COVER STORY
By Tina Cauller
One-of-a-Kind
Government Jobs Towering steel structures required precision and extreme quality tolerances Variable Height Tower, Eglin Air Force Base, Okaloosa County, Fla. Class I (up to $500,000) Erector: Ed Emmons Steel Erectors Inc. Structural Engineer: Joe DeReuil Associates Fabricator: Bell Steel Company Detailer: Bell Steel Company GC: Lord & Son Construction Architect: Heffernan Holland Morgan Architecture Contract Value: $116,225 Tons of Steel Erected: 112
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he scope of two award-winning steel erection projects—one for the U.S. Air Force and the other for NASA—were at opposite ends of the spectrum but shared many common challenges. A top secret project at Eglin Air Force Base had a steel erection contract value of just $116,225 and 112 tons of steel, while a high-profile refurbishment of the Vehicle Assembly Building at Kennedy Space Center came in at more than $25 million and 5,500 tons of steel. Despite the disparity in the overall scope, the two jobs both faced designs with extremely tight tolerances. Jacking columns on the Air Force’s variable height tower had to be perfectly plumb, while NASA expected a zero-defect installation where ironworkers used a micrometer to gap each connection to +/-0.01 inches and 300% welding inspections. The teams working for Ed Emmons Steel Erectors and S&R Enterprises are understandably proud of the work they completed on these two jobs, which were recognized as winning Projects of the Year by SEAA. Both companies received awards at the 45th Annual SEAA Convention in Myrtle Beach in April 2017.
■■Ed Emmons Steel Erectors Undertakes Top Secret Construction
NASA’s Vehicle Assembly Building High Bay No. 3, Kennedy Space Center, Cape Canaveral, Fla. Class IV (over $2.5 million) Erector: S&R Enterprises LLC Structural Engineer: RS&H Fabricator: Steel LLC
Ed Emmons Steel Erectors Inc., Pensacola, Fla., was handpicked for a steel erection project at Eglin Air Force Base by the general contractor, Lord & Son Construction. A long relationship between the principals of the two companies and high level of trust established over many years of working together were critical to top secret construction of a research lab consisting of a Variable Height Tower. Eglin Air Force Base is situated just east of Pensacola in Okaloosa County, Florida. At roughly the size of the state of Rhode Island, Eglin is the country’s largest military installation and the largest air force base in the free world. The Variable Height Tower is a military testing facility constructed on a firing range for development and testing of next-generation
Detailer: IDS GC: Hensel Phelps Architect: RS&H Contract Value: $25 million Tons of Steel Erected: 5,500
Tina Cauller is a graphic designer and freelance writer with 30 years of experience reporting for trade and technical publications in building construction and real estate markets. She can be reached at tinacauller@gmail.com
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weapons. The tower’s specific function was top secret. The new facility enables researchers to take improved sensor data because it reduces signal interferences caused by the warmer air and objects near the ground. “We were not allowed to know any details about its purpose, other than it involved firing lasers down range at various heights,” said David Emmons, President. Constructing the Variable Height Tower was demanding due to the extremely tight tolerances that were required between the moveable platform, jacking columns and gears, and guide rails. The distances between the two towers had to be precisely controlled for the moveable platform, which tops out at 90 feet, to raise and lower smoothly in 10-foot increments. Too close together or too far apart, even by a fraction of an inch, and the drive train mechanism wouldn’t work. Emmons explained, “We are used to working within AISC tolerances, and we’ve had experience with assemblies that required more precision, but no one wanted to specify exactly how true we had to keep the towers. We knew that any error would come back to haunt us because in these tall vertical towers