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Institute for Computational Design Institut fur Computerbasiertes Entwerfen Institut fur Tragkonstruktionen und Korstruktives Enterfen

Universitat Stuttgart

L a Tour de L’ A r c h it e c t e

10935 CA RIS S A DRIV E DA L L A S, T X 75218

In 2012, during a year of study at the University of Stuttgart, I had the opportunity to work with a small team to design and build an event space for a stone tower built in the 1500s and designed by Leonardo da Vinci. The project, known as Textile Hybrid M1 at La Tour de l’Architecte, showcased the combined efforts of six architectural students and two professors. The project involved the use of textile and bending-active materials developed at the Institute for Computational Design (ICD) and the Institute for Building Structures and Structural Design (ITKE). The Textile Hybrid M1 is situated on a historically protected site located in western France in the small village of Monthoiron. Because we were working on such a delicate historic structure, we had to ensure that our design exerted only minimal force on the tower and abutting buildings. The canopy also had to avoid contact with areas containing delicate archaeological material. The longest span of the canopy, of approximately 8 meters, provides cover to an area where one of the foundations for the tower’s stone buttresses sits. The minimal external structural exertion was accomplished through the use of interwoven bending rods that formed leaf-like shapes.

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M ATERIAL B E H AV I O R COMPUTATION OF MATERIAL BEHAVIOR The project team experimented with numerous materials and the building of several prototype materials and various designs of structures that would act both in tension and compression to support the weight of the canopy without exerting external pressures on the tower structures. Placement of the concrete footings was determinded during our initial site visit and was an important aspect of the team’s efforts. It was necessary to know exactly where these footings would be placed so that the geometry that went into designing the canopy would be completely accurate. Analytical programs designed by our professors were used to generate bending-active leaves in a behavior based modelling environment.

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The canopy is oriented towards and existing arched wall, which once defined a large, domed space. This overlaps an area that holds the foundations of one of the tower’s buttresses below ground. The longest span of the structure is designed to run across this part of the courtyard, preventing any of the structure from invading the area where the tower foundations sit below.

Plan of the existing tower and surrounding structures and Textile Hybrid M1 with overlay of locations for the original tower buttresses, showing overlap with the courtyard site. Drawing of the original tower design with buttresses based upon da Vinci’s sketches and archeological information. This is copied against a 3D construction of the current tower.

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We also experimented with different lashing and lacing techniques for the lightweight rods. The goal was to lock the rods into a rigid frame. This continues at the base of the structure where the rods are tied into bundles and laced to the glass-fiber reinforced polymer (GFRP) foundation posts. Together with the membranes, the structure takes advantage of the accumulation of multiple layers and structural elasticity. These features enable the system to withstand varying stressing of wind, rain and snow, yet rebound to its initial form. The cells provide a similar structural function at a smaller localized scale, but are more oriented towards offering an integrated strategy for spatial differentiation. The cells are constant in their topology, yet differentiated in their form. Utilizing Polyamid textiles for tensile rigidity in the cells and variation of light transmittance, the cell surfaces are articulated at more minute scales.

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The shape of the integrated material system was accomplished with GFRP rods. These rods had diameters ranging from 3mm – 24mm and were combined with textile membranes as continuous surfaces and open weave meshes. The highly elastic rods gain their stiffness from bending them into curved leaf shaped modules that were networked into the overall system. The rods were further stiffened by further bending and through the integration of a pre-stressed membrane surface. The structure is comprised of 110 meters of GFRP rods, 45 m2 of membrane material covering an area of approximately 20 m2 and anchored to the ground with only 3 foundations resting against the existing stone structures that are adjacent to the tower. In total, the building weighs approximately 60 kilograms (excluding foundations), with clear spans ranging from 6 to 8 meters.

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Overall, our project exemplifies a true textile hybrid system, where the organization of bending-active beams and tensile surfaces allows long-span arches, overlapping grid-shells and double-curved tensile surfaces. The material system of M1 explores the structural capacity and formal variability of a lightweight structure comprised of highly elastic rod elements and membrane surfaces. M1 serves La Tour de l’Architecte as an exemplification of innovative structures generated by experimental means, as well as provide fundamental function for meeting, workspace and archaeological study within the complex of buildings as the site undergoes redevelopment. The University of Stuttgart will use the M1 site as a prototype for hybrid force-active structures and the use of computational design methodologies.

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Instilation of top Membrane fixed to GRFP rods

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Cantilevered brow (top-right in photo) exhibiting complex equilibrium between bending-active GFRP rods and pre-stressed membrane surface.

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Completed textile-hybrid self-structured cell system. Detail of GFRP rod and Polyamid textile cell assembly, exhibiting differentiated geometry and variable opacities in the tensioned textile.

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Installation of cell system into meta rod and membrane structure.

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Completed M1 structure with top membrane, bottom mesh and internal cell structure.

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Overall view of completed Textile Hybrid M1 showing the cantilevered brow in foreground (at top in photo). Pictured at left are details of the composite textile structure: lacing between GFRP rods, textile membrane and textile mesh.

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Institute for Computational Design (ICD) – Prof. Achim Menges Institute of Building Structures and Structural Design (ITKE) – Prof. Jan Knippers Scientific Development Computational Design, Programming of Material Morphologies, and Experimentation in Textile Material Systems Sean Ahlquist Structural Design, Programming of Form-finding and Structural Analysis, and Material Testing Julian Lienhard Concept Development David Cappo, Angel Pontes, Andreas Schoenbrunner System Development, Building Design, Detail Design, Fabrication and Construction Markus Bernhard, David Cappo, Celeste Clayton, Oliver Kaertkemeyer, Hannah Kramer, Andreas Schoenbrunner Funding DVA Stiftung The Serge Ferrari Group Esmery Caron Structures “Studiengeld zuruck”, University of Stuttgart Additional material donations CG Tec GmbH Carbon- und Glasfasertechnik (Carbonscout) Fibrolux GmbH PENN Textile Solutions Client The Armbruster Family, La Tour de L’Architecte

La Tour de L’Architecte