Last week, during the 2017 International Bridge Conference in National Harbor, Md., the American Composites Manufacturers Association (ACMA) held its 17th consecutive technical workshop at the International Bridge Conference. Through a series of presentations, the workshop showcased advancements in the design and specification of FRP products to build steel-free concrete structures, as well as retrofit and rehabilitate aging bridges.
As engineers at the conference learned, composites offer light weight, corrosion resistance and design flexibility. In retrofit and rehabilitation situations, composites extend the service life of the bridge, are faster to install and require minimal disruption to the structure. Over the past 20 years, these properties have convinced engineers all across North America to build more than 500 bridges with composites.
ACMA staff and volunteers showed a number of examples of successful application of FRP in bridges, including the 186-foot Halls River Bridge in Homosassa, Fla. When it opens, the bridge will likely have more composite elements than any vehicular bridge in the United States. The steel-free design features Hillman Composite Beams, GFRP reinforced bridge deck and bent caps, and carbon strand pre-stressed concrete piles. These elements, according to ACMA, will extend the service life of this bridge.
Another presentation focused on the Nipigon River cable-stayed Bridge in Northwest Ontario. The bridge is the first of its kind in the Ontario highway system and the world’s first cable-stayed bridge with GFRP reinforced concrete (RC) deck slabs. Four hundred and eighty GFRP-RC precast panels were fabricated for the bridge deck.
The workshop also highlighted Columbia River Skywalk’s Old Trail Bridge, based in Trail, British Columbia. Using prefabricated FRP decking from Composite Advantage gave the city a budget-friendly, low maintenance, high-strength pedestrian bridge deck that is now a staple of the region.
To supplement those case studies, ACMA’s Transportation Structures Council also conducted an experiment at its booth. Two pieces of rebar, one steel and one fiberglass, were placed side-by-side in containers of saltwater. After 20 hours in saltwater, the saltwater containing steel turned yellow, showing corrosion, but the solution with fiberglass remained clear.
For more information on the role composites play in infrastructure, visit www.compositesinfrastructure.org.