Kyoung Sun Moon
Associate Professor
Yale University, New Haven

Tall buildings are one of the most viable solutions to deal with the global phenomenon of rapid population increase and urbanization. Indeed, Frank Lloyd Wright proposed his visionary mile-high “Illinois Tower” for 130,000 inhabitants more than a half-century ago. While tall buildings are an essential building type to accommodate an ever-growing urban population, as buildings become taller and taller, many design challenges also arise. As floor plates are stacked vertically, occupants’ natural horizontal circulation-based social interactions are also limited. As buildings become ever taller, safe evacuation to the ground level becomes more challenging in emergencies. With respect to safety as well as serviceability, one of the most fundamental design challenges of exceedingly tall buildings is their structural systems.

While many different design solutions can be sought to resolve the aforementioned issues, as well as other design challenges of extremely tall buildings, this presentation investigates the potential of conjoined towers to create more livable and sustainable mile-high vertical cities. Emphasis is placed on the social and structural capabilities of conjoined towers in providing enhanced social interactions and more efficient ultra-tall structures. The related brief history of conjoined towers is presented. In order to understand their current status, the contemporary design practices of conjoined towers are discussed. Finally, new conjoined tower concepts such as “super-tripod-ed” conjoined towers and “super-framed” conjoined towers developed for exceedingly tall building complexes are introduced through design studies. Though envisioning future tall buildings in cities a half-century from now is very challenging, conjoined towers can clearly be among the strong candidates for more sustainable mile-high sky cities.