U.S. Air Force Memorial
The US Air Force Memorial was dedicated in October, 2006, as a testament to the service of the men and women of the Air Force. The principal components of the Memorial are its three curving stainless steel spires. The structures were designed by architect James Ingo Freed with Arup Consulting Engineers.
The skin is ¾” stainless steel plate, through-welded to form a stiff skin. Welds are ground and polished to make the spires appear seamless. The internal structure of ach spire is composed of reinforced concrete, internal stiffening plates and a system of ball-in-box counterweights housed within the spires. The integrity of the welds and the proper function of the counterweights are critical to the overall performance of the spires.
In 2011, we, won a contract to direct the first 5-year inspection of the spires. The designers built looped rope anchor points into the rear face of the structures, provided threaded port holes for internal viewing, and left the Memorial Foundation with a detailed written guide as part of their as-builts. Working with the guide and with access provided by a rope access firm, we conducted the inspection in one week. All surfaces and welds were visually inspected and if found to be suspect, measured with ultra-sonic thickness gauges or tested with dye penetrant. The interior structure was viewed with a boroscope for signs of corrosion, cracking, or malfunction of the counterweights. We provided a detailed report to be used as the basis for future inspections.