STRUCTURAL GLASS FACADES - USC School of Architecture

Morphology
There is no body of work to draw on for this evaluation study, because few if any tensegrity
structures have been employed in façade applications. Tensegrity structures in the context
of the façade structures discussed herein are most closely related to cable trusses and grid
shells with cable bracing, in that they combine complementary tension and compression
elements in the basic structural form. If cable trusses are developed as 3-dimensional
systems with multidirectional spanning behavior, they would qualify as a hybrid tensegrity as
categorized in Table 6-2. The original definition of tensegrity derived from the work of
Kenneth Snelson included only closed system geometries. Fuller broadened the definition in
several respects, and the large stadium tension structures such as the Georgia Dome (see
Chapter 2.2.7) are typically referred to as tensegrity structures. Double-layer cable nets are
conceivable, with compression struts separating the nets, and could be regarded as hybrid
tensegrity structures in this categorization scheme. Tensegrity structures have been built
from repeating cellular units, such as the Needle Tower shown in Chapter 2.2.7. It is easy to
conceive of geometries such as these being developed into quite interesting façade
structures.
Design Considerations
Aesthetics: Tensegrity structures present a compelling aesthetic. Compression elements
appear to float in a tensile net.
Transparency: The development of a tensegrity façade design is likely to emphasize the
unique structural system more than the pursuit of transparency, although the result will most
certainly represent a high-transparency façade.
Geometric flexibility: Many geometric forms have been explored by Snelson and others, and
mathematicians have cataloged variations of tensegrity geometries (Connelley & Back 1998)
that remain largely unexplored in architectural applications.
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