Semiramis - The Hanging Gardens of Zug, Switzerland

At the entrance to the new Tech Cluster Zug, a tower called "Semiramis - The Hanging Gardens of Zug" will reach a height of more than 72.17 ft. The hanging gardens will provide a habitat for native plants and small animals, thus bringing natural diversity to the new district. Timbatec was responsible for the structural and dynamic analysis of the structure. It utilized RWIND Simulation for the wind flow analysis.

Structure

The tower's columns are made of steel, and the plant bowls, with a diameter of up to 33 ft, are made of cross-laminated timber panels. The team of Gramazio Kohler Research at the ETH Zurich (which conceptually designed the architectural timber structure) has also developed, together with various internal and external partners, a completely robot-supported assembly method for the precise positioning of the cross-laminated timber panels. Four robots working at the same time enable this method.

The cross-laminated timber panels are connected to the faces by means of TS3 cast resin, by joint grouting without applying pressure to the faces. Timbatec developed this process in several research projects with the ETH Zurich and the Bern University of Applied Sciences. Currently, it is used mainly for the construction of floor slabs, but it also enables structures such as “Semiramis".

The tall, slender structure is planted with large bushes and trees. On one hand, the structure has considerable dead weight; on the other hand, it represents a large contact surface for the wind. Thanks to the advantageous round shape of the plant bowls, the wind is redirected around the structure. Nevertheless, the stiffening of the structure with its eight slender columns is a challenge.

In order to determine the wind pressures and suction on the columns and plant bowls for the design, a wind flow analysis was carried out in a digital wind tunnel utilizing RWIND Simulation. In addition, due to the slender construction, resonance effects along and across the wind direction had to be taken into account in the calculations.