While developing a concept for YPQ’s new international air terminal building, we were asked to consider a hangar structure for the Boeing 737 aircraft that would be used for these short-haul flights. While a pre-engineered steel building is the typical response for large-span, economical structures, we wondered if a wooden structure could be just as economical while offering superior fire resistance, daylighting and aesthetics. The question was then how to span 64m clear with a wooden structure while keeping joints as simple, effective and inexpensive as possible? With advisement from Blackwell, Canada’s foremost structural engineering firm, our idea for a large-span timber tensegrity structure was quickly eliminated due to the fact that the radii required for steel cable was untenable and/or too expensive to execute at every joint. But if a tensegrity structure is effectively flattened or squashed, then the tensile element is reduced to a simple threaded rod, and while some bending is introduced in the wood members, a pattern of self-reinforcing beams can network to form more than the sum of the parts. These structures are better known as ‘reciprocal frames’ first modelled by Leonardo Da Vinci. To help us better understand them, a mix of digital and physical models was explored.
They say a picture is worth a thousand words. So we hope these 26 images can capture our process over the last 8 months. Mostly so we don’t have to write 26,000 words! Credit for custom software programming and scripting to support our physical models must go to David Bowick for steering us towards RF Structures, and then to Philip Chi-Wing Fu, Shufang Wang, Peng Song, at the École polytechnique fédérale de Lausanne (EPFL), Universities of Tel Aviv and Singapore, as well as Mike Lanctot our ArchiCad GDL programmer/architect/math whiz in Toronto. If you’d like to learn more about reciprocal frames as an affordable alternative to tensegrity structures – or what we now call ‘flattened tensegrity structures’, contact us by email and we can send you some of the research. We aim to build larger scale models in Summer 2019 for demonstration purposes.