The Trolls is a design by:
Design: DDI Rudolf Brandstötter,
Constr: Acht. Ziviltechniker GmbH
AustriaTaken from the designer’s concept:
High-voltage transmission line towers mostly have a very technical character. As this infrastructure is designed by engineers the structure is very well optimized but in the majority of cases the optical impact to the environment is very rude. Framework structures are very efficient structures and so they are very popular for high-voltage towers. It is often heard that a framework structure is transparent – but in reality it is not!
So we decided to go for a box shaped plate girder in order to design an elegant and compact structure. It is our main goal to create a tower with charisma. As the towers are set into a beautiful and unique landscape it is very important that the tower gets part of it. A up to 35 m high tower always well be seen – whatever kind of structure it is!
So it is important to deal with the structures appearance – and that is what we do. We try to make that mechanical structure more human – more anthropogenic. For that reason we think that the towers will be seen as a friend, supporting the people with energy and not as a mechanical obstacle which disturbs the outlook.
In our design proposal the tower gets part of the landscape as a kind of sculpture. It takes area of our nature and therefore it has to be an acceptable object with an adequate design.
The towers are made of welded box steel girders.
The main structural system is a fixed girder, so the peak of stress is near the ground. Therefore the structure is broadening near the ground and it gets more slender in the upper areas. The smaller sides of the boxes have a coned shape. This can be easily produced by rolling the steel sheets. The plate girder gives a very compact structure which is easier to maintain against corrosion then a framework is. In order to achieve economic life – cycle – costs this is an important argument. Furthermore the box girder provides more torsion stiffness, which is important in case of a single cable rupture. To avoid stress peaks near the junctions the structure is organically shaped. The junction plates are designed according to a bionic approach. The form of the plate is shaped like the connection between a trunk and a branch.