Experimentally Based Investigations on the Degradation-Process of Concrete Under Cyclic Load

In concrete structures fatigue can become relevant, when the construction is exposed to cyclic loads. For consideration of accompanying degradation processes also a large scatter of such variations have to be considered. For validation of already developed simulating models the mechanical degradation processes of concrete resulting from cyclic loads were studied experimentally within various cyclic tests on drilled cores. The attention was focused on the changes in the relevant properties of plain concrete. The main aim of these investigations was to get quantitative information about the changes in mechanical strength, stiffness and fracture energy caused by microcracks in the concrete structure during uniaxial cyclic loads. It could be proved, that during some few thousands of load-cycles microcracking already takes place to some extent, which mainly can be detected by changes in the dynamic E-modulus. However, it could also be determined, that the results measured in some repetition tests are varying within a large scatter.