Urbach Tower in Germany constructed with self-shaping wood

Materials World magazine
1 Jul 2019

A 14m-tall tower has been constructed in Germany using curved wood components that have been self-shaped. Shardell Joseph reports.

A self-shaping process for curved wood components has been demonstrated, creating an alternative to elaborate and energy-intensive mechanical processes normally used to craft timber.

The Urbach Tower in southern Germany was a joint project between the University of Stuttgart’s Institute for Computational Design and Construction (ICD), and the Institute of Building Structures and Structural Design (ITKE).

Recognising the deformation caused by moisture in timber, a factor that is typically problematic in timber construction, the project used the drying process to accelerate the wood’s characteristic shrinking in order to help change the shape.

According to the ICD and ITKE team, they arranged the wood in a way that utilised the naturally occurring deformation, triggering a designed self-shaping behaviour. ‘In the same way that machines can be programmed to perform different movements, wood parts can be programmed to transform into predetermined shapes when dried,’ said an ICD and ITKE spokesperson.

The curved cross-laminated timber (CLT) components for the tower’s structure are designed and produced as flat panels that deform autonomously into established curved shapes when dried. Manufactured with high wood moisture content and specific layups, the 5m x 1.2m spruce wood bilayer parts are dried in an industry standard technical drying process. When removed from the drying chamber, the parts are precisely curved. They are then overlapped and laminated together to lock the geometry in place, forming larger curved CLT components with form stable geometry.

Although shaping wood is not a new process, recognised in the past by academics and used within industrial processes, the methods used on the Urbach Tower have shown a more advanced approach. The researchers discovered a process that does not rely on brute mechanical force for shaping, and shows a shift in design thinking, as well as new computational simulations for more accurate prediction, allowing the use of moisture-induced swelling and shrinking to design and programme specific self-shaping movements at a larger scale.