July 27th, 2010
HEAVY TRAFFIC CAUSING STRESS?Preserve Infrastructure, by Catherine Higgins.
UDOT and University of Utah researchers are collecting data to find out how a new material reacts under the stress of freeway traffic.
Instead of the usual steel rebar, the concrete deck panels on the Beaver Creek Bridge on US-6 are internally supported with Fiber Reinforced Polymer. The bridge has sensors that measure strain and trigger a camera to snap a photo when the bridge is stressed to a predefined limit. The photos and data collected by the sensors are part of a study that is helping University of Utah researchers and UDOT accumulate information about FRP, a material that may make make bridge decks last much longer.
“The number one cause of degradation of bridges is rusting steel inside concrete,” says Fred Doehring, Deputy Structural Engineer at UDOT. Bridges are designed to last 75 years or longer while decks only last 40 to 45 years.
The GFRP is formed into bars that look similar to rebar. FRP has a tensile strength greater than steel but weighs much less, steel which means the grid is easy to place. Deck panels are also easier to transport.
Beaver Creek Bridge was designed by UDOT’s Rebecca Nix, who says she has really enjoyed the project. Nix is helping to evaluate the new information along with researchers. By using FRP data collected in a real-world setting, UDOT will know how to “design based on what’s really happening.”