Abstract
This paper shows fatigue evaluation method based on field measurements and FEM for RC foundation of wind turbine rated as 40 kW power class. First, field measurements for existing wind turbine were carried out to investigate the relation of action-response of tower-foundation system. Through a data analysis of the results of field measurement, multi-directional bending moment on foundation was expected. Next, a integrated model of tower-foundation system was built up for three dimensional nonlinear FE analysis. Damage process of reaching failure of the model was examined and limit state of concrete in the foundation was defined by numerical simulation. Furthermore, one of the indexes assessing damage state could identify a fatigue limit state of concrete subjected to repetition of loads. Consequently, the S-N diagram derived from the index indicated that the number of repetition of multi-directional loads reaching the fatigue limit state of concrete is much smaller than the number of repetition assuming single-direction loads, and experience of excessive load amplitude can affect the latter fatigue damage.
