40-ton timber arches collapse in Hickory, NC 35

[bugbus]

https://www.wsoctv.com/news/local/n...king-busy-highway/N7L3RUTIKJE23LLTGYBXGJPM5U/

Before:

After:

 

[dik]

In 2D space for sure, but maybe not in 3D space unless you can use symmetry, I think (I'm not 100% sure); I think it's reasonably close to use for analysis. BART knows these things. The bottom connections have to be 'rigid' else you have a mechanism (without plastic design).

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[LittleInch]

In following the artists impression I think they overreached themselves in trying to create a wooden structure in which two curved pieces of wood are shown crossing each other in the same plane without any apparent fixings. Easy to draw - Hell to try and make.

Hence we ended up with a visually pretty pure representation of the sketch, but now with seriously lower bending strength and essentially another hinge.

Doubt anyone will know why it just decided to fall over at that particular moment - maybe a gust of wind, maybe a wire did snap, maybe the hidden hinge between the two sections halfway along decided to bend.

Don't think those videos are going to give us those answers, but it sure looks to me like it bent at that connection from the wishbone to the strut.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dik]

Connections would be a nightmare... Catch the following, Precious Blood Church in Winnipeg

I understand the shop drawings were a b*tch and they ended up just getting a bunch of glulams and cut them to suit on site.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Sym P. le]

video 1 of 3 attached: 2022-02-18-13-06-39-2.mov

 

[Sym P. le]

video 2 of 3 attached: FPS-arch-video.mov

 

[Sym P. le]

video 3 of 3 attached: 2022-02-189508-39-13-806951-2.mp4

 

[hokie66]

Aren't they the same ones you linked above?

 

[spsalso]

Western Wood Structures doesn't say anything about this collapse on their website. I guess they're still "thinking". And I guess their thinking is kind of slooo

http://wwww.

However:

"A dedicated engineering department sets Western Wood Structures apart from the rest."

Does that mean apart from the others that DIDN'T fall down?


And the mayor says it's extremely unlikely they'll rebuild the arches. The mayor SHOULD have said "We're going to rebuild those glorious arches bigger and better and STRONGER than before. And our good friends at Western Wood Structures, and their insurance company, will be covering most of the costs!"

As is, he looks like a loser mayor of a loser town.


I'm going to mention that the more I look at the "before" photos, the more I like this non-structure. I would have liked to walk around/under it. It MIGHT have been a pretty neat piece of work. My biggest aesthetic problem is that there are three bridges here, all together. And the fact that the other two bridges are FLAT takes away from the visual interest. Can't exactly move the other bridges, but it would have looked better with this thing all by itself.


I think what they should have done with all this extra money that they had to spend is to put some nice shady sitting spots on the perfectly flat bridge, so as to allow folks to have a picnic while waiting for a train to watch pass by. THAT is a pleasant way to pass the time!!


spsalso

 

[dik]

We don't know the cause, yet, and Western Wood Structures is very likely looking at this now. Their site is for advertising and this collapse is not good advertising. They may not be the cause; it's a matter of waiting to find out more particulars. It's not good to speculate on who's at fault... who's on first! It's also not the mayor's fault... We have to wait a bit.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[IRstuff]

Nevertheless, a company in that position should at least post some sort of throwaway release ala,
"Western Wood is dedicated to identifying the root cause of the failure of our structure installed by SOMEONE ELSE, and will work diligently with the city to show that it was not our fault, etc. "

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[spsalso]

Western Wood Structure's website is certainly for advertising. But it is also the face of the company, to anyone who goes there. It's what you SEE when you choose to visit.

I suspect we all agree that the design of the structure was by Western Wood, with perhaps some artistic sketches contributed by a Hickory NC local. But they were the folks who ran the numbers.

Yes. It would be interesting to see the installation instructions. If any.

spsalso

 

[spsalso]

That picture of the turnbuckle several posts back keeps sticking. WHY was so much takeup used? My guess is that it was because the top of the structure was brought downwards by the tensioning, which likely would have brought some bending to any joints in the structure.


spsalso

 

[dik]

I agree... my oversight. They should acknowledge the problem, be greatful that no one was injured and stipulate that they are currently investigating what happened and provide information when it becomes available and vet it through their legal department before publishing.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Tomfh]

That picture of the turnbuckle several posts back keeps sticking. WHY was so much takeup used?

To tighten it up. But with a 5 hinged arch it would only tighten so much. And like you say, the motion would have stressed the joints. This is likely related to the joint damage that was repaired earlier on.

 

[MintJulep]

The moment of collapse live, from a rather distant camera.

https://www.youtube.com/watch?v=c_D6RfCLZA0

 

[IRstuff]

That video is one of Sym's links. It's the cleanest of all the videos I've seen, and it certainly looks like the arch bent over at the lower hinges

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[dik]

that's what prompted me to do the sketches...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[spsalso]

WHY was so much takeup used?

To tighten it up. But with a 5 hinged arch it would only tighten so much.

Well, it wasn't actually "loose", so there was nothing to tighten up.

I wasn't actually asking why some person chose to do this. I was asking how the structure allowed so much movement.

The cables pulled downwards with a pretty significant force. This then put a compressive load onto the structure. And rather than being decently rigid, and refusing to compress much, it most likely did a whole lot of bending/bowing. And, yes, twisting of any joints in a way that was likely not contemplated by the designer.

I wonder if the thing would have been still standing if the cables were not used.


spsalso

 

[Tomfh]

I was asking how the structure allowed so much movement.

It’s a 5 hinged arch.

 

[spsalso]

So there are 5 pinned connections, all allowing rotation about the pin?

spsalso