Traditional thinking in architecture and engineering alike is to understand the built environment as static. Build structures resist changes in the environment through stiffness. ‘Hybrid Tower’ asks, what an architecture could be, that is soft and gives in to forces in a controlled yet way. An architecture that embraces the idea of resilience and adaptation.
‘Hybrid Tower’ is an integrated hybrid structure – made from only two components: Bend GFRP rods and custom-made CNC knit. The unique combination of these two materials creates a very light and yet stiff structure, which balances wind and other external forces through an interdependent combination of compression and tension elements. The structure is extremely light and easy to assemble, but yet strong enough to withstand a 3 month outdoor installation on the world cultural heritage side of the central square of Guimaraes/Portugal: Largo do Toural.
The tower was developed in an interdisciplinary collaboration between architects (CITA, Copenhagen) , structural- and textile-engineers (KET, Berlin, Fibrenamics, Guimaraes), material testing specialists (Duisburger…..) and the knitting company AFF (A. Ferreira & Filhos). Together they developed materials and design and fabrication processes, which allowed using knit as structural element in a previously unprecedented scale. The collaboration opens new avenues for textile as building material.
Structural Engineering: Udk – Universitaet der Kuenste Berlin / Berlin, Germany: Christoph Gengnagel, Riccardo La Magna, Michael Schmeck
Textile Testing: Universitaet Duisburg Essen / Duisburg,Essen, Germany: Natalie Stranghoehner, Joerg Uhlehmann
Textile CNC Production: AFF – A. ferreira & Filhos/ Vizella, Portugal: Filipa Monteiro, Jorge Vieira
Special thanks to: David Anders Leon (CITA), Raquel Carvalho (Fibernamics), Irina Maximovich, Ida Friis Tinning (CITA).
Photography: Anders Ingvartsen
Multiple scales in bespoke knitted structure
A core question in the project is the ability to design for and with material performance. This is a core resource for design innovation closely tied to material optimisation.
The project introduces three scales of design engagement by which to examine material performance: the structure, the element and the material.
In order to succeed the project needed to answer, how to support feedback between different scales of design engagement moving from material design, across design, simulation and analysis to specification and fabrication.
Designing a soft tower
‘Tower’ investigates knit as a structural membrane in which active bent GFRP rods are embedded into a knitted fabric, made with bespoke material properties and detailing.
The relationship between skin and structure is a central question in the field of architectural textiles, positioning the textile membrane either as a cladding skin, or engaged in hybrid dependencies in which membrane and scaffold act as an integrated structural system.
The latter requires a high degree of control and understanding of the membrane’s material behavior. ‘Hybrid Tower’ develops new modelling practices needed to devise hybrid behaviors. The project developed the general structural and material system and a set of related computational tools to design and specify these material systems, starting from the global shape and its discretization into patches, that can be produced on the knitting machine to the automated detailing and creation of the tower base.
Simulating soft architectures
The application of knitted fabrics on architectural scale requires a prediction of the overall structural performance in order to guarantee stability. For this new simulation and texting techniques for elastic materials had to be developed. A novel simulation process that interfaces a projection-based relaxation method with a finite element (FE) simulation extends existing approaches and is able to effectively simulate the interaction of the constraining fabric, the many pretensioned actively bent GFRP rods and external forces.
Processes to generate the database underlying the simulation had to be developed, not only as the material has bespoke properties, but especially as materials with elastic behaviors are still a novel field for building industry.
This database included data on the level of the knitted fabric, but also its interaction with other components and forces within the structural continuum.
Interface and priduction of bespoke CNC knitted fabric
‘Hybrid Tower’ innovates the making of fabric structures. The current approach in the production of textile architecture is to cut patches out of large rolls of fabric, to sew these and to apply details later on. This laborious and wasteful process is cut short by the developed processes in ‘Hybrid Tower’.
Here all details are embedded in the material itself and the final shape is directly knitted in the CNC knitting machine. For this an interface between the design environment and the CNC production machines from Shima Seiki machines was developed by CITA and AFF.
This enables the direct creation of the machine code defining the knitting beds, the yarn carries and holding patterns, and thereby controlled the formation of the knitted textile and provide a direct control of the structure, material and shape.
Detailing and assembly
A soft architecture requires new thinking in terms of detailing and assembly. Instead of a storeywise assembly the structural skin of the tower is produced on ground as large prestressed panel. This is subsequently rolled into shape, tensioned, transported horizontally to site and erected to the vertical. The 9 meter high structure is so light, that it can be carried by only 6 people.
In order to ease assembly we developed a set of joints with a puzzle configuration, which can be attached to the round beams after they slid through the channels.
The parts are sliding towards each other and provide a solid connection between GFRP rods. They rest on metal stoppers, which are fixed to the beam in predefined locations and are able to withstand vertical loads of up to 50kg each. This approach allows for fast assembly and disassembly.
As a proof of concept the Hybrid Tower was build on the Largo do Toural – the central square of Guimaraes. ‘Hybrid Tower’ demonstrated throughout the 3 month exhibition period the strength and high performance of bespoke knit material on a large scale and provided an exciting architectural intervention for the town, bringing new experience of a translucent and haptic textile architecture into the old urban environment.
‘Hybrid Tower’ is a project within the Complex Modelling research framework at CITA and was exhibited within the Contextile festival in Guimaraes . The project received further support through the European COST Action “Novel Structural Skins”.