How a student saved Citicorp Center from potential collapse

A design flaw in the 1970s almost led to the demise of Citicorp Center, now known as Citigroup Center, at 601 Lexington Avenue.

The 59-story Midtown East building’s chief structural engineer, William LeMessurier, had initially designed a structure with nine-story stilts at the midpoint of each side. It also had a chevron bracing structure and a 400-ton tuned mass damper that would prevent the tower from collapsing.

At the time, in 1978, an undergraduate architecture student at Princeton University who was studying the building observed that quartering winds – hitting it at its corners – might make the stilts unsteady. LeMessurier and architect Hugh Stubbins ended up taking the advice of the student, revealed years later to be Diane Hartley.

The engineer said he had only considered perpendicular winds, and realized in retrospect that a storm could cause a blackout. In that scenario, the mass damper would be useless. He then coordinated an evacuation plan as Hurricane Ella approached the city. The story, which was first reported in 1995 by the New Yorker, was noted today in a Slate article about great design flaws through history. [Slate] — Mark Maurer