Robotic construction has taken another step forward with the Future Tree, a recently completed timber canopy built with robots in a project by Gramazio Kohler Research and ETH Zurich. Completed in October 2019, following 2 years of planning and approximately 4 months of construction, the Future Tree is a study of complex timber structures and digital concrete. The tree-like canopy was installed over the courtyard of the office building extension of Basler & Hofmann in Esslingen, Switzerland.
An industrial robot was used to fabricate and assemble the Future Tree’s 380 timber elements made from acetylated pine wood and fitted with full-threaded screws and tension cables to form a reciprocal frame. The structure’s canopy-like crown is supported by a single, trunk-like concrete column and anchored to the office building on two sides while cantilevering on the opposite corner.
“The frame’s geometry is informed by its structural behaviour, differentiating its flexural rigidity by playing with the opening of the reciprocal knots to achieve a higher stiffness in the cantilevering part,” Gramazio Kohler Research’s explained. “To integrate geometric, structural and fabrication concerns we developed a custom computational model of the design.”
Perhaps the most noteworthy aspect of the project is Future Tree’s reinforced concrete column, which was made with a novel fabrication process called “Eggshell” that combines an ultra-thin, robotically 3D-printed formwork with fast-hardening concrete. As the first built example using this fabrication process, Future Tree “shows [how] non-standard concrete structures can be fabricated efficiently, economically and sustainably,” according to Gramazio Kohler Research. Because the formwork — which is 3D-printed to a thickness of 1.5 millimeters using a robotic arm — is filled with fast-hardening concrete in a layer-by-layer casting process to minimize hydrostatic pressure, it can be recycled and reused after the concrete has hydrated.
Images by Gramazio Kohler Research, ETH Zurich and Basler & Hofmann AG