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

在申请DFG资助的研究项目的后续申请过程中，将在试验研究和数值参数研究的基础上，消除由于试验结果有限而仍然存在的不确定性，以便能够制定出考虑标准混凝土在火灾冷却阶段的材料性能的一般设计方法。由于用于确定混凝土在火灾冷却阶段的导热系数和热机械行为的现有实验结果的数量很少，由于问题的复杂性以及冷却阶段可能暴露的温度(冷却速度，最大降温速率)，只有冷却阶段的材料参数的第一种方法可用。温度)以及其他参数，如加载度和混凝土强度(CC与HPC的比较)。为了确保和扩展先前项目的现有知识，并发展一种通用的设计方法，在应用项目中将对达到高温(≥500°C)后的冷却阶段进行进一步的试验和数值研究。本申请研究项目的目标可以根据以下子项细分：-正常强度和高强混凝土在冷却阶段的导热系数和应力应变行为的试验研究，-根据从试验调查中获得的知识，制定火灾冷却阶段的本构材料定律，作为标准化普通强度和高强混凝土的一般设计方法--通过对加载的钢筋混凝土柱进行真实规模的火灾试验，在数值研究中验证导出的材料定律。

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.