40-ton timber arches collapse in Hickory, NC 35

[bugbus]

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

Before:

After:

 

[LittleInch]

"The city’s focus is recouping the investment that taxpayers made. This now involves multiple contractors, multiple insurance companies, and multiple lawyers."

Oh boy - That will take years and have a value several times more than the Bridge.

I was once involved in a project which had 5 sets of parties involved between sub contractors, main contractors, operator, designer and owner - all different, each with their own set of insurance companies and lawyers.

As no one could agree on how much compensation to pay for the the damaged tank (in my example) they decided to repair it. Repair costs were easily 5 times what the tank was possibly "worth" and due to its location could not be feasibly demolished and re-built or a new one substituted. Was a great experience for me, but utter madness in terms of value for money.

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

 

[Electronbelt]

The arches are to be cleaned up and removed this weekend per the city...

[URL unfurl="true"]https://www.hickorync.gov/nc-127-road-closure-removal-city-walk-arches[/url]

 

[Electronbelt]

This gentleman has some excellent photos that he took while visually documenting various stages of the arches construction.

They are some of the clearest images of the design choices in question that I have come across, including the (possibly infamous) 'pin' joint.

I do not want to directly link his images or upload them here (without permission), but the album in its entirety can be found and viewed on his flickr page:

[URL unfurl="true"]https://www.flickr.com/photos/raddad/albums/72157719596386082/with/51332009377[/url]

 

[LittleInch]

The joint that is key to this is actually the one at the top of the wishbone I think.

That's where artistic impression of continuous strands of wood gave way to engineering reality and where the failure almost certainly came from

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

 

[dik]

I think so, too... it's interesting that the connection at the very top can likely take the forces; they should'n be huge... and it looks so flimsy, almost a little out of proportion. From a load point of view, it likely works.

I thought it was attractive; now that they know what not to do, can they rebuild it?

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

-Dik

 

[spsalso]

Mighty interesting photos--wish there were more.

The extreme closeup (on the ground) seems to be one of the two pieces of the top connection. I note that the cable anchor is conspicuously missing, and assume it was added after the arch was assembled, and likely cut to length. It kind of messes up the "purity" of the single bolt connection.

In the photo shot directly from one end, you can look up towards the near "outer" connection and see three steel plates assembled together. What is weird is that they're not flat and flush with each other--"bent" would be the word I would use. I could wonder if the person who designed this structure spent much time on figuring out how it would be assembled.


spsalso

 

[Sym P. le]

three steel plates assembled together

You are right. As I see it, each laminated timber member is fitted with a weldment which slots into the members end and extends proud of the member to allow for bolted connections to adjacent members. These individual members are then connected to each other with an additional weldment configured to accept the various members. At the connection to which you refer, you see two end plates and one junction weldment between them.

At the peak junction, you will find an end plate on each member and each of which is bolted to a mount plate. The mount plates then connect with a single bolt.

The following image shows just how minimally, the timbers are connected at the wishbone:

 

I would suggest this might not have collapsed had Hickory used hickory. (Well, that and some better way of connecting the joints.)

By the way, were the bent members fully stable, including through temperature variation? i.e., did they have any tendency to unbend?


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

The joint that is key to this is actually the one at the top of the wishbone I think.

Quite right. I was horrified by the concept as soon as I saw the detailed pictures, and certainly didn't need to do any calcs to back up that impression.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[AusG]

A model, built with pipe-cleaners even, would have identified the weakness of those joints to lateral flexing. There are even lateral triangles in the design, but rendered immediately useless by balancing them on their tips. It is almost anti-engineering.

 

[SnTMan]

STEAM !!

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[spsalso]

The test model that was apparently never built should have been done to a scale of 1:87.1. At 178 fee long, it would be a nice 24" long!

That way, after proving the design (should that have actually happened), it could have been given to the city of Hickory on a platform with the adjoining bridges, and an HO scale train on the railroad track.

That way, it could even have been incorporated into the upcoming visiting (proposed) modular model railroad coming to town on April 1 and 2.

Would'a looked pretty cool if it had visually recreated the boo-boo, also. And saved some money and embarrassment.


A missed opportunity all around, I'd say!


spsalso

 

Well, somebody got a good supply of firewood out of it all.
(We'll overlook the toxic preservatives it contains.)

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[dik]

Not if it's pressure treated, or unless they have a suitable wood burner.

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

-Dik

 

[spsalso]

Just thought I'd post that it appears the local bulldogs of public interest have not been able to find any more information on this topic. Well, that they wanted to share with the world.

A whole month. Maybe they had the vapors.


spsalso

 

[boo1]

$750,000 project to Neill Grading, Dane Construction and Western Wood Structures.

 

[Alistair_Heaton]

They are going to have another go?

 

[LittleInch]

They're having a go at suing them apparently....

https://hickoryrecord.com/news/loca...cle_1f9283c4-c66f-11ec-87ad-13158d398e1f.html

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

 

[Alistair_Heaton]

I actually quite like the look of it. If they can get it to stay up.

 

[hokie66]

No chance they will do that again. Maybe a nice steel sculpture?