What was the core engineering issue for the Citicorp tower?
The chevrons were bolted to each other with over two hundred joints; as built, these posed a serious structural danger, leading to the Citicorp Center engineering crisis. As a result, 2 in-thick (5.1 cm) welded steel plates were installed over each joint in 1978.
What was the structural issue with the Citicorp tower that was discovered?
In 1978, the skyscraper’s chief structural engineer, William LeMessurier, discovered a potentially fatal flaw in the building’s design: the skyscraper’s bolted joints were too weak to withstand 70-mile-per-hour wind gusts. With hurricane season fast approaching, LeMessurier took no chances.
What happened at the Citicorp building in New York?
The Citicorp Center engineering crisis was the discovery, in 1978, of a significant structural flaw in Citicorp Center, then a recently completed skyscraper in New York City, and the subsequent effort to quietly make repairs over the next few months.
What was the unusual problem architects were faced with in designing the Citi Bank Tower?
Hartley claimed, correctly, that the building was unsafe, due to an unusual weakness to winds hitting the corners of the building. Even worse, a construction error changed the original design’s welded joints to bolted joints, weakening the entire building.
What changes were made in the Citicorp building that almost caused a major failure?
Having stilts in the middle of each side made the building less stable, so LeMessurier designed a chevron bracing structure—rows of eight-story V’s that served as the building’s skeleton. The chevron bracing structure made the building exceptionally light for a skyscraper, so it would sway in the wind.
Who was the structural engineer for the Citicorp Center 601 Lexington Avenue )?
Le Messurier Associates
SCI/ James Ruderman
601 Lexington Avenue/Engineering firms
Who designed the Citicorp building?
Emery Roth and Sons
Hugh Stubbins and Associates
601 Lexington Avenue/Architecture firms
Who designed the Citicorp tower?
When was Citigroup Center built?
April 1974
601 Lexington Avenue/Constructions started
How was Citicorp tower fixed?
This scheme, in conjunction with an inverted steel chevron bracing system, cantilevered the corners of the 280 metre tall steel structure, 22 m out over the church. The engineering student had phoned to ask about the location of these columns and their impact on the lateral stability of the structure.
How was Citicorp building fixed?
But rather than putting the stilts in the corners, they had to be located at the midpoint of each side to avoid the church. Having stilts in the middle of each side made the building less stable, so LeMessurier designed a chevron bracing structure—rows of eight-story V’s that served as the building’s skeleton.
Who designed the Citicorp Center?
How is the Citicorp tower an example of ethics?
The Citicorp Tower is a famous case in engineering ethics that is often celebrated as a positive example, rather than the more notorious case studies of ethical failures. In this video, Dr. Michael Loui summarizes the highlights of the case, including the fact that:
Who was the architect of the Citicorp tower?
A skyscraper on stilts. This thing does not look sturdy. But it has to be sturdy. Otherwise they wouldn’t have built it this way. Right? The architect of Citicorp Center was Hugh Stubbins, but most of the credit for this building is given to its chief structural engineer, William LeMessurier.
How tall was Citicorp Center when it was built?
When it was built in 1977, Citicorp Center (later renamed Citigroup Center, now called 601 Lexington) was, at 59 stories, the seventh-tallest building in the world. You can pick it out of the New York City skyline by its 45 degree-angled top.
Who was the engineer at the table in the Citicorp case?
The “engineer at the table” referenced in the above clip is Leslie Robertson, as this more concise account of the case recounts. Robertson, a celebrated structural engineer in his own right who designed the World Trade Center, was directly involved in the Citicorp retrofit, but barely credited by LeMessurier’s accounts in these videos.