MONDAY, AUGUST 12, 2019
Brewer, Maine-based engineering firm Advanced Infrastructure Technologies recently announced the growing development of a fiber-based composite bridge support.
The support system can reportedly be constructed in under 72 hours and is slated to be used on the new Grist Mill Bridge in Hampden, Maine, next year.
About the Bridge Supports
Labeled a “tub girder” for its bathtub-like shape, the composite bridge support is created using a wooden mold and multiple sheets of fiber—not much thicker than a sheet of paper—continuously layered to its desired strength and reinforced with resin bonding materials.
Ken Sweeney, Advanced Infrastructure Technologies’ President and Chief Engineer, reports that the product can be customized even further when choosing materials based on the bridge project.
“The technique of making the composite is developed in the lab, it’s tested in the lab and we take it to the next step,” Sweeney said. “Because every bridge is a little bit different, we custom-design each bridge.”
Because composites are made up of a combination of two or more materials, the company can choose to use fiber sheets made from carbon or glass and reinforce them with a bonding resin, based on the type of project. The length of the girders can also be customized by using shorter or longer molds.
Additionally, the raw materials used for making the composites are locally produced, while the fiber sheets are developed by other Maine-based companies. The product is also reported to be 50% lighter than steel, corrosion-resistant, cost-effective, have over a 100-year lifespan, is easy to transport—as the products can be stacked on top of one another—and has a reduced carbon footprint.
The technology was developed by the engineering firm (which is a spin-off from the University of Maine’s Advanced Structures and Composites Center) and UMaine, with the product being produced almost entirely in the Bangor area.
Bangor Daily News reports that the “Bridge-in-a-Backpack”— designed from horizontal structures that run under and support paved bridge decks—was originally introduced by UMaine several years ago, but that Advanced Infrastructure Technologies developed the bridge girders even further and began commercializing the product.
According to Sweeney, the composite tub girders can be used for roughly 80% of bridges and bridge projects, while the Bridge-in-a-Backpack technology is only useful in about 10% due to factors varying from span lengths to soil conditions. Although the short- and medium-span inflatable arch bridges have been used in 23 locations, the firm envisions the composite tub girders will play a bigger part in the bridger construction market.
The vision comes as a part of the product’s name, “The 72-Hour Bridge,” because the technology can be crafted so quickly, the company hopes that future bridge replacements, from installing supports to final pavements, can be completed within that timeframe.
What’s Happening Now
Due to the successful testing of the product’s prototype, the Maine Department of Transportation agreed to use the fiber girders on the new Grist Mill Bridge, becoming the first bridge to be constructed using the technology.
Working as a subcontractor, Advanced Infrastructure Technologies is manufacturing five tub girders for the project, each 76 feet long.
“We think this new technology has great promise,” said Joyce Taylor, Chief Engineer at the Maine Department of Transportation.
“Our engineers are excited to use it and sought it out for this project. We are looking for other opportunities to use this technology on upcoming projects, and we’ll be sharing it with other departments of transportation around the nation.”
The total cost for the project is $2.4 million; however, according to the Department’s three-year work plan, $3 million had be budgeted.
Tagged categories: Bridges; Bridges; fiber girder; Girder; Infrastructure; Infrastructure; Program/Project Management; Research and development; Technology
