Degradation in concrete structures due to cyclic loading and its effect on transport processes—Experiments and modeling
Degradation in concrete structures due to cyclic loading and its effect on transport processes—Experiments and modeling
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循环荷载引起的混凝土结构退化及其对运输过程的影响——实验和建模
DOI：
10.1002/suco.201600180
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发表时间：
2017
影响因子：
3.2
通讯作者：
Hofmann
中科院分区：
文献类型：
--
作者：
Przondziono;Timothy;Krütt;Breitenbücher;Meschke;Hofmann
根据1498课题组的研究目标，本文研究了循环弯曲荷载引起的混凝土结构的退化效应。我们的目标是确定它们对材料内的流体输运过程的影响，实验结果和数值模拟的基础上。总的问题是，外部供应的碱的进入和随后的碱-硅反应在多大程度上受到微观结构中这种改变的影响。混凝土微观结构退化的特点是超声波测量以及微观裂纹分析。此外，水渗透到所研究的材料的行为进行了实验。通过经典的Karsten管实验、核磁共振法和时域反射技术研究了侵彻损伤前混凝土微结构的行为。为了建立一个合适的模型，材料的退化对水分传输，达西定律被用来描述部分饱和混凝土中的流动。通过取决于降解状态的有效渗透率来考虑材料降解。这种有效的渗透率是通过微机械均匀化的代表性基本体积（REV）中的流动与分布的椭圆形微裂纹嵌入在多孔介质中。在微观裂纹分析中获得的数据被用作微观力学模型的输入。非饱和流的有限元模拟使用的微观力学模型进行了比较，实验结果显示出良好的定性和定量的协议。
According to the objectives of the research group 1498, this paper deals with degradation effects in concrete structures that are caused by cyclic flexural loading. The goal is to determine their influence on the fluid transport processes within the material on the basis of experimental results and numerical simulations. The overall question was, to which extent the ingress of externally supplied alkalis and subsequently an alkali‐silica reaction are affected by such modifications in the microstructure. Degradation in the concrete microstructure is characterized by ultrasonic wave measurements as well as by microscopic crack analysis. Furthermore, experiments on the penetration behavior of water into the investigated materials were performed. The penetration behavior into predamaged concrete microstructures was examined by the classical Karsten tube experiment, nuclear magnetic resonance method, and time domain reflectometry techniques. In order to create an appropriate model of the material's degradation on the water transport, the Darcy law was applied to describe the flow in partially saturated concrete. Material degradation is taken into account by an effective permeability that is dependent on the state of degradation. This effective permeability is obtained by the micromechanical homogenisation of the flow in an Representative Elementary Volume (REV) with distributed ellipsoidal microcracks embedded in a porous medium. The data gained in the microscopic crack analysis is used as input for the micromechanical model. Finite element simulations for unsaturated flow using the micromechanical model were compared with the experimental results showing good qualitative and quantitative agreement.
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