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A 34,000-square-foot kinetic media facade represents the themes of Korea’s international exhibition
Opened last month in the coastal city of Yeosu, South Korea, the 2012 International Exhibition’s theme, “The Living Ocean and Coast,” is a way for attendees to examine challenges and solutions to development on oceans and coastlines. As the architect of the expo’s thematic pavilion, Vienna-based Soma Architecture designed a kinetic media facade to act as a counterpart to the show’s location by the water and to its multimedia presentations. Working with Stuttgart- and New York-based structural engineering firm Knippers Helbig as facade consultant, the team developed a constructible solution for building one of the largest adaptive structures in the world.
Soma drew its inspiration for the facade by studying the natural sway of various types of vegetation. Because of its high tensile strength and low bending stiffness, glass-fiber reinforced plastic (GRP) was an ideal choice for construction of 108 twisting fins that would give movement to the facade. Architects refer to the fins as lamellas, the name for the ribs on the underside of a mushroom cap. Fabrication of the lamellas was done locally using traditional GRP molding techniques. Their media components—LEDs—are embedded in a 4-inch grid, with additional LED strips lining the edge of each fin to emphasize its movement.
The way the facade moves, however, is far from traditional. It explores new possibilities for active facade design with an analog approach to movement. The lamellas occupy more than 34,000 square feet, each one with a free span of 10 to 50 feet. The spears move when actuators apply compressive stress to the top and bottom of each one. The pressure creates a complex elastic deformation in each segment, causing the facade to open. The wall’s 216 actuators, each of which consists of a servomotor that drives a ball screw spindle, are activated by a coordinating control unit. Sensors continually check each lamella’s position, relaying information back to a server. Because upper and lower motors often have opposite power requirements (as with driving a car versus breaking it), the system can feed energy back into the local system to operate more efficiently.
Typhoon-strength wind loads were one of the design’s greatest concerns, so the facade must be able to close completely if necessary. When the facade closes, the lamellas are stabilized as the actuators stretch the fins and allow each to press against its neighbor. The applied pre-tension can be adjusted according to wind load; the adaptability will increase the fins’ durability by allowing the minimum amount of stress to be placed on each segment. The facade’s energy consumption is also reduced during the pre-tensioning process, allowing up to 13 fins to move at once.
According to the project team, the facade’s final technical solution was inspired by a research project at ITKE University in Stuttgart that investigated how biological moving mechanisms can be applied to architecture. The Expo will run through August, but its pavilion may influence new biomimetic approaches to facade design well into the future.