Page 239 - Solar Power in Building Design The Engineer's Complete Design Resource

HEARST TOWER 209

zones. The office zone starts 100 ft above street level at the 10th floor rising to the
44th-floor level. Below the 10th floor, the building houses the entrance and the lobby
at the street level, the cafeteria, and an auditorium on the 3rd floor with an approxi-
mately 80-ft-high interior open space. At the seventh-floor elevation, the tower is con-
nected to the existing landmark facade by a horizontal skylight system spanning
approximately 40 ft from the tower columns to the existing facade.

STRUCTURAL DESIGN
The structural design is based upon a network of triangulated trusses of diagrid net-
works connecting all four faces of the tower, which has resulted in a highly efficient
tube structure. The diagonal nodes are formed by the intersection of the diagonal and
horizontal structural elements. Structurally the nodes act as hubs for redirecting the
member forces. Figure 7.11 Figure is photograph of the old Hearst building and 7.12
depicts photograph of the new Hearst Tower in New York, NY.
The inherent lateral stiffness and strength of the diagrids provide a significant
advantage for general structural stability under gravity, wind, and seismic loading
conditions. As a result of the efficient structural system, the construction consumed
20 percent less steel in comparison to conventional moment frame structures. Figure 7.13
depicts digital structural members of the new Hearst tower.
Below the 10th-floor level, the structure is designed to respond to the large unbraced
height by using a megacolumn system around the perimeter of the tower footprint,
supporting the tower perimeter structure. The megacolumn is constructed of steel tube
sections that are strategically filled with concrete.

Figure 7.11 Old Hearst Building. Photo courtesy of Hearst Corporation.