The resistance of concrete to cyclical loads is usually quantified in force-controlled fatigue tests. The cyclical loading leads to a heating of the concrete specimen in the experiment. The causes are seen in the material damping on the micro level of the concrete structure. The heating of the concrete specimens is mainly influenced by the load frequency, the stress range and the test duration. Larger stress ranges and higher load frequencies lead to faster and higher heating. Experimental investigations on fatigue-stressed concrete bodies show that concrete specimens that are tested at high loading frequencies and thus higher concrete temperatures fail earlier than at low loading frequencies and thus lower temperatures. The fatigue strength of the concrete samples is therefore influenced by the degree of warming.

Within the proposed research project, the heating behavior of fatigue-stressed concrete test specimens is to be investigated experimentally and described using models. The planned research activities are based on an energetic model approach. This approach defines the amount of heat released in the fatigue-stressed concrete specimen. Using numerical simulations that take into account the heat transport in the concrete specimen and the heat transfer to the environment, the temperature development of the specimen can be calculated. The temperature curves recorded in the fatigue tests are compared to the calculated temperature curves. The quality of the results will be an indication of the correctness of the energetic model approach. On the other hand, the effects of the heating on the concrete specimen are to be assessed. These concern on the one hand the temperature expansions that occur and the reduced fatigue strength.

Funded by:
DFG

Project duration:
10/2017 - 09/2019

Contact person:
Dr.-Ing. Albert Vogel
Tel. +49 3643 584706

Project partner:
Prof. Dr.-Ing. Steffen Marx
Institut für Massivbau
Leibniz Universität Hannover