A skyscraper that could have toppled over in the wind (1995)
23 comments
·June 15, 2025socalgal2
userbinator
If you're not familiar with it, steel is actually surprisingly strong for its size. Look up "ultimate tensile strength" and "compressive yield strength". They are many tens of thousands of pounds per square inch for structural steel. Even the tensile strength of small fasteners like bolts is very high in "human" terms:
https://www.engineeringtoolbox.com/us-bolts-tensile-proof-lo...
The bottom floor of a 100 story building is holding up 99 floors of weight.
That's not how it works. All the load of the floors above is held by the columns, which go into the foundation.
i_am_jl
>Maybe a need a physics simulation game like 3d world of goo that lets me see how such structures hold together.
Bridge Designer, formerly West Point Bridge Designer is a physics simulation that does almost that, though is more a learning tool than a game.
adgjlsfhk1
I think a lot of the answer here is in the foundation. a 100 story building isn't sitting on top of the ground. it has several stories of foundation below the ground, and likely has concrete piles that go hundreds of feet further down.
EGreg
This. It is like roots of a tree for instance. The trunk by itself is actually much smaller than the branches — like the opposite of a pyramid.
I guess most of the stress is distributed throughout the building frame going into the foundation - like they drive those pylons into the ground before building a large building.
But still, it could snap from all that stress, like a tree that’s been felled by the wind…
That is why the other part is that skyscrapers are designed to sway in the wind and have the entire structure above the ground absorb the kinetic energy and sorta cancel it out before it reaches the base.
Some buildings use tuned mass dampers (like the giant pendulum in Taipei 101) to counteract swaying by moving in opposition to the wind-induced motion.
In fact, a lot of the time the majority of the building’s outer shell (glass etc) can be blown out by the wind, if it is too strong, and the steel structure will then have a lot of holes in it for the wind to pass through.
They test these structures for how the wind and water will flow around them. Look at the base of the Burj Al Arab, and how they built it to withstand the 100-year storm.
DiggyJohnson
What you think of as a “floor” is more accurately described as hanging off the support structure.
Bengalilol
That podcast shines it all
https://99percentinvisible.org/episode/structural-integrity/
ilinx
I know virtually nothing about architecture or structural engineering, but I imagine all the weight isn’t necessarily going down from floor to floor, but a lot of the weight is attached to support columns, and the floors are built out from that.
All the weight is still on those support columns though, and I also have a hard time wrapping my head around how something like that is possible. Engineering is amazing.
antod
I think what they meant was not literally the bottom floor, but the columns at the bottom floor.
neilv
> On Tuesday morning, August 8th, the public-affairs department of Citibank, Citicorp's chief subsidiary, put out the long-delayed press release. In language as bland as a loan officer's wardrobe, the three-paragraph document said unnamed "engineers who designed the building" had recommended that "certain of the connections in Citicorp Center's wind bracing system be strengthened through additional welding." The engineers, the press release added, "have assured us that there is no danger." When DeFord expanded on the handout in interviews, he portrayed the bank as a corporate citizen of exemplary caution -- "We wear both belts and suspenders here," he told a reporter for the News -- that had decided on the welds as soon as it learned of new data based on dynamic-wind tests conducted at the University of Western Ontario.
> There was some truth in all this. [...] At the time, LeMessurier viewed this piece of information as one more nail in the coffin of his career, but later, recognizing it as a blessing in disguise, he passed it on to Citicorp as the possible basis of a cover story for the press and for tenants in the building.
Seems questionable to lie to conceal that kind of catastrophic risk.
Knowing that the skyscraper would fail in some kinds of winds is information that could be used by rational people to help protect themselves and their businesses.
> Shortly before dawn on Friday, September 1st, weather services carried the news that everyone had been dreading—a major storm, Hurricane Ella, was off Cape Hatteras and heading for New York. At 6:30 a.m., an emergency-planning group convened at the command center in Robertson's office. "Nobody said, ‘We're probably going to press the panic button,' " LeMessurier recalls. "Nobody dared say that. But everybody was sweating blood."
> As the storm bore down on the city, the bank's representatives, DeFord and Dexter, asked LeMessurier for a report on the status of repairs. He told them that the most critical joints had already been fixed and that the building, with its tuned mass damper operating, could now withstand a two-hundred-year storm. It didn't have to, however. A few hours later, Hurricane Ella veered from its northwesterly course and began moving out to sea.
I see gambling people.
Presumably, some were gambling to avoid temporary public disorder in the city, or temporary disruption to general commerce there.
But it sounds like others of them wanted cover up a scandal in which they and the company were now implicated. And they were willing to gamble with other people's lives and businesses to do so.
neilv
This is one case in which our layperson's naive intuition would've been the right answer (for the wrong reasons):
https://en.wikipedia.org/wiki/File:53rd_St_Lex_Av_td_08_-_Ci...
sdoering
There’s a great keynote by Nickolas Means [1] about this building and the story around it.
gosub100
Veritasium covered this recently and did some debunking about the original student.
pylua
Just walked past this building in person the other day. I had to a triple take when I saw the base. It seems very unintuitive that it could stand safely.
throwaway2562
What a great story: remarkable how the New Yorker of 1995 has the same efficient but easy-going clarity as 2025.
riordan
Seriously - I find myself coming back to read this once every few years because of how riveting the piece is (oh no -just realized the pun)
Also I’ve heard wonderful things about The Great Miscalculation[0], a recently released book about the Citicorp Tower incident
belter
2 years ago: https://news.ycombinator.com/item?id=37684604
tomhow
Thanks! Macroexpanded:
A skyscraper that could have toppled over in the wind (1995) - https://news.ycombinator.com/item?id=37684604 - Sept 2023 (21 comments)
paulpauper
The irony that this was printed just 6 years before 9/11. The lesson is it's hard to anticipate all the possible risks. The two WTC towers were engineered to withstand a jet plane impact (a 707, which was a common passenger jet at the time in the late 60s), just not not a modern airplane packed with fuel at max speed.
crazytony
As far as weights go, the 707 and the 767-200s that hit the towers were fairly close in size, weight and fuel capacity and that is demonstrated by both towers surviving their impacts. The problem was the fire and specifically the inability to fight the scale of the fire effectively.
iwontberude
And insufficient modelling for the heat of jet fuel mixed with office supplies which severely weakened the structure allowing it to pancake in a cascading fashion from the first support columns to buckle.
wat10000
The designers also assumed that the airplane would be moving pretty slowly if it was so close to the ground, either departing from or landing at a nearby airport, not coming in at near top speed.
I don't know the physics involved nor do I have any knowledge of architecture or building construction but when I look at tall buildings it's really hard for me to imagine how they remain standing.
The bottom floor of a 100 story building is holding up 99 floors of weight. The base of a 100 story building it really thin relative to it's height. If I built anything out of legos to the same dimensions it would not be structurally sound. Well, the legos at the bottom would easily hold the weight). Yea I know reinforced steel and concrete is not legos. Other examples though, every piece of furinture I own has some degree of wobbliness. It's easy to see how the pyramids hold up. It's not so easy to see how the Vancouver House Building stays up (https://en.wikipedia.org/wiki/Vancouver_House). The one in the article as well just looks, at the bottom, like it has to tip over eventually. (not saying it will, only that it looks like it)
I'm not in any way denying science. I'm only in awe that more builings don't fall down. Bridges too. I'm surprised to some degree an 93 year old steel bridge being sprayed with salt water for the entire time hasn't had its cables snap.
Maybe a need a physics simulation game like 3d world of goo that lets me see how such structures hold togehter.