Further investigations to describe the material behaviour of concrete in the fire cooling phase

在本次申请的dfg资助研究项目的后续应用过程中，将在实验调查和数值参数研究的基础上，消除由于实验结果有限而仍然存在的不确定性，以便能够制定一个通用的设计方法，以考虑标准化混凝土在火灾冷却阶段的材料行为。由于用于确定混凝土在火灾冷却阶段的导热性和热力学行为的可用实验结果的数量很少，因此，由于问题的复杂性以及冷却阶段可能存在的多种温度暴露（冷却速率，最大温度），只能使用冷却阶段材料参数的第一种方法。温度)以及其他参数，如加载程度和混凝土强度（CC与HPC相比）。为了确保和扩展先前项目的现有知识，并制定通用设计方法，应在应用项目中对达到高温（≥500°C）后的冷却阶段进行进一步的实验和数值研究。在此申请的研究项目的目标可以根据以下列出的子项目进行细分：-在冷却阶段对普通强度和高强度混凝土的导热性和应力-应变行为进行实验研究；-根据从实验调查中获得的知识，开发火灾冷却阶段的本构材料规律，作为标准化普通强度和高强度混凝土的一般设计方法通过钢筋混凝土柱实尺火灾试验，验证了数值研究中推导出的材料规律。

In the course of the follow-up application of the DFG-funded research project applied for here, uncertainties still existing due to only limited experimental findings are to be eliminated on the basis of experimental investigations and numerical parameter studies in order to be able to formulate a general design approach for the consideration of the material behaviour of standardised concretes in the cooling phase of fires. Since the number of available experimental results for the determination of the thermal conductivity and the thermo-mechanical behaviour of concrete in the fire cooling phase is small, only first approaches for material parameters in the cooling phase are available due to the complexity of the problem and due to the multitude of possible temperature exposures in the cooling phase (cooling rate, max. temperature) as well as further parameters such as degree of loading and concrete strength (CC compared to HPC). In order to ensure and extend the existing knowledge from the previous project and to develop a general design approach, further experimental and numerical investigations for the cooling phase after reaching high temperatures (≥ 500 °C) shall be carried out in the applied project.The objectives of the research project applied for here can be subdivided according to the subitems listed below:- Experimental investigation of the thermal conductivity and stress-strain behaviour of normal-strength and high-strength concrete during the cooling phase,- Development of constitutive material laws for the fire cooling phase as a general design approach for standardised normal-strength and high-strength concrete on the basis of the knowledge gained from experimental investigations- Validation of the derived material laws in numerical investigations through real-scale fire tests on loaded reinforced concrete columns.