Bascule shelters: A novel erection strategy for origami-inspired deployable structures

Abstract

Rapidly deployable shelters are critical for housing on forward operating bases and for relief following natural or anthropogenic disasters. In addition to meeting structural performance criteria specified by design code, key design priorities include a low self-weight (preferably being person-portable), deployability (i.e., capable of being packaged in a small volume to enable transportation by air, rail, ship, or truck), and an erection strategy that does not require heavy lifting equipment. Due to the high cost of fuel, energy efficiency in heating and cooling these structures is also a priority. Existing military soft wall (canvas) shelters provide a low self-weight and high deployability (defined by volume expansion ratio), but offer little thermal insulation for energy efficiency. Rigid wall counterparts provide enhanced insulation but have high self-weights, limited deployability, and require heavy lifting equipment for placement. The art of origami can be harnessed as a source of inspiration for a hybrid solution: offering deployability through folding, while providing insulation through rigid panels. A key challenge in implementing rigid wall origami-inspired deployable shelters, however, is an erection strategy that does not require heavy lifting equipment. This paper presents a novel erection strategy for origami-inspired shelters based on the principle of counterweighting. More specifically, loads are applied to a detachable lever to balance the mass of the shelter as it is rotated into position (analogous to the behavior of a bascule movable bridge). This paper first reviews existing soft wall and rigid wall solutions. Then it presents a series of origami-inspired concepts which meet the design priorities and implement this novel erection strategy. One concept will be highlighted in detail, including finite element analyses as the structure deploys and in its deployed form under loads prescribed by the United States Army Natick Soldier Research, Development & Engineering Center. This highlighted shelter concept is demonstrated through a small-scale prototype. Applications for this erection strategy extend beyond deployable origami-inspired shelters, including temporary storage facilities and modular homes.