The Cauley Ferrari dealership in West Bloomfield, Mich., has a unique live load to support on the second floor of the stunning showroom and storage area: cars. The flooring system selected is composed of a 3-inch concrete slab on 2-inch composite, 20-gage floor decking supported by composite joists. It was chosen for its ability to support more than 292,000 pounds of moveable live loads and span up to 50 feet without shoring.
The second floor needed to accomplish many architectural goals. The upscale dealership’s mezzanine was designed to not only showcase the sportsters through large windows, but also to actually store a number of cars.
“The 20-gage, 2-inch composite deck on composite joist system chosen for the mezzanine and second floor was selected because it could span 50 feet unshored and still support both the enormous dead loads as well as the moveable live loads,” says Kurt Voigt, engineering manager for New Millennium Building Systems.
Composite deck has embossments in the vertical ribs that bond with a poured concrete slab to develop a composite floor system. Once the concrete cures, the resulting composite floor system provides superior strength and stiffness.
Considering what is going to be supported, the project features relatively shallow joists: just 28 inches deep. This is possible thanks to the composite action of the flooring system.
“Headed shear studs were welded to the top chords of the joists on-site to provide something for the concrete to bond and cure with,” Voigt says. “Also, using composite joists instead of beams allowed the project team to run mechanical, electrical and plumbing (MEP) components through the web members instead of having to cut through the beams or run beneath them, saving time and money and enabling the architectural vision.”
Headed shear studs welded on-site to the top chords of the joists prior to pouring concrete. When the concrete cures, the steel joists, embossed decking and concrete become an integrated component. The resulting composite system is considerably stronger than the components.
“This second floor is designed not only for showing cars in those huge windows, but it is built for car storage as well,” says Jason Kimmel, New Millennium engineer. “Cars are lifted via an industrial elevator to the second floor for long-term storage. We get the strength needed because each joist can support a service live load of 329 pounds per linear foot. So that translates to roughly 292,000 pounds total of live load support for car storage.”
More than just supporting one or two stationary cars for show, the second floor of the dealership was designed for the longer-term storage of a number of cars—more than 292,000 pounds of live load.
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