And why you should care.
If non-architects know the Citicorp Center—New York’s youngest landmark when designated at 38—they know it for its flaw. Shortly after its completion in 1978, a student called the office of its engineer, William J. LeMessurier, and asked about the four 24-foot-square, 100-foot-tall “super” columns, unusually positioned at the center of each of the skyscraper’s facades, that help to hold the building up.
In designing the building’s innovative structural system, LeMessurier had correctly calculated the strength of the wind hitting each face of the building straight on, but had failed to reckon with the extra strain of the “quartering” winds which hit the building’s cantilevered corners. In responding to the student’s questions, he realized he had made a mistake—one compounded by the substitution of bolted structural joints for welded ones, which are much stronger. By his calculations, a storm strong enough to topple the building hits the city every 55 years.