The Crown and the Curtain Wall

by Dudley G. McFarquhar, (A.M.ASCE), Struct. Engr.; Curtain Wall Design & Consulting, Inc., 10450 Brockwood Rd., Dallas, TX 75238,

Serial Information: Civil Engineering—ASCE, 1992, Vol. 62, Issue 8, Pg. 62-65

Document Type: Feature article

Abstract: Crowning the complex curtainwall of an 870 ft concrete tower with a 150 ft high crown of aluminum masts in concentric rings above the 60th floor required ingenuity and extraordinary cooperation among architects, engineers, contractors and subs. The $118 million Nations Bank tower in Charlotte, N.C. (formerly NCNB Corporate Center) is a poured-in-place concrete tower with bowed walls. Because mast sizes, anchorages and wind loads are so varied, and because nothing exactly like them had been constructed before, the 350 masts required individual design and analysis. Below, the 60 floors of aluminum, glass and handset stone curtainwall also required intensive analysis to satisfy the architect's design intent. Between the crown masts and tower curtainwall, some 285,700 aluminum pieces were manufactured from 10,250 part drawings and 270 different extrusion dies. Mast configuration is based on an 8 in. aluminum pipe and back fin core with standard rectangular end shapes. Widths vary from 6 in. to 2 ft 4 in., and depths from 3 in. to 21 in. Mast heights range from 10 to 67 ft, with a maximum cantilever of 45 ft. The masts are supported individually, while the horizontal bands of aluminum channels visually accentuate the ring effect of the crown.

Subject Headings: Towers | Cast in place | Concrete | Curtain walls | Aluminum (material) | Poles |

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