| Fiber-reinforced polymer tub-girders that are corrosion resistant and designed to last over 100 years with little to no maintenance 


Grist-Mill Bridge, Hampden, ME

  • System for replacement on US Rte. 1
  • 75’ span length
  • 40’-4” out-to-out width
  • Girders designed by Advanced Infrastructure Technologies (AIT)
  • Remaining project designed by T.Y. Lin International 
  • Design and analysis support by UMaine
  • Global buckling during construction 
  • Numerical analysis of shear and impact loading


The GBeam is a fiber-reinforced polymer (FRP) tub-girder that  is corrosion resistant and designed to last more than 100 years with little to no maintenance. GBeams are ¼ the weight of an equivalent steel girder and are a promising, sustainable, low-cost alternative to steel and concrete that is easy to install.

The many benefits of the composite GBeam technology are attracting interest from Departments of Transportation across the U.S. The technology is already slated for use in bridge replacement projects in Washington, California, Florida, and Rhode Island. GBeams are fabricated by AIT Bridges and shipped to destinations nationwide.


  • Patented at the Advanced Structures and Composites Center through their University Transportation Center (UTC)
  • Licensed to AIT Bridges in 2019
  • U.S. Army Corps of Engineers ERDC and US DOT funding 
  • Following rigorous testing to determine their strength and fatigue resistance, GBeams were first deployed in December 2020 for the construction of the Grist Mill Bridge on US Route 1A in Hampden, Maine. 
  • Concept-to-deployment time of five years


Carbon & glass fiber reinforced polymer U-shaped girder 

  • Composite, reinforced concrete deck 
  • High flexural strength-to-weight ratio 
  • Weigh as little as one-quarter of an equivalent steel girder

Designed to replace and build bridge structures up to 120’

  • Easy installation 
  • Corrosion resistant
  • Depth and camber are easily adjusted based on project requirements.

100+ year service life

  • Little to no maintenance needed
  • Lower cost solution and longer service life than steel and concrete

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