99% Invisible - 110- Structural Integrity

Episode Date: April 15, 2014

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 … Continue reading →

This is 99% Invisible. I'm Roman Mars. I'm going to tell you a story first about how a building got designed, a very unusual building in New York. The City Corp Tower. When it was built in 1977, City Corp Center was, at 59 stories, the seventh tallest building in the world. You know, I can still remember the first time I saw the City Corp Center. As you exit the local six subway station at Lexington and 53rd in Midtown Man, Hatton-Yor confronted by a sheer 915 foot building face, shooting up right from your feet. That's reporter Joel Werner.

With its gleaming facade, glass and steel and striking 45 degree angle crown the CityCork Centre is truly one of the most spectacular skyscrapers on a skyline known for its spectacular skyscrapers but really it's the base of the building that takes your breath away this massive 59 story skyscraper levitates mid air, hovering 115 feet above the street corner. At first glance, the building seems to violate the basic laws of physics. When you look up, you look directly at the underside

of the building corner, it overhangs the sidewalk. I mean, we'd expect a collar more even the grounds. Instead there's nothing. Just in there. Of course the building isn't really levitating. It's propped up on stills, which join the building at the midpoint of each side. It does not look starting. But it's got to be starting. It's got to be safe and they wouldn't have built it this way. Right? Yeah well that's a secret about this building. And it was literally a secret for nearly two decades after it was built.

The City Corp Center could very well have blown over in the wind. What I wanted to know was when was this building going to fall down? The architect of the City Group Center was Hugh Stubbins, but most of the credit for this building is given to the chief structural engineer William Lamezir. You're laughing me, but I did conceive it on a napkin at a Greek restaurant in Cambridge. Lamezir passed away in 2007. This is him giving a talk at MIT in 1995.

The whole problem was to build a building on a site that has a church in one corner. St. Peter's Lutheran Church. A chummy old building. It was the lowest point of Victorian architecture. I don't think it was that bad. St. Peter's sat at the corner of the lot. And when the church sold their land to CityCorp, it was on the condition that they build a new church in the exact same location. Beyond that, the company was free to build their skyscraper around the church and in the airspace above it. So, a plan was hatched to float the building over the church, hence the stilts. And because the church was in the corner of the lot,

LeMesh put the stilts in a kind of a weird place. You couldn't have columns in the corners where they ought to be in a conventional building, so they were removed to the middle. Placing the columns at the midpoint of each side, rather than in the corners, made the building less stable. So, for additional support, LeMesh had designed a chevron-bracing structure. Essentially, rows and rows of Vs each 8 stories high, pointing down the middle of each building face, to where the supporting columns had been moved. Actually, the architect wanted to keep the building simple,

that it's skinned because there was so much drama going on at the bottom and at the top. Anyway, he said, no, if you're going to have any diagonals, I don't ever want to see them. So the Chevron Brazing Structure was slipped under the skin of the building. It formed the CityCorp Center's skeleton. Now, one of the amazing things about this Chevron Bracing structure is that it's so lightweight that when the wind blows, it is more dynamically excitable than a building that weighed twice as much. In other words, it moves with the wind, which most people find really unsettling. Understandably, right? So, LeMeshert added something called a tuned mass damper.

The tuned mass damper is a massive concrete, which is 29 feet square and about 8 feet thick and weighs 400 tons. It is floated on pressurized oil bearings. The device sits at the very top of the building and acts to steady the oscillations. It offsets the wind gusts. So to recap, we have a 59-story tower floating on 115-foot stilts. Stilts which are not in the corner where you'd expect them, but rather in the middle of each side of the base with a skeleton of beams shaped like V's which make it super light

for a skyscraper. And to stop it from swaying in the wind, there's a 400 ton block of concrete on the roof, totally ingenious, really cutting edge design. And LeMesh's a pro, so in accordance with the New York City Building Code, he runs all kinds of mathematical models to make sure the building is going to hold up. And everything seemed just fine until, as LeMedre tells it, he got a phone call. June, 1978. I'm in my office.

I got a call from a student. I do not know the school. I wish he would call me from the past he never has, but anyway, as a real student from New Jersey, I think he was an architectural student, and his teacher had given him this building to study and report on because it's unusual. As LaMesa tells it, this precocious college senior calls him up to ask how his building structure is going to cope

with quartering winds. An undergraduate student calling out the head of a world-renowned engineering firm on one of the most innovative skyscraper designs of it today. Cordering wins, the wins that caught the students' attention, are those that hit the building on the corner, exerting pressure on two faces at once. Lamexious calculations on the perpendicular wins, wins that hit the face of the building square on, seem to be fine.

But as the story goes, the student raised the alarm about CityCorp Centre being particularly vulnerable at its corners. It turns out the measure had never run the numbers on what cornering winds would do to the building because normally buildings are strongest at their corners. But this is no normal building. Remember what's going on here? Supporting columns shifted to the midpoint of each building face, the chevron bracing skeleton, and the unusually light mass of the building.

Taken alone, no one of these design quirks should have presented a problem. But as the student told LaMesa taken together, they left Citicorp Centre particularly vulnerable to a wind striking the structure at its corners. And when Lemezure started to investigate the student's claims, he realized that the root of the problem had to do with a change that had been made to the original plans. It had to do with how the Chevron Bracene structure was fastened together. Lemezure's plan originally called for the joints to be welded.

With full penetration welds, but the contractor had suggested using bolts instead. Bethlehem Steel actually designed beautiful bolted connections for the forces that my people gave them. It was a cost-saving measure. Lamejra says that this change would have happened without his knowledge. Given the wind load calculations Lamejra's team had supplied, welding these v's together was overkill. Run the math, and it looked like bolts would do just fine.

And bolts would have done just fine, I'm pretty much any other building, except City Corp Center had an Achilles heel on each of its four corners. Lameja could now see what no one else had. No one except for that Pesky student from New Jersey. And as Lameja started looking into the students' claims about these quartering wins, he realized the situation wasn't just bad. It was a disaster waiting to happen. The return period to failure was 16 years.

Think about that. Here's what that means. Lameja calculated the quartering win velocities required to topple the city corp center. He then matched these velocities to weather patterns to see how frequently, on average, winds strong enough to blow the building over, occurred. Lameja found that a storm strong enough to knock over the building hits New York City on average, once every 55 years. But that's only if the Tune Mass damper is working.

The Tune Mass damper needs power to run, and if you're getting a huge storm, the measure realized it's not unlikely that the city could suffer a blackout. The measure ran the numbers again, this time imagining the damper without power. Without the damper, a storm strong enough to topple City Corp Center hits New York on average once every 16 years. To put this another way, for each year the building was standing there was about a one-in-sixteen chance of a storm potent enough to take out the City Corp Center. This building is 915 feet high.

If it failed, it would topple sideways in the wind, crashing into other Manhattan skyscrapers. A whole slew of buildings from mid-downto central park would fall like dominoes. What is this thing in real trouble? This brand-new skyscraper was on the verge of catastrophic failure. But the imminent disaster wasn't the result of one glaring oversight. Rather, it was a sequence of minor issues. Let's remember how we got here.

This building was on stilts because they had to build over the church. And stilts placed at the corners would have been just fine, except the church was at the corner of the lot, so the stilts had to be in the middle of each face. And that could have been a-okay, except the offset stilts led Le Mégis to use an ultra-light chevron-bracing structure, which would have been perfectly adequate, except in the end, those chevron-vies were bolted, not welded together. And even that could have been fine, except no one thought about how vulnerable this crazy

design was to wind blowing at its corners. No one except an anonymous college student. The measure went to CityCorp Chairman Walter Riston and told him they would need to open up the building and weld it back together. And how much is going to cost? I don't think it's going to cost an awful lot. Million or two? That's nothing. We're building

the cost of $155 million and if it falls down. From here, the Measure and E's team worked with the city called Big Wigs to coordinate emergency repairs on the building. 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 wind storms. They welded through the night and quid at daybreak just as the building occupants returned to work.

But all this happened in secret over three months without telling anyone who worked there. Which is the part of the story I kinda have a problem with. I mean, isn't this situation serious enough to warrant informing the building's tenants? My wife works in a skyscraper in Midtown Manhattan and you know, it's about informed consent. I'd want her to be able to make the judgement called about whether or not to go work in a faulty building. Not to haven't made for her.

Their thinking was, a contingency plan was in place and ready to be invoked as soon as a storm strong enough to blow the building down was in striking distance of New York. Except… There was a giant storm racing up the east coast. Hurricane Ella. Lameja says the powers that be were just hours away from calling in the evacuation. But the hurricane veered into the Atlantic before it hit New York, and in the end, the public was never notified. And I know what you're thinking. If only there was some kind of independent organization that serves the public's right

to know that might wonder why. City Corp Center was a glow with blow torches all night every night, you know, something like a newspaper. Except the New York Times was on strike. Not only did the New York Times go on strike, but all the newspapers in the war went on strike until October. So we had a pressed blackout and that was the greatest thing that ever happened. So word never got out and construction was finished.

And City Corp Center has remained standing ever since. Long enough to be renamed City Group Center and later, 601 Lexington. And this whole thing remained a secret for almost 20 years. In the early 90s, writer Joe Morgan Stern overheard the story being told at a party. He interviewed LaMesa and broke the story in the New Yorker in 1995. LaMesa went on to tell the story publicly, like he did at MIT, which is how we have him talking about this. And after the story got out, it was written up as a textbook case of good ethics in structural

engineering. New York was spared a tremendous loss of life and the annihilation of its skyline, all because Bill Lamege was humble enough to give time to the inquiry of an undergraduate student. Thank goodness for this uppity-colored senior and his thesis and kudos to Bill Lamege who, through his humility and heroism, saves the day. And that's really the end of this story. Accept. Now wait a minute, there are a couple more things here.

Let's take a step back and remember how this story starts. I got a call from a student. He was a real student from the Jersey. It was an architectural student. This teacher had given him this building to study. I do not know the school. I wish he would call me. The way LaMesha tells it and had Joe Morgan Stern told it in the New Yorker,

the college student, the young hero of our our story was lost to history. Okay, wait for it. Wait for this moment. It's a good one. Here it comes. It would have been some time in the early 90s. I remember being upstairs in my bedroom and had one of my sons. He was sort of hanging off me as I was trying to put him down to go to bed. And suddenly my husband who had been downstairs started yelling a little bit and saying, Diane, Diane, quick, quick turn on the TV. Your thesis building is on TV. This is Diane Hottley. As far as we can tell, she was the student in the measure story. And so I, you know, holding the baby with one arm, I fumbled for the remote and got to the channel

just in time to hear... This building could have killed tens of thousands of people. The extraordinary chain of events began with a phone call out of the blutes from a student in New Jersey whose professor had told him to write a paper on the city called Tower. William Lamejert. And I explained to the student in the telephone call that he could tell his professor. I was a guest. I nearly dropped my baby. This was the first time Diane had ever heard of the emergency retrofits around the clock

weather monitoring the evacuation plans in the involvement of a student. So, when she heard LaMesa reference a student, a male student, I, of course, assumed, you know, gosh, there was some guide studying the building as well. And wow, you know, how could I miss this? Wow. So, it was pretty remarkable, but I, of course, assumed at the time that there was another fellow who had been a better researcher than I had been. In fact, Diane never even considered that she might be the student in the story. That is, until she went to a Princeton event honoring her thesis advisor David Billington.

When I showed up at the event, David said, well, have you ever heard of the problems with the City Corp Center? And I said, yes, have you ever heard of the problems with the City Corp Center? And I said, yes, isn't that pretty remarkable? I wonder who it was that discovered this problem. And he said, you know, Diane, there are very few engineering schools in New Jersey. And quite frankly, I know all of them. And I know the heads of the programs of all of them and I've talked to all of them There was no other student from New Jersey that was studying the building except for you

So it must have been you. Yes, it's I don't know about any other student This is David Billington the thesis advisor. Yes, my name is David Billington That's correct and I'm an engineer thesis advisor. Yes, my name is David Billington, that's correct, and I'm an engineer, spent 53 years at Princeton as a faculty member. I was Diane Hartley's thesis advisor. She wrote the most outstanding thesis of anybody who was a very low of your seeing it. Two big volumes, yes, anyway.

To hear Diane Hartley and David Billington tell the story, Diane wasn't some in your face nodal. Here's her version of the events. So I was 21 years old and I was a senior at Princeton University where I was studying architecture and urban planning. My thesis, I had selected the topic of the City Corp Center in New York, which had only recently been completed and occupied. She reached out to Lamejus firm to get the calculations that they had run, and then she tried

to replicate the math herself. To do the work again from the start and see if she got the same answers as Lamejus engineers. David Billington, her advisor, asked her to ask Lamejus firm about the quartering winds. The quartering wind, I thought that was a problem and that it should be looked at. So I obtained calculations from the design engineer from Lamejus office and I concluded the governing loading condition was the wind hitting the corner of the building. But the math just wasn't coming out right.

I was struggling with the calculations. I assumed, of course, that the engineer had done the right thing and any inconsistency that I might find would be my error. The building was standing. After all, she was just a college senior and LaMessia and his people were established, internationally renowned, professional, structural engineers. Diane got back in touch with LaMessia's firm, although she never talked with LaMessia herself. I never called LaMessia, I never said these things that were documented in the various reports that had been published today.

Diane did talk to a junior engineer, LaMeshna's New York office, named Joel Weinstein. She showed him her calculations. But at the end of the day, no, I didn't feel that I had put my finger on a major problem. I assumed I was wrong and wasn't understanding things. Even David Bellinton, who had told Diane to look into the quartering winds in the first place, didn't think there was any imminent threat. I mean, I don't think either of us really were in a position to say at the time, you've got to do something Bill right away.

We didn't have that feeling. I had the feeling that she should talk to the designers and find out whether this quartering wind had been considered and if so what was the outcome. But somehow Diane's discovery got silently passed up the totem bowl within LeMessage's firm. We asked Joel Weinstein the engineer about meeting check with Bill. I would have been the logical thing to do and he probably did that. I never heard that. You never heard it, I guess. We asked Joel Weinstein the engineer about meeting Diane and what happened afterwards, but he says he has no memory of this either way. Though he does acknowledge that if Diane

remembered speaking to him, then it probably happened. And that in such a circumstance, he would have passed her message on to LeMeshah. So it could be that's why LeMameja remembers speaking to a male student. He was conflating Diane Hartley, the student with Joel Weinstein, his own staffer. Now, of course, it is possible that there was a male student. A third man. Who somehow had the same data as Diane and actually did talk to Lameja on the phone. But I find it really hard to believe that such a person didn't come forward and claim

the spotlight after the story broke. Gender aside, Diane definitely doesn't fit the image of the precocious student. She identified a problem without even recognizing the significance of what she had done for decades. It's not that I did something. It's that perhaps my questions helped someone figure something out. Perhaps my questions were meant to be. I think if I had really realized that there was a problem and put my finger on it and raised it up the flagpole, I could pat myself on the back for having done something that was pretty remarkable. But at the end of the day, I feel like I was a bit player in a play

that had a happy ending. So yes, she deserves more credit than she's gotten. You can tell her that. I think that's right. That's the, I think, the code for this. 99% Invisible was produced this week by Joel Werner and Sam Greenspan, with Katie Mingle Avery Troubleman and me Roman Mars. Special thanks to Michael Verdaro, who wrote the AI-A Trust White Paper about City Corp Center, Samille Raghavan at the National Academy of Engineering for help and has tracked down archival audio of William LaMesa and Alan Bello's of the website, Damn Interesting for talking to me about this about two years ago at this point.

We are a Project 91.7 Local Public Radio KALW in San Francisco and produced out of the offices of ArcSign, beautiful architecture firm and beautiful downtown Oakland, California. You can keep up with this show and all the people who make this show on Facebook, Twitter, and Tumblr. If you want to see some pictures of CityCorp Center, go to 99pi.org. All right, I make sure you say that. Wait, sorry, I said something. I say this is not architecture we're talking about.

This is structure, engineering structure. I'm very sensitive about that. I don't want to mix up these things. I think that in this case, the measures design was a brilliant structural design but it was all covered over typical of architects to cover it over so you could never see it. Most people make that decision about tall buildings that they wanted to be architecture and that's why most of them are so

bad. But anyway that's a prejudice. So it will be clear this is structure not architecture. But what we're talking clear this is structured not architecture. But what we're talking about is structure, not architecture. Radio to be. From PRX.