Sandwich tower
The sandwich tower is a construction method for towers developed by the Institute for Steel Construction at Leibniz University Hannover , which is of particular interest in the field of wind energy generation . In 2008, the idea was awarded first place in the special “proKlima” prize awarded by the Stadtwerke Hannover .
construction
The name is derived from the construction method : the lower part of the tower consists of two steel tubes , one inside the other ; these are fully stiffened by an intermediate composite material . Various grouting mortars , including pumpable elastomers and epoxy resins, can be used as composite materials ; these are filled in ascending order from the base of the tower into the annular gap. In addition to the rigidity and compressive strength of the filling materials, their bond strength is of essential importance for the load-bearing behavior of the sandwich cross-section.
The top section is designed in the conventional way as a steel pipe section, which is positively connected to the lower sandwich pipe section by means of the so-called sandwich joint . This pipe-in-pipe connection works without fatigue-critical ring flanges and high-maintenance screws. The sandwich construction increases the shell stability and the bending moment capacity, as the composite material not only has a stiffening effect, but also participates in the load transfer.
The higher load capacities and the division of the required sheet metal thickness between the inner and outer tube allow a larger diameter at the tower base of a wind power plant, which means that larger and more stable towers beyond 100 meters hub height can be erected. In the field of wind energy, large total heights are of interest, since the energy yield of wind turbines increases disproportionately with height.