Development of a Strengthening Method Using Spring-Type Dampers for Tower–Foundation Connection in Existing Wind Turbines

Embedded steel ring connections are widely used in onshore wind turbines (WT) to transfer loads from the tower to the foundation. The structural behavior of the embedded steel ring connection greatly affects the structural integrity of wind turbines under ultimate loads. Approximately 90% of the bending loads (bending/overturning moments) are carried by the base flange of the embedded ring and the embedded ring–concrete contact surfaces. Damage that may occur in these areas significantly affects the tower’s stability and may lead to the tower overturning. The damages that may occur in these areas are the most dangerous that can occur in wind turbines. This study proposes a strengthening method for wind turbine foundations with damaged tower–foundation connections. In order to investigate the effect of the developed strengthening method on the structural behavior of the tower–foundation connection and also to verify the analytical models, 1/15 scale models of an existing wind turbine and its foundation were created. The effect of the developed strengthening method on the tower–foundation connection was investigated by testing the created models in a laboratory environment.