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

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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.