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Washington Monument, Washington, D.C.
At just over 555 feet, the Washington Monument is the tallest unreinforced masonry edifice in the world. Thornton Tomasetti designed the structure of a full-height scaffolding system to facilitate a two-year top-to-bottom restoration of the exterior.

The scaffold tapered at a 1° angle to mirror the slope of the Monument and consisted of 37 linear miles of aluminum tubing. The use of corner and center braces with plastic foam pads stabilized the scaffolding without attaching it to the stone or mortar of the Monument. The elevator and stairs concealed within the design required the elimination of cross-supports in this section and necessitated the use of special horizontal trusses. This careful design not only protected the Monument from further damage but also created a striking appearance.

Interior renovations included structural modifications to floor framing for reconfiguration of the observation platforms, relocation of the existing stairs to enhance visitor circulation, and testing of historic wrought iron to determine material properties and yield strength.

The perimeter security upgrade, completed in 2005, reconfigured the surrounding landscape to incorporate low granite walls in interlocking rings and solid marble benches that serve as barriers to protect the Monument from vehicles. Retractable bollards at walkway entrances allow access for maintenance and other authorized vehicles. The design enhances the natural and historic landscape of the grounds, providing unobtrusive security for this American icon.

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