Chicago's Sears Tower Gets the Ledge: Metals Provide the Key

This week, Chicago's famed Sears Tower opened four glass boxes called "The Ledge" which hang from the building's 103rd floor. The Ledge promises great views as far away as 50 miles to four states (on a clear day of course) Here are a couple of views from the boxes:

Photos Courtesy of:  The Skydeck Website

Of course being the metals gal that I am, I wanted to know more about the metal structure supporting the box. MetalMiner caught up with Lou Cerny, project manager at MTH Industries, the contractor working with Skidmore Owings & Merrill LLP, the firm who originally designed the Sears Tower. The 4 boxes (made of glass) are 10' x 10' with a 4' cantilever over the edge. For those of you architect buffs, the cantilever concept became popularized through Frank Lloyd Wright (below is Wright's famous "Falling Water" house built for the Kaufman family):

Photo Courtesy of Google Images
The "Ledge" is essentially a suspended glass structure with no steel framing. The 8' x 8' x ½' structural ceiling front hangs from high strength steel beams, custom fabricated plate and high strength tube, custom machined pieces, stainless steel connections and a lot of little pieces. The entire box is suspended from bearing rollers, similar to wide flange beam traveling rollers. The system is run by a rigged chain drive overhead motor. Think of it as a "very expensive garage door opener", according to Cerny. The glass corners are hung with fasteners every 18" - 2'. And even Cerny admits, "it took me a few times to get comfortable inside and we manufactured it."

But MTH Industries is no stranger to interesting architectural projects particularly here in Chicago. That firm has done all of the bronze work at the Palmer House, the Cloud Gate Structure at Millenium Park, all of the space frame within Navy Pier and the aluminum doors at the new Modern Wing of the Art Institute as well as the bronze work for the Penny Pritzker residence (you may recall Ms. Pritzker was in charge of fundraising and finance for President Obama's presidential campaign)
Let us know if you go to the "The Ledge." We're not sure we're ready to step out yet....

-Lisa Reisman

http://agmetalminer.com/