Every day millions of people across America drive over bridges without any regard to their structural integrity or proposed lifetime. But according to , in 10 years one in four of bridges in the U.S. will be 65 years or older, and the average designed lifespan is 50 years.
At the University of ÁùºÏ±¦µä, Reno a team of researchers from multiple branches of engineering are collaborating on a self-sensing adaptive bearing (SSAB) system that attempts to resolve the problem of bridge degradation by implementing modern technological advancements to improve bridge safety.
"Right now what is implemented in bridge bearings is a passive system," said Faramarz Gordaninejad, a professor of mechanical engineering and project principal investigator. "But this system is basically semi-active. Electricity flows through, creating a magnetic field that will stiffen the controllable rubber when and how you want."
Also involved in the project as co-PIs are Ahmad Itani, civil engineering professor; Gokhan Pekcan, associate professor of civil engineering; and Nelson Publicover, emeritus professor of electrical and biomedical engineering; and Majid Behrooz, postdoc in mechanical engineering. Students working on this project include Siddaiah Yarra, Ph.D. student in civil engineering; David Mar, undergraduate research assistant in computer engineering; Blake Muznich, undergraduate research assistant in mechanical engineering; and Nathan Pinuelas, undergraduate research assistant in mechanical engineering.
According to Faramarz, the National Bridge Inventory stated in 2011 that approximately 45% of the nation's inventory of 590,000 bridges is quickly reaching the end of its intended design life.
Gordaninejad's team believes they have a two-pronged solution that will advance the technical safety of bridges. By systematically distributing iron particles within rubber bearings, they can use electromagnets within the structure to pull and push the iron particles together, making the bearings adapt their stiffness as needed. Sensors, made of the same controllable rubber (magneto-rheological elastomers) throughout the system, automate this process. Engineers can set threshold warnings so when a bridge reaches a predetermined level of vibration, they can be notified anywhere in the world by text messages.
"This system also stores all the data of what the bridge goes through, acting like a black box," Gordaninejad said. "After a bridge breaks or collapses, we can figure out what went wrong and when it went wrong, in order to find safer solutions in the future."
Gordaninejad and his team hope to advance the safety of both current and future bridges by developing a system that will become standard in future bridges and can also be retrofitted into existing bridges. The project is funded by the Federal Highway Administration.
