Friday 30 August 2013

Building with Earth | Thin Shell Structures

AA Visiting School Lyon, Synchronised Movements 2013: A 10-day design-build workshop exploring a collaboration between digital design methods + workflows and the hands-on nature of building with earth. More details: This was the first of an annual series of workshops, that will contribute to furthering the research agenda every year. It's held at the Les Grands Ateliers in Villefontaine, France, which also hosts the CRATerre festival of Earthen Architecture at the same time as the workshop.

The image series below documents the design + fabrication process of a thin-shell structure built during the workshop using principles of catenary arches and minimal surfaces. There wasn't a feasible way of precisely controlling thickness: it varies from 5-10mm and its built using 4 layers of earth with two layers of loosely woven jute as reinforcement.

Architectural Association | Christopher Pierce, Priji Balakrishnan
Zaha Hadid Architects | Marie-Perrine Plaçais, Suryansh Chandra
Stéphanie Chaltiel Architecture | Stéphanie Chaltiel
Chiara Pozzi Architecture | Chiara Pozzi
Morphogenesism | Zubin Khabazi
Les Grands Ateliers | Patrice Doat
Grenoble School of Architecture | Philipe Liveneau

Design Iterations: Mostly dictated by the size limits of the CNC machine and our ambitions.

Design Process: Polygon to CNC millable pieces

Fabrication Data for Machine: Nested in sheets and labelled

Fabrication Data for Human: Assembling the shell one pizza slice at a time.

The Machine: doing its thing..

The Machine: did its thing.

The Humans: doing their thing. The big and small things you see all around are some of the other tests and structures that we built..

Assembly complete.

Time for Fabric: This fabric is the main formwork on which the earth will be applied. The plywood is just so the fabric can take the correct shape.

One Pizza Slice at a Time: Don't go by the laughing faces, it took some serious pulling to get the fabric taut.

Undo: Going wrong meant painstakingly ripping the fabric and removing the pins.

Fabric complete.

Putting the pizza together: Each slice was assembled separately, so it took clamping/bolting to bring the shell together

Brace: The fabric was so taut that it was pulling the arches too far in.

Braced: All braces in place keeping the arches vertical. The first coat on the fabric is a stiffener, and it also makes the surface fairly rough. This helps earth stick a lot better.

Indiglo: the stiffener coat is almost complete. Halogen lamps were put inside to expedite the drying process.

Hands-on: Marie-Perrine applying the first coat of earth..

Tactile process: using hands to apply earth has a sculptor-like quality due to its tactility - a rare quality in an increasingly digital world.

First layer of earth complete.

The oven: Drying time was a big factor in a 10-day workshop with rainy weather. An army of halogen lamps and plywood sheets were used to turn the entire shell into an oven. In an ideal world one could be more eco-friendly given more time and less rain.

Coat 2 begins..

Nasty Edges: Chiara ensuring the edges get enough earth. Due to the design and planarity constraints, the edges often got too narrow to be able to apply earth properly. 

Coat 3

The Sag: As more coats were applied, previously dried up coats would also soak some moisture and get soft. This led to a bit of sagging and the inner arches started to protrude on the outside - not exactly how it was designed.

The Sag: the increasing weight of earth with each coat was starting to get concerning, as it introduce some unpredictable forces within the shell.

Demoulding Begins: The shell felt very firm upon drying and we decide to stop adding more earth to avoid increasing self-weight. Demoulding begins by cutting out all the fabric first.

Demoulding: the pizza slices seem to hold without the fabric..

Arches Off: The first external arch comes off, and for the first time we perceive how thin the shell really is - and it's anyone's guess if this will stand.

All Arches Off: All 5 external arches are out, only the 5 inside remain - those are the real challenge. We were very tempted to leave the inner arches in place to hold it up, but then it wouldn't be worthy of an experiment if we play safe.

The Show: Quite an audience is starting to gather around, as eager as us. Whether this stands or collapses, this is going to be quite a show.

Demoulding: Removing the inner arches was extremely tricky because they locked each other like keystones, and the shell had sagged around them, making it very difficult to slide them out of place.

Hacksaws and Brute Force: All kinds of crazy ideas were on the table to get these off.

Twist, Rotate, Push, Pull: After some serious cajoling, the inner arches were starting to come off. The shell shook quite a bit while we applied so much force - and we were somewhat scared that it might just collapse on us while we're still pulling these arches out.
The Smiles and the Wonder: The last half-arch remains and it's the first time we get the sense that its probably going to be able to stand on its own :)

Its Off: We take the last arch out and run.. in case it comes down.

It Stands!: The finish of the edges leaves much to be desired, and could even be fixed after demoulding but this was the last day of the workshop and we were out of time.

Pride: The structure hosted the convocation ceremony of the workshop.

Unfortunately, the shell didn't have too long a life: it needed to be moved in order to make room for other activities, and didn't survive the lateral loads imposed by the move. Oh well, such is life.

We were personally extremely impressed at the fact that it could stand at such minimal thickness, and earth did extremely well given that the design process ensured that it was mostly compression forces in the structure. The works of the BLOCK Research Group, Anna Herringer, Carl Giskes, Kinya Maruyama, and many others served as valuable precedents for us, and we thank all the great Earth Experts who constantly advised and steered us novices with just about everything. We certainly need to improve our skills at working with earth: the (very) rough edges of the structures are a testament to our novice-level skills at this.

A big thanks to everyone involved for bringing your ideas, expertise, energy, and yourselves to this fantastic workshop. A big thanks to the students and other tutors for giving us the picture that you see above.

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