U.S. Air Force Academy Center for Character and Leadership Development, Colorado Springs, Colo. Photo: SOM © Magda Biernat
features five, 55-foot-wide by 75- to 95-foot-high, curtain wall-clad structural steel hydraulic mechanized pivoting wall panels. The lightweight ETFE enabled structural engineers to provide primary roof support with a single, 970-foot steel ridge truss, resulting in cost savings and a striking visual lightness. Orchestration of such a large and complex structure required the use of the software Rhino with the parametric plugin Grasshopper. The design team used Grasshopper to optimize the roof pitch and slope to minimize snow accumulation and reduce roof snow loads. Thornton Tomasetti’s Advanced Project Delivery approach employs specialized connection design engineers and steel detailers working side-by-side with the structural engineer- ing design team to conceptualize the connections early in the design phase once member geometry is set and initial force magnitudes are available. Transfer of connection design information was validated for constructability by Thornton Tomasetti’s modeling the connections in the 3D fabrication software, Tekla Structures. Coordination items were addressed real-time through the use of a shared live Tekla model utiliz- ing a Panzura system that allowed Thornton Tomasetti’s engineers to work side-by-side with the fabricator’s detailer. Projects $15 million to $75 million National Award: U.S. Air Force Academy Center for Character and Leadership Development (CCLD), Colorado Springs, Colo. — The CCLD, serving as an education and research center, features a cantile-
vering 105-foot Skylight consisting of diagonal steel plates composed in a triangular grid and precisely calibrated to resist lateral forces due to wind loading. This calibration was achieved by considering the deflected shape of the Skylight geometry under an inward pres- sure. When combined with the original geometry, this deflected shape became the inner boundary of the Skylight’s steel plates, providing a varying depth across each face. The product is a triangulated system of plates of varying depth, which creates a normalized stiffness profile across each face to provide a stable base for attachment of the glazed cladding units forming the outer skin of the Skylight and allows for the optimized glass joint dimension. The AESS is devoid of all embel- lishment or ornamentation. Through the use of an iterative analysis and design method, structural steel was added only at locations where it was required by the performance of the structure, resulting in maximized material efficiency. Analysis of the Skylight also included consideration of both global and local buckling analyses for geometric and material non-linearity, as well as a check of stresses in the plate members to highlight the flow of loads through the structure and areas of stress concentration. Architect and structural engineer is Skidmore, Owings & Merrill LLP, New York City. Merit Award: University of California, Davis Jan Shrem and Maria Manetti Shrem Museum of Art, Davis, Calif. — The project’s signature feature is the 50,000-square-foot undulating “Grand Canopy” that cov-
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