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Canadians stranded after bridge splits amid intense cold
3

Canadians stranded after bridge splits amid intense cold

RE: Canadians stranded after bridge splits amid intense cold

I believe there is a railroad that crosses Canada. So to say this splits Canada is not exactly true.

It also read they don't know what happened. So much for media getting the story.

RE: Canadians stranded after bridge splits amid intense cold

One of the witnesses said it was right in the middle of a high wind event.

Speculating here, but is it possible the slide bearing didn't have any uplift resistance?

RE: Canadians stranded after bridge splits amid intense cold

This is indeed a new bridge of a style, cable-stayed, that has become popular over the last 30 years or so.

In 1985, Professor Henry Petroski published a book titled, "To Engineer is Human: The Role of Failure in Successful Design" (which I highly recommend) where he talked about, among other things, why it is that there has always been, and will continue to be, bridge failures particularly when a new style has started to gain popularity, but generally only one example of a failure will occur. This is because (to paraphrase the good professor) "When it comes to designing a new style bridge, since virtually all bridges are paid for with taxpayer money, in order to reduce costs, safety factors for these new and radical designs will be reduced until there's a failure, at which point the engineers will go back to the last example that did not fail and it will thus become the minimal standard going forward."

In fact, at the end of the chapter covering bridge failures in the above mentioned book (the cover of which shows a bridge failing, the infamous Tacoma Narrows Bridge), Petroski predicted that with respect to the newly introduced 'cable-stayed' designs, that is was just a matter of time before we would see at least one significant failure of this type of bridge.

Now I'm not sure that we could call this Canadian incident a "significant failure", but in terms of the potential impact on the traffic, both commercial and private, on the Trans Canada Highway, to say nothing of the impact on US 28, the primary East/West (and almost all two-lane) highway across the UP (Upper Peninsula) of Michigan, which was mentioned in the news item as being the only practical alternative route, this could be a long remembered failure. And with this being winter, anyone familiar with the UP (I lived there for six years) knows that with lake-effect snow coming off of Lake Superior, that the Trans Canada Highway, despite being further North, is a much less treacherous route this time of year (see image below where green shows approximately where the Trans Canada Highway runs versus the red which is basically the route US 28, shown during what is called a 'lake effect' snow storm):



Some interesting links:

https://en.wikipedia.org/wiki/Henry_Petroski

http://www.amazon.com/gp/product/0679734163/ref=as...

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

RE: Canadians stranded after bridge splits amid intense cold

Some discussion in the other thread indicates temperature shortening of the cables. A look at the temperature records for the last year or so might tell something. Here in Wisconsin we are having our first very cold days of winter and we are not far from that bridge.

RE: Canadians stranded after bridge splits amid intense cold

Quote (JohnRBaker)

"When it comes to designing a new style bridge, since virtually all bridges are paid for with taxpayer money, in order to reduce costs, safety factors for these new and radical designs will be reduced until there's a failure, at which point the engineers will go back to the last example that did not fail and it will thus become the minimal standard going forward."

RE: Canadians stranded after bridge splits amid intense cold

The temporary fix would be of interest here.

http://www.chroniclejournal.com/news/national/dama...

I also found this:

Harvey said the bridge has only been open for about two months ago and was the largest most expensive bridge project ever undertaken in Ontario.

RE: Canadians stranded after bridge splits amid intense cold

With the roadbed heaving/separating by nearly 24 inches (60 centimeters) on a bridge that has been in service for only 2 months, would you honestly feel safe driving even a private vehicle over whatever sort of makeshift 'patch' that they've managed to lash together in a couple of days in the middle of winter? I know I wouldn't, but then I have acrophobia and besides, I've never learned to swim winky smile

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

RE: Canadians stranded after bridge splits amid intense cold

I did a Google search for temperature effects on these bridges and there is a whale of a lot of info there, mostly recent and from China, etc. Temerature measurements generally show the main girder top and bottom are different and less variable as cables.

Here is a little. It looks like they are in need of a lot more study. Now this is a good time for Canada to instrument this one if it is not already so equipped.

http://shm.sagepub.com/content/10/5/523.short

CONCLUSIONS
Based on the measurements taken on Ai-Lan Bridge from September of 2010 to
date, the modal frequencies of 18 cables and the temperatures of air and different
structural components are analyzed and cross-examined in this paper. The results
clearly indicate that temperature is the major environmental factor to cause the
variation of cable force. A simplified model proposed in this study also demonstrates
its effectiveness in correlating the variation of cable force with an effective temperature
variation simultaneously considering the temperature effects from the pylon, girder,
and cable. With this progress, a structural health monitoring methodology mainly based
on the identified cable frequency from measurements will be further explored and
applied to Ai-Lan Bridge in the near future

RE: Canadians stranded after bridge splits amid intense cold

In that picture, posted earlier in this thread, looking down the length the bridge, it almost seems like the roadbed is bowed upward, which would be the case if the longer cables, being longer, contracted more than the shorter ones. Since, unlike a conventional suspension bridge where any contraction/shortening of the vertical cables would have simply 'raised' the roadbed, in a cable-stayed bridge, the contraction/shortening of the cables would have put the roadbed into both a compressive and a bending moment, raising the ends and perhaps causing them to fracture/separate away from the abutments.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

RE: Canadians stranded after bridge splits amid intense cold

John: There is another shot in a newspaper article showing that curve clearly. However, none of this would have happened if the various parts of the bridge were all at the same temp and had the same coef. of temperature dimension change. Some of the info I have reviewed shows for several such bridges equal temps just does not happen. A quick check on concrete (the slab) indicates it is highly variable.

Here is the link showing the curve. Seems like north side is worse, maybe due to being warmer due to more sun exposure on the slab per the photo.

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

RE: Canadians stranded after bridge splits amid intense cold

The longer cables will contract a greater absolute distance thus creating the upward force on the outer ends of the bridge where it's connected to the abutments.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

RE: Canadians stranded after bridge splits amid intense cold

(OP)

Quote:

The new structure is a replacement for the existing two-lane bridge over the Nipigon River. The new bridge is a four-lane, two-span structure with spans of 112.8 meters and 139 meters. - See more at: http://www.hatchmott.com/projects/nipigon-river-br...
The bridge appears to be asymetrical. Is this correct and could this be a contributing factor?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Canadians stranded after bridge splits amid intense cold

So, why have the comparable cable-stayed bridges in Europe not pulled up their ends? Not as cold? Or a compensator on the longer end cables? Or the "end point" conditions of the two abutments different here, so the ends didn't move up far as actually needed?

RE: Canadians stranded after bridge splits amid intense cold

I think you'll find that the 'asymmetry' was the result of there being a pedestrian walkway located outboard of the suspension cables on only ONE side of the roadway (you can see this clearly in the video showing the bridge under construction that was at the bottom of the page linked in the first post of this thread).

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

RE: Canadians stranded after bridge splits amid intense cold

The bridge is asymmetrical longitudinally and is somewhat asymmetrical (albeit minor) sectionally due to the pedestrian lane.



RE: Canadians stranded after bridge splits amid intense cold

(OP)
John

Quote (Butch Cassidy and The Sundance Kid)



Butch Cassidy: Alright. I'll jump first.

Sundance Kid: No.

Butch Cassidy: Then you jump first.

Sundance Kid: No, I said.

Butch Cassidy: What's the matter with you?

Sundance Kid: I can't swim.

Butch Cassidy: Are you crazy? The fall will probably kill you.

Sundance Kid: Oh, shit...

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Canadians stranded after bridge splits amid intense cold

(OP)
I was asking about the longitudinal asymmetry. The longest cables seem to attach at different spacing and at different angles.
On another note:
Business is probably quite good at Tim Hortons about 2 miles west of the bridge. (Tim Hortons, A Canadian version of Starbucks)

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Canadians stranded after bridge splits amid intense cold

Interesting question. From the original conceived bridge "photo" and the would be three sets of cables and a divided highway. Apparently what was built was a single two lane roadway, not a divided highway. Looking at the many comments of the public, sounds like a fun time for attorneys and engineers in Canada now.

This link shows the open bridge, a two land bridge, not divided highway. Note the weights on one and to "hold it down"? I guess the design could act like a "teeter-todder" otherwise.

http://www.tbnewswatch.com/

RE: Canadians stranded after bridge splits amid intense cold

Yes, it appears that the biggest difference, longitudinally, is the distance between the main pylon and the abutments but that portion of the span where the cables are actually attached appears to be very nearly symmetrical with the possible exception of the first two cables on the far Left in Ingenuity's longitudinal diagram, however I'm not sure if the difference is enough to be significant. BTW, does anyone know if the rupture took place, relative to Ingenuity's longitudinal diagram, at the Left or Right end of the span? From the picture earlier in this thread, if the rupture were at an abutment, which would seem logical, it would apepar to be the Left end of the bridge.

Again, I think it will be determined that with this style of bridge, cable-stayed, that the difference in the lengths of the cables and thus the difference in the absolute contracting/shortening of the individual cables due to extreme cold temps, one can clearly see from looking at Ingenuity's longitudinal diagram how it is that this could cause the roadbed to bow up at the ends due to the uneven stress in the cables creating a bending moment in the structure of the span.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

RE: Canadians stranded after bridge splits amid intense cold

I suggest closing down this thread because there is another thread that has more detail. Specifically there is a video from Thunder Bay TV with an engineer explaining things. From that video the anchrage at one end failed. The kentledge (weights) brought that end back down to original elevation. Look under "Structural Other"

RE: Canadians stranded after bridge splits amid intense cold

(OP)
There was a rumour that the engineers first suggested a small ramp to allow traffic to cross the bridge.
The politicians went into a panic. They wouldn't allow anything that could be said to be "Ramping Up" Canadian seperatism.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Canadians stranded after bridge splits amid intense cold

This picture, from a link in that other forum, sure gives the impression that the bridge's roadbed did indeed bow-up on the end as I had speculated previously:

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

RE: Canadians stranded after bridge splits amid intense cold

And with a 'better' displaced shape after the addition of concrete barrier kentledge:

RE: Canadians stranded after bridge splits amid intense cold

The failure is on the northern deck at the sorter western end. They have opened only half of the bridge so far while they demolish the existing concrete bridge ( I think the existing bridge has partly gone so can't be used as a diversion) to allow them to construct the Southern half of the bridge.

I wonder if they have designed / tensioned the cables to handle the full weight of the bridge, but been caught out because there is only half of it built so far??

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

RE: Canadians stranded after bridge splits amid intense cold

Bolt failure? I wonder if off-shore steel (bolts) the cause.

RE: Canadians stranded after bridge splits amid intense cold

The latest news article states the bolts were manufactured in New York.

http://www.theglobeandmail.com/news/national/engin...

Quote:

One possible factor being looked at is the role of the 40 bolts, which are 22 millimetres in diameter and 150 mm in length, and secured the deck of one lane to beams. The bolts were manufactured by R.J. Watson, a reputable firm, in New York State.

RE: Canadians stranded after bridge splits amid intense cold

I'd be inclined to them finding the bolts meet the specs. However, tensioning, as by "turn of the nut" or other factors as well as uneven loading are more likely to come up. Then the zipper effect, whereby end bolt parts followed by the rest of them, one at a time does the job. The detail of the end anchorage system deserves attention.

RE: Canadians stranded after bridge splits amid intense cold

The appearance of "twist" in the photo from 11 January interests me.
It looks like the grade of the road deck goes one way on the abutment, and the relaxed bridge grades the other way now that it's "popped up".
That tells me that the stay cables on the bridge centerline are shorter than the cables used for the sides.
What are the chances that the centerline stay cables were installed on the side?
(pretty unlikely, I'm sure...)

STF

RE: Canadians stranded after bridge splits amid intense cold

@Sparweb

The twist may come from the anchorage on that abutment only failing catastrophically on one side, not necessarily relating to the length of the cables in and of themselves. Potentially the left side gave way, which caused further failure in the right side which is still somewhat constrained to the abutment.

RE: Canadians stranded after bridge splits amid intense cold

Last daily update as of February 26: http://www.mto.gov.on.ca/english/highway-bridges/u...

"•We are able to move forward with construction at this time as we are confident that the recent issues will not reoccur. The temporary repair has been reviewed by an independent engineering firm and found to be appropriate. The bridge is safe for the travelling public.
•Testing of the bolts continues at the two independent labs and work is ongoing to determine the cause of the failure. Once a cause has been determined, the information will be made public and posted here."

RE: Canadians stranded after bridge splits amid intense cold

I think the temporary hold down systems are not designed with redundancy. At those yellow "boxes" there are what appear to be two bolts per "box". Pop one of them and the whole device fails.

RE: Canadians stranded after bridge splits amid intense cold

(OP)
Thanks for the update JStephen. It's good to have "closure" on the closure even if we are still wondering; Why?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Canadians stranded after bridge splits amid intense cold

Red Green could have repaired the damage using duct tape alone....

RE: Canadians stranded after bridge splits amid intense cold

Linked item can also be read as, 'The report hasn't been released yet.'



RE: Canadians stranded after bridge splits amid intense cold

The Order of the Engineer was formed as the result of a Canadian bridge failure.

RE: Canadians stranded after bridge splits amid intense cold

To be more accurate, it was the Ritual of the Calling of an Engineer and the Corporation of the Seven Wardens that were the result of a Canadian bridge failure - the Quebec Bridge to be exact. The Order of the Engineer came about later after and was inspired by the success of the aforementioned ritual and organisation, not the original bridge failure.

The irony now is that The Ordre des ingénieurs du Québec has recently lost its ability to self-regulate, which is the first time I can recall that happening to a professional body in Canada.

RE: Canadians stranded after bridge splits amid intense cold

...lost its ability to self-regulate...
That's the opposite of the trend in Alberta. What's happening in Quebec?

STF

RE: Canadians stranded after bridge splits amid intense cold

I don't know the details of what is happening in Quebec. Only what was in the email news notification from my local association, which said that they had been placed under temporary government stewardship.

RE: Canadians stranded after bridge splits amid intense cold

RE: Canadians stranded after bridge splits amid intense cold

I fear the corruption that we've heard about in Quebec may unfortunately be making its way to engineers.

RE: Canadians stranded after bridge splits amid intense cold

Thanks for the update.

STF

RE: Canadians stranded after bridge splits amid intense cold

Here is a link to the 2015 report that resulted from the original inquest (I am linking the English translation, not the French original). If it's a members only document, I can dig up the link from Manitoba which might not be. APEGA seems to not have a direct link to it.

https://www.apeg.bc.ca/getmedia/08003931-f44b-4d77...

Here's the related APEGBC article on the issue:

https://www.apeg.bc.ca/News/Articles/Regulatory-Bo...

RE: Canadians stranded after bridge splits amid intense cold

Ouch, they're having a rough time.
Excerpt: ...Motion demanding the removal of the Executive Committee and director general...

Apparently the old director(s) are suing the new directors, and it's a "circus" in the words of many members.

STF

RE: Canadians stranded after bridge splits amid intense cold

It's not my industry, but the executive summary was certainly an interesting read! Thanks

RE: Canadians stranded after bridge splits amid intense cold

Yes, it does look like it was written for a very broad audience. I did note that item 10 in the list of findings seems to support, to some extent, my comments from 11-12 January.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
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

RE: Canadians stranded after bridge splits amid intense cold

Did not see what the pretension in the suspended cables is in the report. The high possibility is that The contraction thermal load in the cables pull the steel deck/beams up.

RE: Canadians stranded after bridge splits amid intense cold

(OP)
A question for the structural guys;
Do I understand that it was the repeated stretching and relaxing of the bolts that led to failure and if the bolts had been tighter they would not have relaxed and would have held?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Canadians stranded after bridge splits amid intense cold

To waross

High strength bolts is pretensioned to 0.7 times of the minimum tensile strength of the bolt. That means the tension in the bolt does not change if the uplift load from the cables is less than the sum of the bolts pretension. Also fatigue failure does not occur if the stress range is less than some amount or the stress cycle is less than certain times.

possible explanation of the failure is that the cable contraction force overcome the structure weight and bolts tension, then pull the deck up.

RE: Canadians stranded after bridge splits amid intense cold

waross,

Yes, the fact that the bolts were not tightened was one factor. Flexure within the joint with resultant prying was another.

RE: Canadians stranded after bridge splits amid intense cold

(OP)
Thanks for the explanations.
Bill

Bill
--------------------
"Why not the best?"
Jimmy Carter

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