Active Bending and Tensile Pantographic Bamboo Hybrid Amphitheater Structure

The present paper describes the design process of a textile hybrid bamboo amphitheater dome built in the tropical climate of Brazil, employing a mobile free-form space structure spanning a 17 x 12m area. The structural system is designed applying pantographic gridshells pre-stressed by acrylic membranes and braced by self-stressed active bending beams reinforced by steel cables and strut scissors, avoiding buckling of the members. The structural system consists of an adaptable supporting space structure using hinged bamboo bipods. The connection of the structural modules on a free-form geometry has a self-stabilizing behavior, therefore reducing the use of heavy foundations. Flexible hinged lashed joints with textile-based techniques were developed. A form-finding method based on the developed physical models established the topology of the building site, generating the assembly procedure. The full-scale model was constructed on the inclined site at the banks of the Rainha River at the campus of the Pontifical Catholic University of Rio de Janeiro, PUC-Rio. The modular space structure was mounted in stages on the ground, then erected with the aid of lifting bipods, without the need of cranes and heavy machinery. The 200m² built structure had a weight of 14 kN corresponding to 0,07 kN/m², consisting a sustainable ultra-lightweight space structure.