Monday, April 22, 2013

Race Against Impending Disaster

In the early 1970's architect William LeMessurier had a unique obstacle to overcome when planning the construction of New York's Citigroup Center. 

St. Peter's Lutheran Church occupied the northwest corner of the proposed building site and permission was granted to Citicorp, to demolish the old structure and to go ahead with the skyscraper on condition that a new church was built on the same corner, with no physical connection to the building. The church essentially wanted to remain where they were as a standalone structure.

In order to meet this requirement, the skyscraper would somehow have to be suspended in the air. Rather than admitting defeat, LeMessurier opted instead to design an entire building that hung above a quaint little church.

The structure had been built on stilts before Engineer Joel Weinstein, determined that quartering winds (winds that strike the corners of the building, rather than the flat faces) would result in far more loading force than initially thought. LeMessurier himself looked into it and discovered that rather than wind joints being welded on, as he had ordered in the design, the plans were instead switched to bolts during the construction phase.

With the bolts in place instead of welds, experts predicted that on an average of every 55 years, New York City was hit by a storm that could topple it over. To make matters worse, in the event that the tuned mass damper inside it failed, the average dropped to every 16 years.

Amazingly the initial reaction to this discovery was to keep it secret. The area was not evacuated at the onset of storms and people weren't warned of impending disaster. Instead, a press release was sent out stating that the building was in no danger at all. The only action taken which took into account the immediate safety of the public, was a request that the Red Cross create secret emergency procedures in the event of a collapse. 

In a deadly race against the impending hurricane season, construction workers who only operated at night, again to keep it secret, hastily welded the joints every evening. That year, Hurricane Ella headed right toward New York City and the storm most certainly would have created winds fast enough to topple the building however by a huge stroke of luck, Ella changed course and the building was repaired without incident.

Had the building collapsed, due to the domino effect The Red Cross estimated the death toll at a staggering 200,000 people, with 156 city blocks taking further damage.

Source: and

Ernest Roper
membership Services Manager


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