Citicorp Center, opened in 1977, used an unusual design with support columns at the middle of each face and a tuned mass damper to counteract wind sway.
Structural engineer William LeMessurier discovered in 1978 that the building’s chevron exoskeleton was vulnerable to diagonal “quartering” winds and that many bolted joints lacked the necessary weld strength.
A storm strong enough to collapse the tower was estimated to occur once every 16 years if the mass damper lost power, posing a dire risk to thousands of occupants.
Princeton student Diane Hartley and architecture student Lee DeCarolis independently flagged calculation inconsistencies to LeMessurier, prompting his reanalysis of wind loads.
LeMessurier organized covert emergency plans, installed stress gauges, hired weather monitors, and had crews reinforce bolted joints by welding steel plates at night, preventing collapse.
Secrecy driven by a newspaper strike kept the crisis hidden from the public until 1995, when full details were published and the episode became a landmark engineering ethics case.
The skyscraper, now called 601 Lexington, still stands today after the repairs ensured its long-term stability.
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