Nearly a dozen private companies, in partnership with industry organizations and university researchers, collaborated in the construction in north central Tennessee of a fiber-reinforced polymer (FRP) composite material bridge deck embedded with fiber optic sensors. The project was led by Composite Applications Group (McDonald, Tennessee, USA) under the working umbrella of the Institute for Advanced Composites Manufacturing Innovation (IACMI) (Knoxville, Tennessee, USA), a partnership of industry, academic institutions, and federal, state and local governments united to benefit the nation’s energy and economic security.
Located in Morgan County, the new FRP bridge replaced a damaged, decades-old concrete crossing which was rated structurally deficient and outdated. According to Joe Miller, highway superintendent for Morgan County, officials were looking for a low-maintenance bridge that could be installed more quickly and at a lower cost than traditional methods.
According to the American Society of Civil Engineers, about 8 % of the more than 617,000 bridges in the U.S. are structurally deficient and need repair. According to IACMI, FRP composites offer a low-cost, low-maintenance alternative for rural bridges that need to be replaced.
“This composite bridge has already made a positive impact on Morgan County,” says Miller. “We have numerous bridges within the county and hundreds across the state that are in need of repair and could benefit from this technology.”
Lightweight and easy to install, the FRP bridge developed by Structural Composites Inc. (Melbourne, Florida, USA) came at no cost to the county. The 16 ft- (4.9 m-) long, 25 ft- (7.6 m-) wide bridge deck is engineered for high strength and is 90% lighter than concrete. In addition, the bridge has two 8 x 25 ft (2.4 x 7.6 m) corrosion resistant FRP deck panels that were fabricated offsite in a controlled environment.
The completed bridge sections were so lightweight that they were transported to the bridge site and installed in one day using a forklift, thereby reducing installation time and energy costs. According to John Unser, technology manager for IACMI, composites have long been used for bridge deck applications, but that many transportation departments—particularly those from smaller jurisdictions—need to become more familiar with the technology. To that end, IACMI and its industry partners are developing a comprehensive study based on the Morgan County bridge project that will familiarize federal, state, and local officials with FRP composites, including a comparison of total costs between a typical concrete bridge and one using an FRP bridge deck.
Researchers from the University of Tennessee, Knoxville (UTK) and engineering students from UTK’s Fibers and Composites Manufacturing Facility embedded smart fiber optic sensors into the bridge that are used to monitor the composite deck system over time to give critical performance and safety data. In addition, wireless technology developed at UT monitors the response of the bridge system and traffic counts remotely via cloud computing.
“Lack of durability data is one of the major barriers of the adoption of novel and advance materials including carbon, basalt, or glass fiber reinforced polymeric composites in civil infrastructure,” says Dayakar Penumadu, the Fred N. Peebles Professor in the Tickle College of Engineering at UT and Characterization Fellow for Materials and Processing for IACMI.
“This is a major obstacle for integrating new materials and structures quickly and thus require successful demonstration as being done through this IACMI project,” adds Penumadu. “Bridge decks are the most damage prone elements, and we are integrating smart sensors distributed throughout the composite bridge deck that will provide us valuable performance data with time for years to come.”
Source: IACMI – The Composites Institute, https://iacmi.org.