HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Alexander Wolfe
User Rank
Blogger
Re: Sensors and bridge EOL symptoms.
Alexander Wolfe   11/17/2011 3:40:57 PM
NO RATINGS
The sensor networks described here could have a dual purpose, both for inspection as well as for longer-term infrastructure maintenance. I keep advocating for infrastructure spending as a way to both jump-start the economy and also to embed high-ROI electronics (like these sensor nets) within said projects. Whether it will happen is another story. (Unfortunately, it won't.)

William K.
User Rank
Platinum
Sensors and bridge EOL symptoms.
William K.   8/29/2011 10:13:56 PM
NO RATINGS
While it is undoubtedly true that the deflection of a bridge under a specific load does increase as strength elements fail, it seems like it will be quite a challenge to find the actual correlation of that data with real failure.

I would offer instead a means of change detection that would need fewer sensors, a much less complicated algorithm, and has already been demonstrated as working, although on a much smaller scale. That method is to monitor the bridge resonance, both frequency and decay rate. The immediate benefit is that fewer and easier to calibrate sensors could be utilized, which the fact is that accurately calibrating a strain gage installed application is complex and requires both skill and patience. (Just ask any of the load cell manufactrers.) An accelerometer for the lower frequency , lower amplitude ranges is much simpler to calibrate. 

While a change in resonance would not point to the exact location of a fault, it should be a very reliable indicator that a failure has ocurred. 

Ivan Kirkpatrick
User Rank
Platinum
Ultrasonic Crack Detection
Ivan Kirkpatrick   8/29/2011 3:58:36 PM
NO RATINGS
I did not see or perhaps I missed a mention of an ultrasonic crack detection sensor.  I would think putting a few of those in strategic locations on the structure might be helpful but perhaps they are too expensive.

So what are the warning signs that a bridge is about to reach the end of its safe life?  Extra deflections past some norm?  Cracks that begin to spread more rapidly?  Perhaps unusual noises when a load is imposed?  Any other ideas?

What is the cost associated with these sensors and this kind of monitoring?  I am sure it is less than the cost of a catastrophe.  

BridgeExpert
User Rank
Iron
Using Sensors on Bridges
BridgeExpert   8/5/2011 5:04:48 PM
NO RATINGS
Hey folks: Glad to see a few interesting comments.  But you need to know the subject matter is hardly new.  My firm has been doing this type work on bridges for over 10 years with excellent results.  Makes me wonder why the author or the PhD student mentioned thinks this technology is some new, whiz bang development. It's a simple fusion of sensors, wireless and the Internet - reasonably well understood technologies.  The biggest issue facing our industry is when the FHWA or AASHTO will start demanding its use instead of relying solely on visual inspection, which is highly variable and quite subjective.   

Also, there is no reason to expect a "cloud" algorithm will ever resolve all the sensor data in a magic puff.  Determining condition or remaining life span for a bridge is not a subject that can be treated with precision mathematically without human intervention.  It still takes a lot of engineering judgment and must be left in the hands of highly experienced bridge engineers with insurance coverage and frankly, something to lose.

I would like to remind all of you that I-35W was given a "clean bill of health" by the University of Minnesota a few years before it collapsed.  Expecting a University PhD student to make these determinations and then using that information for bridge management is the height of foolishness.  So, while the article is interesting in context, I hope I've added some much needed realism to the comment stream.   

sensor pro
User Rank
Gold
Re: Bluetooth too?
sensor pro   8/5/2011 4:02:10 PM
NO RATINGS
On www.aositilt.com you can find numerous high resolution tilt sensors and signal conditioners. For an analog output a set of sx-003D-NULL high resolution sensor and an EZ-TILT-3000 module were used to provide clients angular resolution of about 0.001 arcdeg. If a small system like that is installed in a flex joint of the bridge, then angular changes of lets say 0.05 for 3000lb  are easily detected and can be differentiated from other diflections. This is a very low cost method to count trucks vs cars crossing the bridge.

It is true that you can find other suitable sensors and modules on that site, but this one worked great. the only two additional items needed were regulated power source and a DAQ.

Hope that helps.

 

Beth Stackpole
User Rank
Blogger
Re: Bluetooth too?
Beth Stackpole   8/5/2011 3:47:49 PM
NO RATINGS
@ SensorPro: Sounds pretty cool. Would love to know more specifically about what you did for your client.

sensor pro
User Rank
Gold
Re: Bluetooth too?
sensor pro   8/5/2011 1:36:51 PM
NO RATINGS
You are correct. our client did exactly that. The data was used to count trucks and cars based on the diflection. then it was used to monitor slow degradation of the curve and try and predict service of the bridge.

Beth Stackpole
User Rank
Blogger
Re: Bluetooth too?
Beth Stackpole   8/5/2011 1:25:04 PM
NO RATINGS
This seems like a really compelling example for sensor networks and one that could really deliver huge benefits. What about using that sensor-collected data and feeding it into FEA or another type of simulation analysis tool to pinpoint and perhaps correct problem areas and leverage that data for future bridge designs?

Doug: I have to laugh at your example of a talking GPS. Thing is, it's not so far-fetched.

sensor pro
User Rank
Gold
Re: Bluetooth too?
sensor pro   8/5/2011 12:41:47 PM
NO RATINGS
It is clearly very interesting. We supplied many tilt sensors to be embedded into small bridges to monitor diflection and to differentiate between small and large vehicles. Very interesting stuff. Keep the good work.

Douglas Smock
User Rank
Platinum
Bluetooth too?
Douglas Smock   8/5/2011 12:21:02 PM
NO RATINGS
Next Chuck, you're going to be telling us that the data from the strain gauge  sensors can be transmitted to Blutetooth in our cars and we can know before we approach a bridge that it may be unsafe for the size of load we're carrying.  A voice will announce: "Buirdge may collapse, Seek alternate route." Cool stuff.



Partner Zone
Latest Analysis
Take a look through these film and TV robots from 1990 through 1994.
The Soofa is an urban smart bench that provides mobile device charging as well as collects environmental information via wireless sensors.
Sciaky, provider of electron-beam additive manufacturing (EBAM) services, will start selling these machines commercially in September. The company has used its EBAM 3D printing technology for making very large, high-value, metal prototypes and production parts for aerospace and defense OEMs.
At this year’s Google I/O, the spotlight was pointed on gender inequality in the high-tech industry. Google has established a new initiative that it hopes will even out the playing field, Made w/Code. Part of this initiative will fund free online courses in basic coding.
Self-driving vehicle technology could grow rapidly over the next two decades, with nearly 95 million “autonomous-capable” cars being sold annually around the world by 2035, a new study predicts.
More:Blogs|News
Design News Webinar Series
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
7/17/2014 11:00 a.m. California / 2:00 p.m. New York
6/25/2014 11:00 a.m. California / 2:00 p.m. New York
5/13/2014 10:00 a.m. California / 1:00 p.m. New York / 6:00 p.m. London
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Aug 4 - 8, Introduction to Linux Device Drivers
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Class: August 12 - 14
Sponsored by igus
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service