Behavior of concrete under extreme loading - explosion and fire

• Applicant: Professor Dr.-Ing. Josko Ozbolt
• Subject Area: Applied Mechanics, Statics and Dynamics
• Term: from 2011 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 198787889

In the framework of the preceeding project: "Numerical modeling of concrete under extreme loading - explosion and fire", experimental and numerical studies on concrete and reinforced concrete structure exposed to extreme loading conditions was carried out. To better understand the behavior of concrete exposed to high temperature and subsequently loaded under high loading (strain) rates, the experiments on compact tension specimens were carried out. Subsequently, in cooperation with BARC (Mumbai, India) experimental tests and numerical studies on reinforced concrete slabs and frames exposed to fire and impact load were carried out. The results of the investigations showed that the concrete that is damaged by the fire load behaves differently under dynamic load than the concrete under room temperature. As the temperature increases, the influence of the strain rate on the resistance of the concrete decreases, i.e. the progressive increase of the apparent strength is much lower in case of damaged concrete. It has also been demonstrated that the proposed constitutive law for concrete in which the effects of the high strain gradients and the temperature are coupled is principally able to simulate the behavior of concrete structures damaged by fire under dynamic load. However, there are still open questions to be clarified: (1) the agreement between the numerical and experimental results is in some points still not good enough, and (2) the loading scenario, e.g. fire after an earthquake has not been investigated so far. Therefore, in the follow-up application a number of experimental and numerical investigations should be carried out in order to clarify the still open questions.

• DFG Programme: Research Grants