Steel building

Use of high strength steel in wind turbine towers. The main topic is the use of higher strength steel in tubular towers used in wind turbines.

The towers are loaded not only by self weight but also by dynamical loads from the wind and the rotation of the rotor blades. The dynamical load is modeled as the cyclic loading and therefore, fatigue is one of the main concerns especially in the assembling connection of the different tower sections.
A European Research Project, called HISTWIN, was launched to investigate possibilities of using the higher strength steel in the towers. A new connection solution was proposed: Instead of flange connections the tower sections should be assembled via friction connections. In addition to the better performance in fatigue this type of connection is easier to assemble and the higher steel may be used in towers. This lead to less steel used, lower tower weight which means that the total costs for the tower might be reduced significantly.

The second issue within steel tubular towers which is of concern in Christine’s project is the optimization of door openings. Traditionally, the door opening is rather expensive detailed due to complicate geometry and production costs due to welding of rather thick stiffeners.
Due to the change in geometry and material thickness, the design procedure of this part differs significantly from the design of the rest of the tower. Research on a dominate failure mode and possible improvement of detailing around the opening by using the higher strength steel is important for the optimization of the steel tubular towers.

PhD student: Christine Heistermann
Supervisor: Milan Veljkovic