Norway bridge collapse 17

[dylansdad]

I have not seen this posted.

https://www.msn.com/en-us/news/worl...pc=U531&cvid=21c615cd186b4a9ca98f678474e34cd7

 

[Alistair_Heaton]

https://www.dezeen.com/2022/08/17/norway-timber-tretten-bridge-collapse/

Seems it was inspected not that long ago.

Also some links to the various parties. The only one I can't find is the contractor who I think is Spanish.

 

[LionelHutz]

JohnRBaker - Here's a wooden covered bridge you can still drive over.

https://www.google.ca/maps/@43.5859...NQ!2e0!5s20210501T000000!7i16384!8i8192?hl=en

I was told they were covered to keep the water from scaring the horses.

 

[spsalso]

"It's Norway, after all. What else could you expect?"

This is called ironic humor. By many. I had assumed that the cited characteristics were actually uncommon, and thus my comment would be humorous.

I was trying to get Retrograde to respond with some actual examples, and it was done as a prompt.

Of course, if Norway is indeed a hotbed of corruption and malfeasance, then it would perhaps be seen as a straight correct statement. That is a possibility I had not thought of, but apparently others view it as at least slightly possible.



spsalso

 

[JohnRBaker]

Here's another one that you can drive on.

Of course, this one was built in 1962 and is a tourist attraction in the village of Frankenmuth, Michigan. The entire town is a tourist attraction set in a Bavarian theme, famous for, among other things, German cuisine, Christmas decorations, beer, and horrible traffic jams on weekends. We know about the traffic jams since this is where my wife and I lived our first year out of college. We always loved coming to Frankenmuth and when I got a job in Saginaw, just about a 12-mile drive to work, we decided to rent an apartment there and see if perhaps we'd like to stay in the area. That's when we learned that it's a lot different living IN a tourist attraction than coming to visit once in a while. After a year, we moved into Saginaw where both of us were closer to our jobs and away from the total weekend gridlock. We still occasionally stop and visit when we're in Michigan, but I would never live there again.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[spsalso]

Here's a nice shot of the wood railroad bridge I linked to, earlier:

It's a working railroad bridge, at least in 2019. It was built in 1936 as a replacement for a flood damaged one. Of the three spans of this bridge, it is the newest.

It is NOT a covered bridge.



spsalso

 

[Sym P. le]

Model of Tretten bridge using drawings from pdf posted earlier. Approx 2m slope down to the west, lower chord is straight line, upper chord scaled from drawing. I'm using one unit of load at each lower chord node and twenty units at node 17. I don't have any control of the output. Blue is tension, red is compression.

 

[Retrograde]

I was trying to get Retrograde to respond with some actual examples

So why didn't you just ask that?

 

[spsalso]

I noted that you did not volunteer any of those examples. I was trying to prod you to do so.

If you care to give such examples, I am sure you will.


spsalso

 

[spsalso]

Sym P. le,

Would you please run that same program with a nice handsome loading about where the loaded track was, at the time?


spsalso

 

[dik]

The collapse was likely due to one of three items. The timber structure had deteriorated, or the bridge was underdesigned, or the bridge was overloaded. We need additonal information in order to comment. Timber bridges can be designed to accommodate significant loads. I doubt that the ends were capped, but copper is a good choice due to it's antifungal properties. Capping can trap moisture... the bane of wood construction. I was involved in a project about 50 years back that used a timber treatment called the Boliden treatment. The architect was from Iceland and it was a common preservative back then and was excellent. I'd never heard of it back then... and, I don't think I've heard of it since.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[spsalso]

Deteriorated. In 10 years.

IN 10 YEARS!

Yikes!

If someone believes that could happen, they really should explain why. Then they could continue and explain why the design team didn't account for it.




spsalso

 

[Sym P. le]

news article on abnormal movements in the Tretten bridge felt by locals when heavier vehicles on bridge

 

[MintJulep]

There has been a kind of rocking in the bridge recently, which has not been there before.

Something changed. I.e. something broke and the parts that tried to compensate weren't happy.

 

[hokie66]

Some pure speculation on my part. Both abutments seem to be capable of resisting a large horizonal force. Therefore, the bridge may have tried to act as an arch rather than as a truss. The arch forces would have been reasonably constant over the length of the top chord. The part of the top chord without the lateral truss, at each end, could have developed stability issues, buckling laterally.

 

[LittleInch]

You do wonder if the new two pile supports settled a a bit compared to the stone supports which were part of the original bridge.

It's also interesting that the longitudinal members of the road deck itself also appear to be timber.

And that the road is offset from the centre of the bridge. You have a two lane road then a cycle / pedestrian section within the bridge.

This offset loading can't be good and maybe isn't recognised in the design calcs?

Note also the timber joint in this photo which is one bay inland from the new two pile support.

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

 

[Brad805]

The study cited by Sym P Ie noted a bridge failure in 2016. The report suggests the design of the "Perkolo bridge at Sjoa," is similar to this bridge, but looking at the pictures it seems the similarity is limited to a truss and wood elements. In that failure one researcher noted over reliance on complex modeling.

 

[Sym P. le]

There is a construction joint at node 16 (see model above) and I'm thinking there is also one at node 15 on the lower chord. That would be my focus. Note the upper chord snapped at node 14. That took a lot of force and something close by had to give way to cause it.

 

[spsalso]

Here is a nice picture showing the side of the failed bridge where the large load was applied when it fell:

I note that the two support posts are not parallel at this time.

Here's another nice one:

spsalso

 

[Sym P. le]

Frequently, a moving load will have time to move away from the destruction it caused. In this case, we find significant issues behind the lorry, not in front of it. That's why I moved away from the east end of the structure after a cursory review. The modeling didn't show anything worth being excited about at the east end either.

 

[Sym P. le]

This bridge may become a prime example where old skool principles are foo-fooed for esthetics because we have computers and know too much.