The collapse of the Interstate 35W bridge in Minneapolis has sent universities into overdrive promoting the wireless and nanotechnology research going on in their labs that could one day make bridges and other structures safer.
This sort of technology PR flood in the wake of a tragedy hasn’t been seen since Hurricane Katrina struck two years ago.
At Clarkson University in Potsdam, N.Y., a professor has created a system for remotely monitoring bridges using a dense network of wireless sensors.The work is being funded by the state, which is trying to improve oversight of its bridges.
The sensors developed and rolled out by Kerop Janoyan, associate professor of civil and environmental engineering, measure bridge vibration and strain, according to the school. Data is sent from microprocessors and transceivers to a base station for monitoring and review.
North Carolina A&T State University claims a professor there has developed “technology that could have possibly prevented the bridge collapse in Minneapolis, Minn.” Mannur Sundaresan,professor of mechanical engineering, has come up with a “single channel continuous sensor” that can spot cracks in bridges and other structures before too much damage is done. The sensors are off the shelf, but they are configured in such a way as to be able to acoustically monitor structures, according to the school. The Department of Defense originally funded the research behind the Acoustic Emission Sensoring Technology, which is now licensed by UTEK.
“Small cracks are like cancer,” Sundaresan says in a statement. “They’re usually not noticed until they’ve grown large enough to cause serious damage. These sensors will detect the growth of cracks in their early stages just as our nervous system alerts us of any injury immediately so that we can take action to limit the damage.”
Sticking with the human body metaphor, the University of Michigan has created what it calls a “new skin” for bridges and other structures that “could be a sixth sense for inspectors looking for cracks and corrosion that could lead to a catastrophic failure like the recent Minneapolis bridge collapse.”
The school’s College of Engineering has created a polymer-based black coating that could be painted or sprayed on structures. The coating consists of carbon nanotube networks that can test numerous things, such as cracking and pH level changes that can signal corrosion. Here’s how it works, according to the school:
“The perimeter of the carbon nanotube skin is lined with electrodes that are connected to a microprocessor. . . . To read what’s going on underneath the skin, scientists (or inspectors) send an electric current through the embedded carbon nanotubes. Corrosion and cracking cause changes in the electrical resistance in the nanotube skin. The microprocessor then creates a two-dimensional visual map of that resistance. The map shows inspectors any corrosion or fracturing too small for human eyes to detect.”
More details can be found in this paper from Jerome Lynch, assistant professor in the College of Engineering.
An assistant professor at the University of Missouri-Columbia says the bridge collapse will have a huge impact on how states prioritize bridge inspections and repair funding.
"There are almost 600,000 bridges in this country, with an average age of 42 years," said Glenn Washer, assistant professor in MU's Department of Civil and Environmental Engineering, in a statement. "With that many aging bridges, accidents can happen. The only way to completely eliminate the risk is to not drive on bridges. There is a massive effort by State Departments of Transportation to inspect, monitor and maintain bridges, but implementing some of the new technology and getting the work done is a significant challenge."
Washer has received $109,500 from the National Academy of Sciences to develop a system to continuously monitor piers - the primary support systems of a bridge – to warn of weaknesses. The New York Department of Transportation plans to test the system. The Missouri Department of Transportation has awarded Washer an additional $240,000 for his work on infrared imaging to detect defects in concrete bridges.
A host of other universities, from New Mexico State to the University of California at San Diego and Stanford also have research underway to safeguard bridges.
The University at Buffalo hasn’t been highlighting any research on bridge defect detection, but did issue a press release on the topic of bridge phobia and how the Minneapolis bridge collapse will fuel fears.
"Certainly, for people with bridge phobia, this will activate them and make them worse," said anxiety expert Nancy Smyth, dean of the UB School of Social Work, in a statement. "A lot of how people react depends on how closely they identify with the people who were hurt or killed. If there is someone your age or who has a life similar to yours, you are likely to identify with them, with someone who is like you."
Also chiming in on bridge defect detection this week is Sandia National Laboratories, which is working on networks of sensors for continuously monitoring for structural defects in bridges (what it calls structural health monitoring, or SHM). The Labs says its SHM work is an extension of work on detection of aircraft defects.
Sandia’s bridge-sniffing sensors look for cracks, fatigue damage, corrosion and more. Among the sensors it is examining is one that is about the size of a dime and looks like a rubber patch.
The work overall is aimed at moving toward smart structures that can phone home when trouble arises.
“There is widespread recognition that SHM’s time has come, an opinion you would not have heard from many people a few years ago," said Dennis Roach, who leads the Sandia team, in a statement.
Bob Brown,
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