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Ontario Cable Stay Bridge Failure

Ontario Cable Stay Bridge Failure

Ontario Cable Stay Bridge Failure

(OP)
Some engineers in Spain are going to have an interesting few days of review/discussion ahead of them. 2' of movement seems to suggest something was fundamental was missed. It is posted in the failure section too, but it would be interesting to hear some comments from people that design cable stay bridges.

Link to news story: http://www.cbc.ca/news/canada/thunder-bay/nipigon-...

RE: Ontario Cable Stay Bridge Failure

looks cold
thermal movement?

RE: Ontario Cable Stay Bridge Failure

Looks like thermal movement "shortened" the longest cables on the ends, which lifted the (somewhat flexible) ends of the bridge platform up (off of the static bridge end platform).

Did the other end lift up as well?

At this end, there seems to be one platform segment that did not move up. A different support piece spanning a gap between the dirt-supported roadway and the first cable-suspended roadway section?

RE: Ontario Cable Stay Bridge Failure

(OP)
I believe the other end lifted as well. I agree it seems to be cable shrinkage, but that seems a fundamental consideration if you open the bridge code and look at the degree days where your structure is being built. Much of Canada is very cold in the winter.

RE: Ontario Cable Stay Bridge Failure

Thermal issues seem pretty plausible, especially since the bridge was just built.

The article claims a "gust of wind" but I find that very unlikely.

RE: Ontario Cable Stay Bridge Failure

This is a curious design and construct though. See http://www.enl-tbay.com/NipigonBridge/plans-drawin...

It looks like one side is longer than the other and the final design is to have three towers and cable systems, but they opened one half while they demolish the old bridge to make way for the second half.

This picture looks like they have just weighted it down with a lot of concrete to get it back in place.... http://topoflakesuperior.ca/north-superior-news/ni... scroll down to the 4th photo

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

RE: Ontario Cable Stay Bridge Failure

In a cable stayed bridge Unequal spans = potential for uplift under certain loading conditions. The photo caption said "mechanical failure" I wonder if the tiedowns failed.

RE: Ontario Cable Stay Bridge Failure

(OP)
Would this would be the start of the tiedowns?

RE: Ontario Cable Stay Bridge Failure

Littleinch's links were good. yes, the span are slightly different in length, but the cable system looks symmetric.

Looking at the stack on concrete, I wonder if one cable system and bridge deck gave out (allowing them to jury rig something to get the other side of the bridge open ?

I'd be surprised if thermal expansion/contraction wasn't considered in the design. It can't be a surprise that it gets cold in Canada in winter !

another day in paradise, or is paradise one day closer ?

RE: Ontario Cable Stay Bridge Failure

Update – 18:33EST – Thunder Bay Superior North MPP Michael Gravelle reports that he is being informed that the bolts that connected the bridge have broken.

http://www.netnewsledger.com/2016/01/10/nipigon-br...

RE: Ontario Cable Stay Bridge Failure

pictures LittleInch linked show they tried to load the bridge with barriers

RE: Ontario Cable Stay Bridge Failure

What does it mean for a pile supported cable-stayed bridge to "heave"? And which bolts? Darn lay people.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Ontario Cable Stay Bridge Failure

Well now, as a temporary measure you see, ya load down one end of the bridge with weights until the deck is level with the roadway, but leave a lane open. Load up the traffic on that end, then drive the traffic over the bridge to the far end (goinguphill just a little bit obviously) that lowers down the far end, and you clamp that fat end down until the traffic drives off. Then you release the far end, it goes up, the near end goes down, and you repeat. Now, if traffic had to go both ways, you just alternate ends: one high, one low, then swap until the weather warms up and both end cables expand far enough.

Ought to work, right? 8<)

RE: Ontario Cable Stay Bridge Failure

Brittle fracture of the pre-loaded vertical hold-downs on the shorter span end, resulting in abrupt uplift then downward crashing of the deck superstructure end onto the abutment?

Some eyewitness accounts report that the end of the bridge abruptly uplift then crashed downward, reported like a buffet/burst of wind.

From Link

Quote (CBC Canada)

"As we turned [onto the highway], we saw the whole bridge — a kind of big gust of wind came underneath it and blew it up and then it came back down," she said, adding it shifted by about half a metre.

"We watched two pickup trucks come flying over. … They didn't see us, didn't hear my horn honking, and they flew over and smashed their front ends down on the cement."

There is a photo that I saw (but cannot now locate) that shows some acute deflection in the subject span adjacent to the abutment.

RE: Ontario Cable Stay Bridge Failure

Deflected span after failure and BEFORE kentledge:



Same span AFTER install of concrete barrier kentledge:

RE: Ontario Cable Stay Bridge Failure

What's the load path in a cable stayed bridge? For uneven spans, is the central pier designed to cantilever in bending due to more tension on one side? Maybe the central pier wasn't stiff enough so the all the load was transferred through the abutment opposite abutment in uplift. But I don't know anything about how cable bridges work.

RE: Ontario Cable Stay Bridge Failure

I'm wondering if the fact that the bridge is only half built had anything to do with it. The complete design is three sets of cables and two double lane decks so presumably the middle set are twice as big to hold the central piece and two decks, but they have opened the bridge with only one half built while they demolish the old bridge on the south side.

There must be some sort of differential loading / response here and maybe they didn't analyse the single deck operation quite as much as the whole bridge?

I'm pretty sure it is the "short" side which has jumped up, which tends to show that the uplift force has not been well anchored down.

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

RE: Ontario Cable Stay Bridge Failure

I'm not a bridge guy, just wondering how thermal effects are typically handled in cable-stay bridges.

So in an unrestrained condition, when the cables shorten due to lower temperatures the bridge deck would go up (most notably at the ends), correct?
Were the bolts that "broke" used to hold the deck at the same elevation as the rest of the roadway as the cables shrank? Essentially taking care of thermal effects by increased stress in the cables and bolts?

RE: Ontario Cable Stay Bridge Failure

the tension cables are (looks like symmetric) and the difference in spans in a short "overhang" span.

another day in paradise, or is paradise one day closer ?

RE: Ontario Cable Stay Bridge Failure

Also not a bridge guy -

So when they're building one of these bridges - do they have to calibrate the installation stress in the cables to the temperature during installation? The forces induced with the temperature there must be massive.

RE: Ontario Cable Stay Bridge Failure

Littleinch

It is unlikely that the root cause was the opening of the bridge with only two lanes. This is standard procedure (at least in Canada) for replacing bridges which are critical links. This is not a new situation for the design firm.

RE: Ontario Cable Stay Bridge Failure

I can appreciate it often happens to part open a bridge, but I always wonder if the same level of design analysis went into the "temporary" design compared to the "final" design.

It does look though like the holding down system / bolts / structure has failed, but the uneven nature of the pull up may have something to do with only half of the bridge being built?

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

RE: Ontario Cable Stay Bridge Failure

Let's get a detail of the hold down system before speculating. To say temperature contraction was not in the design also is speculating and likely a false presumption. Bridges are always built to allow for temperature changes of dimensions.

RE: Ontario Cable Stay Bridge Failure

following the partial assembly storyline ... the 1/2 bridge, 1 road deck supported by 2 towers, is possibly better than the full design, 2 decks with 3 towers. By eye the 3 towers and cable systems look alike, and the middle tower should have something like double the load on it ... maybe a tower has the capacity to carry the load from 1 deck (ie 2 1/2 decks and make all the same as the highest loaded one) or a minimum of 2/3rds of a deck (ie 3 towers, 2 decks).

another day in paradise, or is paradise one day closer ?

RE: Ontario Cable Stay Bridge Failure

An unlikely scenario is frost heaving of the pier footing. A good case for not contracting Spanish engineers/Design firms. Only contract/hire those experienced in very cold weather.

RE: Ontario Cable Stay Bridge Failure

my 2c ... the cables contracted with the cold and overloaded the fasteners (rivets?) on the deck vertical face, between the cable stayed span and the short cantilever, in shear.

another day in paradise, or is paradise one day closer ?

RE: Ontario Cable Stay Bridge Failure

For the discussors here take a look at various references and papers that come up when you search for "Cable stay bridge design". Looking at all the details and inputs to consider, the attorneys will surely have a great time with this one. While cost per foot of span may be cheapest, this one bridge probably will make changing that opinion an obvious one for future bridges.

RE: Ontario Cable Stay Bridge Failure

(OP)
You can see the makings of a significant tie down in the picture below. There are massive anchors protruding into what appears to be the start of a huge cap to deal with the uplift forces bridge buster alluded to. I bet the bolts that failed were the one between the steel girder that would have extended to the caps.

RE: Ontario Cable Stay Bridge Failure

We're all guessing, but thermal contraction in combination with other factors is what pops out to me as well.

I'm wondering if someone forgot to check the half built case in the cold and distributed the thermal effects from the centre set of cables into both bridge decks and their anchorage instead of just one. Then it's winter time with only one deck built and suddenly the centre cables aren't facing the resistance that was expected. From the short term fix, it seems like it just needed a bit more weight to get it back to the right elevation, so the .

I can very much see a situation where someone goes "It's extra strong when there's only one deck there" so only does a surface level check of things and then misses the strange case where it's not.

Or maybe the whole thing was designed just fine and there was a construction problem, or some sort of crazy unexpected load action.

RE: Ontario Cable Stay Bridge Failure

Just to head off any further comments about Spanish design firms not knowing cold weather - I beleive the firm is a conglomerate that owns many other firms. The two firms that took part in design of the bridge are both Canadian. Here is the Canadian Consulting Engineer article on the start of the bridge construction:

http://www.canadianconsultingengineer.com/transpor...

Quote:

The engineering design for the bridge is by McCormick Rankin Corporation of Mississauga, in conjunction with Buckland & Taylor of Vancouver, who have designed cable-stayed bridges around the world.

RE: Ontario Cable Stay Bridge Failure

(OP)
@gwynn: Yes, I was told that there was a design firm involved before I noticed that the lead team was North American. My error.

RE: Ontario Cable Stay Bridge Failure

From what I can find, this firm was involved with overall responsibility. Note the area of their projects seems a little far away. Note the MBE status.

HOWEVER WITH THIS EDIT NEXT POST CORRECTS ME. THANKS

http://www.iegroup.net/about.html

RE: Ontario Cable Stay Bridge Failure

@Brad805
No worries. The news has been plastered with comments about a Spanish firm designing a Canadian bridge, so I am sure a lot of people thought that was the case.

@oldestguy

You have the wrong Infinity Engineering. My understanding is that they were doing the construction engineering, not the bridge design.

http://www.infinity-engineers.com/
http://www.infinity-engineers.com/infinityprojects...

RE: Ontario Cable Stay Bridge Failure

TLHS probably hit on something about this partial build situation. Note the apparent diameter of the cables on the south side. Twice the size of the north side?

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