Washington - July 27, 2000 - The Advanced Electro Optical System (AEOS) facility on the Hawaiian island of Maui can pinpoint anything from high-flying aircraft to toaster-oven-size satellites orbiting earth hundreds of miles up. But this giant 3.67-meter azimuth-elevation telescope couldn't do its job without some high-tech ground anchoring achieved through state-of-the-art structural engineering.
The ultra-sensitive AEOS telescope, owned by the U.S. Air Force Research Laboratory, is not like fixed-position telescopes used for astronomy. The finely tuned 150-ton optical instrument is designed to swiftly scan the heavens both horizontally and vertically, locking on to and tracking moving objects such as an intercontinental ballistic missile or a supersonic jet.
But such precision comes at a price. Even a tiny vibration from activities in adjacent laboratories or the telescope's own high rotational starting and braking torques can distort visual images. What's more, the telescope's location 10,000 feet above sea level atop Mount Haleakala regularly experiences winds that can reach hurricane force. Here, just standing upright is difficult; imagine trying to collect high-accuracy data about distant objects in the sky.
To help the AEOS maintain its optical integrity under such demanding conditions, the Honolulu consulting engineering firm of Sato & Associates engineered a unique $18.2-million, 41,000-square-foot structure that houses the telescope and many vital support operations. The engineering project team, led by Rockwell Power Systems Company, designed a 60-foot, cone-shaped supporting pier to contribute maximum stiffness to the structure and achieve the specified minimum vibration frequency of 25 hertz -- ten times higher than a typical building of similar size.
Because loose volcanic cinder deposit below the foundation tended to reduce the natural frequency of the structure, Sato & Associates created a 120-foot-diameter, seven-foot-thick concrete mat, which is isolated from the facility by expansion joints. This large pier base adds to the pier's stability, and minimizes the effect of interaction between the rock/soil and the telescope's foundation.
To isolate the steel columns supporting the pier platform and dome from the pier base, the project team grounded the columns on individual footings well below the concrete mat, with annular space around each column. This enables the structure to withstand the wind-driven lateral and uplift forces as high as 175 miles per hour. The foundation and structure were designed to accommodate an additional 500-ton, 8-meter-diameter telescope that will be added in the future.
The AEOS telescope serves more than just the nation's security needs. Seven laboratories located in a two-story octagonal building surrounding the telescope's pier and dome are designed to receive the light path from the telescope via a coude' (elbow) methodology for data collection, analysis, and experiments in areas such as atmospheric science, sensor technology, and optical and infrared astronomy.
Based on these and other engineering innovations, the AEOS 3.67-Meter Telescope Facility recently earned the top honor in the American Consulting Engineers Council's 34th annual Engineering Excellence Awards. The award program recognizes the accomplishments and contributions of engineering to the betterment of our society and our world.
The American Consulting Engineers Council (ACEC) is the business association of America's engineering industry, representing more than 5,000 independent engineering companies throughout the United States engaged in the development of America's transportation, environmental, industrial, and other infrastructure. Founded in 1910 and headquartered in Washington, D.C., ACEC is a national federation of 51 state and regional organizations.
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