The supreme commander of allied forces in Europe in World War II would have been proud of the strategy to transform a four-acre site into the first national presidential memorial of the 21st century. Located south of the National Mall, the $74-million memorial showcases a 450-ft-long, 60-ft-tall transparent, woven metal tapestry depicting an image of a peacetime scene of the Normandy coastline. The tapestry is supported by a cable net system and stainless-steel box beams integrated with a series of eight 80-ft tall, 9-ft-dia cast-in-place concrete megacolumns.

Because four of the eight mega-columns were located directly over existing utilities, the project team expedited site preparation by synchronizing foundation installation with utility relocation work. The megacolumns themselves were unique, the team says, with solid end units to counter the movement of twelve 1.5-in.-dia stainless-steel post-tensioned cables that support more than 600 artwork tapestry panels. The remaining columns are hollow, requiring an additional set of forms for their interior surfaces. What might have been a long, complicated fabrication process was simplified thanks to a specially designed, retractable four-part round internal form that shrunk for stripping, and could be reused for other pours.

The top of the tapestry is supported and framed by a full-length, exposed structural steel box beam that spans the full tapestry. It was fabricated in five sections, each about 87 ft long and weighing about 56,000 lb. The design called for exacting chamber requirements of 0.25 in. Anchoring the cables’ spanning system are more than 70 stainless steel “saddles,” each set in an exact three-dimensional location in the megacolumns. Twenty-five overlapping laser scans of the site verified the precise location. Comparing the virtual model to the architect’s plans ensured the design’s extremely tight tolerances were achieved.

The megacolumns are clad with 3,800 180-lb pieces of radially cut Spanish limestone. In addition, the columns’ concrete tops needed to be poured after massive stainless steel box beams were set. As a result, these activities were completed 85 ft in the air by manlifts and workers standing atop the columns and securely tied off with a safety system. The entire tapestry system had to be installed above ground level, a process completed using boom lifts and free climbers suspended from the box beam.

Lasers also proved instrumental in executing the memorial’s extensive landscaping. Four 40-ft-tall specimen trees were scanned on farms in Pennsylvania and New Jersey, capturing the location of each branch. These scans were used to determine the exact placement and orientation of each tree for planting on site. Completed on time and on budget, the project, with its columns, caught the judges’ attention. “The aesthetic of the design was hard to beat,” one judge says. “It’s a presidential monument, the only one in the 21st century at this point; I thought it was extraordinary.”

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