Director, Structural Engineering
Skidmore, Owings & Merrill LLP, New York City
Conventional legacy systems in the design of supertall towers employ belt trusses, outriggers, and perimeter-bracing to achieve the required tower performance at the expense of open architecture. The Ladder-Core System developed at SOM presents a novel method in the design of supertall structures, enhancing the flexibility of architecture while providing the ductility, redundancy, and uniformity of stiffness compromised in legacy systems.
The Ladder-Core System features eight mega-columns at the perimeter, which form the vertical rails of the ladder on either side of the core. Composite-coupling beams act as the ladder rungs, connecting mega-columns at the perimeter to the interior core, and thereby creating a comprehensively stiff lateral system. Using 28-meter-long beams to funnel perimeter gravity loads to the mega-columns eliminates the tension produced by overturning moments. Overall, the Ladder-Core System is defined by unobstructed occupant views, a simple floor plate, and inherent structural stability.