About the research
Glued-laminated wood (glulam) has been used in construction for over 100 years. Its development had originally been encouraged because of the lack of adequate solid timbers. Glulam can be fabricated in many shapes and sizes and has been used significantly since 1942 for building and bridge construction, including both bridge girders and bridge decks.
Glulam, like reinforced concrete, can be reinforced in the tension regions to more effectively use the compressive strength of the wood, which allows lower grade wood to be used. Fiber-reinforced polymers (FRP) have been shown to be effective in reinforcing the tension regions of glulam girders. With falling costs for the FRP material and the development of efficient manufacturing techniques, FRP-reinforced glulam has the potential to be an economically viable bridge alternative.
The bridge application was constructed as a single-span bridge in Delaware County, Iowa. The bridge is owned by the county. The bridge has a span length of 75 ft and a width of 30 ft. The bridge is comprised of FRP-reinforced glulam girders and has a transverse timber deck. The design is based on recommendations and performance data supplied by the manufacturer. The Bridge Engineering Center documented the design, construction, and performance of the bridge. Project features include the following: comparison of design performance parameters with field-measured performance and long-term evaluation of the FRP-to-timber interface integrity.