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The Design Flaw That Almost Wiped Out an NYC Skyscraper
Hugh Pickens DOT Com (2995471) writes "Joel Werner writes in Slate that when Citicorp Center was built in 1977 it was, at 59 stories, the seventh-tallest building in the world but no one figured out until after it was built that although the chief structural engineer, William LeMessurier, had properly accounted for perpendicular winds, the building was particularly vulnerable to quartering winds — in part due to cost-saving changes made to the original plan by the contractor. "According to LeMessurier, in 1978 an undergraduate architecture student contacted him with a bold claim about LeMessurier's building: that Citicorp Center could blow over in the wind," writes Werner. "LeMessurier realized that a major storm could cause a blackout and render the tuned mass damper inoperable. Without the tuned mass damper, LeMessurier calculated that a storm powerful enough to take out the building hit New York every 16 years." In other words, for every year Citicorp Center was standing, there was about a 1-in-16 chance that it would collapse." (Read on for more.)
Pickens continues:
"LeMessurier and his team worked with Citicorp to coordinate emergency repairs. With the help of the NYPD, they worked out an evacuation plan spanning a 10-block radius. They had 2,500 Red Cross volunteers on standby, and three different weather services employed 24/7 to keep an eye on potential windstorms. Work began immediately, and continued around the clock for three months. Welders worked all night and quit at daybreak, just as the building occupants returned to work. But all of this happened in secret, even as Hurricane Ella, the strongest hurricane on record in Canadian waters, was racing up the eastern seaboard. The hurricane became stationary for about 24 hours, and later turned to the northeast away from the coast. Hurricane Ella never made landfall. And so the public—including the building's occupants—were never notified.
Until his death in 2007, LeMessurier talked about the summer of 1978 to his classes at Harvard. The tale, as he told it, is by turns painful, self-deprecating, and self-dramatizing--an engineer who did the right thing. But it also speaks to the larger question of how professional people should behave. "You have a social obligation," LeMessurier reminded his students. "In return for getting a license and being regarded with respect, you're supposed to be self-sacrificing and look beyond the interests of yourself and your client to society as a whole.""
Until his death in 2007, LeMessurier talked about the summer of 1978 to his classes at Harvard. The tale, as he told it, is by turns painful, self-deprecating, and self-dramatizing--an engineer who did the right thing. But it also speaks to the larger question of how professional people should behave. "You have a social obligation," LeMessurier reminded his students. "In return for getting a license and being regarded with respect, you're supposed to be self-sacrificing and look beyond the interests of yourself and your client to society as a whole.""
No way! This is America! You're supposed to extract as much wealth as you can for yourself! Society as a whole doesn't exist!
So what if the building blows over and kills thousands - I guess we won't buy another building from those guys will we! The market takes care of that sort of thing - it's like magic!
HW
Shoes for Industry. Shoes for the Dead.
It's not clear at all to me why the OP or the editors wouldn't at least mention that this information is taken nearly word-for-word from the really excellent weekly podcast 99% Invisible, so I'm making this comment to get it on the record. Also, here's a gratuitous link to the podcast: http://99percentinvisible.org/ and the episode: http://99percentinvisible.org/episode/structural-integrity/
Yes, it does, pretty well. I've used a PE (Professional Engineer) for exactly that reason - they "sell" trustworthiness, objectivity. The person I bought my house from and I paid the PE precisely because we know they sell the truth, rather than telling either of us what we want to hear.
That's the same thing CPAs sell - the market pays Price Waterhouse Coopers to find the truth, rather than skewing things.
If you read the damninteresting.com article in the expanded summary it mentions that no one knew about it because there was a press strike. Wikipedia confirms that all 3 major New York City newspapers were on strike while the building was being repaired.
The repairs were only "secret" because no one was asking questions about it.
When did (s)he graduate? Where did (s)he end up? Doesn't (s)he deserve at least a minor credit in this story?
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Another engineering fail is the collapse of indoor walkways at a Kansas City hotel. Except the fail actually killed over 100 people:
http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse
Interestingly, the _original_ designs for both the walkways and the Citigroup Center tower case were safe. In both cases contractors requested design changes, and the engineering firms didn't do a proper review when approving them.
I wish I could find an appropriate citation - the example I recall was a bridge which needed to be torn apart and repaired because of the use of a different type of bolt securing the framework. The replacement had similar tensile and shearing strength, but several years later the bolts started failing at a much higher than expected rate, requiring the bridge to be retrofitted with the original fastener. It turned out that the new bolt (while actually stronger in some respects than originally required) was subject to vibration stresses. The review permitting the substitution focused on the strength of the bolt required for the application, but the data showing that the bolt was subject to metal fatigue if subjected to extended vibration wasn't available or considered at that time.
Changes such as these are actually not too rare; I suspect that in most cases, the substitutions work exactly as expected, but when we're discussing infrastructure elements of this scope a single failure is not merely troublesome but often catastrophic.
A teetering bank towering over a church?
I want to be in support of unions, but then you read about shit like this. Basically, "Hey, let's render inoperative some vital equipment necessary to make the determination on whether 10 blocks of Manhattan need to be evacuated because they weren't wired by union electricians"...
One time, the readings went off the chart, then stopped. This provoked more bafflement than fear, since it seemed unlikely that a hurricane raging on Lexington and Fifty-third Street would go otherwise unnoticed at Forty-sixth and Park. The cause proved to be straightforward enough: When the instrumentation experts from California installed their strain guages, they had neglected to hire union electricians. "Someone heard about it," LeMessurier says, "went up there in the middle of the night, and snipped all the wires."
Yeah, I remember how well that worked in the 90's
Remember when Arther Anderson stood up to Enron and refused to sign their books. And in turn sacrificed the lucrative consulting contracts with Enron for only CPA fees.
As opposed to simply adding a footnote disavowing the report before signing it anyway.
Your ad here. Ask me how!
So all the newspapers of the USA were closed and no TV stations were broadcasting news? Certainly today it would make a strong story - after all we're resurrecting it after all these years; I'm dubious that the fact that the newspapers of New York were shut would be a such a barrier then.
Those were much different times. There were no 24 hour news channels, no internet, and radio was somewhat different then. Print was just about the only place this kind of thing would have showed up. And since most papers were more focused on the city they were based in, it's unlikely it would be reported in another cities paper. Remember, TV news was an hour, at best, in the evening. Even if it would have ended up on the evening news, it would probably have been mentioned in a 30 second bit at best. There wouldn't have been a 2 hour "special report" on it.
I've heard news reporting before on this subject. The way it goes is this: the architect submits his designs, which are subject to review. Once the green light's given, construction begins. Now, engineers on the project notice a way that they can cut costs or construction time, or somebody requests a modification to the original design (perhaps to add a restroom or breakroom, perhaps to add or remove a wall or subdivide a floor differently). ...
I wish I could find an appropriate citation ...
The Kansas City Hyatt Regency Skywalk disaster, 17 July 17 1981, is an excellent case study. Before the collapse of the WTC South Tower it was the deadiest structural collapse in U.S. histories (dam failures are another story entirely). Until 9-11 the CitiCorp Center was well placed to beat it.
In the Hyatt Regency case the design of the double skywalk was changed during constructution, replacing a continuous steel rod that supported both skywalks with two rods, one from the roof to the upper skywalk, and one from the upper skywalk to the lower. Problem was the design had the continuous rod bearing the full load, the change made the upper skywalk bear the load of the lower skywalk (and the people on it) when it was only supposed to be holding up people on the upper skywalk and nothing else.
As built the skywalk was so overloaded that eventual collapse was possible even without any load. Naturally when it did fail it would be at a time when both the upper and lower skywalks were heavily loaded with people, and the floor crowded below. 114 died, 216 were injured - many seriously.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
According to TFA the undergrad student was a she not a he. From the article:
Damninteresting:
Diane Hartley contacted him to ask some technical questions about the design, which he was delighted to address. Hartley's professor had expressed doubts regarding the strength of a stilted skyscraper where the support columns were not on the corners. ... But the conversation got him thinking, and he started doing some calculations on just how much diagonal wind the structure could withstand. He was particularly interested in the effects of an engineering change made during construction which had seemed benign at the time: numerous joints were secured with bolts rather than welds.
Slate:
According to LeMessurier, in 1978 an undergraduate architecture student contacted him with a bold claim about LeMessurier’s building: that Citicorp Center could blow over in the wind. The student (who has since been lost to history) was studying Citicorp Center and had found that the building was particularly vulnerable to quartering winds (winds that strike the building at its corners). Normally, buildings are strongest at their corners, and it’s the perpendicular winds (winds that strike the building at its faces) that cause the greatest strain. But this was not a normal building. LeMessurier had accounted for the perpendicular winds, but not the quartering winds. He checked the math and found that the student was right. He compared what velocity winds the building could withstand with weather data and found that a storm strong enough to topple Citicorp Center hits New York City every 55 years. But that’s only if the tuned mass damper, which keeps the building stable, is running. LeMessurier realized that a major storm could cause a blackout and render the tuned mass damper inoperable. Without the tuned mass damper, LeMessurier calculated that a storm powerful enough to take out the building his New York every 16 years.
people.duke.edu:
The student wondered about the columns--there are four--that held the building up. According to his professor, LeMessurier had put them in the wrong place. "I was very nice to this young man," LeMessurier recalls. "But I said, 'Listen, I want you to tell your teacher that he doesn't know what the hell he's talking about, because he doesn't know the problem that had to be solved.' I promised to call back after my meeting and explain the whole thing." When LeMessurier called the student back, he related this with the pride of a master builder and the elaborate patience of a pedagogue; he, too, taught a structural-engineering class, to architecture students at Harvard. Then he explained how the peculiar geometry of the building, far from constituting a mistake, put the columns in the strongest position to resist what sailors call quartering winds--those which come from a diagonal and, by flowing across two sides of a building at once, increase the forces on both. For further enlightenment on the matter, he referred the student to a technical article written by LeMessurier's partner in New York, an engineer named Stanley Goldstein. LeMessurier recalls, "I gave him a lot of information, and I said, 'Now you really have something on your professor, because you can explain all of this to him yourself.'"
...
LeMessurier had long since established the strength of those braces in perpendicular winds--the only calculation required by New York City's building code. Now, in the spirit of intellectual play, he wanted to see if they were just as strong in winds hitting from forty-five degrees. His new calculations surprised him. In four of the eight chevrons in each tier, a quartering wind increased the strain by forty per cent. Under normal circumstances, the wind braces would have absorbed the extra load without so much as a tremor. But the circumstances were not normal. A few weeks before, during a meeting in his office, LeMessurier had learned of a crucial change in the way the braces were joined.
No. They had an idea to save time and money (to use bolts instead of welds for certain braces), and they submitted it to LeMessurier's firm, which approved it after some analysis, which turned out to have been done wrong. It wasn't the contractor's fault, they didn't have the expertise to evaluate whether the change would work or not, and they properly submitted it to those who did.