Skidmore, Owings & Merrill LLP, San Francisco
In recent years, a number of buildings with exterior diagrid frames have been designed and built in various parts of the world. Characterized by a regular pattern of diagonal members that form an inclined “mesh”, diagrid frame members resist both gravity loads and lateral loads, without the need of vertical elements. Much has been written about the benefits of using diagrid frames; not least of which is the fact that they are stiff and efficient, and typically eliminate the need for outriggers, which present design and construction challenges. With the spirit of integration of innovative structural engineering and architecture, the authors of this presentation have, over the past few years, had the opportunity to work on a number of tall buildings where diagrid frames were combined with other structural principles to yield hybrid and evolved exterior bracing systems.
The presentation reviews the 206-meter-tall Ningbo Guohua Tower, which has a classic diagrid frame now under construction in Ningbo, China, and the 312- and 212-meter CITIC Towers in Shenzhen, China, where the pattern of meshing in the diagrid frames was derived using the principles of optimization and inspired by “Michell Trusses”. Finally, the presentation covers the 460-meter Wuhan Guohua Tower in Wuhan, China, where the exterior bracing works with the building’s folding geometry to yield additional outrigger action, which enhances lateral system behavior.