A tower made of self-shaped structural timber

Researchers at the Institute of Computational Design and Construction at the University of Stuttgart, Germany, designed what they say is the first multi-level, walkable building to use self-shaped, structural timber components.

Called the Wangen Tower, the structure is 23m tall and is composed of 12 curved cross-laminated timber (CLT) segments, each with a slender cross-section of 130 millimetres. The tower was designed using computational design strategies that integrate material behaviour and fabrication constraints.

The CLT is made of locally sourced spruce, which was processed after slight air drying. The material was made with altering layers of 30 mm thick ‘active’ layer and a cross-laminated 10mm ‘restrictive’ layer, which were laminated in a flat vacuum press. The flat panels then underwent controlled kiln drying, in which the active layer shrunk perpendicularly to the fibre direction of its boards, effectively shaping the panels into their predicted curved form. Three of these curved panels were then stacked with a 10 mm elastically bent locking layer to create the final panels.

The components were pre-fabricated with precision to the millimetre and featured with precision-milled connection details. This allowed for onsite assembly within three days, including seamlessly integrating the tower’s steel staircase, glass skylight and observation platform. The curvature of the segments provides additional stiffness to the timber surface, similar to a corrugated sheet. The central spine of the staircase supports the vertical live loads on the steps.

The Wangen Tower is the first structure with multiple-habitable levels to use curved components based on large-scale self-shaping manufacturing derived from the moisture-induced shrinking of wood.

For a similar project, click here.

Photos: University of Stuttgart / Nina Baisch