Engineering smart bridges that can thoroughly discuss their health with inspectors is the goal of a new $19-million project led by the University.
A year and a half after the I-35 bridge collapse in Minneapolis, the five-year project aims to create the ultimate infrastructure monitoring system and install it on several test bridges whose precise locations are not yet determined.
The monitoring system is envisioned to include several different types of surface and penetrating sensors to detect cracks, corrosion and other signs of weakness. The system also would measure the effects of heavy trucks on bridges, which is currently impossible. And through enhanced antennas and the Internet, the system would wirelessly relay the information it gathers to an inspector on site or in an office miles away.
Funded in large part by nearly $9 million from the National Institute of Standards and Technology’s (NIST) Technology Innovation Program (TIP), the project involves 14 researchers with the College of Engineering and the U-M Transportation Research Institute (UMTRI). In addition, engineers at five private firms in New York, California and Michigan are key team members. The remaining funding comes from cost-sharing among the entities involved and the Michigan Department of Transportation. MDOT has offered unfettered access to state bridges to serve as high-visibility test-beds showcasing the project technology.
“This project will accelerate the field of structural health monitoring and ultimately improve the safety of the nation’s aging bridges and other infrastructures,” says Jerome Lynch, principal investigator on the project and assistant professor in the Department of Civil and Environmental Engineering.
Four types of sensors will contribute to gathering data. Victor Li, professor of civil and environmental engineering, has developed a high-performance, fiber-reinforced, bendable concrete that’s more durable than traditional concrete and also conducts electricity. Researchers would measure changes in conductivity, which would signal weaknesses in the bridge. On test bridges, the deck would be replaced with this concrete.
A carbon nanotube-based sensing skin that Lynch and a colleague in chemical engineering are developing would be glued or painted on to hot spots to detect cracks and corrosion invisible to the human eye. The skin’s perimeter is lined with electrodes that run a current over the skin to read what’s happening underneath based on changes in the electrical resistance.
Low-power, low-cost wireless nodes could look for classical damage responses like strain and changes in vibration. These nodes would harvest energy from vibrations on the bridge or even radio waves in the air. They are being developed by Dennis Sylvester, an associate professor in the Department of Electrical Engineering and Computer Science; and Khalil Najafi, chair of the Electrical and Computer Engineering Division.
The fourth type of sensor would be housed in the vehicles that travel on the bridge. UMTRI researchers will outfit a test vehicle to measure the bridge’s reaction to the strain the vehicle imposes. Leading this effort is Research Professor Tim Gordon, head of UMTRI’s Engineering Research Division.
Other parts of the system will organize data into meaningful displays and communicate it from the sensors to the inspector. Vineet Kamat, assistant professor in civil and environmental engineering, will lead the human-infrastructure interaction effort.
“The NIST TIP initiative is timely given the deteriorated state of our infrastructure today. The success of the University of Michigan team, led by Professor Lynch, exemplifies both the excellence of our faculty and how they are engaged in high impact research that solves the world’s most challenging problems,” says Nancy Love, chair of the Department of Civil and Environmental Engineering.
Additional U-M researchers include associate professor Mingyan Liu, professor Amir Mortazawi, associate professor Michael Flynn and professor Atul Prakash, Department of Electrical Engineering and Computer Science; professor Amit Ghosh, Department of Materials Science and Engineering; and senior research associate Steven Karamihas, research scientist Ralph Robinson, and business development manager Todd Anuskiewicz, UMTRI.
