Miami supertall rises with nine offset cubes and 25 ft cantilever

Construction of the Waldorf Astoria Hotel & Residences in Miami is approaching its final height, with the 1,049 ft tower set to become Florida's first supertall building and one of the city's most structurally distinctive high-rises.

The approximately 1.6 million sq ft tower is formed by nine offset glass-clad volumes stacked vertically, with each section shifting in position relative to the one below. The arrangement creates the appearance of a series of large glass blocks balanced above one another, while introducing significant structural demands as the building rises.

The most pronounced offset occurs at the uppermost section, where Cube 9 cantilevers approximately 25 ft from the main structure. The alternating geometry generates eccentric loads and increases torsional effects, particularly under wind loading. A central reinforced concrete core therefore forms the primary structural spine of the tower, providing the stiffness required to resist lateral and torsional movement.

Wind behaviour is a particularly important consideration for a building of this height and slenderness. Near the top of the tower, a tuned mass damper will use a steel mass of approximately 1,000 tons to reduce wind-induced accelerations felt by occupants. The mass is designed to move independently in the opposite direction to the tower's motion, dissipating energy and reducing the amplitude of oscillation.

The damping system is primarily intended to improve occupant comfort rather than provide basic structural stability. Even when stresses remain within acceptable limits, acceleration and perceptible movement can become important design criteria in very tall and slender buildings exposed to strong winds.

Construction has progressed at an average rate of around one floor every 10 days, with the tower already exceeding 870 ft and topping out expected later in 2026. The project is estimated to require approximately 130,000 cubic yards of concrete and 23,000 tons of reinforcing steel.

The irregular geometry has required extensive coordination throughout the structural and concrete works. Transferring forces from the offset volumes back into the central structural system becomes increasingly complex where floor plates extend significantly beyond the tower's primary vertical elements. The 25 ft upper cantilever has therefore received particular attention, including multiple structural reviews before and during construction.

The tower illustrates how architectural form can directly influence almost every part of supertall structural design. Vertical gravity loads remain fundamental, but eccentricity, torsion, wind response, occupant comfort and construction sequencing become increasingly interconnected as the geometry departs from a conventional vertical stack.

As Miami continues to add taller buildings to its skyline, the project represents a particularly demanding example of translating an intentionally unbalanced architectural form into a buildable high-rise structural system.