Cheongna, South Korea

Twister

City Tower, Cheongna

INTRO

This dynamic building responds to its environment, adjusting continuously to optimize energy use, giving pleasure to occupants and visitors while ensuring that Cheongna becomes a world-class destination for business, leisure & pleasure. The Cheongna City Twister’s advanced ecological systems and simple bold form will make it a global landmark, leading by example to beneficial constructs of the future. It changes character from day and night and throughout the seasons: shimmering tornado by day to glowing serene tube by night.

SITE

The site is a powerful intersection of energies of the Cheongna City, both of the systematic canals and the orderly grid of blocks. As a landmark observation tower, the taught, elegant form and inherent energy of the Twister will gather the city’s flows and patterns and focus them into the sky.

REVOLUTIONARY STRUCTURAL SYSTEM

The aerodynamic form reduces structural sizes and minimizes turbulence at street level. The inner structure is of typical core / column construction. Lateral stability is provided by shear walls and fanned bracing supporting eccentrically loaded floor plates. The structural system for the outer glass tube is revolutionary. Suspended by thin steel cables off a ring beam 466 m high, the entire glazing systems twists responding to climate changes and the hour of day. This ring is supported at an angle by 8 helical beam/columns, each countering the others push and pull in perfect balance. Each helix is a continuous welded rail – a very strong form of hot-rolled steel, proven since the 1950s in railroad tracks. Each 9 m segment is thermite-welded to form one continuous coiled beam/column that is 1.2 km long when stretched out.

Coil zone 1: base = 169 m Coil zone 2: transition = 209 m Coil zone 3: to the sky = 876 m Total length= 1254 m Rotating ring beam: radius = 11 m

Like a shock absorber, this gracefully counters lateral seismic and wind energies, distributing them evenly along its logarithmic profile. With eight of them together, the structure is redundant ensuring a high level of safety even if one coil fails. Each rail expands in summer and shrinks in winter due to thermal expansion/ contraction: in this case 3.2 m over its length. Anchored at the bottom, the dynamics are focused at the top ring beam which receives the coils at an angle. The result: the outer glazed tube rotates 1.6 m relative to the fixed inner glazing, providing shimmering light effects throughout the day and ecological benefits throughout the seasons.

ECOLOGICAL BENEFITS

In summer the active double skin is open due to thermal expansion of the coil beams. Air is heated under the glazed atrium picking up moisture from the canal and water park. This warm moist air rises between the active double skin where plants filter harmful particles and cool it through evapo-transpiration. The result: cool, clean air that improves Cheongna’s microclimate.

In the wintertime the coil beams contract, transforming the double glazed system into a thermally insulated airspace, within which plantings thrive in a greenhouse environment providing shade and pleasure for the occupants. The 1.2 m wide space between the glazing systems is enough for easy cleaning and maintenance.

BIRD FRIENDLY

Low-e glass, while of superior insulating value and clarity, is also dangerous to birds who mistaken its reflections for sky. Thousands of birds die every year due to crashing into buildings. Bold contrasting patterns showcasing depth are more readily recognizable by birds. The helical structural coils of the Twister offer enough visual contrast to protect them, thus ensuring their survival.

By harnessing the earth’s natural thermal energies, and at zero cost to activate, the Twister demonstrates that being “green” can be exciting as well.

Europaconcorsi Beta

Twister