影响外，主要的重点将是表征ASR引起的损伤。将采用与第一阶段类似的建模战略，其特点是充分考虑各种运输和破坏机制的空间和时间尺度。通过对活性骨料内部和周围局部损伤的细观描述，在宏观尺度上，该模型应该能够通过适当的均匀化方案考虑局部ASR诱发损伤过程的影响，以及外部载荷对微裂纹演化的反向影响。将传输和ASR损伤模型相结合，并集成到多场有限元程序中，将能够预测各种情况下混凝土结构的预期未来退化，例如环境条件或特定的混凝土混合料。除了ASR耐久性预测的模型开发和软件设计外，该项目还旨在更深入地了解受ASR影响的混凝土结构中影响(外部循环荷载、环境因素)与运输和破坏过程之间的相互作用。