How one design flaw almost toppled a skyscraper - Alex Gendler
TED-Ed・4 minutes read
Diane Hartley discovered a critical flaw in the Citicorp Center's design, which could lead to the tower toppling in strong winds due to weaker bolted joints. A secret reinforcement project in 1978 successfully strengthened the building's structure, preventing a potential disaster that was only made public in 1995.
Insights
- The Citicorp Center's design flaw, discovered by Diane Hartley, could have caused the skyscraper to collapse in winds as low as 112 kilometers per hour due to weakened bolted joints, highlighting a critical oversight in the building's safety calculations.
- A secret reinforcement project led by LeMessurier's team in 1978 effectively strengthened the building's joints, preventing a potential disaster during Hurricane Ella and showcasing the importance of swift and discreet action in addressing structural vulnerabilities.
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Recent questions
What critical mistake was discovered in the design of the Citicorp Center?
Diane Hartley discovered a flaw in the building's design, where welded joints were replaced with weaker bolted joints, making it vulnerable to winds if the power failed.
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Summary
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Citicorp Center's Secret Reinforcement: Averted Disaster
- Diane Hartley discovered a critical mistake in the design of the Citicorp Center while working on her architecture thesis in 1978. The skyscraper, built on stilts due to the presence of St. Peter's Lutheran Church, had a unique design with stilts at the center of each side, supported by v-shaped chevrons forming an exoskeleton to counter strong winds.
- Hartley realized that a change in the building's design, replacing welded joints with weaker bolted joints, left it vulnerable to winds if the power failed, deactivating the counterweight's sensors. This flaw could lead to the tower toppling in winds as low as 112 kilometers per hour, a risk that had not been accounted for in safety calculations.
- To address the issue, a secret reinforcement project was undertaken by LeMessurier's team in 1978, working at night to strengthen the bolted joints. Despite a close call with Hurricane Ella, the covert construction was completed successfully, averting a potential disaster that was only revealed to the public in 1995.
