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I wasn’t just training laborers, however, but teaching students as a part of the ETHiopia Urban Laboratory Summer School, hosted by the EiABC and run in conjunction with the ETH Department of Architecture, ETH Sustainability, ETH North-South Centre and the BLOCK Research Group. The participants of the summer school were ETH and EiABC students of architecture, entrepreneurship, and water and sanitation, as well as representatives of local construction cooperatives.
I should hope that the juxtaposition of the phrases “training laborers” and “teaching students” raises some red flags here; indeed, the inversion of these teaching modes is a relevant topic in the context of capacity building in Ethiopia, and probably one of the more invisible aspects of the success of the workshop. The students had one week of lectures, followed by two weeks of the practical component of the workshop – enabling a translation from theory to praxis. Rather than merely “training laborers” and “teaching students”, we were also training students as laborers and teaching laborers as students.
As a part of this program, we set up test vaults on the ground for students to experiment with the techniques of tile vault construction. The foundations built for the test vaults established three types of boundary conditions, the purpose of which was to facilitate practical experience in the constructional and structural principles of each vault typology:
1. A Single-curved barrel vault (similar in basic geometry to the full scale SUDU)
2. A Double-curved barrel vault
3. And a Double-curved vault, springing from edge arches
The group’s exploration of catenary structural principles was evident in the development of their guide-work strategies – perhaps ‘easy’ when any material is available, but quite challenging when one has no reliable lumber or cutting tools.
For the students of architecture, there was of course a different goal employed in the teaching strategy, beyond that which overlayed construction method and structural system. Just as in the full scale construction, the materials, the tools and the available skill-sets were limited. The students were asked to engage in a process of design unique to these circumstances, designing everything past the boundary conditions with only the few tools available to them: A chain, some mixing tools, and some scrap wood from broken-down furniture. Guidance was provided with respect to material techniques, formwork strategies, structural behavior, and tiling logics to keep the vaults stable during construction – but mistakes which produce collapses are, more often than not, more valuable learning experiences than instruction. The constructional solutions developed by the students were manifold and demonstrated an extremely creative use of ‘nothing’, among them: the use of nails in recycled boards to set the first masonry arches in cantilever, materials such as telephone wire for string, sliced bamboo for formwork, strips of eucalypis peeled from neighboring trees to describe curved masonry surfaces.
Material resourcefulness and frugal use of material went together. Danny, one architecture student at the EiABC, noted that while others’ had criticized his craftsmanship, the tiling pattern he developed nevertheless greatly reduced the use of the most expensive construction material, gypsum.
All the while, this Summer School occurred – rather uniquely – in the context of a the construction of our full scale vaulted SUDU prototype, spanning approximately 5 meters with a 7 meter length. So, as the students pursued their own problem-solving on the ground, the project managers and laborers engaged in some of our own at the full-scale laboratory study. While the first cautious steps were taking in loading vaults with varying heights of less than one meter, great care was demanded in the construction and loading of the full scale vault.
The test vault serves a critical function both for students and for laborers, allowing for the development of skills in a safe and controlled manor, while serving as an analogue to the full scale structure. They are an effective tool for the development of knowledge in applied structural principles – clarifying critical topics such as the outward thrust of a vault, the function of tension ties, the benefits of stabilizing ribs, etc. A collapse teaches the boundaries of structural stability during construction – yet without such training in the structural behavior of masonry vaulting, constructions at full scale may take unnecessary risks.
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