Due to the progressive development in the field of concrete production, high-strength concretes are used more often and are nowadays indispensable especially for highly loaded engineering structures. In addition to the question of the static load-bearing capacity, a secure prediction of the behavior under high cyclic loading plays the major role in the design process. Exemplary are wind exposed structures like wind turbines, which have to withstand up to N = 109 load cycles during service life.
As part of a joint research project to investigate the material fatigue of wind turbines made of reinforced and prestressed concrete, the Technische Universität Dresden dealt with the bond behavior of high strength concrete and steel reinforcement in the high cycle fatigue range (N > 2·106).
The experimental program included 67 quasi-static and 56 cyclic pull-out and beam-end tests with two high-strength concretes classes, C80 and C120, and one normal strength concrete. The tests were carried out with reinforcing bars with a diameter ds = 16 mm and a bond length of 2·ds. The majority of the tests were performed with a loading frequency of 5 Hz and up to 20 million load cycles. Some specimens were also cyclically loaded with twice and four times the frequency.
The presented article deals with the experimental and instrumental setup and test results of bond fatigue tests. The influences of concrete strength and loading frequency are discussed particularly. In addition, the results are classified in context of existing studies and S-N curves.