Canadians stranded after bridge splits amid intense cold 3

[waross]

Canadians stranded after bridge splits amid intense cold

http://www.theweathernetwork.com/ne...ts-brand-new-bridge-strands-canadians-/62165/

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

 

[oldestguy]

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/

 

[JohnRBaker]

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.

 

[oldestguy]

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"

 

[waross]

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

 

[itsmoked]

there is another thread that has more detail

thread507-401708

Keith Cress
kcress -

http://www.flaminsystems.com

 

[JohnRBaker]

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.

 

[Ingenuity]

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

 

[MacGyverS2000]

And it looks like the short end, too...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[LittleInch]

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.

 

[Andy10]

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

 

[gwynn]

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

http://www.theglobeandmail.com/news...on-bridge-by-end-of-february/article28263339/

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.

 

[oldestguy]

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.

 

[Sparweb]

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

 

[allgoodnamestaken]

@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.

 

[JStephen]

Last daily update as of February 26:

http://www.mto.gov.on.ca/english/highway-bridges/updates/index.shtml

"•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."

 

[oldestguy]

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.

 

[waross]

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

 

[SectionIX]

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

 

[JStephen]

An update saying they still don't know what the problem was:

http://www.tbnewswatch.com/News/388441/Nipigon_River_Bridge_failure_still_a_mystery

 

[VEBill]

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