Wind turbine towers are normally erected by assembling several cylindrical or conical shaped elements on top of each other. These elements are built by fabricators in lengths which are practical to transport and to handle, including lifting at site, see figure.
The most practical way of assembling these elements is by joining using bolted connections. A number of different designs have been developed, built and installed over the years, but still the industry is experiencing challenges with the existing tower flanged connections.
The main challenges are related to;
There have been several collapses of wind turbine towers where the cause of the failure has been from poorly bolted joint design. The industry also has a challenge with the new and bigger wind turbines requiring higher capacity connectors to transfer to loads to the foundation.