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Researchers Develop Stronger Material for Earthquake-Resistant Bridges

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naperlou
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Scaling up
naperlou   9/13/2013 9:25:01 AM
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Elizabeth, wow!  Talk about scaling up!  From eyeglass frames to bridge supports.  It is incredible that the engineers would have thought to use it.  And, 3% is not bad for a safety critical improvement.

TJ McDermott
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Re: Scaling up
TJ McDermott   9/13/2013 11:42:16 AM
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Elizabeth, I agree with Naperlou.  3% cost increase for materials does not sound like a significant concern.  Projects of bridge and tunnel scale go over budget by vastly more than that every time.

There was no mention of corrosion reisistance.  Is Nickel-Titanium more resistant to corrosion than the steel used in re-bar?

Charles Murray
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Re: Scaling up
Charles Murray   9/13/2013 6:01:50 PM
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I agree with naperlou and TJ on all counts. Superelasticity -- which I assume describes the ability to recover (and not deform plastically) from massive stresses -- would be the natural solution. In a sense, I assume this is similar to battery research in that the researchers spend lots of time looking for a chemistry with just the right material properties. To get there for only a 3% bump in cost sounds miraculous. Great story.

NadineJ
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Re: Scaling up
NadineJ   9/14/2013 6:36:25 PM
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It seems like this would be more viable for elevated freeways than for bridges. Images of the freeway collapse in the 1995 Kobe Quake are more haunting than the section (or seam) that detached on the upper deck of the Bay Bridge in 1989. 

A little flexibility in a bridge is good.  Too much is frightening.  The Golden Gate Bridge has a nice sway on a windy day.  How would this material react to high wind?   What additional precautions are needed to prevent corrosion? 

Overall, I agree that a 3% increase is marginal and worth the benefits.

Elizabeth M
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Re: Scaling up
Elizabeth M   9/16/2013 4:08:18 AM
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These are all really good points, Nadine. There could be such a thing as too much flexibility. I don't know how many people would feel comfortable on a bridge that is noticeably swaying (I personally never felt bridges like the Golden Gate sway and I think that's the point--they do, but you can't feel it). But I think with testing and perfecting of the material these issues could be addressed.

JimT@Future-Product-Innovations
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Re: Scaling up
JimT@Future-Product-Innovations   9/17/2013 11:18:03 AM
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I worked with Nickel Titanium in the 80's & 90's, while designing Antennas for portable VHF radios.  Picture those large brick-like UHF/VHF radios used by Police and many municipalities, and recall the protruding  12" over-molded whip antenna.  The base structure of these radiating elements is Nickel Titanium Rod, highly flexible, super-strong, and corrosion resistant.  It behaves like stainless or surgical steel in outdoor (even salt) environments.  Great stuff; we called it NiTi rod.

kenish
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Re: Scaling up
kenish   9/16/2013 12:56:06 PM
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The newly opened Bay Bridge in San Francisco has nonstructural "fences" on the underside to control sway and loading in high winds.  They are in a zig-zag pattern.  Interesting that many aircraft have small "fences" in parallel rows on the top of the wing to keep laminar flow attached while on the bridge they're arranged to prevent it!

The Bay Bridge was severly over-budget, IIRC about 5x-6x over the original $1.5bn budget.  Schedule slip was bad too, and when defective bolts were discovered early this year there was a political push to open on Labor Day no matter what...some engineers feel that trumped proper corrective action.

 

 

Elizabeth M
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Re: Scaling up
Elizabeth M   9/17/2013 4:15:33 AM
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I was actually living in SF when they were retrofitting the Bay Bridge. It seemed to take ages and I remember there were probems with it, probably the ones you mention, kenish. The structural design is interesting, let's hope it holds up if there is a big quake.

Charles Murray
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Re: Scaling up
Charles Murray   9/18/2013 6:27:40 PM
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Yes, Nadine, too much flexibility is definitely a bad thing. I believe that was the case with the famed Tacoma Narrows Bridge Collapse, I think the consensus (if there is one) was that the bridge's long stiffening girder was too long and too flexible. See link.

http://www.youtube.com/watch?v=j-zczJXSxnw

Elizabeth M
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Re: Scaling up
Elizabeth M   9/16/2013 4:10:37 AM
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Thanks, Chuck. I do think this is quite a significant breakthrough as well. And having lived in SF and felt several earthquakes there (not Lomo Prieta, though) and also here in Portugal, where I live now (which is also prone to quakes), I think anything that can keep structures safer without being too much of a financial burden is a good thing.

Elizabeth M
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Re: Scaling up
Elizabeth M   9/16/2013 4:11:26 AM
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Good question on the corrosion issue, TJ. I would have to check on that, I don't know off the top of my head.

vimalkumarp
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cost - benefit
vimalkumarp   9/14/2013 12:29:09 PM
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the high cost could be recuperated in long-term maintenance and other benefits in using the material will justify its usage. alongwith SHM ( Stuctural Health Monitorign) systems this will reduce danages even with a strong earthquake.

Critic
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Cost
Critic   9/16/2013 9:32:13 AM
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3% seems like a low figure.  I am willing to bet that this material is much more expensive than steel.  What is the source of the cost information?

OLD_CURMUDGEON
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Believe that & I'll sell you a bridge....
OLD_CURMUDGEON   9/16/2013 9:58:50 AM
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3%?????  Ask any decent machinist or toolmaker how easy it is to work with nickel and/or titanium, and he'll bend your ear for hours. 

As a layperson in this discussion, but having some awareness of fabricating items from these metals, it is very difficult for me to digest ONLY a 3% increase in cost.

Look at some of the recent major road/tunnel/bridge projects in the U.S., most notably, the "Big Dig" in the Boston area.  The total cost ballooned to about 100 times the original estimate.  Can't believe that the cost of using exotic materials for bridges / structures won't also incur massive cost overruns....

Elizabeth M
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Re: Believe that & I'll sell you a bridge....
Elizabeth M   9/17/2013 4:31:11 AM
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It seems to be the consensus among our expert readers that this material will be a lot more expensive than researchers think to use. I think maybe they were generous in their estimates. I guess the financial cost will come when and if this material is ever commercially used.

Jim S
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Cost Estimate
Jim S   9/16/2013 12:31:42 PM
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I believe the 3 % figure is an order of magnitude off. Nickel & Titanium are not plentiful like iron & carbon. The cement costs are also at least 30% more than conventional concrete.

Elizabeth M
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Re: Cost Estimate
Elizabeth M   9/17/2013 4:21:50 AM
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You could very well be right, Jim S. Sometimes researchers don't present the full story financially of what a new invention might cost, or maybe they just aren't aware. I guess until it's put into practice, the full financial impact just won't be known.

OLD_CURMUDGEON
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Re: Cost Estimate
OLD_CURMUDGEON   9/17/2013 9:03:43 AM
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Elizabeth....

"Sometimes researchers don't present the full story financially of what a new invention might cost, or maybe they just aren't aware. I guess until it's put into practice"

OH!, you mean like AFTER the contracts are signed & work begins, and then the paying public gets to learn the TRUTH, which was purposely concealed from the outset so that certain individuals, groups could reap the reward, and the rest of us get SCREWED?  Is that what you mean to say?  Well, there, I said it!!!!!

Elizabeth M
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Re: Cost Estimate
Elizabeth M   9/18/2013 12:05:21 PM
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Hi, OLD CURMUDGEON. Thanks for your comment. So I take it you've had some experience along these lines? It's a shame that this is probably an all-too-frequent scenario!

OLD_CURMUDGEON
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Re: Cost Estimate
OLD_CURMUDGEON   9/18/2013 12:19:12 PM
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Elizabeth: 

NOT me, personally, BUT me as part of a community which through our taxes has paid for civic projects that became boondoggles, wells of corruption, graft, mismanagement, etc.

There are two blatant examples of such projects in recent U.S. history..... In the 1970s, LILCO (LONG ISLAND LIGHTING CO.) decided to build a nuclear electric power generating facility on the north shore of the Island.  The proposal was for $65 MILLION.  By the time it was sold to the State of New York, after 20 years of re-engineering, graft, corruption, etc., it cost the ratepayers of L.I. about $4 BILLION, and it never produced one watt of electric power for consumption by the public.

The second glaring example is the "BIG DIG" in the Boston area.  Again, the cost overruns & incompetent engineering & other factors turned this project into the debacle of the century.  It was so bad that the TV program, 60 MINUTES, did a segment on it.

I'm sure that IF one set his/her mind to it, they could find countless examples across this country of similar examples!

Elizabeth M
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Re: Cost Estimate
Elizabeth M   9/18/2013 12:24:12 PM
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I completely understand where you're coming from, OC. I traveled a lot to Boston while the Big Dig was going on and know what a nightmare that was for everyone it affected, either directly or indirectly. There definitely should be more fiscal responsibility from the outset for such projects.

Ann R. Thryft
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Re: Cost Estimate
Ann R. Thryft   9/20/2013 1:01:14 PM
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I remember traveling to Boston, for the first time, and the Big Dig was in process. What a complete mess! My fellow editor, an excellent driver and navigator who did all the driving and had gone to the same show in the same location a zillion times before, got lost, for the first time ever, on the way from the airport.

AnandY
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RE: Researchers Develop Stronger Material for Earthquake-Resistant Bridges
AnandY   9/19/2013 2:13:20 AM
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Earthquakes have for long been the cause of major destruction of infrastructure and these stronger materials should not only be used in bridges but everything else. Being able to have an earthquake that will only shake the ground and that's it is something that would come as a blessing since it is practically impossible to stop the earthquakes. What I am more worried about is the costs of the materials. The nickel titanium is not something that is as abundant as iron. This is a good idea but the sources of these minerals should also be considered. As far as the cost is concerned I do not thing it would be a bad idea since they would also last.

Elizabeth M
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RE: Researchers Develop Stronger Material for Earthquake-Resistant Bridges
Elizabeth M   9/19/2013 3:42:20 AM
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Yes, AandY, your comments and concerns echo what a lot of our readers think about this. While most agree it's a good step forward to strengthen structures against damage from quakes, they worry about the potential expense.

Elizabeth M
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RE: Researchers Develop Stronger Material for Earthquake-Resistant Bridges
Elizabeth M   9/25/2013 10:26:18 AM
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Thanks for the comment, AandY. I think it points to the opinion of the researchers, which expect that there will be other benefits that outweigh the increased costs of the material.

Ann R. Thryft
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Correct scale?
Ann R. Thryft   9/24/2013 11:33:49 AM
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Aside from the potentially larger cost differential, I also wonder if the simulations and other testing the researchers did adequately took into account the scale involved of the actual columns. Were the models full scale or smaller?

Elizabeth M
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Re: Correct scale?
Elizabeth M   9/25/2013 9:47:21 AM
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Good question, Ann. I'd have to go back to my notes to see about the scale of the models. The closer to real-life deployment, the better, of course.

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