Dark Secret Story of a New York City Skyscraper Was Hidden From the Public For 20 years.
New York Citicorp Center engineering crisis. The Citicorp Center in New York City was an engineering marvel designed by William LeMessurier. However, it faced a major problem: the structural system had significant deficiencies, and hurricane season was approaching, putting the building at risk of collapse.
To accommodate the construction of the skyscraper next to St. Peter's Lutheran Church, a condition was set that no columns could pass through the new church. LeMessurier overcame this challenge by positioning four massive columns at the center of each side of the tower, allowing it to cantilever over the church. He used a system of inverted chevron-shaped load-bearing braces to redirect the loads towards the center and then downward into the ground.
However, during construction, the contractors made a critical mistake by replacing the welded connections in the diagonal steel members with cheaper bolted joints. Unaware of this change, LeMessurier received a call from a concerned student in 1978, prompting him to investigate. He discovered severe structural deficiencies due to the overlooked impact of quartering winds and the use of bolted joints.
LeMessurier proposed a solution to strengthen the bolted joints. He applied thick steel-welded plates, resembling elongated Hs, on each side of the joints as a permanent fix. The repairs were carried out secretly and swiftly during the night, completed in October 1978. The public was not made aware of the retrofit until almost two decades later.
Today, the Citicorp tower stands as a symbol of resilience and the commitment of engineers to prioritize safety. The story serves as a reminder that even grand structures can face unexpected challenges, but with expertise, integrity, and decisive action, nightmares can be overcome.
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