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.
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.
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.
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.
Bridge Designer, formerly West Point Bridge Designer is a physics simulation that does almost that, though is more a learning tool than a game.
https://99percentinvisible.org/episode/structural-integrity/
The support structure that is carrying the weight of the building is not a floor.
It's bedrock, a/o concrete pylons. Force doesn't ever take a 90-degree turn. Floors are only structural to carpet, furniture, and meatbags (tensioning members aren't part of the floor, even though they run parallel to them).
The vertical supports that carry the weight of a floor run vertically through that floor. They also carry the weight of all the higher floors. So there are vertical structures that pass through the bottom floor that support the weight of the bottom floor, plus the weight of every floor above it.
By the way, trust engineers and never trust physicist with these things. Physicists do have the theoretical tools to handle such problems, but they rarely have the practical knowledge to successfully implement them. :)
A skyscraper that could have toppled over in the wind (1995) - https://news.ycombinator.com/item?id=37684604 - Sept 2023 (21 comments)
Also I’ve heard wonderful things about The Great Miscalculation[0], a recently released book about the Citicorp Tower incident
Leslie Robertson, who lead the WTC structural engineering team along with John Skilling, is on tape making the 707 claim, but no surviving documentation has been uncovered to reveal the specific scenario that was modeled or the calculations used.
An important reason why the towers survived the impacts at all was the presence of the two hat trusses, which allowed the increasingly unsupported loads to be redistributed to the surviving exterior columns. Najib N. Abboud of Thornton-Thomasetti has given a detailed account of the findings of the forensic investigation that's available on Youtube[1].
> 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.
Compare that with the evacuation of Fukushima after the incident at the nuclear plant, which released a very minor amount of radiation. Many people suffered severe psychological stress at not being able to return home and not knowing when or if they'd be allowed to go home. Some to the point of suicide. In that case the issue was more about unnecessary evacuation as opposed to messaging, but the point stands the unnecessary panic can cause real harm.
Throughout the article, from the beginning, the writer keeps going out of their way to exonerate the main character.
But elsewhere they do acknowledge the risks to the company's stock price, individual reputations, etc.
So it does seem that was a factor for some, and a potential conflict of interest.
It's also such a nuanced issue, with bolts vs welds and arguably no one having done anything wrong individually, that I can't imagine a way to explain this to the public that people could understand and be like "yea that makes sense" and proceed to act rationally. Add to that the fact that there's so much probability involved in the potential path and strength of any storm and I'm not sure a member of the general public could reach a rational conclusion.
Of course we'll never know, but the point is that the man did the right thing, and of course we should celebrate that.
Maybe the writer was trying to celebrate, and to head off some kneejerk criticisms, but still with the idea that people would be looking over this reporting, and that there'd be a place for constructive criticism?
https://en.wikipedia.org/wiki/File:53rd_St_Lex_Av_td_08_-_Ci...
georgecmu•7mo ago