Tall diagrid structures: Unique behavior and design considerations of an unusual structure type

Diagrid structures, typically steel or composite, combine lateral and gravity load resistance into the same members arranged in a diagonal pattern on the exterior surfaces of structures. By virtue of the unique arrangement and function of their structural components, these structures behave in ways that are not encountered in conventional structures, especially when they are tall. Detailing and fabrication, particularly of connections pose challenges that have to be carefully addressed during design in order to ensure constructability. On the flip side, the repeating geometrical patterns that form the basis of this system make prefabrication and modular construction comparatively easy. There are relatively few tall diagrid structures in existence around the world today, and this paper presents the unique behavior and design considerations associated with them along with solutions that have been implemented to address them using two recent case examples of structures in China: The 161m tall Poly International Plaza project in Beijing completed in 2017 and the 206m tall Ningbo Guohua Financial Tower recently topped-out structurally in Ningbo.