KnitNervi – An actively bent, knitted formwork for ribbed concrete shells

© Photo by Mariana Popescu

Knitnervi is a pavilion-scale demonstration of a ribbed concrete shell constructed with a flexible formwork system. A bending-active gridshell serves as falsework and reinforcement and is encased by CNC-knitted shuttering. Knitnervi project by the Block Research Group (BRG) at ETH Zurich and Dr. Mariana Popescu from the Faculty of Civil Engineering and Geosciences at Delft University of Technology, constructed for the exhibition “Technoscape: The architecture of engineers” at the MAXXI National Museum of 21st Century Arts in Rome, Italy, 2022.

KnitNervi takes inspiration from Pier Luigi Nervi’s pioneering Palazzetto dello Sport to reimagine ribbed, thin-shell, reinforced-concrete construction. By proposing a construction system that eliminates the need for complex, wasteful molds, the project departs from the prefabrication and standardization paradigms that enable expressive and efficient concrete shells.

© Photo by Mariana Popescu

The installation is a ribbed reinforced concrete shell formwork system on a flexible formwork system. The form’s highly articulated, doubly-curved geometry was discovered to act in pure compression with a tension ring at its perimeter. A bending-active gridshell serves as the primary formwork structure as well as the integrated reinforcement of the final concrete shell. KnitCrete encapsulates the expressive geometry, a CNC-knitted flexible stay-in-place shuttering.

© Photo by Mariana Popescu

The pavilion shell is 9.0m x 9.0m x 3.3m and has a covered area of 56.6 sqm. The weight of steel reinforcement is 533 kg, and the weight of the formwork system is 10.8 kg/sqm.

Part of the Technoscape exhibition at the MAXXI, KnitNervi offers a roadmap for interdisciplinary co-development in architecture, engineering, and construction. The ambition is to nurture a conversation on sustainable and structurally-efficient architecture in the XXIst century.

© Photo by Mariana Popescu
© Photo by Thom de Bie

Project Credits

ETH Zurich – Block Research Group (BRG) & TU Delft – Prof. Mariana Popescu
Location: MAXXI National Museum of 21st Century Arts, Rome, Italy
ETHZ BRG: Lotte Scheder-Bieschin, Serban Bodea, Tom Van Mele, Philippe Block
TUDelft: Mariana Popescu, Nikoletta Christidi
Structural engineering
ETHZ BRG: Lotte Scheder-Bieschin, Philippe Block
Knitted formwork
TUDelft: Mariana Popescu, Nikoletta Christidi
Fabrication and construction
ETHZ BRG: Kerstin Spiekermann, Lotte Scheder-Bieschin, Serban Bodea, with support of Eva Schnewly, Damaris Eschbach, Rolf Imseng, Stefan Liniger
TUDelft: Mariana Popescu, Nikoletta Christidi
Project and site construction coordination
ETHZ BRG: Serban Bodea
TUDelft: Mariana Popescu
The exhibition content, coordination, and curation
ETHZ BRG: Lotte Scheder-Bieschin, Serban Bodea, Mariana Popescu, Kerstin Spiekermann, Noelle Paulson, Katharina Haake, Philippe Block with support of Eva Schnewly, Rolf Imseng
Sponsors: NCCR Digital Fabrication, ETH Zurich, Debrunner Acifer, Doka Switzerland and Italy, Jakob Rope Systems, NOWN, Symme3D
Documentation and Video
Footage: Thom de Bie, Mariana Popescu, Lotte Scheder-Bieschin, Serban Bodea
Editing: Thom de Bie
Animations: Lotte Scheder-Bieschin, Michele Capelli

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