The Denver Union Station Train Hall was conceived as an efficient and formally expressive means of clear-spanning 180 feet across multiple railway tracks. The structure is a rational response to a series of programmatic requirements. The result is a steel-and-fabric canopy that rises 70 feet at the head-end platform, descends in a dynamic sweep to 22 feet at the center, and then rises again at the far end. The Train Hall's stunning oculus form creates a new structure that is functional, contemporary, and contextual; a new grand civic space for the city of Denver.
The primary structural system consists of eleven steel 'arch trusses' spanning nearly 180 feet from a single large-diameter pin connection atop 18-foot-tall arched column supports. Each truss is stabilized by bracing struts between trusses. In the central region of the train hall, the arch-trusses are replaced by cantilevered trusses. Each truss is supported about 20 feet above the ground by a series of steel 'kick stands,' which support vertical loads and horizontal thrust. Each 'kick stand' is rigidly connected to the foundation with heavy anchor bolts. The arch-trusses and cantilevered trusses support a tensioned PTFE fabric.
Every structural connection and member is both a structural and load-carrying, and also an architecturally expressive element. As such, the engineering team took great care to fully detail all members and connections in the contract drawings in order to control the design and evaluate aesthetics prior to the shop drawing phase. This work had the additional benefit of eliminating fabricator connection engineering time and cost. To keep the design within budget, the submitting firm engineered the exposed connections to use only conventional structural steel fabrication techniques and materials ' bolts, welds, pins, and plates ' but took great care to shape the connections to be aesthetically minimal and consistent.