In late December of 2012 Mr. Geoffrey Harrison, President of the SDG Design Group approached Bob Darvas to study and propose an affordable structural scheme for the planned East Entry Canopy to the COBO Center. An earlier structural scheme was rejected for being far too costly.
There were several major components to the architectural concept. The glass-clad front had to be on the surface of a torus with a minimum span of 180 ft. plus 40 ft. extensions. The members were to project a so-called dia-grid pattern. The glass cladding had to be eccentric to the structure in order to provide space for the large video screen. The glass clad roof extending to the west at the top had to be large enough to provide protection to people traversing toward the main entry doors of Cobo Hall. Finally, the structure had to present a light, visually clear appearance.
Based on our many decades of experience with the design and construction of complex structures, it was quite clear to us that the successful solution required in developing a node, where the rigid (moment) connection of the six crossing members of the dia-grid can be easily accomplished by bolting. This concept allowed us to create a reticulated toroidal shell made up of steel members, fully continuous at the nodes, easily absorbing the bending moments at the nodes from the eccentric weight of the glass and the video screen.
RDA’s design has saved several millions of dollars in construction cost by reducing the structural steel to less than 1/3-rd when compared to the earlier scheme and creating an easily constructible structure. As Mr. Harrison commented: “Bob, without your design, the canopy would never have happened.”
Visit online at www.cobocenter.com.
The Globe Building, which is home to the new William H. Milliken State Park and Harbor Outdoor Adventure Center in Detroit, was awarded the Engineering News-Record Midwest’s Best Project of the Year in Renovation/Restoration for 2014. To introduce Michigan’s vast recreational offerings to a demographic far removed from the wilderness, construction team members converted Detroit’s 120-year-old Globe Trading Company Building—a condemned 40,000-sq-ft structure—into a showcase for the state’s natural resources. Shuttered for decades, the Globe served as an early example of steel-framing when first constructed. To preserve its place in history, project team members elected to salvage large portions of the beams, columns and unique Wellman-style trusses.
When team members first arrived on site, however, they were confronted with crumbling brick, shattered windows and concrete panels hanging from ceilings. Creating a safe jobsite was the first item of business, requiring extensive evaluation of the existing conditions. This process also assisted in identifying structural members of sufficient strength to include in the project. Among other tasks, crews pressure-washed every square inch of the interior to expose problems and determine where the building’s existing steel required replacement or reinforcement. Where reinforcement was required, designers engineered new members to fit within the existing framework. Investigative efforts, which required months, presented a large but necessary risk and exposed an array of unknowns. In all, about 40% of the existing structure required removal, with an intricate bracing system erected to support remaining portions during demolition. Due in part to careful hand removal, team members likewise incorporated more than 40,000 original bricks into the refurbished structure. Similarly, salvaged clay roof tiles were incorporated into a reconstructed parapet cap.
The Outdoor Adventure Center hosts exhibits and programs that showcase a variety of endeavors native to Michigan, from boating and camping to fishing, hunting and trapping, all while educating visitors about the state’s ecosystem, state parks, animal habitats and conservation programs.
The reconstruction was completed in just one year despite it being the state’s snowiest winter on record.
William G. Milliken State Park and Harbor Outdoor Adventure Center for the Michigan Department of Natural Resources, Detroit
Owner: Roxbury Group, Detroit
General Contractor: Walbridge, Detroit, Michigan
Architect: Hobbs + Black, Ann Arbor, Michigan
Structural Engineer: Robert Darvas Associates, Ann Arbor, Michign
MEP Engineer: Strategic Energy Solutions, Berkley, Michigan
Civil Engineer: Mason Browns Associates, Bloomfield Hills, Michigan