Nanfang'ao bridge collapse Yilan Tiawan 2

[charliealphabravo]

I haven't found any mention of fatalities. Reported 20 injured.

Location

Collapse video

Bridge details

Photo of bridge system.

Edit: Updated dead video link. Thanks to JAE.

 

[Tomfh]

Yikes.

You can see one of the tendons fail where it connects to the arch. (from video above)

 

[itsmoked]

Yep that tendon.. Pretty much right after that big truck blew by under it. Ohhh and looking again that truck doesn't make it onto the approach. That's one serious injury. Most the others were likely on that ship the bridge landed on.

I could see where that truck loaded the bridge as a rolling point load that set up a traveling wave that went both ways to the ends and rebounded meeting at the middle for a large over-stress. Perhaps if there'd been more traffic the reflections wouldn't have made it back intact or as single amplitude waves?

Could the truck have been overweight or overweight-speed?


It always bothers me when something like a bridge is made with lots of single point failures, no chance of saving the structure or even clearing it of potential victims.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Denial]

I am being told (by Chrome browser) that the video is private.

 

[LittleInch]

try

https://www.mirror.co.uk/news/world-news/breaking-taiwan-bridge-collapses-onto-20376796

or

https://www.taiwannews.com.tw/en/news/3787909

Very strange - Just looks like the tendons decided to give way, but why it wasn't good to handle at least one failing without collapsing??

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Also: If you get a response it's polite to respond to it.

 

[itsmoked]

The others snapped about 100ms after the first one.

Some idiots are yanking the vids. The last one Little put up is the best one anyway. I screen captured it if it all goes away.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[3DDave]

Wild Guess Flag -

I'll throw out a wild guess and say that some detail of the attachment may have allowed corrosion where it was tough to see and that, while the as-built brand new bridge could have survived the loss of any or even several tendons, that corrosion brought the margins down to where they were just barely able to hold the weight leaving the rest ready to domino.

 

[bones206]

I heard there had just been a typhoon there prior to the collapse.

 

[JAE]

A simpler video to access than those above:

https://www.youtube.com/watch?v=ZC9_X2mEhqg

And another one from an adjacent dock/road:

https://www.youtube.com/watch?v=ljy2W8p1pBw

 

[Denial]

Some of the cables seem to have broken at their tops, others at their bottoms.

 

[JAE]

Top cable seems to go first - the lower ends are fairly dark so it's hard to see.

 

[charliealphabravo]

The protection of these cables from corrosion is apparently not a trivial matter. The marine exposure in this case would be an obvious consideration. As would the recent earthquake and typhoon of course.

I may be mis-remembering but corrosion was discovered in the cable stays of Tampa Bay's Sunshine Skyway in the mid-2000s. My recollection was that they determined that the chemical environment inside the protective polyethelene ducts around the cables caused corrosion of the stays as the ducts were being grouted during construction. This condition was especially bad near the top where the gasses accumulated as the ducts filled with grout. I wasn't able to find much on this when I went to look it up.

Edit:

Some of the cables seem to have broken at their tops, others at their bottoms.

That reminds me of the first demonstration our instructor performed in high school physics. As a poor dumb farm boy I can still remember the exact moment like magic. A weight was hung from a piece of string and a piece of string hung from the bottom of the weight. If you quickly pulled the bottom string then the lower string would break. If you applied load firmly and gradually to the bottom string, the upper string would break. Not necessarily applicable here but it could be an interesting clue to point of origin that the first cable breaks under static load near the top and the others subsequently break under dynamic load near the bottom.

 

[epoxybot]

The bridge cab;es all pass through an opening in the bottom of the arch, which does not appear to offer much in the means of access for inspection.

 

[SFCharlie]

The wikipedia say the bridge is a steel arch, but the photos of the broken ends look like concrete. Does anyone have any more specific info?

SF Charlie
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[SFCharlie]

More detailed article:
Snapped cables at center of investigation into bridge collapse in Yilan, Taiwan

SF Charlie
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[IRstuff]

JAE's second video shows the arch intact, after the collapse, so it's likely not to be concrete.

It would seem to me that the cables would have to have been grossly under-designed if, even accounting for corrosion, the remaining cables couldn't support the weight after the fire cable failed as evidenced by the near simultaneous failure of the next 4 cables to snap.

image from other article shows weld seams and tearing of the structure

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[msquared48]

Wow! Obviously a "Bridge Too Far"!

Probably will develop into a big coverup...

Mike McCann, PE, SE (WA, HI)

 

[Agent666]

Least what's left seems fairly intact. Especially the arch, so I'd think if failure initiated there as videos suggest it would be fairly easy to establish initial cause.

 

[charliealphabravo]

Since the arch is steel then I'm guessing their must be a hatch and an internal passage for inspection and maintenance of the stay anchors. That would have to be there for the original installation I think. There is even a ladder in the @IRstuff photo but I suppose that could just be for changing the light bulbs.

 

[hokie66]

The arch itself is intact, but it came adrift from the wishbones. In addition to the hangers and their attachments, the joint at the arch and wishbone should be investigated. Probably the connections to the abutment as well.