Validated offshore applicable approaches in structural health monitoring can reduce the maintenance costs of offshore wind farms. To evaluate such for grouted connections, large-scale model tests are carried out at the Test Center Support Structures in Hanover. Their results are used to identify the process of damage at an early stage. For this purpose, a support structure model with a grouted connection was designed containing fiber Bragg grating sensors placed at certain positions of the grout layer. In this contribution the test strategy and its set-up are presented. Finally, the suitability of the sensors is shown by means of first results.
Offshore wind energy accounts for a steadily increasing share of renewable energy in Germany. In a few years, first German offshore wind farms are going to face a reduction in feed-in tariffs after 12 years of operation. This fact increases the need to evaluate the wind farm performance, the opportunities in reduction of operational costs and the perspectives in lifetime extension. Improvements in the structural health monitoring (SHM) of offshore support structures can be promising, as they reduce failures of structural components by means of an effective predictive maintenance approach.
Due to their hybrid design, grouted joints can be considered as good-natured and robust connections. They are used for offshore wind turbines both below and above water level to connect the foundation piles to the substructure (e.g. jacket or tower structure). Their design considers the type of load transfer and their high dynamic loading.
However, damage occurred at some grouted connections in the past (Schaumann et al., 2010). As they usually occur inside, they are hard to detect. In addition, the proof of an adequate quality of the grouting and hardening process is ambitious, see Lohaus and Werner (2012). These issues may be identified by monitoring the connection in service.
