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(Slate)   A look at the design flaw that almost destroyed an NYC skyscraper. No, not thermite   (slate.com) divider line 116
    More: Scary, New York City, emergency evacuation, Lutheran Church, structural engineers, black outs, 53rd Street, Invisibles  
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16953 clicks; posted to Main » on 17 Apr 2014 at 3:35 PM (36 weeks ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2014-04-17 08:02:20 PM  
I found the article I read on this when this story was posted to Fark a few years back.
 
2014-04-17 08:04:46 PM  
Every time I click on a Slate article I am disappointed. When they report on something interesting, invariably someone has done it better. And anytime they have some original article/editorial/etc it unthoughtful, poorly written, and in the end is not even worth the electrons.
 
2014-04-17 08:36:55 PM  
Ooops.
 
2014-04-17 08:52:54 PM  

This text is now purple: OKSteveOK: Hurts my brain to imagine the pucker factor experienced by the engineer when he figured out his building might fall down.

Worse, it might have fallen over.

[farm6.static.flickr.com image 850x592]

Consider how many other buildings it would have dominoed over. It was considered possible the building failing laterally could have started a building cascade extending to Central Park.


Doubtful.   Pretty sure it would just be 2 buildings.  Building A falls (let's say) East into building B.  A tears itself apart against B's facade (while doing MASSIVE damage to B) but doesn't provide enough of an Eastward "push" to knock B over.  The most severe damage is done to the lower floors of building B (building A's a total loss) so B loses enough structural supports to fall in the direction it's weakest, the damaged Western side.  It falls down and a bit west (towards the place building A used to stand) and basically "falls on top of A."

AT least, that's my guess.
 
2014-04-17 09:01:45 PM  
The building on stilts that wasn't designed to take wind loads?

*clicks*

Yep.

But still neat.
 
2014-04-17 09:08:45 PM  

AlHarris31: Every time I click on a Slate article I am disappointed. When they report on something interesting, invariably someone has done it better. And anytime they have some original article/editorial/etc it unthoughtful, poorly written, and in the end is not even worth the electrons.


It's like the old joke about a rejection slip from an editor:

"Dear sir,
You're writing was both funny and original. Unfortunately, the funny parts weren't original, and the original parts weren't funny."
 
2014-04-17 09:22:53 PM  

Smeggy Smurf: WelldeadLink: Smeggy Smurf: Fissile: I tend to go off on on rambling tangents when it comes to architecture.

Do you wander around, tilting at windmills?

Nope, I fight gazebos


I fought piranhas!
http://youtu.be/GqXZr6ByVIk

// It's Jack White
 
2014-04-17 09:44:14 PM  

peterquince: Walking near the WTC (I work down the street), I heard some people discussing Sept 11. One of them said his uncle or his grandfather or whoeveritwas worked on the construction of the towers and they were built by mob-family-owned construction companies. And that they used less steel than the construction specs called for in order to save money.


One of my professors was involved in the WTC investigation, and he thinks that the mob paid off the inspectors to turn a blind eye to skimpy fireproofing.  He didn't find any evidence of less steel being used.

It wouldn't have mattered.  The problem was the design - not that it was flawed, but it was vulnerable to being flown into by a plane full of fuel.  Most tall buildings have heavy columns every 30' or so; they would tear a plane's wings off.  Most buildings have interior columns too, and normal beams holding up the floors.  If a beam fails, you only lose perhaps a 10'x30' area of floor.

The Twin Towers were designed by a guy scared of heights, so he came up with a design that had HSS (box) columns every 4' or so around the perimeter.  With so many columns, they could each be thin, like 3/16" or 1/4" thick in the upper stories.  An airliner's wing can apparently penetrate that and deliver its payload inside.  Also, there were no interior columns between the core and the perimeter tube columns.  Architects love that because it means wide open spaces.  But it means you have to replace the beams with long trusses, and like most trusses, these were statically determinate.  Lose one member and the whole thing fails.  In the heat of a fire steel doesn't melt, but it loses a percentage of its strength - probably around 50% in this case.  That was enough to cause a floor failure, and the falling floor caused the next one to fail, etc.  I don't remember all the details, like what happened to the core, but the point is that this kind of fire was more harmful to these particular buildings than to most others.  Al Qaeda had engineers among them.
 
2014-04-17 10:04:18 PM  

carlisimo: One of my professors was involved in the WTC investigation, and he thinks that the mob paid off the inspectors to turn a blind eye to skimpy fireproofing. He didn't find any evidence of less steel being used.

It wouldn't have mattered. The problem was the design - not that it was flawed, but it was vulnerable to being flown into by a plane full of fuel. Most tall buildings have heavy columns every 30' or so; they would tear a plane's wings off. Most buildings have interior columns too, and normal beams holding up the floors. If a beam fails, you only lose perhaps a 10'x30' area of floor.

The Twin Towers were designed by a guy scared of heights, so he came up with a design that had HSS (box) columns every 4' or so around the perimeter. With so many columns, they could each be thin, like 3/16" or 1/4" thick in the upper stories. An airliner's wing can apparently penetrate that and deliver its payload inside. Also, there were no interior columns between the core and the perimeter tube columns. Architects love that because it means wide open spaces. But it means you have to replace the beams with long trusses, and like most trusses, these were statically determinate. Lose one member and the whole thing fails. In the heat of a fire steel doesn't melt, but it loses a percentage of its strength - probably around 50% in this case. That was enough to cause a floor failure, and the falling floor caused the next one to fail, etc. I don't remember all the details, like what happened to the core, but the point is that this kind of fire was more harmful to these particular buildings than to most others. Al Qaeda had engineers among them.


Designed by a guy afraid of heights?  Um, no.

Ever been inside the Empire State Building?   There are lots of interior columns.  Lots of floor space is taken up by those columns......floor space that you can't rented because that space is taken up by columns.

The original WTC was built the way it was for two reasons: 1) It provided an open floor plan around a central core.  2) It used less steel...that made it cheaper to build.  Costs less to build, generates more in rent.  Get it?
 
2014-04-17 10:17:39 PM  

TheOtherMisterP: "LeMessurier calculated that a storm powerful enough to take out the building his 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. "


No, that's not how math works!


The second sentence is correct.
 
2014-04-18 12:29:20 AM  
Ingots of pure selenium?


They don't build them like they used to!
 
2014-04-18 12:31:48 AM  
Mr. Eugenides
2014-04-17 03:41:39 PM


So Slate writers are plagiarizing off of old episodes of Nova now?

Which still beats 99% of gawker's greenlights which are articles talking about youtube videos.
 
2014-04-18 03:49:16 AM  

dinch: lostcat: I was expecting the article to talk about current day. Has the building's structure been altered in any way? Is just standing as is? Do people work there, and realize that it could collapse in strong wind?

Am I expecting too much from my journalists?

The engineer came forward and admitted to the mistake. Repairs on the welds were done in secret and completed pretty dang fast. It can now withstand a 700 (I think) year storm, so it's actually one of the most sound buildings standing today.


it would have been nice to add that to the story,  like have a reason why the used term "almost" was used to indicate it now wont happen .
 
2014-04-18 08:19:14 AM  
I used to work in that building.  It was always pretty cool walking into it every work day.
 
2014-04-18 08:04:21 PM  

NIXON YOU DOLT!!!!!: The Bestest: NIXON YOU DOLT!!!!!: If only they had discussed that on the article...

It didn't?

My understanding of the situation is this: it was designed to withstand a 55-year storm, but turns out someone forgot to carry the 2 and was only rated as a 16 year storm, so some emergency welding later and viola, it can now withstand a 700 year storm.

My question is, if you knew of a way to make it 14x as strong as (what you thought was) your original design, why wouldn't you in the first place?

The architect didn't account for quartering winds, since in a NORMAL building those are the lesser threat.


How is it possible to miss that?

I'm a dumbass, but even my immediate thought the first time I ever saw that building was that they had to approach the structural engineering as if it were rotated 45 degrees.
 
2014-04-18 11:14:41 PM  

DrunkWithImpotence: Mikey1969: I figured it was going to be about this:
http://en.wikipedia.org/wiki/B-25_Empire_State_Building_crash

Because a B-25 bomber crashing into your skyscraper is definitely NOT by design...

The Empire State Building was was over-enigneered, there is probably twice as much steel in that thing than absolutely necessary.  In a gale force wind I think the top floors sway only an inch or so, if that.  It is not however, resistant to giant ape attacks.


The frame was specially redesigned after it was decided to put a dirigible mooring mast on top, to withstand gale-force winds pulling on a dirigible.
 
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