The Citigroup Center is a 59-story, 915-foot-tall (279 m) tower clad in glass and metal facade. Close. people didnt figure out a proper weld procedure until all the welds from the 80s cracked during the northridge quake. 99% Invisible is a great podcast for those who are into that sort of thing. http://people.duke.edu/~hpgavin/cee421/citicorp1.htm, Thanks, Woolybugger. Posted by 5 years ago. The reason LeMessurier had originally designed the building with its columns located at the centre of each face was the presence of St Peter’s Lutheran Church. Also, imagine the litigation! At this point LeMessurier describes himself as feeling “pretty shaky” because his calculations indicated that the forces in the bolted connections increased by 160 per cent due to these winds. But LeMessurier suddenly discovered this was not the case for the Citicorp tower: due to the innovative bracing system, the calculations indicated that the quartering winds increased the forces in four of the eight chevrons by 40 per cent. It would be undertaken at night. The cathedral has been reduced to the state of toxic waste,” the association said shortly after the fire, urging authorities to detoxify the tonnes of rubble, ash and wastewater produced in the disaster. To realize that the wind-bracing system he designed for a skyscraper like Citicorp Center is flawed – … Pract., 123 (1), pp. The Department of Buildings was alerted, it commended LeMessurier on his courage and candour, and asked to be kept informed. what tuned mass damper requires electricity to operate? No litigation ensued, and Stubbins was held harmless. But the steel supplier for the project, Bethlehem Steel, proposed that cheaper bolted connections, instead of welded connections, could be used. [Podcast] In 1978, an engineering student discovered a fatal structural flaw in New York City’s just-completed Citicorp Tower. Dr. Perrodin’s “Safety Doc Podcast” negotiates school and community safety. Work continued in earnest, but on September 1, the weather service reported that a storm, Hurricane Ella, lay off Cape Hatteras and was heading for New York. In true engineering style, LeMessurier had conceived this structural solution (literally) on the back of a napkin in a Greek restaurant in Cambridge, Massachusetts. He was a thoughtful engineer and put the design of the tower through its paces with wind test scale simulations in the world’s best lab and worked the standard battery of industry calculations. The electrical mass damper acted as secondary protection. Interesting: Citigroup Center ^(Chicago) | Citigroup Center (Los ^Angeles) | One Sansome ^Street | 399 Park ^Avenue, Parent commenter can toggle ^NSFW or ^delete. The building was fitted with a 370t concrete tuned mass damper on the top floor to reduce building sway under normal wind loading conditions. During the meeting, workman removed sheetrock to expose an actual bolted joint on a vacant level in the tower, and it was concluded that LeMessurier’s solution was practically feasible. At 8pm, welding of the plates would commence and continue to 4am, when labourers would clean up the mess before the first office workers arrived. And the most wonderful part of my story is that when I did it nothing bad happened". This allowed construction to begin over a hundred feet above the small church. In the original design, the engineer calculated for wind loads that hit the building straight-on, but he did not calculate for quartering wind loads, which hit the building at a 45-degree angle. Every detail, from materials to construction, must be considered and evaluated with utmost care if these towering buildings are to stay upright. As one who commutes I appreciate the diversion. Advised that he had little choice but to talk to the media, but not looking forward to being interrogated, he called the New York Times to find that all journalists, along with the journalists from all the major papers, had just gone on strike. This design change had been approved by LeMessurier’s New York office, but LeMessurier himself only became aware of it one month prior to receiving the student’s call and long after construction was complete. Faced with this information, LeMessurier essentially blew the whistle on himself on August 2 and alerted Citicorp. Thanks to the tireless efforts of these construction workers and the meticulous attitude to the architects and engineers involved, the Citicorp Center tower remains upright to this day. The architect defended his decision but was rattled by the inquiry. Press J to jump to the feed. 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Dr. Perrodin notes that similar “defiant” articles are surfacing that both bring awareness to the lead contamination and bluntly state the dire short and long term health risks associated with approximately 500,000 pounds of lead vaporized from the cathedral’s roof. He double-checked the plans and discovered a horrifying mistake. Will also delete on comment score of -1 or less. The plot Citibank had planned to build their skyscraper in the early 1970s already had a preexisting structure: St. Peter’s Lutheran Church. This was the story on the 99% Invisible podcast this week. The Citicorp tower design flaw that could have wiped out the skyscraper: 99% Invisible by Roman Mars. Before deciding what to do, LeMessurier wanted to understand, in more detail, how the structure responded to wind loading, so he travelled to Canada on July 26 to meet with Alan Davenport, the director of the Boundary Layer Wind Tunnel Laboratory at the University of Western Ontario. The tower had a tuned dampening system that would offset such winds, but it was electrical – and if the power went out during a storm – well, lights out! Discussions continue with respect to the ethical nature of this statement and the role LeMessurier played in its release*. The Citicorp crisis of 1978 was hidden from the public for almost 20 years. The tower was built in an innovative way to accommodate an existing church. LeMessurier recalls the feeling that they were probably going to have to hit the panic button, but a few hours later the hurricane changed direction and began moving out to sea. LeMessurier the Citicorp brass, insurance folks, NYC officials and the NYC welder’s union acted in unison to quickly fortify the tower. 23–29. The parishioners weren’t going to move, so architect William LeMessurier came up with an equally unusual structural design. Based on an article originally published in 'The New Yorker', Sean Brady reflects on the Citicorp tower crisis One day in June 1978, William LeMessurier, then 52 years old and one of North America’s most respected high rise engineers, received a call from a New Jersey engineering student. The solution consisted of welding 50mm thick plates across each bolted joint - essentially providing a permanent ‘band aid’ solution in the truest sense. r/engineering is a forum for engineering professionals to share information, knowledge, experience related to the principles & practices of the numerous engineering disciplines. I laughed pretty hard when I saw it in that slide since I had learned about the same thing in an engineering class. The Citigroup Center is a 59-story, 915-foot-tall (279 m) tower clad in glass and metal facade. Instead of being welded, as LeMessurier instructed, the construction crews had bolted them instead, significantly reducing their strength against vicious corner winds from storms. Never heard of that building, but jeeze it makes me uneasy looking at, You'll also love The Rainier Tower in Seattle. http://tinyurl.com/SafetyDocApplePodcasts, Research Perspectives / Public Policy / Social Science, School of Errors - Rethinking School Safety in America, SUBSCRIBE to “The Safety Doc” YouTube channel, Follow David & The Safety Doc Podcast on Twitter @SafetyPhD, Email Dr. Perrodin email@example.com.
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