Fatigue of structural concrete driven by a cumulative measure of shear strain

该项目的主要目标是为混凝土疲劳行为的分析和表征开发一个一致的理论，数值和实验框架。该框架将提供一个更深入地了解的损伤机制驱动的疲劳传播的混凝土在亚临界水平的负载的基础。与最先进的方法相比，改进的疲劳现象学反映将减少可靠表征高周疲劳响应所需的昂贵实验的数量。的理论和数值的发展的目标是建立一个多尺度的建模框架的基础上一致的表示与累积循环变形在亚临界水平的负载耗散机制。通过捕捉关键的耗散机制，我们将能够显着提高混凝土结构疲劳模型的有效性和效率。该战略将始终结合联合收割机离散模型的材料结构在中尺度和宏观唯象模型的微平面类型。与此同时，它将引入设计一个加速的时间积分方案的高周疲劳响应的有效模拟的可能性。建议的多尺度建模策略将刺激系统的校准和验证方法的发展，包括一系列的基本测试设置。系统的测试方法将部署的目标，以隔离混凝土的疲劳行为的特定影响，以揭示和描述它们的关系，假设的基本耗散机制。这种发展的目标是提供一个合理的解释仍然令人困惑的疲劳现象，如从根本上不同的疲劳行为的混凝土在拉伸和压缩循环加载与变幅相比，最先进的疲劳表征方法，所提出的方法将建立更有效的表征和评估钢筋混凝土的疲劳行为的基础。从长远来看，所开发的方法将有助于制定可靠的和经济的设计概念和规范的结构混凝土暴露于疲劳荷载。拟议的研究项目将结合联合收割机的两个合作团队在不同学科的专业知识。特别是，离散，中尺度建模和有效的时间积分沿着寿命域将是布尔诺大学的团队的重点。宏观，唯象建模和实验方法将在RWTH亚琛大学开发。

The major objective of the project is to develop a consistent theoretical, numerical and experimental framework for analysis and characterization of fatigue behavior of concrete. The framework will provide the basis for a deeper understanding of damage mechanisms driving the fatigue propagation of in concrete at subcritical levels of loading. The improved reflection of the fatigue phenomenology compared to the state-of-the-art methods will reduce the number of expensive experiments needed for reliable characterization of high cycle fatigue response. The goal of the theoretical and numerical development is to establish a multi-scale modeling framework based on thermodynamically consistent representation of the dissipative mechanisms associated with cumulative cyclic deformation at subcritical levels of loading. By capturing the key dissipative mechanisms, we will be able to significantly enhance the validity and efficiency of fatigue models for concrete structures. The strategy will consistently combine discrete models of the material structure at the mesoscale and macroscopic phenomenological models of the microplane type. At the same time, it will introduce the possibility to devise an accelerated time integration scheme for an efficient simulation of high-cycle fatigue response. The proposed multi-scale modeling strategy will stimulate the development of a systematic calibration and validation methodology consisting of a sequence of elementary test setups. Systematic test methods will be deployed with the goal to isolate particular effects of fatigue behavior of concrete in order to uncover and describe their relation to the postulated elementary dissipative mechanisms. The ambition of this development is to provide a sound explanation of still puzzling fatigue phenomena, like the fundamentally different fatigue behavior of concrete under tensile and compressive cyclic loading with variable amplitudes.In comparison to the state-of-the-art methods of fatigue characterization, the proposed approach will establish the basis for more efficient characterization and assessment of fatigue behavior of reinforced concrete. In the long run, the developed methods will contribute to formulation of reliable and economic design concepts and codes for structural concrete exposed to fatigue loading. The proposed research project will combine expertise of the two partner teams in different disciplines. In particular, discrete, mesoscale modeling and efficient time-integration along the lifetime domain will be the focus of the team at Brno University. The macroscopic, phenomenological modeling and experimental methods will be developed at RWTH Aachen University.