Recently, Composite Advantage, a premier manufacturer of composite bridge structures, published a case study outlining the use of its FRP products to replace an aging pedestrian walkway in Albany, N.Y.
Last year, when deterioration forced the State of New York Office of General Services (OGS) to close the walkway, the crew determined a need to replace its bridge components and enlarge the sidewalk. The pedway supports daily foot traffic of nearly 700 state employees and links agency offices with parking. The OGS crew considered traditional concrete and lightweight concrete but both options proved too heavy for the vehicle bridge.
An internet search led OGS to Composite Advantage’s FRP FiberSPAN-C cantilever sidewalk system. The composite pathway was the only product that provided pedestrian access without exceeding load capacity. According to Composite Advantage, FiberSPAN–C panels are 80 percent lighter than traditional reinforced concrete panels. And because the cantilevered sidewalk is prefabricated, construction is quicker and installation costs lower. FRP’s corrosion resistance to chemicals and water means zero maintenance for a structure that will last nearly a century.
“The original structure had a concrete sidewalk 4 in. deep,” says Composite Advantage President Scott Reeve. “It took just six years for the sidewalk deck pans to rust and the concrete walkway to deteriorate beyond safe usage. The new FRP design expanded the sidewalk without reducing the rating of bridge members. When OGS approved the use of FRP, we were able to match the original sidewalk depth, yet modernize and expand the structure.”
Uniform live load was 75 psf with mid-span deflection limited to L/400. Wind uplift load was 30 psf. Dead plus live load bending strain was limited to 20 percent to ensure a strength safety factor greater than 5. Thirty-six prefabricated FRP panels were delivered to the work site. The FRP cantilever sidewalk was fastened to supporting longitudinal steel beams with connection clips bolted into steel plates embedded inside FRP panels. Installation took approximately four days.
The FiberSPAN-C walkway was 763 ft. long and 64 ¼ in. wide. Deck thickness was 3 7/8 in. with 1/8 in. wear surface for a total thickness of 4 in. A non-slip polymer aggregrate overlay was applied by Composite Advantage’s factory to enhance pedestrian safety. The FRP sidewalk re-opened in November 2017.