Bamboo-based architecture is common in Bali, but even then the Arc gymnasium by Ibuku is a feat unlike any other in the world of sustainable architecture! The structure has been designed for a private school campus featuring a complex double-curved roof made entirely from bamboo. The Green School has a 12-year history of pushing boundaries and pioneering for sustainable education and Arc is the first of its kind!
The bamboo structure is built from a series of intersecting 14-meter tall bamboo arches spanning 19 meters, interconnected by anticlastic gridshells which derive their strength from curving in two opposite directions. It employs one of nature’s greatest strategies for creating large spaces with minimal founding pillars. For example, in a human ribcage, there are a series of ribs working in compression are held in place by a tensioned flexible layer of muscle and skin. This creates a thin but strong encasement for the lungs. Similarly in Arc, arches working in compression are held in place by tensioned anticlastic gridshells. These fields of gridshells appear to drape across the spaces between impossibly thin arches soaring overhead and although the gridshells appear to hang from the arches, they actually hold them up.
Its unique shape forms a protective roof sheltering a multipurpose sports court with a floor area of 760 square meters. The lightweight building’s geometry brings the structure into a state of equilibrium, which means a dramatically decreased necessity for structural material. This also means an unprecedented inner volume with an impossibly thin structure and without any distracting trusses. The Arc is truly a magnificent, minimal, and organic structure that shows we can dream big, make an impact, and strive to be more sustainable on a grand scale without compromising on our purpose.
“The concept structure for The Arc is totally unprecedented,” claimed Ibuku project architect Rowland Sauls. “Embarking on a design never before executed required some bravery and optimism. We were creative and stubborn enough to research and develop the answers needed for the success of the project.”
“The gridshells use shape stiffness to form the roof enclosure and provide buckling resistance to the parabolic arches,” said Atelier One director, Neil Thomas. “The two systems together create a unique and highly efficient structure,” he added, “able to flex under load allowing the structure to redistribute weight, easing localised forces on the arches.”