Experimental Investigation of the Steel-Concrete Joint in a Hybrid Tower for a Wind Turbine under Fatigue Loading

This study investigated the fatigue behaviors at the joint of a hybrid steel–concrete wind turbine tower. A fatigue design approach was proposed for the joint based on CEB-FIP model code 1990 and Eurocode 2. In addition, to estimate the long-term fatigue performance related to continuous wind changes at the joint, two types of specimens were fabricated and tested. Each specimen consisted of steel and concrete sections, which were connected with anchor bolts, and they were designed to investigate the effect of the embedded length of the anchor bolt. Two million cycles of cyclic loading were applied to the specimens, after which a monotonic static loading was applied to investigate the residual performance of each specimen. The experimental results demonstrate that the joint of a hybrid steel–concrete wind turbine tower designed using the proposed approach retained sufficient fatigue performance. Thus, this approach can be effective for fatigue design of the joint.